Liebler
Basic Member
Posts:334
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| 25 Jan 2012 11:56 AM |
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In planning my "dream house" I have been giving a lot of thought to and researching how to reduce air leakage. The airtight drywall approach + an exterior envelope that's well sealed as well to reduce "wind washing" of the insulation (dense pack cellulose) is what I'm planning. The devil is in the details, here are some thoughts: If I have a basement the basement becomes the bottom of the inner air barrier unless I teat the door to the basement stairway as an exterior door with weather stripping etc. With a weather stripped basement door I still need to assure that the drywall on the interior walls around the stairwell is properly sealed and I'll need to seal all the penetrations of the sub floor as it is the bottom of the airtight shell. On the other hand if I don't weatherstrip & seal the basement I can ignore the sub floor but must instead seal up the basement and assure a good air barrier in the connections between basement walls and the drywall on the inside of exterior walls. This means sill plate gaskets, rim joist gaskets etc. In either case the ceiling is a vital air barrier & penetrations of it must be sealed. A particularly vexing set of penetrations occur at the places my ERV ducts enter or exit the living space. I think I've come up with a plan for the ERV ducts. First I'll use 6 " PVC thin wall irrigation pipe (SDR-81) for these ducts, the necessary fittings appear to be available but I haven't found someone who'll sell them to me, and at each penetration I'll install an EDPM "boot" normally used as a flashing to a plywood piece that'll be right behind the drywall. Has anyone else used these boots? If I use the weatherstripped basement door I'll probably use smaller EDPM boots for all the pluming penetrations of the sub floor.
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Dana1
Senior Member
Posts:6991
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| 25 Jan 2012 03:02 PM |
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The biggest air leak into basements is usually at the band joist and foundation sill, which are best treated by insulating them with 1-2" of closed cell foam right up & over the rigid foam on the foundation wall. Sill gaskets don't really cut it, and unless you caulk the band joist to the sill, and the sill to the subfloor that micro-crack ends up being several square inches of cross sectional hole. But a spray foam seal & insulation should take care of it. (Closed cell is more reliable at air sealing jobs than open cell.)
Dryer vents are worth more air leakage than all the windows & doors you might have in the basement.
Sealing between the basement and first floor is a nightmare of 5 gianormous holes, 50 big holes, 10,000 small ones. It's better to use the exterior walls, as a rule. But air sealing between floors can still reduce stack-effect drives. In particular plumbing & electrical chases where a drain-stacks etc can run from the basement to the attic need treatment, sealed at both bottom and top (and anywhere it might be penetrated in between.)
There's no substitute for blower door verification and rectification if you're hoping to get it under 2ACH/50. Some of the bigger penetrations seem obvious, but may still leak after treatment, and there are myriad less obvious leaks that can still add up to something substantial. |
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Bob I
Veteran Member
Posts:1435
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| 25 Jan 2012 06:44 PM |
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"Sill gaskets don't really cut it" I agree the cheap ones don't.
One of the techniques I used to get my last house under 1.0ACH/50 was EDPM rubber sill gaskets from Conservation Technology.com. I used them at the foundation/PT and at the bottom wall plate/subfloor. Also used EDPM rubber drywall gaskets stapled to the top wall plates. (that or caulking is an Energy Star requirement; I thought caulk would lose the battle with the drywall hangers, so used the gaskets.) I avoid trying to seal the basement from the house; the basement should be within the envelope and well insulated anyway. We also used ZIP wall sheathing and spray foam at the rim joist.
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| Bob Irving<br>RH Irving Homebuilders<br>Certified Passive House Consultant |
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greentree
Advanced Member
Posts:587
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| 25 Jan 2012 07:04 PM |
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Alot of steps for effective air sealing needs to be done during construction which goes against the grain of a schedule so you need someone in charge of it and onsite at all times to complete it.
For example, after floor framing but before sheathing the floor. After tipping some walls but before tipping others. Before wrb is complete. Before trusses are set, after trusses are set, before backers go in and on and on.
Defining the boundary is critical for those who are building the home so it will be apparent when construction work needs to stop and air sealing needs to begin.
If you don't do this you won't accomplish your target infiltration and you'll switch to band-aid mode after the fact which won't be as effective or durable.
If you do build your dream home and DIY your air sealing and plan to buy caulk by the gross, please learn about joint design and installing caulk correctly. Otherwise you may get a good number after the build, but after shrinkage and seasonal movement all your hard work will go by the wayside quickly. |
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ICFHybrid
Veteran Member
Posts:3039
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| 25 Jan 2012 08:41 PM |
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I couldn't agree more with you, greentree. What I have found is that the very same tradesmen who can argue for hours over the finer points of sealing something up, or doing something "green", don't actually do ANY of it.
It's all laid out in detail, instructed, and the materials are supplied, but there are big surprised faces when the work is actually inspected. After surprise comes denial, then anger and then the argument about whether sealing makes any difference or not.
Goodness only knows what happens on spec houses if they can't be bothered to do it on custom builds. |
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Liebler
Basic Member
Posts:334
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| 25 Jan 2012 10:00 PM |
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Thank you all for very help full comments! Philosophically, I believe gaskets are preferable to caulk wherever both could be used. I believe every penetration of or interruption of exterior wall and ceiling needs to be gasket-ed or caulked. Similarly every penetration of the outer sheathing/house-wrap needs to be gasket-ed if possible or caulked. In addition basement/crawlspace wall to sub floor needs to be sealed, this is probably best done with spray foam.
