Interior wall to become exterior wall

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Author Message Richard Baxter, AIA, CSI Senior Member Username: rbaxter Post Number: 17 Registered: 12-2004 Posted on Wednesday, October 05, 2005 - 05:17 pm:    I have a project, here in Salt Lake City, where an existing building is going to be demolished, exposing a sizeable, previously unexposed gypsum shaftwall on the remaining adjacent building. The wall will remain exposed for up to 4 years before the new exterior (probably metal paneling) will be installed over it. Does anyone know of a good way to temporarily weatherproof the remaining wall? Do any of you have any experience or suggestions for dealing with this kind of a situation? I believe most waterproofing products are designed either for below grade, below paving, or for roofing – not for temporary waterproofing of exposed vertical walls. We want an inexpensive product that can later be removed without significantly damaging existing walls. It needs to protect the shaftwall and protect the interior of the adjacent building. I’ve been hearing suggestions including Visqueen, vapor barrier products, EPDM, TPO, and adhered sheet waterproofing. I’d appreciate any suggestions. George A. Everding, AIA, CSI, CCS, CCCA Senior Member Username: geverding Post Number: 77 Registered: 11-2004 Posted on Wednesday, October 05, 2005 - 05:51 pm:    The problem with the lightweight solutions (visqueen and tyvek, etc.) is keeping them in place against wind for four weeks, much less four years. EPDM and so forth should last. What about some sort of paint or higher performance coating right on the shaft wall? Maybe an elastomeric or cementitious type coating? You may need to do something for the shaftwall studs, if exposed. I don't have a specific product to suggest, but I bet there is something out there that would work. Don't know how it would fit into your budget, but I bet it would be less than the roofing or waterproofing materials. John Bunzick, CCS, CCCA Senior Member Username: bunzick Post Number: 420 Registered: 03-2002 Posted on Wednesday, October 05, 2005 - 06:10 pm:    If it's going to be four years in the Salt Lake City climate, it would seem to me that you need a "real, genuine" cladding system, not a piece of plastic. That's so long that who knows what will happen in the meantime. Plus, if I was the owner of that building, I'd insist upon it for proper weather protection. Since GWB is very susceptable to moisture damage and mold, you really can't afford to fool around with it. I'd consider something that can be readily removed later, such corrugated as metal siding panels which can be easily unscrewed. Julie Root Senior Member Username: julie_root Post Number: 23 Registered: 02-2004 Posted on Wednesday, October 05, 2005 - 06:32 pm:    I am working on a project here in Los Angeles where we have a temporary wall protecting a very significant historic part of a interior building to be reused. The wall is assumed to be in place for two years at least and will protect the existing building from construction going on near by. Now bear in mind it is Southern CA. We specified 3/4" exterior grade plywood screwed at the edges 8" o.c, alternating joints over two layers of 15 lb. felt paper. At one time I had battens at each joint to help the edges from peeling, but serveral colleagues argued that we really did not need them in our sunny climate. It has been up for 6 months and so far so good. It is about 30' high. At the very beginning I had consulted with a friend who does a lot of restoration in Northeast and she used the same type of temporary wall except that she would use two layers of 3/4" exterior ply joints layed perpendicular with two layers of felt between the plywood and two layers before the studs. She had found that this was the most economical and lasted long past the two years her projects typically needed. I also flashed the roof condtition and base conditions as you would with a real wall. Good luck. Marc C Chavez Senior Member Username: mchavez Post Number: 137 Registered: 07-2002 Posted on Wednesday, October 05, 2005 - 06:46 pm:    I'm with John on this one. 4 years is NOT temporary; especially in Salt Lake and not even in LA. Bite the bullet. Either build a real protective wall or live with leaks and the high probability that you'll end up replacing the shaft wall, which you may end up doing anyway. Other questions include: Is the existing shaft wall up to current code etc.? What are you really protecting the shaft wall or the other buildings interior? Can the shaftwall be sacrificial? It will not last long by itself, but how good the covering is will effect how long it will last and it IS all about money. David R. Combs, CSI, CCS, CCCA, MAI Senior Member Username: davidcombs Post Number: 81 Registered: 08-2004 Posted on Thursday, October 06, 2005 - 08:56 am:    I think the waterproofing is only part of the problem. What about resistance to wind load? You might want to check the size and gage of the shaft wall studs; chances are they were only designed for probably 5 (maybe 10) psf, at L/180 or L/240. How does that compare to the code-required design wind load imposed on a "conventional" exterior wall assembly? And what about insulating that existing shaft wall assembly? Is there an energy code in place that requires a minimum R-value? I think the prudent thing to do would be to treat / design that wall as a true (permanent) exterior wall, as if that proposed addition will never get built.