Last week I started Phase 2 to the Timberframe cabin expansion. Here is the plan overview if you haven’t seen it yet. Phase 2 consists of taking in an approximately 100 square foot section of the existing wrap around porch and converting it to a dining/living room.
The first order of business was ripping up the deck boards and then installing insulation and the subfloor. Insulating a raised floor is a little tricky because of a phenomenon known a thermal bridging. Essentially, the floor joists to act as a conduit for heat to escape from the house (or get in depending on what your interior climate goals are).
I borrowed an idea I saw in a Fine Homebuilding article to create a thermal break. The article is about creating a thermal break in wall assemblies but I think it can work with raised floors as well. Or maybe not. I guess I could send an anonymous hypothetical question about it into the Fine Homebuilding Podcast to get my idea shot down publicly.
Anyway, here is a short explainer video I put together about thermal bridging and raised floor systems:
And here is full subfloor assembly video:
Wow! Good solution! You are braver than I to crawl under your house!
Ingenious. I might not be keeping up with current affairs, But to put the insulation on to the bottom of the joists (to make them thermally broken) means you have to crawl under and attach them. Or is there a cunning plan? Perhaps lift up the inside floor boards and lower sections below the joists and reach down to attach them? Sounds tricky. Or perhaps you are very hardy.