New bath addition with tile walls inside: What is most foolproof wall assembly?
Will use rain screen approach outside. Will use a layer of 3/4″ plywood behind Durock or similar on inside of wall to attach grab bars anywhere in future. Plywood behind wall finish is suggested by various websites for handicap bathroom. Closed-cell spray foam is in budget. Using all pressure-treated lumber. Will use sealants in all appropriate locations to prevent air leaks.
Will install bathroom fan with humidistat.
My concern is the limited drying potential of this wall. I will allow all wood to dry before completing wall finishes using a dehumidifier if necessary. The choices seem to be stud wall with closed cell foam sprayed from inside or 2″ EPS outside of sheathing and some cavity insulation. it seems to me that the simple stud wall with rain screen approach might provide some limited drying to the outside through the wood frame. The outside foam might impede the little drying potential that exists.
Floor is suspended concrete slab on an ICF foundation. Roof will be vented, conventional rafters with adequate amount of closed-cell spray foam,
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Guy,
First of all, if the tile is part of a shower enclosure, I assume that your tile contractor will include a waterproof layer (for example, a liquid-applied membrane such as Laticrete Hydro Ban or Mapei Mapelastic AquaDefense) -- products that are installed on the interior side of the backerboard.
Your wall will be able to dry adequately to the exterior, especially if it includes a ventilated rainscreen gap between the OSB or plywood wall sheathing and the siding.
Thanks, Martin. Probably using a Kerdi membrane. If that was not optimal i could ask the tile contractor to use one of the liquid membranes that you suggest. Walls that are not part of shower enclosure will have tile to about 36" off floor. Absolutely using a rain screen gap under siding. Guy W.
Try researching the foam shower boards available from manufacturers such as Schluter or Mapei. Read the instructions carefully, as to not inadvertently create a double vapor barrier, and I'm sure you'll never run to the Durock solution again. They are light, waterproof, easily workable, and very affordable when you account for time in handling, stress and ease of use in comparison. They offer complete shower systems and accessories that simplify the project, and there's no more concern about airborne silicates either. I've been using nothing but for over a decade, and I truly wish I knew about them sooner. 100% satisfaction among installers and clientele.