ARdolson
Registered Users
Posts:10
 |
| 04/09/2008 3:17 AM |
|
I am ready to finalize my houseplans. Would like to have this forum scrutinize and provide feedback on my plans, and offer suggestions to my questions. I will contract out most work, do some myself (elec, cabinets, run some PEX, central vac, etc.) Attempting to minimize construction cost while making home as efficient as possible. Low dollars per efficiency unit. There will only be me and my wife living in the home.
Summary:
West Central Arkansas (Russellville). South facing, 1.65 acre hillside lot overlooking lake. Rocky ground. ~ 3000 sq ft house. Main level on top - walk out 1/2 basement on slab. Mechanical equipment in unfinished portion of basement.
ICF below grade including safe room.
Stick built above grade probably using Mooney wall technique to reduce thermal bridging.
[Mooney Wall - 2x4 stud walls (16" oc) with perpendicular (horizontal) 2x2s (16" oc) for thermal break.]
Considered SIPs but with diesel costs so high and construction activity down may be able to get stick/foam built for less.
Either wet, dense packed cellulose -or- spray foam insulation. Spray foam is better but more expensive. When I get estimates, I may use the extra $ to put toward a geothermal unit. I haven't seen much info on this forum about dense cellulose. Sprayed on wet w/ glue is supposed to be better than it used to be - reduced or eliminated settling. Any informed opinions on this?
Probably geothermal HVAC using desuperheater to heat water stored in Marathon water heater. Geothermal is higher but more efficient plus can provide water heating. The other side of the debate is with superinsulated shell, a high efficiency heat pump may be adequate and much cheaper - but no free water heat.
Engineered floor joists w/ HVAC ducts in conditioned space.
Fireplace (inefficent) for aestetic value and power outages. Will not be on external wall. The other option is using the money on and emergency generator.
PEX plumbing.
Thinking about unvented attic (closed cell XPS under roof decking). Would like to use roofing system that includes air gap either under decking or above. If under, can cover with spray foam but would need sofit and ridge vents.
Elec floor heating in some areas - master bath, kitchen, maybe pathways - strictly for confort.
Fairly large south facing low e windows to take advantage of the view and the solar heat gain. I need to know a good percentage range for window area.
Any and all help would be appreciated.
Thanks,
Don Olson
|
|
|
|
|
|
|
ARdolson
Registered Users
Posts:10
|
| 04/09/2008 4:50 AM |
|
Forgot to mention we will have a Heat Recovery Ventilator (HRV). Should it exhaust into the 'conditioned' attic?
Don O |
|
|
|
|
wes
Registered Users
Posts:289
|
| 04/09/2008 7:45 AM |
|
ICFs--yes.
framed wall in lieu of SIPS--I'd have to think about that.
Defiantly us spray foam instead of cellulose--if you frame the walls
If your site is plate rock, I would reconsider the geothermal system (cost of drilling wells in rock), check out some of the super high eff. (SEER 16.0 +) air to air units.
Defiantly unvented, insulated attic with spray foam on underside of roof decking.
Everything else looks good.
|
|
Wes Shelby
Design Systems Group
Murray KY
wandr@ainweb.net |
|
|
buyerres
Registered Users
Posts:5
|
| 04/09/2008 9:24 AM |
|
Don: Don't give up on ICF construction. If you use ICF's you will probably be able to say cost in 1) insulation, and 2) less HVAC tonage, overall lower utility bill. One needs to look at total cost at time of building and future. Also, consider using Radiant Barrier on the roof.
DMB |
|
|
|
|
gregj
Registered Users
Posts:105
|
| 04/10/2008 1:01 PM |
|
| In Arkansas an ERV may be more suitable than an HRV. Exhaust either one outside. If you can, use the lake for your geothermal. A generator makes more sense than a fireplace but I like the fireplace. If you go geo then use hydronic heat instead of electric where you wanted radiant floor heat. When in doubt spend the money on improving insulation. |
|
|
|
|
cmkavala
Registered Users
Posts:578
|
| 04/10/2008 2:20 PM |
|
Posted By ARdolson on 04/09/2008 4:50 AM
Forgot to mention we will have a Heat Recovery Ventilator (HRV). Should it exhaust into the 'conditioned' attic?
Don O Never exhaust back into conditioned space
|
|
Chris Kavala
chris@southernsips.com
1-877-321-SIPS |
|
|
ARdolson
Registered Users
Posts:10
|
| 04/10/2008 5:28 PM |
|
Thanks for all the help so far.