Lots of details to attend to! I like the EDPM gaskets from Conservation Technology and plan on using them around all my windows and doors both on the inner stud wall and the outer.
Dana,
My solution to the dryer vent problem is a condensing dryer (un-vented). The only one available in the US are in washer dryer combos & the largest is by LG.
Bob, did you gasket all the interior, as well as exterior walls at the top plate? How about the stud next to an exterior wall on all interior walls? (I'm trying to estimate how much gasket to buy) How do you seal pluming vents where they go through an interior wall's top plate? I'm thinking this is another place for an EDPM 'boot'. |
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Rosalinda
Basic Member
Posts:353
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| 25 Jan 2012 11:13 PM |
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Dryer vent - this one seems to work well in my house -
Heartland SPV21000789
http://www.amazon.com/HEARTLAND-Heartland-Dryer-Vent-SPV21000789/dp/B004HDXMH4
A few suggestions:
Lots of polyurethane caulk in the exterior sheathing seams, windowpaning wherever sheathing meets framing on the interior, every penetration of the sheathing by nails or screws. Foam all the electrical boxes and where the holes are cut in framing for electrical wires. Stagger joints and taping the exterior foam.
-Rosalinda
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| Sum total of my experience - Designed, GCed and built my own home, hybrid - stick built & modular on FPSF. 2798 ft2 2 story, propane fired condensing HWH DIY designed and installed radiant heat in GF. $71.20/ft2 completely furnished and finished, 5Star plus eStar rated and NAHB Gold certified |
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Bob I
Veteran Member
Posts:1435
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| 26 Jan 2012 07:34 AM |
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"did you gasket all the interior, as well as exterior walls at the top plate"
Yes; that is an energy star requirement.
EDPM boots are the best way to seal the pipes.
I agree with you on the gaskets vs caulk. Caulk lasts until the wood moves; the gaskets will last indefinitely.
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| Bob Irving<br>RH Irving Homebuilders<br>Certified Passive House Consultant |
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Liebler
Basic Member
Posts:334
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| 26 Jan 2012 09:33 AM |
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It seems to me that a gasket on the top plate isn't as important as a gasket on the bottom plate. The top plate to wall corner seam at the top is sealed by the drywall tape etc. The bottom plate to sub floor is, or should be, sealed with a gasket So the bottom of the drywall needs to be either gasket-ed or caulked to the bottom plate of exterior walls. I'd prefer to NOT depend on spray foam as well as caulk. So I have devised the following: After the basement walls are up and ready for the PT sill plates I'll put a strip of "Celotex" asphalt impregnated fiberboard atop the basement walls. Then I'll put a 4 ft wide piece of plastic sheet (say 8 mill polyethylene) a-top the wall with about 2" overlap of the outside piercing the plastic for the sill attach bolts. Next attach the outer sill plate. then fold the sheet so about 2" is inside the basement wall line. Pierce the top layer of plastic with the inner sill plate's attach bolts and attach the inner sill plate proceed with floor framing till the sub floor is on (sub-floor covers inside wall area only). Wrap plastic over rim joist & staple to sub floor, do this on all sides note sides parallel to the joist have sheat-ed stub walls instead of rim joist. Make and "pre-plumb" any necessary penetrations of the rim joist using EDPM boots on the outside of the plastic. Tape the corners of the plastic where rim joist join stub walls. Now build and erect outer exterior walls then inner exterior walls that have a gasket on their bottom plates. After exterior walls are up remove staples from subfloor & staple plastic to the inside of the inner exterior wall & install "drywall gasket" on bottom plates. After all exterior walls are up but before roof trusses are set place another plastic sheet over the tops of both exterior walls stapled to the inner face of the inner wall's top plate and over lapping the exterior sheating by a few inches tape to the exterior sheating. Set trusses & proceed. |
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Dana1
Senior Member
Posts:6991
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| 26 Jan 2012 02:46 PM |
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Posted By Rosalinda on 25 Jan 2012 11:13 PM
Dryer vent - this one seems to work well in my house -
Heartland SPV21000789
http://www.amazon.com/HEARTLAND-Heartland-Dryer-Vent-SPV21000789/dp/B004HDXMH4
A few suggestions:
Lots of polyurethane caulk in the exterior sheathing seams, windowpaning wherever sheathing meets framing on the interior, every penetration of the sheathing by nails or screws. Foam all the electrical boxes and where the holes are cut in framing for electrical wires. Stagger joints and taping the exterior foam.
-Rosalinda
I have a similar version at my house, and yes, it does improve the basement or first-floor infiltration aspects. It may be less effective if your dryer vent is on the second or third floor, but I haven't seen a good solution for that scenario. But by inserting first a relatively tight 90 degree turn followed a uber-short radius 180, it increases the effective duct length by ~15'. They are best used with the shortest & straightest ducting to the dryer as possible, as the additional duct impedance cuts into dryer efficiency, even if the total effective length still meets code. You'd have to be doing a LOT of laundry for the lowered drying efficiency to match or exceed the heating/cooling savings of the lowered infiltration though. |
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Lbear
Veteran Member
Posts:2740
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| 26 Jan 2012 08:02 PM |
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How does one handle the bathroom vents? They are mandatory but once again, they are a source of energy loss.
