To spray foam or not?
taylorbritain
3 years ago
last modified: 3 years ago
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taylorbritain
3 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 MoreMoist spots on cinder block after spray foam installed.
Comments (12)Thanks for your responses. This is a home in Florida. The block is the walls of the home ( no basements in Fla) This injection spray foam is done to fill up gaps in the cinder block to increase insulation and seal up the home. What my husband and I have noticed is small areas of dampness on the interior and exterior surfaces of the cinder block and it must be coming from the insulation. Wondering if anyone has any experience in this happening to their homes/ jobs and what to do about it. Our gut feeling is that the foam mixture was not mixed properly not allowing the foam to harden....See MoreCleaning off bad mix spray foam off good foam
Comments (1)Can you mechanically take it off with a rag or paper towel? you could also use a serrated blade like a bread knife to try trimming off a thin layer of good foam to get off the bad. Something like dynasol would disolve it but might damage the good foam....See MoreSpray Foam New Home Framed with Ridge Vent
Comments (6)Spray foam insulation applied to the underside of the roof sheathing is usualy done for unvented (conditioned) attics where there would be no ridge or eave vents. The presence of a ridge vent (and eave vents) suggests there will be baffles between the rafters to create an air space between the insulation and the roof sheathing to allow ventilation. In either case, the foam insuation would cover the ridge. If the insulation is in the floor of the attic, the ridge and eave vents would be open to the unconditioned attic space. Double check the design intent....See Moretaylorbritain
3 years agomissenigma
3 years ago
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