Will be using radiant barrier on roof system.
Didn't know there was a distinction between HRV and ERV - ERV sounds right.
Will exhaust outside. I just thought it would keep the attic cooler, but I guess you don't want to exhaust 'bad' air into the house - even if its the attic.
Still wondering how close dense pack cellulose gets to spray foam. I guess it depends on the price difference. I've heard 'save the money and put it toward a geothermal unit'.
Also, I've seen a percentage number associated with proper amount of sq ft of window area. What is it a percentage of - floor area or total wall area? |
|
|
|
|
cmkavala
Registered Users
Posts:578
|
| 04/10/2008 5:39 PM |
|
Posted By ARdolson on 04/10/2008 5:28 PM
Thanks for all the help so far.
Will be using radiant barrier on roof system.
Didn't know there was a distinction between HRV and ERV - ERV sounds right.
Will exhaust outside. I just thought it would keep the attic cooler, but I guess you don't want to exhaust 'bad' air into the house - even if its the attic.
Still wondering how close dense pack cellulose gets to spray foam. I guess it depends on the price difference. I've heard 'save the money and put it toward a geothermal unit'.
Also, I've seen a percentage number associated with proper amount of sq ft of window area. What is it a percentage of - floor area or total wall area? AR;
Technically if it is condtioned space it is no longer and attic and should be unvented
, ERV or HRV need to exhaust to the outside
|
|
Chris Kavala
chris@southernsips.com
1-877-321-SIPS |
|
|
bobgieser
Registered Users
Posts:32
|
| 04/22/2008 7:35 PM |
|
I used ICG from the footer all the way to the roof truss. Certainteeds Form-a-Drain for forming the footer and draining ther water and radon gas. Fab form Bag in the footer to keep moisture/not temp. out of the wall systrem.
WaterFurnace Geothermal preheats the water in my Marathon only in winter and summer when either heat or cooling is running. Preheats only, it does not fully heat. Every little bit helps. You can buy an option to deat all year round, price it vs electric/gas rate in your local area. i
I used Wirsbo Pex in the basement floor as well as whole house plumbing. One of the better things I have done after the ICF.
I have view windows tripple glazing, on s/sw facing fixed windows.
EPS closed or open cell attic spray was three X the price of blown in cellulose. Check out the difference in your area. |
|
Bob Gieser
Sales and Technical Support
Holdfast Technologies
Master Distributor for Nudura ICFs
(916) 214-4398-cell |
|
|
Mark Fleming
Registered Users
Posts:162
|
| 04/24/2008 12:23 PM |
|
I used a DIY spray foam (tigerfoam) with fiberglass insulation in the walls. One inch of foam stops all air leaks and eliminates any chance of a condensation point. Then, you can get the FULL benefit of whatever less expensive insulation material you add. I don't care what the "official" R value is, I just know that I heated my 550 square foot shop this winter with a 1,500 watt floor heater. I needed a second heater when it was below freezing.
A traditional fireplace is a waste. Get an insert that's actually an airtight stove. Take the extra time to connect it to any heating/cooling duct work. When the house is super-insulated, you'll be amazed at how much you can heat with a cord of wood. Be sure to put an ERV exhaust intake near the stove to exhaust any smoke that gets out of the stove, plus, to distribute the heat. Sure, it will send your 100 degree hot air right out through the ERV, but the incoming fresh air will likely still be 80 degrees and distributed around the house. When diesel is $11 a gallon two years from now, you'll be glad you can burn tree trimmings and scraps from the woodshop instead of using a noisey generator.
I did the research on an unvented attic with an air space under the roofing material. I decided to use EPS foam between the trusses and then sprayed with foam to hold it in place and seal everything. I didn't use an air space under the roofing; just sheathing, roofing felt, and asphault shingles. There were an equal number of people pro and con on the air space issue, but in my mind the logic favored the con. Pro had tradition, old technology, but no facts on its side.
Window percentage range may be governed by your state's energy code.
Mark |
|
|
|
|
ARdolson
Registered Users
Posts:10
|
| 04/24/2008 10:49 PM |
|
Bob,
Thanks, I needed the info on the footings. I'm not sure what "Fab form Bag in the footer to keep moisture/not temp. out of the wall systrem." means. I will compare prices between cellulose and foam.
Mark,
I like the idea of sealing with thin layer of foam and then adding less expensive insulation. I'll price it that way and check. How did you address the thermal bridging issue? Good idea putting the ERV suction near the wood stove (not fireplace).
