Cantelievered Bump Out

Old 11-18-07, 12:23 PM
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Cantelievered Bump Out

Since the exterior subfloor of the cantelievered portion of my house is not enclosed, that section of the house is much colder. How do I enclose the subfloor and what materials do I use?
Old 11-18-07, 02:58 PM
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Covering the bottom of the cantilever with rigid foam insulation will help isolate the joists from exterior temperatures. This foam would then need to be covered with additional plywood sheathing, or soffit, or similar because it shouldn't be left exposed to the elements. Reducing air infiltration is highly important in such areas, so the taping of joints and sealing of edges would be pretty important details to give attention to. If the subfloor has not yet been installed, adding additional rigid insulation between joists can help improve r-values, especially if any ductwork reduces the amount of space available to insulate. If fiberglass insulation is used, you would not overfill or compress the insulation by cramming more in than you should, instead use the correct size insulation for the space available. Warm-side vapor barriers are often forgotten in such areas, which could lead to potential condensation and mold. If used, exterior housewrap details should have taped seams to reduce air infiltration, and should wrap around the rim.

Just a few thoughts to get you going.

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