Spray foam in part of attic (seperate from rest of attic)
athensmomof3
11 years ago
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tnanock
11 years agoRelated Discussions
Rigid foam vs. spray foam under crawlspace
Comments (12)love this forum that you can do a little diy advising! ok the mold in the supply boxes and on the grills probably isn't from the duct takeoffs @ the plenum. it takes a long time for mold to travel that far..and if there isn't moisture & food source it won't spread to that area. it isn't always mold..sometimes it is just dust. so mold/dust buildup at the ducts @ plenum is lack of proper air seal. mold in supply boxes & on grills is lack of proper air seal at the cut in the sheetrock ceiling where supply grill is attached to the box. nine times out of ten..you can solve the issue by sealing supply boxes to sheetrock. see attached picture. hardcast brand #1402 mastic tape is used to seal supply box to sheetrock. this tape is 3" wide. I split the 3" into 1 1/2" lengths. stick to sheetrock and fold into supply box. as the tape adheres to many surfaces you need to be careful to keep it within the area covered by the supply grill. once it sticks to the sheetrock..you'll lose paper if you try to move it. surfaces have to be clean & dry for tape to adhere. and once in place you'll want to press it in place as it is somewhat pressure sensitive. the tape is strong enough to keep the box tight to attic floor on the attic side when installing the supply grill. wash the dust off the grills, wipe inside the supply box & into the duct. reinstall the supply grill. oh and when you remove the supply grills..take a sharpie and mark what direction they faced (throw to window..dirveway side whatever note you need to put them back in same position) this way you'll put them back as they were. I've tried several other brands of mastic tape. hardcast 1402 is the best. the others are 2" width and mastic is thinner, resulting in less strength and useful life. why would I chose spray foam for my floors? I've sealed floors several ways, foam is the easiest albeit more costly, once prep work is done. there isn't enough room to physically install foam sheathing to the bottom of the floor joists. I'll seal any big holes..like under tub then do 3" foam. I've looked at froth packs like tiger foam..but having worked with so many foam companies locally, will just have them do my floor when they are in my area. the software is pricy. we lease it yearly. once upon a time we bought the cd..but too many people abused it. so now it is a download & upgrades to original install. a lot of mastic isn't always an indication of a good seal. it doesn't take a lot if you put it in the actual leaks. you can feel around the duct take offs on the plenum while unit is running and feel some of the leakage. also checking plenum connections to the equipment at the same time. I use mastic tape to connect plenums (after screwing them in place) much easier to seal under the plenum to equipment with tape than painting mastic upside down....See MoreClosed vs Open cell Foam/ roof rafters vs attic floor
Comments (10)this is the trade off Richard. Time, materials and effort to air seal vs cost to foam insulate& air seal in one step. one takes considerable effort and time although materials are less the other takes little time little effort and higher cost. air sealing is the KEY to insulation performing as spec'ed. foam just makes it easier. And haven't you noticed that FAQ's are ok for the other guy..but this is MY house ans I have specific to me questions...LOL! Just the way it is... OP, in my cooling climate we insulate to R-38 there is a diminished return on investment with more insulation..but it starts diminishing when you insulate over R-19 as the first few inches of insulation work the best.However most states mandate R-30 and above and there is a good savings in higer values. Just how much for above R-38?? Don't know for heating climates..ask Joe @ bulding science! I'm glad to hear that you would remove the batts before foam sealing the attic floor. Personally this is the location I would purchase in your situation. No mechanicals or ducts in the attic make the roofline install more of a profit for the foam co than actual benefit to you. If I were you I would opt for this, but with the specification that the insulation at the eaves of the house be installed from attic floor to soffits to roof making this an air tight install. (it won't be 100% air tight...even though they sell it as such) This will seal exterior walls at top plates which is always an air infiltration site. Oh and WELCOME YOU! Merry Christmas all!...See MoreInsulating the attic - spray foam?
Comments (23)I'm glad to come across this thread because I'm also trying to figure out whether/how to add blown-in insulation to our attic, and possibly radiant foil. I hope I'm not derailing the thread by tacking on. Our home is a roughly 120 year old Victorian, and it also has a sprinkling of old insulation in the (sealed) attic, but nothing more. And when I say attic, I should clarify--we actually have a finished attic/third floor but the very peak of the attic, above the ceiling of the finished area, is unfinished. It's like a capital A, where the lower half is the finished portion and the upper half is unfinished. I'm sure there's proper terminology for that but I don't know what it's correctly called. We use the finished portion regularly, or at least we would if it didn't get very hot up there in both the winter and the summer. In the winter, we can counteract this by closing the HVAC vents so the attic is only heated by the hot air rising through the house, and that works well enough. But in the summer, we add two window units in addition to the house AC (to cool a space that's probably 400 sqft)--the window units are kind of a mixed bag because with the way they're installed, they let in a good portion of hot outside air around them through the window. We're contemplating replacing the window units with a minisplit system in the attic alone, but I feel like it's worth exploring all the various possible ideas to try to keep summer heat out of the finished portion of the attic before installing a whole new additional system. Any thoughts or ideas for me?...See MoreRetro-insulating sloped roof from attic
Comments (7)There is no easy solution. There needs to be air baffles for air circulation, if not you will have intense heat and moisture. If you have access and can install them along with blow-in insulation then it will be fine. In regards to Vapor Barrier, many paint companies make a VP paint and it works. Old houses have a lot of air leaks therefore moisture is not a big issue. I remodeled at least 50 100 year old homes and there was never a problem with moisture, leaks yes. If you can get to the side wall install the batts with the paper side in and install a wind barrier on the outside part of these wall such as fan fold or insulation board. This does work well....See MoreEpiarch Designs
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