Thanks,
Don |
|
|
|
|
Mark Fleming
Registered Users
Posts:162
|
| 04/25/2008 12:11 PM |
|
The thermal bridging of the studs? I don't think most construction addresses this, other than offset double studs. Adding foam as your first inch or two increases the R value so that you can live with the low value of the studs (R1 per inch). I tried to put in 1 inch of foam, but it usually ended up averaging 2 inches. That's okay because then cheap glass insulation for 2x4 construction (R13) fits perfect. That makes a total R value of R25-27 as opposed to R19 glass only for 2x6 construction.
Probably as important is the seal the foam provides. Stuffing glass into the stud bays looks like it seals, assuming your stud spacing is perfect, your studs are perfectly straight, your glass mat is perfectly straight, you don't have any electrical, you never have moisture in the wall, etc., etc. The weakest insulation point for glass is probably right next to the stud, which is also where air movement is most likely and where R value is lowest.
It wouldn't surprise me to find out that 1/2 inch of spray foam and an R13 fiberglass batt (total R 16) would outperform straight R19 fiberglass in every situation. Achieving the claimed R value of glass is dependent on there being no air movement or vapor transfer, neither of which glass provides. Foam allows glass to perform as claimed.
Mark
|
|
|
|
|
Jelly
Registered Users
Posts:189
|
| 05/07/2008 8:44 AM |
|
Posted By Mark Fleming on 04/24/2008 12:23 PM
I used a DIY spray foam (tigerfoam)...
I did the research on an unvented attic with an air space under the roofing material. I decided to use EPS foam between the trusses and then sprayed with foam to hold it in place and seal everything...
Mark, could you elaborate a little bit - you used tigerfoam for the roof as well as the walls? So on the roof, you attached EPS foam boards to the bottom side of the sheathing, and then sprayed tiger foam over that thick enough to cover the trusses? Did you find this more economical than just spraying all the way to the sheathing?
How was the tigerfoam to work with? Was it truly DIY friendly?
|
|
|
|
|
Mark Fleming
Registered Users
Posts:162
|
| 05/07/2008 9:33 PM |
|
The walls had an inch of foam (more like two) and then glass for 2x4 construction (R13). The gables were all foam, as they were trusses and didn't have any depth. I started to foam the roof (under the sheathing), but it took lots of time and foam. The foam goes on about 1/4 inch and that expands to one inch and stiffens if a few minutes. Then, you can go over it again with another inch. I opted to buy styrofoam panels and cut them to fit between the 24"oc trusses. The insulation dept. of a big hardware store will have pieces of wire cut to length to hold fiberglass insulation against a roof betrween the trusses. I used these to hold the styro panels in place. Then, I shot a layer of foam, but when I went back over with the second inch, I pulled the wires (they bow down). Perfect completely sealed roof.
My permit was for "unheated storage" above a garage. Right. The inspector saw the amount of insulation I was putting in and was only interested in knowing about foam. I'm living there now while I build the house. My experience is that the foam is way for efficient than glass, forget about the R value. I don't have rafters or ceiling studs conducting heat out of the building and it doesn't matter how windy it gets.
Foam is messy stuff. The walls weren't too bad. The problem is that some nozzles just don't spray cleanly. You should get plenty of nozzles with the kit, so change them out if one doesn't work right. Get a Tyvek painters suit, wear clothes that you can throw away. Mask and goggles. Even still, I ruined a pair of glasses, until just the other day I found the miracle fix.
Moderate Mark |
|
|
|
|
Jelly
Registered Users
Posts:189
|
| 05/08/2008 2:59 AM |
|
Mark, thanks for the details. So the only thing holding up the styrofoam panels is the spray foam? Is there a reason why you pulled the wires out? And will you have to sheetrock over the foam for fire protection?
What's the miracle fix - the goggles?
Lots of questions I know but I'm trying to figure out if I can really pull this off myself! I thought about your approach - building a garage and living in it while I finished the house. But the budget makes it look like I may have to do away with the garage altogether at least for a few years. What part of the world are you in? |
|
|
|
|
Mark Fleming
Registered Users
Posts:162
|
| 05/08/2008 12:13 PM |
|
Foam is the only thing holding the styro panels in. Although it's conditioned space in the attic, it's not exposed to the living area and doesn't need drywall. In fact, my entire space above the garage is permitted as "unheated storage" and doesn't "require" any drywall. I have scissor trusses, so the drywall is below the foam with no living area directly exposed to the foam. There is a nice conditioned storage area over the part that doesn't have scissor trusses (essentially, the kitchen and bath area).