Having an attic that is not vented, I assume you would have to utilize a SIP or concrete roof? Don't most codes frown on un-vented attics?
What about kitchen exhaust vents? That is another sore spot.
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Liebler
Basic Member
Posts:334
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| 26 Jan 2012 08:51 PM |
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I'm planning to exhaust 50 CFM from each bathroom and 50 CFM from the kitchen through a central ERV and distribute the returning fresh air to the bedrooms, family room, living room & dining room. It's my understanding this is code accepted and eliminates individual bathroom fans. The ERV should recapture 60% to 80% of the energy for about 75 watts of elctricity. My attic will be vented with sofffit vents and ridge vent. The "attic" is above the 20"+ of loose cellulose. I'm still debating with myself whether to use a recirculating range food or provide for a range hood exhaust. Another option is the Panasonic ERV bathroom fan (FV-04VE1). |
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Lbear
Veteran Member
Posts:2740
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| 26 Jan 2012 10:45 PM |
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Posted By Liebler on 26 Jan 2012 08:51 PM
I'm planning to exhaust 50 CFM from each bathroom and 50 CFM from the kitchen through a central ERV and distribute the returning fresh air to the bedrooms, family room, living room & dining room. It's my understanding this is code accepted and eliminates individual bathroom fans. The ERV should recapture 60% to 80% of the energy for about 75 watts of elctricity. My attic will be vented with sofffit vents and ridge vent. The "attic" is above the 20"+ of loose cellulose. I'm still debating with myself whether to use a recirculating range food or provide for a range hood exhaust. Another option is the Panasonic ERV bathroom fan (FV-04VE1).
What about the plumbing vent stacks and vent pipes? Those CANNOT be recirculated into the homes air, not only is that smelly but dangerous. They have to vent outside. |
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ICFHybrid
Veteran Member
Posts:3039
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| 27 Jan 2012 01:27 AM |
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How does one handle the bathroom vents? They are mandatory but once again, they are a source of energy loss. You can integrate the run-time for the bathroom fans into the minimum necessary ventilation for the home. I like those electronic timers that the user can punch to select the amount of run time until they gturn off automatically. You can also go wild and use the Panasonic ERV that Liebler mentioned above for each bathroom if you can't stand losing the heat, or you can use a whole-house HRV that runs 20 min each hour or so with an over ride switch in each bathroom to make sure a user can start the venting when needed. I have a toilet room in each bathroom on the theory that it makes the bathroom usable by two people at the same time. The toilet rooms are vented by plain old-fashioned vent fans on timers. What about the plumbing vent stacks and vent pipes? There is a water trap on those pipes. They exist to allow a small amount of air to enter the drainpipes to equal the water going down the drains. It doesn't represent much volume and the water traps help seal them from free air exchange |
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cmkavala
Veteran Member
Posts:4324
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| 27 Jan 2012 07:46 AM |
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Posted By Lbear on 26 Jan 2012 08:02 PM
How does one handle the bathroom vents? They are mandatory but once again, they are a source of energy loss.
Having an attic that is not vented, I assume you would have to utilize a SIP or concrete roof? Don't most codes frown on un-vented attics?
What about kitchen exhaust vents? That is another sore spot.
Kitchen exhausts can be ventless and in some instances not required at all |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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greentree
Advanced Member
Posts:587
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| 27 Jan 2012 08:53 AM |
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Posted By Liebler on 26 Jan 2012 09:33 AM
It seems to me that a gasket on the top plate isn't as important as a gasket on the bottom plate. The top plate to wall corner seam at the top is sealed by the drywall tape etc. The bottom plate to sub floor is, or should be, sealed with a gasket So the bottom of the drywall needs to be either gasket-ed or caulked to the bottom plate of exterior walls. I'd prefer to NOT depend on spray foam as well as caulk. So I have devised the following: After the basement walls are up and ready for the PT sill plates I'll put a strip of "Celotex" asphalt impregnated fiberboard atop the basement walls. Then I'll put a 4 ft wide piece of plastic sheet (say 8 mill polyethylene) a-top the wall with about 2" overlap of the outside piercing the plastic for the sill attach bolts. Next attach the outer sill plate. then fold the sheet so about 2" is inside the basement wall line. Pierce the top layer of plastic with the inner sill plate's attach bolts and attach the inner sill plate proceed with floor framing till the sub floor is on (sub-floor covers inside wall area only). Wrap plastic over rim joist & staple to sub floor, do this on all sides note sides parallel to the joist have sheat-ed stub walls instead of rim joist. Make and "pre-plumb" any necessary penetrations of the rim joist using EDPM boots on the outside of the plastic. Tape the corners of the plastic where rim joist join stub walls. Now build and erect outer exterior walls then inner exterior walls that have a gasket on their bottom plates. After exterior walls are up remove staples from subfloor & staple plastic to the inside of the inner exterior wall & install "drywall gasket" on bottom plates. After all exterior walls are up but before roof trusses are set place another plastic sheet over the tops of both exterior walls stapled to the inner face of the inner wall's top plate and over lapping the exterior sheating by a few inches tape to the exterior sheating. Set trusses & proceed. When we test houses we usually find lots of air leakage at the upper corner joints behind the drywall. It comes from the wall cavities, not the inside of a room, so your upper gasket is indeed very important. Your poly plan sounds like an old article in JLC from many years ago that a builder from WI was doing? I don't think poly is very reliable to air seal, it does good until puntured and that likelyhood is quite high. |
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Liebler
Basic Member
Posts:334
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| 27 Jan 2012 10:05 AM |
