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The original builders of my house used a material called "Aluma Sheath", also known as Dennyboard, to sheathe my house. Dennyboard is a radiant coating on two sides of a 1/8 sheet of a fiberous material similar to what pegboards are made out of. It disintegrates when it gets wet and is very susceptible (and seemingly quite delicious) to insects, which eat out the core and leave nothing except the sheet of metal or mylar that's not thick enough to be used as tinfoil. It obviously was never providing any lateral rigidity, so in theory none should be required now although it is called for in code.

In the past thirty-two years, the Dennyboard has rotted as it was exposed to the elements. There was no tarpaper, housewrap, or other material between the Dennyboard and the brick. So I'm left with brick, which while a decent and fireproof rainscreen, is decidedly not waterproof, and there exists (many,many) ways for insects and moisture to directly access the insulation and sheetrock layers of the building envelope.

Is there a good and code-compliant way -- and barring that, just a good way -- to rectify this situation WITHOUT REMOVING THE BRICK OR INTERNAL STRUCTURE? My current concept is not code compliant as far as I'm aware. (It might be, but I don't have the experience to know.) I am planning to remove all of the sheetrock and insulation in the affected rooms, cut the brick ties (most of which are rusted anyway) after supporting the fascia from the exterior, slip housewrap between the studs and the fascia, and then slip a sheet of 4x8 1/2" (or less, I think I saw 1/4") of extruded foam sheathing between the studs and the housewrap. The entire thing will be re-anchored and affixed from the outside using CTP Grip Ties or a similar product. This should provide a watertight, sheathed, and even (insufficiently) thermally broken envelope without having to do any tearout work beyond the sheetrock.

Can anyone comment on the legality or feasibility of this idea? Tearing down the brick fascia is not possible; I'm very hesitant to alter the structure of the house in any way without getting a lot of (expensive) engineering advice first. Note: I have not begun tearout of the drywall yet and won't until this winter; the assumption that the brick ties are mostly rotted is because the fascia moves pretty freely and after doing a bunch of work to the roof and trim above this area I got a good look down inside between the fascia and the internal wall and saw the rotted dennyboard.

  • Also: Hey, y'all, long time no see. Sorry, work and the amount of things I've found wrong with this house have kept me off the internet by and large. This one's a right puzzler, though, and I though it'd be worth posting. – Karl Katzke Aug 7 '12 at 20:43
  • Wow, this is an awful problem. I can't tell if your proposed solution is crazy-brilliant or just crazy. Considering the cost of supporting the exterior brick and destroying/redoing the drywall and insulation, might it not just be easier/cheaper to tear down the brick and sheathing from the outside, and then re-sheath and re-side that? – Shimon Rura Sep 7 '12 at 21:43
  • Shimon - It would be time consuming to remove the old brick without breaking it, and it would be impossible to match the old brick with a new brick (I've tried for some other repairs I wanted to do...) -- so yes, I'm still going back and forth on the brilliant vs. crazy myself, but have yet to find a solid answer. – Karl Katzke Sep 9 '12 at 2:19
  • Does the brick veneer extend down to the ground, or how is it supported at the bottom? (I'm assuming there's an airgap/drainage plane between the veneer and the ex-sheathing -- this needs to be maintained) – ThreePhaseEel Aug 25 '16 at 2:24
  • Also, how big is the existing air gap between the brick and the ex-sheathing? – ThreePhaseEel Aug 25 '16 at 2:38
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"Is there a good and code-compliant way -- and barring that, just a good way -- to rectify this situation WITHOUT REMOVING THE BRICK OR INTERNAL STRUCTURE?"

No.

"I am planning to remove all of the sheetrock and insulation in the affected rooms, cut the brick ties (most of which are rusted anyway) after supporting the fascia from the exterior, slip housewrap between the studs and the fascia, and then slip a sheet of 4x8 1/2" (or less, I think I saw 1/4") of extruded foam sheathing between the studs and the housewrap. The entire thing will be re-anchored and affixed from the outside using CTP Grip Ties or a similar product. This should provide a watertight, sheathed, and even (insufficiently) thermally broken envelope without having to do any tearout work beyond the sheetrock."

Your plan sounds like it could work, (except for the challenge of slipping 4x8 sheets of anything between studs and your bricks).

As a suggestion, I would use diagonal metal strapping for lateral brace across the studs if you are not using structural sheathing (i.e. foam).

See this article (goto page 2) and below image from finehomebuilding.

http://i.stack.imgur.com/r5AGo.jpg

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There is but one sane option in this situation: remove the sheetrock and insulation, then spray foam into the cavities up against the backsides of the bricks, essentially creating a rigid monolithic foam structure that envelops the studs and joins everything together. It will seal out moisture perfectly and also grip the bricks, becoming essentially a new wall of brick ties. This will solve the stated problems as well as hugely increase the thermal comfort of the house, but it won't be cheap. Make sure you use closed cell spray foam, as it is stronger.

I'm not a big fan of spray foam in general but the product is a good match for this unusual situation.

  • There's a problem here -- the lack of a drainage plane (air gap) in your solution is going to keep the bricks from drying properly which will lead to freeze-thaw damage, as well as allowing hydrostatic pressure to send water squirting through every hole in the foam. See BSI-047 and BSI-038 for more information. – ThreePhaseEel Aug 25 '16 at 2:36
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I recently was part of an inspection audience for A Flood Safe presentation. Part of they're procedure was to fill the wall with a cementacias slurry between the brick and sheathinand creating a water resistance solid masonry wall. They were only able to go the 3 ft as any taller would require substantial structural reinforcement. This is also part of they're "flood safe" process.

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Instead of completely filling the airspace between the brick and the new sheathing with spray foam, why not just spray small spots between the two since the foam is so sticky? It would leave the required airspace in 95% of the area, and still attach the brick to the new sheathing. Perhaps you could drill a hole for the spray foam applicator to go though the new sheathing.

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