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Looking for guidance!!! Need advice. Post New Topic | Post Reply
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sean riha
Posted: Apr 23, 2007 11:58 AM
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Looking for guidance!!! Need advice.
Hi all. I've been scouring the net for info for a couple weeks now and STILL have yet to find the answers to my questions. Here is the background: I have an old (100 yrs plus) 4 unit building in Chicago. I plan to finish off the attic space. My current roof is in need of replacement soon. It is a simple roof: pitched the same for the full length of the building. No dormers or valleys... just pitched (maybe 9:12 ) the entire length. Currrently no leaks, but there are a bunch of built up layers of old asphalt shingles. The rafters are true 2x6" and spaced pretty far apart (maybe 30" in some spots). i know that's far. anyway, the rafters are solid enough so i am gonna have a tear off down to the hardwood (which is spaced with 3" gaps) decking and then have 1/2" ply put down and then my roof with all the requisite material. I have NO soffit or vents, so an unventilated spray foam scenario is looking like a great route for me. The issue: So, I've been going BACK AND FORTH seeing how some choose closed cell and some choose open cell for the underside of the roofdecking. There seems to be many reasons to choose one or the other. I have no idea which way to go!! As I said I live in Chicago. It can get nasty cold and nasty hot here. I plan on finishing off (drywall, rooms, etc...) the attic space. Can any of you guys PLEASE steer me into the right direction??? I'm frazzled and I don't want to get misled by any installers just b/c they carry a certain product... i just want to do this right. |
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Todd Baxter
Posted: Apr 23, 2007 05:19 PM
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I would say go with closed cell. you could do open cell but you will to seal it better r valve with closed cell |
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Edward Brassington
Posted: Apr 23, 2007 10:38 PM
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Most definitely go with closed cell 2 pound foam. I have installed both 1/2 pound and two pound foam. In a six inch cavity you will not have enough room to get the required R value. Open cell foam is only R3.6 per inch or R21. 2 Pound foams are typically R6.8 per inch at 5 inches you will have at least R34, I don't know what your code requirements are for Chicago, The two pound foam will also significantly increase the structural strength of your building. With half pound foam you will have to have a vapor barrier, you may be required to install ventilation above the foam, some jurisdictions require this. Two pound foam will be more expensive but it is the only way to go. |
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Edward Brassington
Posted: Apr 23, 2007 10:47 PM
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Also go to the "Documents" section of this website and read the document" The difference between half pound and two pound foam. |
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Posted: Apr 24, 2007 11:02 PM
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PERFECT EXAMPLE OF WHERE CLOSED CELL FOAM GIVES YOU THE BEST BANG FOR YOUR BUCK. VAPOR BARRIER,MORE STRUCTURAL STRENTH, AND TWICE THE INSULATION VALUE OF OPEN CELL. AIN'T NO CONTEST WITH OPEN CELL! |
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sean riha
Posted: Apr 25, 2007 09:16 AM
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I had an open-cell installer over last night for an estimate. While there, I brought up the whole open vs. closed dilemma i face. He claimed that closedcell is so rigid that it could crack should my roof/rafters shift throughout the seasons. He also said that closed cell will "crumble" if it ever gets wet. And he also mentioned the roof leak issue and how I wouldn't be able to track down a leak if I ever get one with my new roof. I wasn't sure what to think after he left. |
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Posted: Apr 25, 2007 10:06 AM
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utter nonsense! your attic has been expanding and and contracting for close to 100 years.any nails pulled out of the beams yet? closed cell foam in your application will triple the strenth and double the r-value over open cell.(NAHB wall tests) roof leak with closed cell? ANOTHER SALES SCARE TACTIC. possible section of roof deck would be replaced.(my opinion:I dont like 5 gallon buckets in the living room of the rental apartments and plaster falling in) the more homework you do, the better! |
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sean riha
Posted: Apr 25, 2007 11:02 AM