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Yes plumbing vents are required. Their penetrations of the airtight "envelope" are best handled with EDPM 'flashing' boots. Plumbing vents should not, however, contribute to air leakage as they all have water filled traps to stop air under normal pressure differences. On the topic of pluming, exterior faucets, are typically 'frost free' and penetrate the air barriers in the rim joist area. I'm planning to use a pipe within a pipe for these with a piece of 2" pvc as the outer pipe that's "booted" to the air barriers and ends flush on the outside, the actual plumbing will be inside that pipe and the space between filled with spray foam. Regarding the reliability of poly as an air barrier, I don't see an alternative that is self sealing if punctured. Booting the necessary penetrations is a price of air tightness. |
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Dana1
Senior Member
Posts:6991
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| 27 Jan 2012 10:16 AM |
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Poly is a double-edged sword due to it's extremely high vapor retardency. If it CAN be designed out of the assembly, it SHOULD be, especially in areas where masonry meets wood. As greentree correctly points out, it's easily damaged and not the greatest air-barrier, but even when ripped an riddled with holes it's still a powerful vapor barrier, and defines the direction in which the materials MUST dry. It's usually possible to come up with local-climate appropriate stackups that allow reasonable drying rates toward both the exterior and interior, making the assembly much more robust & fault-tolerant. In the 1980s, even into the '90s poly sheeting was often viewed as "the solution" to moisture management but being commonly mis-applied and so susceptible to damage it seems to cause as many moisture problems as it avoids, in the real world.
Using rigid & rugged structural sheathing as the primary air barrier is preferable. Air tight wallboard techniques work in the short & intermediate term, but are still susceptible to a "death of a thousand cuts" over decades of occupancy. Poured concrete/ICF has the best long-term prospects for air tightness, but how it's detailed at the windows/doors and top interfaces with the roof/ceiling makes it or breaks it. |
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Liebler
Basic Member
Posts:334
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| 27 Jan 2012 10:46 AM |
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Dana,
Would a strip of poly under the sill plates atop a concrete block basement be desirable? Then a strip of moisture permeable house wrap, under the inner sill plate wrapped over the band joist, or stub wall, under the bottom plate, gasket-ed, inner exterior wall & over the bottom plate but under the drywall gasket, be better? |
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Dana1
Senior Member
Posts:6991
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| 27 Jan 2012 11:19 AM |
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Putting poly on the top of the masonry as a capillary break separate the masonry from the wood is fine, but it's not a good air-barrier for the crack.
The EPDM sill gaskets recommended by BobI are a much better solution.
Detailing the rigid foam as part of the air barrier system is also good, and can be part of the primary continuous overall air-barrier for the building. (You have to work a lot harder to punch holes through a few inches of foam than through 8 mils of poly, eh? :-) ) |
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jeepster
Basic Member
Posts:153
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| 27 Jan 2012 03:30 PM |
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Posted By Liebler on 26 Jan 2012 08:51 PM
I'm planning to exhaust 50 CFM from each bathroom and 50 CFM from the kitchen through a central ERV and distribute the returning fresh air to the bedrooms, family room, living room & dining room. It's my understanding this is code accepted and eliminates individual bathroom fans.
I would worry about doing this. Bath fan size recommendations are 6-8 air changes per hour. If you figure a 10' x 10' bathroom with 9' walls has 900 cubic feet. Multiply this by 8 ACH and you'd have 7200 cu ft of air you need to remove in an hour. Divide 7200 by 60 to figure out what CFM fan you need and it'd be 120 CFM. This is not a large bathroom, yet it's calling for almost 2.5 times what you are planning on installing. Kitchen fans need to be even larger. You are building such a tight house, how will 50 cfm exhaust the smells and humidity from the bath/kitchen. |
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Liebler
Basic Member
Posts:334
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| 27 Jan 2012 08:00 PM |
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I'm basing it on the recommendations for whole house ventilation, but will 'upsize' the whole house system & operate it on a duty cycle to provide the recommended whole house ventilation. When on continuously I'll have 200 CFM total divided between 3 bathrooms and kitchen. The layout of the house has one bathroom next to the kitchen.
The old ASHRAE ventilation recommendation was 0.33 ACH For my dream house comes out to 113CFM
The newer, current ASHRAE ventilation recommendation is 3CFM/100 SQ ft +7.5 CFM/person comes out to only 99 CFM
So I'm well above either. If things get too bad windows and doors could be pressed into service. |
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jeepster
Basic Member
Posts:153
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| 27 Jan 2012 08:58 PM |
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Correct me if I'm wrong, but aren't the ASHRAE ventilation recommendations for continuous ventilation, not including localized ventilation requirements such as bathrooms and kitchens? I'm building a pretty tight ICF house with an ERV, but I elected to install bath fans in each bathroom. A 210 CFM in the master bath, which is about 10' x 16'; a 80 CFM in a half bath (fart fan), which is only 5' x 5'; and a 110 CFM in each of two bathrooms that are about 8' x 10'. The kitchen fan also vents outside. I know this is going against the premise of having a tight house, but tight houses also hold in moisture. |
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Liebler
Basic Member
Posts:334
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| 27 Jan 2012 10:25 PM |
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Jeepster,
You are correct, the ASHRAE recommendations I mentioned are for continuous ventilation. By running a 200 CFM ERV 1/2 the time I'll get an average of 100 CFM as recomended with the capability to have 200 when needed. I believe these recommendations account for the needed moisture removal.
