What Wall Assy. Actually Works!?
Starting to think there are no good “Super” or “Above Average” insulated walls due to moisture problems!?
How would you fix:? Tiny 1 bedroom house 1950’s. Frame is Old Fir 2×4 wich hold up fairly well due to tight grain. Interior is Std 1/2″ drywall. Exterior is 2′ drywall “sheathing” horizontal with 3/4″ x8 shiplap nailers between the drywall strips. Then 3/4″ Fir T&G Vertical siding. The vertical siding doesn’t quite touch the exterior drywall because shiplap is 3/4″ so that is a good thing.
Problem is at some point someone blew in cellulose insulation. The exterioir drywall is ice cold so gets huge amount of condensation on its back that the cellulose then absorbs. Its amazing that its not more rotten but I’d like to get rid of the stuff anyway (exterior drywall) since putting in new windows. AND – the exterior drywall could be HAZ-MAT ?
Would this work:? Pretty sure Seattle is Marine Zone 4. Want to use new interior drywall over 1/2″ Foil Poly-Iso Foam Sheets, R11 F’glass unfaced batts in stud cavities, 1″ Poly-Iso Foil Faced Foam on outside of studs carefully taped and then 4×9 LP SmartSide panels for siding. (If siding was CEDAR I’d re-use it but its fir and the paint is in bad shape + it has no shear strength)
QUESTIONS – Is the interior 1/2″ Poly-Iso Foil Foam a bad idea? AND- What should I use between the 1″ exterior Poly-Iso and the 4×9 LP Smartside. Nothing?, Tyvek Housewrap?, Tyvek Drainwrap?, “Rainslicker”?, 15″ AsphaltFelt? OTHER?
When I look at the Building Science website it seems to indicate that an interior vapor barrier is NOT needed BUT that it also would be ok to use one in Marine Zone 4. Can’t afford the Brick Veneer 2″ airgap 12″ thick wall wich seems to be the only proven construction method that lasts more than 10-20 years!
Should I just forget it and use 1/2″ drywall over Kraft Faced R11 F’Glass Batts and attatch exterior panels directly to studs either with or without Tyvek OR “Tarpaper”
Electric BB Heat if that makes a difference. Thanks anyone – very confusing issue.
Fiberglass gets a bad reputation due to air currents being able to flow through it fairly easily. I think a better solution would be dense packed cellulose. Even better would be sprayed on closed cell foam, which can also provide structural rigidity. It may be possible for you reuse the exterior siding with foam due to the adhesive qualities of it.
Adding exterior foam, plus having interior foam will have the dreaded double vapor barrier. This sometimes creates problems due to trapped moisture. Exterior foam also can make the house harder to detail properly.
I'm surprised that the walls are so cold in a relatively mild climate. You may find that the job was poorly done, and has settled, or never was filled due to blocking, or unscrupulous workmen.
I've used smart side on utility buildings, and I am sitting on the fence as to if I would use it on a house. It has the same issues that t-111 plywood has in regards to flashing. It would be more likely to leak than other siding in a rainy location (generally speaking).
All said, my home in Ohio has fiberglass insulation in a 2x4 wall, and is comfortable. No foam sheets either.
Yeah, I'd be curious as to why the cells got wet in such a mild climate. May be simple lack of a VB, but I'd be more inclined to suspect rain intrusion.
(And we have standard 2x4 fiberglass walls here, in Tropical Southern Minnesota. I wouldn't describe the walls as "warm" when it's -10F out, but certainly tolerable. But the best thing we ever did was to carefully Tyvek the house when we resided about 25 years ago -- pretty much eliminated the "drafts".)
Exterior is 2' drywall "sheathing" horizontal with 3/4" x8 shiplap nailers between the drywall strips.
What is 2' drywall sheathing?
What is 2' drywall sheathing?
Probably 2x8 foot strips of gypsum board. But that's just a guess.
I'm more confused by the "shiplap nailers".
The 2' strips were called gypsun lath and was used beneath a thin brown coat and then white coat of plaster.
I have never seen it used in an exterior application, but would not rule it out. The strips were 2'x4' x3/8", making the final plaster finish about 7/8 to 1" thick. Not sure who made it but I saw plenty of it around in homes built in the early fifties.
Maybe it was just the aluminum frame window insert.
Thanks for all replys. Yes the exterioir drywall is 2x8x 1/2" with what appears to be a black asphaltic "paper" both side instead of regular paper. I may have panicked when i took out the window that had an aluminum frame retro. I guess enough condensation was running down the hollow portions of the aluminum to soak everything near it causing some rot and a little black mold so i was freaking out. Thought it was rain at first but roof has 34" eaves and it hasn't leaked.
Now that I have removed all the drywall and cellulose from that wall it looks like it was in great shape and I should have left it alone! Perhaps its simply a combo of a few bad things: Downspout draining right against crawlspace wall + somehow the crawlspace liner got folded up so this room had bare earth under it for 3-5 years. Both fixed. Still amazed how much drip the aluminum caused. New window should fix that.
Oh well - wanted to update some wiring and add a BB heater anyway. Thanks for all opinions.
Aluminum window frame insert
Most likely the cause
Replaced about 650 windows on a highrise. Aluminum frames were mitred in the corner and then caulked
over the years the caulking failed (could you really picture condo owners with caulking guns???) and water actually drained into the building envelope. What a mess
In older homes we use 1/2" drywall, 6mi poly, R14 Roxul, 2x4 studs (existing), 1//2 ply sheathing, 60min tarpaper, 1/2 PT strips for rainscreen and owner designated exterior finish. Had no problem so far in Vancouver BC
Before you buy BB heaters check out redwell.com regarding far infrared heating