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I'm sure no nails have pulled out completely, but perhaps some have pulled out and pushed back in (ever so slightly i would imagine). All buildings move somewhat. But is that rather small movement enough to cause the closed cell to crack or pull away from the rafters? I love the idea of the cc foam adding strength to my roof, but i would like to feel good knowing it won't be too rigid should some movement occur. |
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Posted: Apr 25, 2007 11:44 AM
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it is not going to crack.Ford Motor put 900,000 sq ft of foam roof on around 1992.hot summer sun, cold winters.(occasional below zero temps up there) zero cracks. your attic will be fine. they put the foam on the roof to stop the leaks.It stopped the leaks.then they found out they saved a healthy amount on heating and cooling. (an added bonus) applied properly by a experienced applicator, you should have no problems. factory certified applicators might be a good option for your concerns. closed cell is the best bang for your buck. |
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Gerry Wagoner
Posted: Apr 25, 2007 09:31 PM
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"Closed cell could crack.." Oh please. Somebody doesn't understand strength-to-weight-ratios very well. Spray foam will put the structure to sleep, and eliminate most of the thermal shock of the building. We've been in the spray foam business since 1984. olger |
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Posted: Apr 26, 2007 06:46 AM
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what olger said,, if your salesman isnt offering you both products, he is a hillbilly foamer,,he just wants the big easy,,closed cell is a pain in the ass when compared to open cell to clean up, amongst other things,,, repeat after me,,,lawn care,,,they should go back to lawn care.... we have a 2x4 garage with exposed full depth closed cell foam,, unheated,,uncooled, i show this to the folks who get the "it will crack" tripe from snake oil salesmen and foam insulators with no consience or credibility... we are in iowa,,this was sprayed in '98, we have had 115 degree highs, with extreme humiditys, we have had 30 below degree lows, we have had straight line winds, and a tornado pass at a 1/2 mile..again, this is unheated and uncooled so it should be "moveing all over the place" with regularity... there are no cracks..anywhere,,this garage closes a lot of closed cell work for me... "crumbles"??? WTF??? it is a THERMOSET PLASTIC,(as is open cell for that matter) if it is manufactured correctly,,,derr.... what end of the crack pipe were these guys pullin on? i would guestion their integridy if they were so anxious to feed you full of tripe...i sure wouldnt let em do my work.. LADIES AND GENTLEMEN: IF YOU/WE CONTINUE TO TALK CRAP ABOUT OTHERS AND THEIR PRODUCTS WE WILL CAUSE GREAT HARM TO OUR INDUSTRY... yes we all need to work,,yes we all have competition...yes we are all applying the same stuff if you look at its chemistry. ....i heard open cell foam absorbs radon gas and time releases it,,,only to the inside... ...i heard closed cell foam has toxic stuff in it that will kill your kitty.... tripe just plain old tripe... shall we come up with a few more nonsensical cliche's that sound real good,,,and confuse the customer even better?? remember....frame-it,,,FOAM-IT...Fxxx-it!!! have a nice day! facts,,10,200 sq ft heated structure,,,geothermal with OC spray foam thruout... enter 5 weeks with temps never going above 15 degrees,,,send customer a $110 utility bill,,, they luv foam,,,they wanted to man my home show booth...oh yeah,,power lost for 4 days,,,temp in home fell to 58,,,and stayed there... long live foam,,, foam good,,whether OC or CC |
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Posted: Apr 26, 2007 07:08 AM
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i would apply 4-6 inches of closed cell in your application as you describe...depending on the depth available and the depth of your pockets... 4 would work,,more would be better,,, (how close to the "edge" do you want to be) it the roof substrate is suspect,,you could staple a layer of builders felt in the rafter run and apply to that,,,this is not the best application possible, but it will stay up there it will not sag it is side to side... and it works, allowing a layer of release if the deck needs to go...you still have side to side seamless and an INSULATION LAYER with the foam... good luck |
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sean riha
Posted: Apr 26, 2007 09:18 AM
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hey, big thanks to everybody for all this info. i'm feeling more comfortable about all of this now. soon i will have estimates in from a few foamers (both open and closed) and will decide largely on that. if i can swing the closed after i've paid for all the other things i'm doing i'll go ahead and do that. |
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SprayFoamSupply.com
Posted: Apr 26, 2007 11:12 PM
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Foamdude has such a way with words! I love reading his posts when he goes off on a rant. What's up Buddy? Geo |