How are you handling the need or make-up air with all that exhaust fan capacity? |
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cmkavala
Veteran Member
Posts:4324
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| 27 Jan 2012 10:32 PM |
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It is not a code requirement to vent the kitchen |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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jeepster
Basic Member
Posts:153
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| 27 Jan 2012 10:56 PM |
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Posted By cmkavala on 27 Jan 2012 10:32 PM
It is not a code requirement to vent the kitchen
Actually, it is a code requirement, but there is an exception listed: M1503.1 General.
Range hoods shall discharge to the outdoors through a single-wall duct. The duct
serving the hood shall have a smooth interior surface, shall be air tight, shall
be equipped with a back-draft damper, and shall be independent of all other exhaust
systems. Ducts serving range hoods shall not terminate in an attic or crawl space
or areas inside the building.
Exception: Where installed in accordance with the manufacturer’s installation
instructions, and where mechanical or natural ventilation is otherwise provided,
listed and labeled ductless range hoods shall not be required to discharge
to the outdoors.
http://publicecodes.citation.com/icod/irc/2012/icod_irc_2012_15_sec003.htm?bu=IC-P-2012-000002&bu2=IC-P-2012-000019 |
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cmkavala
Veteran Member
Posts:4324
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| 27 Jan 2012 11:11 PM |
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Posted By jeepster on 27 Jan 2012 10:56 PM
Posted By cmkavala on 27 Jan 2012 10:32 PM
It is not a code requirement to vent the kitchen
Actually, it is a code requirement, but there is an exception listed:
M1503.1 General.
Range hoods shall discharge to the outdoors through a single-wall duct. The duct
serving the hood shall have a smooth interior surface, shall be air tight, shall
be equipped with a back-draft damper, and shall be independent of all other exhaust
systems. Ducts serving range hoods shall not terminate in an attic or crawl space
or areas inside the building.
Exception: Where installed in accordance with the manufacturer’s installation
instructions, and where mechanical or natural ventilation is otherwise provided,
listed and labeled ductless range hoods shall not be required to discharge
to the outdoors.
http://publicecodes.citation.com/icod/irc/2012/icod_irc_2012_15_sec003.htm?bu=IC-P-2012-000002&bu2=IC-P-2012-000019
There is no requirement to install a hood. The section of the code you are quoting is the requirements IF the hood is installed, however we have built several homes with no hood at all at the request of the owner. One condition of having no hood is that there cannot be anything combustible (wall cabinet) within 30" of the range top |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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jeepster
Basic Member
Posts:153
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| 27 Jan 2012 11:17 PM |
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Posted By Liebler on 27 Jan 2012 10:25 PM
Jeepster,
You are correct, the ASHRAE recommendations I mentioned are for continuous ventilation. By running a 200 CFM ERV 1/2 the time I'll get an average of 100 CFM as recomended with the capability to have 200 when needed. I believe these recommendations account for the needed moisture removal.
How are you handling the need or make-up air with all that exhaust fan capacity?
Haven't really thought about that yet . . . I'm still trying to figure out if my HVAC guys know what they are doing with the ERV. The duct work is roughed in, but no components are in place yet. They basically have an inlet and outlet in the mechanical room. If they are going to plumb it into the return, I'll be curious to see if they place a damper between the fresh air and room air. I'm going to wait and watch, because this will let me know if they have an any idea to what they are doing. |
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Lbear
Veteran Member
Posts:2740
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| 28 Jan 2012 02:20 AM |
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Posted By cmkavala on 27 Jan 2012 11:11 PM
There is no requirement to install a hood.
The section of the code you are quoting is the requirements IF the hood is installed, however we have built several homes with no hood at all at the request of the owner.
One condition of having no hood is that there cannot be anything combustible (wall cabinet) within 30" of the range top
It would depend on the state/county. I know out here in AZ it is mandatory to have a kitchen hood, especially if you are using a gas stove. How else would you vent the by-products of natural gas? |
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cmkavala
Veteran Member
Posts:4324
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| 28 Jan 2012 07:54 AM |
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Posted By Lbear on 28 Jan 2012 02:20 AM
Posted By cmkavala on 27 Jan 2012 11:11 PM
There is no requirement to install a hood.
The section of the code you are quoting is the requirements IF the hood is installed, however we have built several homes with no hood at all at the request of the owner.
One condition of having no hood is that there cannot be anything combustible (wall cabinet) within 30" of the range top
It would depend on the state/county. I know out here in AZ it is mandatory to have a kitchen hood, especially if you are using a gas stove. How else would you vent the by-products of natural gas?
