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We have a 1971 split entry where the first floor is cantilevered two ft. over the basement space in front, where it is above grade. We opened the overhang and found moldy and mousy 3-1/2″ fiberglass insulation and no blocking in the bays between floor joists before going back into the living space. The plan is to put in new fiberglass battsbatsh moisture barrier facing up, and make sure there is airspace between the overhang soffit and the batt.bat.also plan to put small circular vents in these soffits. The question is whether we should also install blocking in the bays over the wall plate. Doing this would be complicated in two of the bays by HVAC ducts servicing the floor above. The climate here is southern New England. Comments on blocking as well as the re-insulation strategy are welcome.
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what size are the joists?
what are the circular vents going to do for you?
there is no reason for air to be moving in this section of the house.
if you use solid blocking at the plate line you introduce a thermal break at the inside corner formed by the blocking....better to extend your insulation past the inside of the wall line...
..i would think about blocking off each bay and blowing cellulose into the box you have formed.. then cover the bottom of the box with a finished soffit material....
*I agree with Mike. Box it off as he described and pack it full of cellulose. That will be the end of your problem.
*Well - they're right - but kill the mold first I think. With old soffit off shouldn't be hard to scrub with bleach and detergent and let dry overnight
*The vapor barrier side does not matter - don't worry about it.No ventsBlock wherever you'd like as long as it touches the top plate - or as an alternate sheathe the underside with OSB or ply. Caulk at the joint where the sheet meets the top plate of lower wall and at band joist of upper wall. This is your air barrier - you will now be moving the thermal envelope of your house to where it belongs.If you don't or can't sheathe, move the A/C duct back inside the house (behind the blocking) - This is the reason for the mold. Hot moist supply air dumps into cold drafty insulation and condenses. The black may be 30 years worth of dust as well, does it have patterns that match seams in the duct?OR - Use PUR foam to fill the whole damn mess as is, put whatever you'd like up for soffit and walk away.Don't feel bad - the house in the picture isn't even built yet - no one has smartened up in 30 years.
*Remove everything, kill the mildew/mold with bleach, let dry, reinsulate with cellulose or foam, seal back up and ignore for the next 50 years.
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We have a 1971 split entry where the first floor is cantilevered two ft. over the basement space in front, where it is above grade. We opened the overhang and found moldy and mousy 3-1/2" fiberglass insulation and no blocking in the bays between floor joists before going back into the living space. The plan is to put in new fiberglass battsbatsh moisture barrier facing up, and make sure there is airspace between the overhang soffit and the batt.bat.also plan to put small circular vents in these soffits. The question is whether we should also install blocking in the bays over the wall plate. Doing this would be complicated in two of the bays by HVAC ducts servicing the floor above. The climate here is southern New England. Comments on blocking as well as the re-insulation strategy are welcome.