How should I insulate under a concrete hydronic slab on stilts?
I have just purchased a little home in western Québec in an area affected by the 2019/2017 floods. My first order of business is raising the house to avoid future floods. My plan is to use tridodetic posts as my foundation, so the property will essentially be sitting on stilts. My second goal is to install concrete hydronic radiant floors.
Does anyone have any experience with DIYing hydronic concrete slabs on stilts. How I would go about insulating underneath to avoid heat loss as the floor will be exposed to the elements being on stilts. Can the concrete floor be poured directly on the plywood subfloor?
There are a few ways you could do that, but have you considered raising the grade and just dropping it on a slab on the ground? The reason I suggest that is that you are talking about a whole lot of weight, so you will be putting a lot of money into screw piles to begin with to carry such a heavy load as a slab on concrete not to mention the house, and you are left with a house that sort of falls short on a couple of fronts, namely – the whole underside will be exposed to cold winter air, so you will pay more for heating (or more for insulation), you are exposed to animals underneath, and houses on posts don’t have as good a resale value.
That said, I would first point you towards either EPS deck insulated concrete forming system to go the screw pile route as you suggest, but if it were me I would sooner raise the grade with compactable fill to the desired level you were going to go with the screw piles and drop a slab right on it. At least I would price it out. In which case you could check out slab on grade form kits. At least
price out both options, The slab is definitely the preferrable choice unless it comes in way higher, and that may depend on exactly how high off the ground you were hoping to put it and how much fill you’d need. Either way, here is our DIY hydronic radiant floor tubing installation video. Laying hydronic tubing is pretty easy work, but designing the zones is best left to a hydronic supplier, Uponor is a brand we used in that video to design the zones for us.