Lbear;
It is not mantatory to have a gas stove either. Most states including Arizona follow the IRC, please tell me the section of the code that states that a hood is mandatory. |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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Bob I
Veteran Member
Posts:1435
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| 28 Jan 2012 02:04 PM |
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RE: Bath vents & poly
I've built several homes without individual bath vents, using the HRV exhaust instead. I've wondered each time if I would get, as has happened in the past with individual exhaust fans, get a call from the homeowner complaining about how long it took to exhaust the moisture. Hasn't happened. I think it probably relates to the fact that the HRV runs continually. I live in an old home without an HRV so have no direct experience, but so far the HRV route seems to be sufficient in the new tight houses. One of my gripes with bath vents is that they seems to be very difficult to air seal so why fight it?
I haven't gotten into the poly discussion, but not convinced that it is necessary to use it in the many applications you're thinking of. If foundation moisture is a concern, you can paint the top of the footing with Drylock; a product that seals out the moisture & prevents it from getting into the foundation wall. That plus a good waterproofing/damproofing on the exterior, plus, of course good (white PVC, not the black corragated junk) foundation drains in stone should keep the moisture at bay.
Bob I |
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| Bob Irving<br>RH Irving Homebuilders<br>Certified Passive House Consultant |
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Lbear
Veteran Member
Posts:2740
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| 10 Feb 2012 02:02 AM |
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Posted By cmkavala on 28 Jan 2012 07:54 AM
Lbear;
It is not mantatory to have a gas stove either. Most states including Arizona follow the IRC, please tell me the section of the code that states that a hood is mandatory.
So with an electric range one can get by without installing a hood vent? When cooking onions and other such foods, would the ERV work to remove the smell? |
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ICFHybrid
Veteran Member
Posts:3039
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| 10 Feb 2012 09:21 AM |
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When cooking onions and other such foods, would the ERV work to remove the smell? Yes, because the ventilator exhausts the stale air to the outside along with the odor-causing components being carried by it. How else would you vent the by-products of natural gas? The byproducts of natural gas are CO2, H2O and heat, the same as you produce upon exhalation. |
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Lbear
Veteran Member
Posts:2740
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| 10 Feb 2012 03:54 PM |
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Posted By ICFHybrid on 10 Feb 2012 09:21 AM
The byproducts of natural gas are CO2, H2O and heat, the same as you produce upon exhalation.
When natural
gas is burned, as in cooking and heating, the chemicals create nitrogen
dioxide, carbon monoxide, fine particulates, polycyclicaromatic hydrocarbons,
volatile organic compounds (including formaldehyde) as well as other chemicals.
It is NOT as "clean" as the gas industry claims it to be. Natural gas contains methane
(which gives the flame its blue color as it does in propane), which is an asphyxiate.
People with allergies, asthma and other lung issues tend to have MORE problems in a home that uses natural gas/propane for its stove top cooking.
So venting natural gas has more to do than just with moisture issues, the by products of burnt gas are toxic, albeit in small quantities but still toxic.
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ICFHybrid
Veteran Member
Posts:3039
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| 10 Feb 2012 04:30 PM |
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It's arguable as to what the actual risk is from using gas to cook with as opposed to resistance electric. The exotic chemicals "created" are normally present in extremely small amounts compared to the CO2 and the H2O.
The air exchange created by the whole house ventilation strategies are designed to deal with the real issues (the CO2, H2O and objectionable odors) and as a natural result, the ventilation also deals with the lower level contaminants you want to focus on.
The huge, powerful hoods that you find associated with the commercial style gas ranges are rarely used at full capacity. They have to be big, because the potential heat output, the potential smoke and the potential vapor generation from a powerful range require it. In reality, you don't use it that much. Unless you are a consistently bad cook. I have seen it before. |
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Lbear
Veteran Member
Posts:2740
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| 11 Feb 2012 08:55 PM |
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With my home design, the cooking area was the kitchen island, and we were going to go with an electric grill top. The issue we did not resolve was on HOW to vent the that area due to the tall vaulted ceiling. One option was doing an "in-slab" duct work, which I did NOT like. The other was install a really tall vent hood, which was the better option and the cost was around $1K plus install.
I will have to research more but I will lean towards NO kitchen vent hood OR a really tall stainless steel vent hood. The tall stainless hoods in a vaulted ceiling kitchen look really aesthetically pleasing.
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cmkavala
Veteran Member
Posts:4324
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| 12 Feb 2012 07:39 AM |
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Posted By Lbear on 11 Feb 2012 08:55 PM
With my home design, the cooking area was the kitchen island, and we were going to go with an electric grill top. The issue we did not resolve was on HOW to vent the that area due to the tall vaulted ceiling. One option was doing an "in-slab" duct work, which I did NOT like. The other was install a really tall vent hood, which was the better option and the cost was around $1K plus install.
I will have to research more but I will lean towards NO kitchen vent hood OR a really tall stainless steel vent hood. The tall stainless hoods in a vaulted ceiling kitchen look really aesthetically pleasing.
Lbear;
I have installed under slab ducts befor and I never cared for them either. As long as you have 30" clearance to anything combustible, you really are not required to have a hood, However,if it was me, I would probably still install a wall or ceiling exhaust up high just in case I needed to exhaust smoke from cooking |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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ICFHybrid
Veteran Member
Posts:3039
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| 12 Feb 2012 12:10 PM |
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The downdraft vents present an even bigger challenge for "green" homes. Don't they need to be more powerful than the overhead units in order to capture the same amount of heat, smoke and vapors and force them downwards? That means more noise, more power required and even more air exhausted. Every downdraft vent I have seen in operation has been obtrusively noisy.
