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lambabbey
Registered Users
Posts:71
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| 03/20/2008 9:15 PM |
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Posted By pcoughlin on 03/20/2008 5:19 PM
I have quite a few sips roof jobs under my belt (including a 3800 sq ft 12/12 house). In my honest opinion if your doing 'open-beam' construction and a fairly simple roof, the bang for the buck factor that you get with the sips roof is hard to pass up. With a competent crew your roof can be up in a few days, it is already insulated, ready for roofing, ready for interior finishes and ready for exterior trim. Just my .02.
I think that the roofing system that you are piecing together will work quite well, I am curious what the difference in price per sq. ft would be in terms of materials and labor with comparing it to sips. - Pete
[/quote]
Pete:
SIPs would have been the obvious way to go. And it was my original intention. But my goal here is to take what would be a good, solid, quick-to-install roof and make a killer one instead---and that includes the soundproofing. SIPs would give me around an STC of 22. The alternative roofing system should knock that up to an STC of 75 to 80. The space directly below this roof will be a library of sorts and on occasion a guest bedroom and I want the STC of the ceiling here to be even better than the ICF walls comprising the rest of the house.
Would the SIPs be cheaper? Of course. Would they go up faster? No question. But I'm looking at pushing the envelope here with this roof and seeing just HOW good of a roof I can make it without it getting absurd from a cost or labor standpoint. And I believe this new configuration has many components to it that have far surpassed SIPs, hands down.
Will it be worth the extra time and money? Have I crossed that line of diminishing returns? One, I could only justify going this route if I look at it from the perspective of a longterm investment in sustainability. Two, I'm still awaiting all the quotes. . .
John
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John A Gasbarre
Lamb Abbey Orchards
PO Box 623
Union, ME 04863
E-mail: orchard@lambabbey.com |
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pcoughlin
Registered Users
Posts:76
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| 03/20/2008 11:56 PM |
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| Cool. Keep us updated on how this pencils out. - Pete |
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glennp
Registered Users
Posts:5
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| 03/23/2008 6:16 PM |
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| I don't get the unvented attic thing I live in south dakota where the temp varies from -40 to 110 deg ferin the only thing i can think of is the spray foam guys found a place to spray more foam |
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lambabbey
Registered Users
Posts:71
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| 03/23/2008 6:43 PM |
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I've got an HRV going into the house that will keep the place properly ventilated, regardless of time of year or weather conditions. I'm making the attic level of this house air-tight because I'm using the space as an additional finished floor in the house.
John |
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John A Gasbarre
Lamb Abbey Orchards
PO Box 623
Union, ME 04863
E-mail: orchard@lambabbey.com |
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dmaceld
Registered Users
Posts:494
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| 03/23/2008 8:54 PM |
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Posted By glennp on 03/23/2008 6:16 PM
I don't get the unvented attic thing I live in south dakota where the temp varies from -40 to 110 deg ferin the only thing i can think of is the spray foam guys found a place to spray more foam Sealing the underside of the roof and the gable walls has the following benefits.
Penetrations through the ceiling, such can lights and electrical wire holes through the top plates of walls, don't need to be sealed and insulated.
Radiant heat during the summer from the roof to the ceiling is eliminated. Fiberglass doesn't do much to stop the radiant heat.
Both fiberglass and cellulose allow heat to be lost from the ceiling due to air currents circulating through the insulation. You can't seal the upper side of ceiling insulation to prevent this circulation because of vapor condensation in the winter.
If you have heat/cool ducts in the attic with a sealed & insulated attic space you don't lose heat/cool to the outside through duct leaks. Also, the ducts won't get heated or cooled by the ambiant air thus cutting duct heat/cool losses.
It's easier to use the attic for storage because you don't need to be concerned about tromping down 10" to 15" of fiberglass or cellulose insulation.
If you want to seal every penetration through the ceiling, don't run ducting through the attic or otherwise are willing to seal it tight and insulate the h*** out of it, plan to never use the attic for storage or whatever, are willing to use a radiant barrier roof sheathing or a radiant barrier under the roof, then a foot or two of cellulose will give you a well insulated ceiling system. But you will have to assure good venting which often means not getting a good layer of insulation at the wall/roof interface in order to leave an adequate air gap from eave to attic.
For myself, I concluded it was easier, and not much more expensive, to get a tightly sealed and insulated house envelope by foaming the underside of the roof.
