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I HAVE A POST BEAM STYLE HOME BUILT ABOVE A ROCK OUT CROPPING. THERE IS NO BASEMENT. THE BOTTOM OF THE FLOORS ARE SHEATHED WITH 1/2 PLYWOOD AND INSULATED WITH STANDARD BATTS. I AM CONSIDERING BLOWING IN CELS OR SPRAYING IN FOAM. IT IS A MAJOR JOB TO REMOVE THE PLYWOOD TO GAIN ACCESS TO THE FLOOR JOISTS. WHICH SYSTEM WOULD BE BETTER.
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What R value do you have in this space now ?
What depth of joist remains free to take insulation?
Do you have an air/vapor barrier inside this joist cavity now; if so, where exactly?
Besides cavity fill insulation, you might have some options to use EPS foam and sheath it to the outside. If you use a blown in glass or cellulose fill, you need a vapor barrier to protect this type of insulation from indoor moisture.
*Moisture barriers on the indoor's side of insualtion are to protect it from saturation, frosting and condensation problems due to the realtively higher moisture and warmer indoor air penetation. Disrediting moisture/air barriers is a dark ages proposition. Don't mislead the man by telling him A/VB's are not used in floors. The floor is probably the most important place for an A/VB and it is even more important since infiltration and stacking starts from the bottom and works up. An exposed, plywood sheathed under-floor is particularly vulnerable to infiltration and in-floor insulation is particularly vulnerable to condensation and frost problems that would undo the R value in the cavity. Comfort is also a function of draft-free and warm floor level conditions.
*Moisture barriers on the indoor's side of insualtion are to protect it from saturation, frosting and condensation problems due to the realtively higher moisture and warmer indoor air penetation. Discrediting moisture/air barriers is a dark ages proposition. Don't mislead the man by telling him A/VB's are not used in floors. The floor is probably the most important place for an A/VB and it is even more important since infiltration and stacking starts from the bottom and works up. An exposed, plywood sheathed under-floor is particularly vulnerable to infiltration and in-floor insulation is particularly vulnerable to condensation and frost problems that would undo the R value in the cavity. Comfort is also a function of draft-free and warm floor level conditions.
*et al, here in Canada and according to courses that I've been involved with, exterior grade plywood certainly is considered to be and effective air/vapour barrier. My preferred method for cold floor construction is to fully batt the floor joist cavity, then across the joist with 1 1/2" styrofoam insulation and then apply plywood sheathing over that with 1x2 battens over the joints.I think that a lot of the problems that arise in these discussions could be solved with effective mechanical ventilation systems. Just how is it that older houses, leaking like sieves, don't experience all of these new-fangled, highly technical problems...is it because they just ventilated themselves naturally? I think that HRV's should be manditory. JimJ
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I HAVE A POST BEAM STYLE HOME BUILT ABOVE A ROCK OUT CROPPING. THERE IS NO BASEMENT. THE BOTTOM OF THE FLOORS ARE SHEATHED WITH 1/2 PLYWOOD AND INSULATED WITH STANDARD BATTS. I AM CONSIDERING BLOWING IN CELS OR SPRAYING IN FOAM. IT IS A MAJOR JOB TO REMOVE THE PLYWOOD TO GAIN ACCESS TO THE FLOOR JOISTS. WHICH SYSTEM WOULD BE BETTER.