I don't really look at my hood as a ventilation device. My motivation stems from fire prevention. Have you ever seen a good grease fire? I'm putting up with the hood, and making it 3" bigger than the range surface on all sides because it provides initial containment for a grease flare-up. |
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Lbear
Veteran Member
Posts:2740
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| 12 Feb 2012 12:17 PM |
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Posted By cmkavala on 12 Feb 2012 07:39 AM
Lbear;
I have installed under slab ducts befor and I never cared for them either.
As long as you have 30" clearance to anything combustible, you really are not required to have a hood,
However,if it was me, I would probably still install a wall or ceiling exhaust up high just in case I needed to exhaust smoke from cooking
Would a furred out steel SIP ceiling hold a stainless steel island hood vent suspended from it? It would be a vaulted T&G ceiling as seen here:  |
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cmkavala
Veteran Member
Posts:4324
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| 12 Feb 2012 09:57 PM |
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Would a furred out steel SIP ceiling hold a stainless steel island hood vent suspended from it? It would be a vaulted T&G ceiling as seen here:
It would depend on weight of hood and thickness/span of panels |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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cmkavala
Veteran Member
Posts:4324
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| 12 Feb 2012 10:01 PM |
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we hang entire metal frame / drywalled ceilings from panel skins, if need be, thru bolting works too |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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Lbear
Veteran Member
Posts:2740
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| 13 Feb 2012 02:00 AM |
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Posted By cmkavala on 12 Feb 2012 09:57 PM
It would depend on weight of hood and thickness/span of panels
What are the SIPs rated at for weight/load? I assume a SIP that has been furred can carry the load of 5/8" drywall and a wood T&G ceiling without bowing or failure, correct? |
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cmkavala
Veteran Member
Posts:4324
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| 13 Feb 2012 06:20 AM |
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Posted By Lbear on 13 Feb 2012 02:00 AM
Posted By cmkavala on 12 Feb 2012 09:57 PM
It would depend on weight of hood and thickness/span of panels
What are the SIPs rated at for weight/load?
I assume a SIP that has been furred can carry the load of 5/8" drywall and a wood T&G ceiling without bowing or failure, correct?
Lbear;
again thickness and span will dictate allowable loads.............
Send us your plans and we will engineer a workable solution...
concentrated load needs to be dealt with differently than the overal spread out roof/ceiling loads. Does the hood weigh 500 lbs or 2,000 lbs.? where is the hood loacted? in the middle span? near the ridge? Near a bearing wall?  |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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Lbear
Veteran Member
Posts:2740
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| 13 Feb 2012 03:50 PM |
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Posted By cmkavala on 13 Feb 2012 06:20 AM
Lbear;
again thickness and span will dictate allowable loads.............
Send us your plans and we will engineer a workable solution...
concentrated load needs to be dealt with differently than the overal spread out roof/ceiling loads.
Does the hood weigh 500 lbs or 2,000 lbs.? where is the hood loacted? in the middle span?
near the ridge?
Near a bearing wall?
We are looking at around 130 - 150 LBS As of now, I don't know the exact location of the hood but once the plans get more finalized, I will have that info. When they furr down a SIP ceiling and install drywall, how do they install the furring pieces into the SIP? Is it just with a screw and how far does it go into the SIP itself? Looking back at the specifications, that vent hood can actually be converted to a DUCTLESS system, but I wonder how efficient that would be. They utilize charcoal filters and then return that air back into the home. |
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cmkavala
Veteran Member
Posts:4324
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| 13 Feb 2012 05:54 PM |
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Lbear;
unless its just the angle of the photo, the hood in the picture looks more massive than 130-150, but if thats all it is , there is no problem 150# is the weight of a small man, no engineering needed.,Just some additional stitch screws in furring |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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Lbear
Veteran Member
Posts:2740
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| 13 Feb 2012 07:17 PM |
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Posted By cmkavala on 13 Feb 2012 05:54 PM
Lbear;
unless its just the angle of the photo, the hood in the picture looks more massive than 130-150, but if thats all it is , there is no problem 150# is the weight of a small man, no engineering needed.,Just some additional stitch screws in furring
The weight of those vent hoods is basically all in the base of the fan/motor assembly. The ducts are just hollow, while a longer duct will weigh more than a shorter duct, it is just hollow sheet metal. Do you have any pics of a SIP ceiling that was furred? I would be curious to see how they furred the ceiling. |
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cmkavala
Veteran Member
Posts:4324
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| 13 Feb 2012 08:40 PM |
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http://www.myspace.com/steelsips/photos/15587200#%7B%22ImageId%22%3A15587200%7D |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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Roberth
New Member
Posts:97
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| 14 Feb 2012 01:17 AM |
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I would avoid poly except in extreme heating climates. Punctures let moisture in the wrong spots and trap it. I believe in redunancy for air barriers. Whereever you have an opportuinty use and air barrier. Gaskets are better than caulks, expanding foam etc.
IF you have a basement then I would assume that you have HVAC in the basement. IF that is the case the basement should be inside the thermal and air barriers. With your talk about isolating the basement I am concerned that you are not planning subslab insualtion and basement wall insualtion. You need to start at the subslab. Insulate under the slab R10 rigid. Poly can be placed over the rigid insulation and act as moisture barrier for subslab moisture.