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Building house - what a way to spend retirement! |
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TerryJ
Registered Users
Posts:14
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| 03/26/2008 6:28 PM |
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| John: Have you looked at tiltup construction (concrete-EPS-concrete). You get thermal mass on inside, up to a true R41 (10 in EPS) and quick construction. Panels can be made either on or off site and quickly installed with a crane. LINK |
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br8080
Registered Users
Posts:1
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| 04/02/2008 4:02 PM |
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great thread!!
although this product isn't an ICF, it may be worth considering for the exterior walls...it's called Apex block ... here's the website and info about it's properties.
http://www.apexblock.com/index.cfm?fuseaction=Home.Product§ion=product
i've not personally used this product, but a very skilled green thinking builder friend has used it and highly recommends it over ICF construction.
bruce |
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Dayton2
Registered Users
Posts:7
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| 04/02/2008 4:25 PM |
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| Interesting thread, does anyone know what the combustion products are for different types of spray foam. Does burning the foam produce gases that are highly toxic in comparison to say wood/ EPS combustion products ( i.e other than CO and CO2...) |
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Bill Simons
Registered Users
Posts:4
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| 04/03/2008 12:02 AM |
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I would also encouage you to think not only of the walls but of the entire system. The walls, the ceiling and the floor, the windows, and especially a properly sized Ground Loop heating system. Insulate the entire envelope and think of the entire package. Strengths are great but where is the weakest link?
Double studding the wall, or using a stagger might work and will give you great savings over a conventional wall but unless you are a good framer and own your own foam gun the high prices to constuct your wall system may take away from having great windows also, or prohibit you form insulating your floor for a total thermal break. Your time is also valuable, especially if you need a constuction loan racking up interest payments.
ICF's will provide you with a proven, very well insulated system that does not have to be invented as you go. Many mistakes and miscues have been made and corrected over time. So being your own guinea pig might not be the most intelligent & effective option. ICFs have been around for a long, long time and also and will not exhibit some of the moisture problems wood are prone to.
You sound like a smart guy... the devils advocate. Best of luck.
Bill |
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Bill Simons
Registered Users
Posts:4
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| 04/03/2008 12:07 AM |
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I do not know what products are produced from the spray foams but I do know this. By the time they burn the stink from your burning carpet, chair, mattress, curtains, carpet or any other number of extremely toxic household items will have already killed you. So I guess you wouldn't really care unless you were the fireman now would ya?
Bill |
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cmkavala
Registered Users
Posts:818
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| 04/03/2008 10:34 AM |
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Bill;
I agree with you on the various houshold toxins kiling you first in a fire, my only concern with insulations are... do they produce any off-gassing after installed? |
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Chris Kavala
chris@southernsips.com
1-877-321-SIPS |
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Dayton2
Registered Users
Posts:7
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| 04/03/2008 4:01 PM |
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In general yes, lot's of poisonous combustion products from everyday furnishings. So to be completely 100% safe, I've decided to furnish my house only with sand and sand byproducts (sandstone furniture, beach sand carpet...and when there are no crawdads, you can eat sand). Doesn't burn, and hey, cleanup is a breeze, since you can't tell when it is dirty. And it's totally natural, though since it is sand, it's not organic....
But I want to drastically increase our ceiling insulation (past the 5 or so inches of almost uselesss blown in fiberglass). Spray foaming the roof instead would allow future use of the attic space. But for the time being, there would be nothing up there but boxes. How those gases would circulate into the living area is a question, but it's a valid point to consider to use when choosing insulation, especially since my childrens room is under the attic.
Offgassing takes place fairly quickley I'm assuming, so isn't as much of a concern since the room will be empty for a couple of years, and could periodically ventilate it, though please correct me if I am wrong. |
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renangle
Registered Users
Posts:91
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| 04/03/2008 6:34 PM |
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I'm going to throw my 2 cents into this about concerns of indoor offgassing and poisonous combustion products from everyday furnishings. If people do have a concern on that end, I would suggest that you review the list of products that have "Cradle 2 Cradle" certifcition at this link http://www.mbdc.com/c2c/ Cradle 2 Cradle certification essentially takes products and break them down to the molecular level so that they can ensure that there are no toxic chemicals in them. It was begun by Bill McDonough, the world's leading green architect, who happens to live in my home town. You can buy office furniture, carpet, diapers, etc.
Cradle 2 Cradle is the real deal, our company just signed a contract to get a punch of products certified with them.
I hope someone might find this helpful.
renangle
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aksmith42
Registered Users
Posts:29
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| 06/15/2008 9:19 PM |
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| if you weren't using the attic space for living area would you still insulate the entire exterior envelope of the house? i like the idea of not having to worry about venting the attic, sealing every electrical box etc. but i've always heard that this would cause you to have more cubic feet of space to condition. |
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freakboy
Registered Users
Posts:32
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| 06/16/2008 5:47 PM |
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If a project can be done with sprayfoam sprayed directly to rafters creating a conditioned space I think this is the way to go. I am still recovering from the brainwashing I recieved over the years about fiberglass insulation. When I did the 2nd floor of my Cape over 2 yrs ago is when that recovery started.
No one could have possibly spent more time that I did trying to fit the fiberglass just right, caulking between studs, sprayfoam and then installing 3/4" rigid foam (taped joints+caulked) under the sheetrock. I still have air leaks in the kneewalls after all that. Friends thought I was nuts going that far and at the time and I thought sprayfoam was overkill. I am happy with what I did but next time it is foam to the rafters for me. |
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Dont run thru the forest with your face on fire
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