What is the best way to insulate a porch floor?
home2
| Posted in Energy Efficiency and Durability on
We have a porch that we wish to enclose to make a 4 season room. We are in Zone 5. The porch is above an unheated portion of the basement. A 3/4 inch pressure treated plywood subfloor is fastened to wood I-joists that are on 12 inch centers. We want to know if 1 inch rigid XPS foam board can be sandwiched between the subfloor and the top floor. The top floor will probably be some type of wood flooring, probably doug fir or oak. Thanks for your help.
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Replies
Ed,
Yes, you can install rigid foam above the subfloor. One inch of XPS is only R-5, though -- you really want to aim for R-30, which is the code minimum for floors in Zone 5.
If you do install rigid foam above your subfloor, you will probably want to install another layer of plywood or OSB above the rigid foam. This second subfloor should be attached to the joists with long screws reaching through the rigid foam.
For more information on this topic, see How to Insulate a Cold Floor.
Ed. Is this portion of the basement isolated from the rest of the basement?
Yes, it is a block wall enclosure with a walkout door to the outside. This basement is attached to the main basement but has no access to it.