I pulled the wires for a couple of reasons. First, they weren't needed after the first coat of foam and made spraying a nice even second shot more difficult. Second, it looked better. Third, I didn't want the inspector to know that part of the insulation was styrofoam (which has a lower R value). In theory, if I applied later for an occupancy permit, I would fail because of insufficient insulation. With 2x4 trusses, there's not much space to fill and I didn't want to actually put on the thickness to meet code for occupied living space. My roof is only about R25 even though it looks to be more and, more importantly, performs to be more. But performance isn't what a building inspector inspects for; they're only interested in a thickness/R value calculation, regardless of actual performance. Without the wires, it's very difficult to tell that it doesn't meet code thickness.
One more benefit of foam. It stiffens up the structure. You don't get any code credit for it adding to the shear performance of walls and truss roofs, but it performs like having hurricane straps everywhere. There's nothing to worry about with "only foam" holding the styro panels in. We slept through a big wind storm with trees falling over, and didn't hear a thing or have the building creak and moan (the neighbors moved to their basement to sleep). I hate to think how difficult it would be to demolish a foamed structure.
The secret fix for getting foam overspray off of glasses is bronze wool. I was using it to remove lacquer off of a brass saxophone without scratching the underlying brass. I thought of my two pairs of glasses that I ruined when foaming, and sure enough, it took off the foam without further scratching the glasses. Now, I've got extra glasses everywhere.
Foam's not cheap. I'd use it even more sparingly in the future, but I'd still use it. For a bigger project, I'd hire it out. I did a ballpark calculation and figured it would cost three times as much for me to foam my project as against just fiberglass insulation. By using a combination of the two, it can be brought down to twice as much or maybe slightly less. You have to need, want, and understand the benefits in order to pay twice as much. Even though foam is kind of a pain to deal with, it's still better than putting in fiberglass. Unfortunately, it seems that both are necessary for the best cost/benefit insulation system.
Here's a picture of my attic access. I found a whole bunch of icebox hardware on Ebay, so that's what my cabinets, closets, etc. have on them. The arch is foam. With the scissor truss ceiling and arched passages, what would have been a box-like storage area really feel nice.
Moderate Mark |
|
|
|
|
Mark Fleming
Registered Users
Posts:162
|
| 05/08/2008 12:28 PM |
|
Forgot. I'm in the Seattle area. The reason that there is sunlight on the walls in the picture is because we have a southern exposure on Puget Sound. That's light reflecting off of the water. Interesting rippling reflections. The vent by the attic access door is part of the HRV system that exchanges the air several times a day, really important for a tight structure. It even exchanges air in the garage below to remove gasoline vapors, humidity from the concrete slab, etc.
Not your ordinary unheated storage space. I actually had the upper floor listed on the permit application as a "studio" as in art studio (painting and ceramics, so lots of noxious fumes, smoke, etc., hence the HRV). The county didn't like the word studio and made me change it before issuing the permit. But they didn't make me change the plans. What? Okay. Strange.
Moderate Mark |
|
|
|
|
DallasBill
Registered Users
Posts:119
|
| 05/08/2008 5:00 PM |
|
| Very cool, Mark! |
|
|
|
|
Jelly
Registered Users
Posts:189
|
| 05/09/2008 5:18 AM |
|
| Mark Fleming, I'm sending you a private message - let me know here if you don't receive it. |
|
|
|
|
teslastones
Registered Users
Posts:28
|
| 05/09/2008 10:20 AM |
|
Adding foam as your first inch or two increases the R value so that you can live with the low value of the studs (R1 per inch). I tried to put in 1 inch of foam, but it usually ended up averaging 2 inches. That's okay because then cheap glass insulation for 2x4 construction (R13) fits perfect. That makes a total R value of R25-27 as opposed to R19 glass only for 2x6 construction.
Mark,
I respectfully disagree with your statement above. I would submit that glass is a great conductor of heat energy. Why spun glass fiber can have resistance to heat energy transfer is if it is fluffed up and thus has trapped air pockets. When you put in two inches of foam into a 3 1/2" space you have 1 1/2" left. When you compress 3 1/2" of fibergalss into a 1 1/2" space you have much less than half of it's stated "R" value due to the lack of trapped air pockets. |
|
|
|
|