Dense-packed cellulose, slab on grade, pole building
Thanks to all who take the time to read this and the responses.
I’m wanting to build an efficient and cost effective house in the 7A climate in northern MN. I’m looking at putting up a pole building ranch style for cheapness with radiant floor heat. Propane boiler (I live in the rural area). Question 1 is I plan on doing a modified truss wall. In the fact that the poles will hold up the roof up. I would stand a 2×4 wall one foot inside of the poles for dense packed cellulose. Can i put the cellulose directly on the heated concrete floor with no problems. Question 2. I will have metal for siding and roof. The metal siding will just be attached by stringers running horizontally across the poles. Will the tin be strong enough to hold back the dense packed cellulose insulation with out bulging? I would put house wrap around the building before the siding. Or do I need to fully sheet the exterior before the metal siding. I know many don’t recommend metal siding and roofing but it’s cost effective and very very low maintenance. I’m sure I will have more questions as the responses roll in. Thanks to all.
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Replies
Paul,
Q. "Question 1 is, I plan on doing a modified truss wall. In the fact that the poles will hold up the roof up. I would stand a 2x4 wall one foot inside of the poles for dense packed cellulose. Can I put the cellulose directly on the heated concrete floor with no problems?"
A. You want to install your PEX tubing in the slab so that the PEX tubing doesn't extend under the exterior walls. Remember that you need two kinds of rigid foam insulation for a heated slab: a continuous horizontal layer of rigid foam (at least 4 inches thick), and vertical insulation at the slab perimeter, extending at least 2 or 3 feet below grade.
Q. "Question 2. I will have metal for siding and roof. The metal siding will just be attached by stringers running horizontally across the poles. Will the tin [steel] be strong enough to hold back the dense-packed cellulose insulation with out bulging?"
A. Yes, but you don't want cellulose insulation to be touching the steel, because the steel will be cold. You'll get condensation on the steel and moisture accumulation in the cellulose. What you need is a rainscreen gap on the interior side of the steel siding, as well as an effective air barrier -- ideally, plywood or OSB sheathing with taped seams -- on the interior side of the rainscreen gap. For more information, see All About Rainscreens.
Q. "I would put housewrap around the building before the siding."
A. Think very carefully about how you would detail your air barrier. Pole buildings have a major drawback: detailing the air barrier can be difficult.
Q. "Or do I need to fully sheet [sheathe] the exterior before the metal siding?"
A. In my opinion, you definitely need wall sheathing.
Q. "I know many don't recommend metal siding and roofing."
A. There is nothing wrong with steel siding and roofing, as long as everything is detailed correctly. You can't skip the usual layers (things like wall sheathing, an air barrier, a water-resistive barrier, and a rainscreen gap).