Spray foam should be used to seal the band joist/sill plate overlapping the foundation and the floor sheating.
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Lbear
Veteran Member
Posts:2740
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| 14 Feb 2012 02:33 AM |
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Posted By Roberth on 14 Feb 2012 01:17 AM
I would avoid poly except in extreme heating climates. Punctures let moisture in the wrong spots and trap it. I believe in redunancy for air barriers. Whereever you have an opportuinty use and air barrier. Gaskets are better than caulks, expanding foam etc.
Do you mean "avoid" polystyrene that are in a Steel SIP? Who are you referring/talking to? |
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cmkavala
Veteran Member
Posts:4324
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| 18 Feb 2012 07:10 AM |
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polyethylene |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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BadgerBoilerMN
Veteran Member
Posts:2010
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| 18 Feb 2012 02:05 PM |
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The poly always goes against the ground - from which the moisture originates in a basement. If you foam the basement you have a barrier. If you glass the basement, the wall should be poly and the glass open to the room. |
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| MA<br>www.badgerboilerservice.com |
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BadgerBoilerMN
Veteran Member
Posts:2010
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| 18 Feb 2012 02:05 PM |
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The poly always goes against the ground - from which the moisture originates in a basement. If you foam the basement you have a barrier. If you glass the basement, the wall should be poly and the glass open to the room. |
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| MA<br>www.badgerboilerservice.com |
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Alton
Veteran Member
Posts:2157
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| 18 Feb 2012 07:52 PM |
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I use the following sequence for a basement slab:
Earth sloped to drain to daylight,
6" minimum of clean tamped gravel,
2" Polystyrene,
Waterproofing membrane,
concrete slab.
Building scientist that I follow say that the waterproofing membrane should go directly under the slab and not under the polystyrene. Your local code official can advise you as to what he will accept. |
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Residential Designer &
Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979 |
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Lbear
Veteran Member
Posts:2740
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| 18 Feb 2012 07:59 PM |
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Posted By cmkavala on 18 Feb 2012 07:10 AM
polyethylene
What is the Steel SIP made out of? |
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cmkavala
Veteran Member
Posts:4324
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| 18 Feb 2012 09:14 PM |
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Posted By Lbear on 18 Feb 2012 07:59 PM
Posted By cmkavala on 18 Feb 2012 07:10 AM
polyethylene
What is the Steel SIP made out of?
Lbear;
we'r talking apples & oranges,
Poly is ployethylene, is visqueen, is plastic sheeting, like zip lock sandwich bags/or a plastic vapor barrier under a slab
SIPs core (steel or otherwise) is EPS = Expanded Poly Styrene, is styrofoam |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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Lbear
Veteran Member
Posts:2740
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| 18 Feb 2012 10:20 PM |
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Posted By cmkavala on 18 Feb 2012 09:14 PM
Lbear;
we'r talking apples & oranges,
Poly is ployethylene, is visqueen, is plastic sheeting, like zip lock sandwich bags/or a plastic vapor barrier under a slab
SIPs core (steel or otherwise) is EPS = Expanded Poly Styrene, is styrofoam
Understood. In regards to steel SIPS and their seismic resistance. Engineers refer to a "continuous load path" when it comes to seismic resistance.
What makes them so good/strong when it comes to seismic loads? In a roof application with ICF walls and a Steel SIP roof, the lateral shear loads will put side to side loads on the home. How does a steel SIP resist that load when an ICF wall is trying to pull and push on a SIP roof? |
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BabyBldr
Basic Member
Posts:123
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| 20 Feb 2012 12:23 PM |
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Posted By Liebler on 25 Jan 2012 11:56 AM
In planning my "dream house" I have been giving a lot of thought to and researching how to reduce air leakage. The airtight drywall approach + an exterior envelope that's well sealed as well to reduce "wind washing" of the insulation (dense pack cellulose) is what I'm planning. The devil is in the details...
Liebler, I'm rather late responding to your original post, but here it is FWIW. I'm in the process of building our home and have become quite passionate about air sealing and insulation. Others on-site might assign another description to my attentions to this issue. ;-) Some of the products/techniques used on our build were a good quality sill gasket, taped zip sheeting, casement or awning windows (instead of DH), bulk quantities of high quality smoke/acoustical sealant with a pump sprayer, high quality air sealing tapes, air tight electrical boxes, and metal duct work (ventilator) with 2 coats of mastic. My limited experience (owner builder) has been that some of the air sealing got done by subs at the correct stage (i.e. during framing) and a lot of it I'm doing (some of it at the right time and some as 'catch up' after the fact). In some ways building your own house (we're doing electrical, plumbing & HVAC ourselves) is frustratingly slow ... but in other ways I welcome the slower pace of my labor and my husband PT on long weekends because it gives me the calander time to work on airsealing while my husband is at work during the week. Some of the efforts are a learn as you go, and require research, testing, and sometimes redoing. My labor is cheap, many of the materials are not really that much in the scheme of the overall project - but the time is takes is a lot (at least DIY). The Jan 2012 issue of The Journal of Light Construction (JLC) has a very good article on air sealing tips by a contractor who does this work on a daily basis. I highly recommend it as background reading. Good luck with your "dream house". |
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