I am building my first spec house and even though it is more expensive I am considering using spray foam insulation. In the past I have always used baffles and fiberglass as do most of us but now that we have spray foam, I have heard that venting the roof is unessasary. Does anyone have advice? ( The house is 7,500s.f with 16/12 rooflines in most places including a large vaulted living room.)
Cleveland Ohio, bcricher
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Replies
You should a advance search. Tons o info on this subject. Yes venting is not nessasary. See this site for more technical info.
http://www.buildingscience.com/
And tax credits are available as well, state and fed. Dont know the specifics of your local.
http://www.energystar.gov/index.cfm?c=products.pr_tax_credits#s6
Wow... 7500 SF for a first spec. I would think that someone buying and heating a house that size would potentially be very interested in how well it was insulated.
You'll be able to find additional info in the archive listing of old threads on Breaktime.
If you scroll up in the upper left corner of your screen there is an advanced search function that will take you to a page of instructions directing you to previous threads dealing with whatever you type in the search bar.
If you type in 'roof venting', 'foam insulation', 'dense cellulose' or other keywords of the subject matter you'll get a supply of data from those old threads.
"A man is rich in proportion to the number of things which he can afford to let alone."
-Thoreau
In my case it was necessary for the shingle warranty. Even had the rep call me direct.
No way was I putting 35 year shingles on the house w/o any warranty.
In the end I went with FG for the cost. The foam guy was looking to retire following my job. Job was just too far away from competitive bidding.
"In my case it was necessary for the shingle warranty. Even had the rep call me direct."What brand shingles? Certainteed and Elk are ok with no venting and foam.
Timberline is one of them.
Plus where I live, our town building dept. requires ALL roofs to be vented.
You do have to make sure your local bldg. dept. will approve the unvented roof; some of them are a bit behind the times with building science.
Elk specifically has a warranty coverage naming the Icynene brand foam as okay. For that reason, we're using both. Although it has been pointed out to me that if you look at the history of roofing companies and their actual practices when there's a dispute, you would just use what you want to. Ex--it wasn't our shingles, they were installed wrong. Etc.
Elk specifically has a warranty coverage naming the Icynene brand foam as okay. For that reason, we're using both.
Elk is now owned by GAF. Wonder if that changes anything?
View Imagehttp://grantlogan.net/
I've never met a man that was owed as much as he thought he was.
I'm watching that situation as the new roof is not on yet.What do you think of the comments I've received as to the general practices of roofing manufacturers in honoring their warranties for any reason? That they try to lay it off on the installers, etc.
What do you think of the comments I've received as to the general practices of roofing manufacturers in honoring their warranties for any reason? That they try to lay it off on the installers, etc.
I've been roofing for 20+ years. I've seen remarkably few warranty problems. But here's what I've seen locally:
The GAF rep wouldn't even show up to look at a problem. I've used few GAF products since this happened. Probably a new rep for this area now, but I've not had any contact with him. I've had problems with the size consistency of GAF products as well.
The OC rep tried to blame blow offs on missing nails. The tabs had snapped off of 3 tabs (the rest of the shingle was still nailed down - the seal strip didn't work). He looked for 15 mins 'til he finally found an undamaged shingle that was short nailed.
The Certainteed rep asks me "what will it take to make you and your customer happy?" and then does what I ask. I've had more Certainteed problems than other brands, but I use way more Certainteeds. Most of the problems have been bad color match. For all I know, the Certainteed rep may be going out of pocket to solve my few problems. If he's on commision, it's in his best interest to keep me happy installing his product.
I've used some Tamkos with zero problems and some Elks with no problems, but probably not a big enough sample to say they're any better or worse.
All of these product opnions should be taken with a grain of salt and could be reversed in your area. Different factories can produce a slightly different quality product, and the local rep can make all the difference in the world.
GAF rep:
View Image
http://grantlogan.net/
I've never met a man that was owed as much as he thought he was.
hooboy glad it was between sips when I saw that pic.
be now that's funny right there!
"As if you could kill time without injuring eternity." Thoreau
Edited 7/19/2007 11:27 am ET by rez
Looks like a fine, upstanding young man to me. How did the talking heads put it..."c'es ca ce'"? )My French leaves a lot to be desired--is pronounced "Kes ke say" and means "What is that, that that is?")
[I showed my step-daughter a picture of the guy who convinced his followers to commit suicide so they could catch up with the spaceship following the comet several years ago (Bo? I think was one of the names he used). Guy had the same eyes. I asked her if she'd trust this guy and she said, "Why not? What's your point?" (Sort of like Pinot, I guess.]
C'est que ce. Roughly translated: "WTF"
View Imagehttp://grantlogan.net/
I've never met a man that was owed as much as he thought he was.
Sounds like the pros way out weigh the cons. Is the brand of foam very important? Also, Ive heard that I might have an added expense of some sort of unit to deliver fresh air to the house. True?
Last time I contacted Elk the rep. directed me to a pdf file so I could view/print out their separate warranty regarding the Icynene. Icynene is named, but I don't remember if there was any "or similar" type language. Icynene has a decades-old track record, so myself I wouldn't go with any other brand foam.If you're building any tight building enclosure these days, whether you use foam or not, you need a ventilation strategy. There's just too much outgassing stuff in the houses and we're all closed up in them.My asthma improved a whole lot once I installed an HRV. I'm putting an ERV in the new house so the humidity will be taken care of as well. Lifebreath has a good product. The insulation is covered with foil well so there's none of it exposed to the airstream. Makes the house much more comfortable and works better than open windows too. My house always smells fresh. Oh, and I have a whole-house air filtration unit with hepa and carbon filters, which helps with air quality, but not everybody needs that.
You need to allow for fresh air since the foam (if installed properly) should yield a tight house. Look into an ERV (Energy Recovery Ventillator) if in a cooling environment or an HRV if in a heating environment.
The plus size is that you will be able to drop your HVAC tonage. MAKE SURE YOUR HVAC PERSON PERFORMS A "MANUAL J" load calc and is familiar with inputs for foam insulation and tight building envelopes. I am doing a 4000 Sq ft home that calls for a single 5 Ton unit. Note that many factors affect this other than foam including window quality, solar orientation etc. DO NOT OVERSIZE YOUR HVAC especially if in a cooling climate. Your HVAC, if right sized will perform your humidity control function. If oversized, it will not run long enough to effectively control your humidity. I urge you to consider a variable speed unit to help with the dehumidification function.
Open cell foam (.5 lb) like icenene or sealection 500 will run anywhere from $1.10 to $1.30 per square ft. My current project is $1.15 or approx $12,000 for the home mentioned above.
Good luck and hold on for the ride!!