WDR Roofing Company Austin - Roof Repair & Replacement
Austin, TX, USA
Your plan will perform fantastic, as long as the layer of rigid foam on top of your roof sheathing has an R-value of at least R-20. If you're using XPS, you require at least 4 inches of foam. When you are using polyisocyanurate, you require at least 3 inches of foam.
Just give us the specs for your work and Advanced Aluminum will put with each other the whole deal like all metallic panels, trim and fasteners desired in considerably less time than every other metal fabrication property.
one. You don't want an inside vapor barrier. In the sizzling humid local climate, the vapor push is usually from the outside toward the inside (assuming your setting up is air conditioned). Should your setting up isn't really ever going to be air conditioned, the vapor travel will still be from the outside to the inside, but there won't be Considerably vapor push.
Really should I exploit airtight baffles or not, I do not see a way to have moisture escaping inside a assembly with airtight baffles, fiberglass and xps on The within, it doesn't matter what the dew stage will be inside of this assembly and possibly generate condensation that cannot evaporate without air flow.
I am creating a home and we are using cellulose in 2x12 roof rafters, and I came upon an item that looked excellent. It is an insulated nailbase termed Cool-Vent by Hunter Panels. It offers as many as twenty five.6 R-worth in foam insulation (in thicknesses as much as six" which contain a one" airspace and plywood) when providing a cooling vent under the shingles, and easy set up for that roofing with the nailbase.
You are proposing an unusual means of insulating your roof. If I understand you accurately, you intend to put in EPS concerning the tops of your roof check it out trusses and your roof sheathing.
Q. "You say 'You do not need an interior vapor barrier,' but You furthermore may say that 'You'll need a good More Bonuses air barrier on either side of the fiberglass batts.' The latter would turn out to be an inside vapor barrier not so?"
A. It is sensible for you as it meets your needs. As you are aware, it's actually not an excellent solution to insulate your roof assembly. But you have got explained it as A brief quit-gap measure.
If you are developing a cathedral ceiling, the biggest air-barrier blunder is to set up tongue-and-groove boards as your finish ceiling without 1st putting in taped gypsum drywall. A board ceiling is notoriously leaky, and this kind of ceiling is commonly affiliated with roof sheathing rot.
2. Put in strong site-developed ventilation baffles in Each individual rafter bay prior to deciding to spray the foam. That way you find yourself with a vented cathedral ceiling.
"The regular roof ventilation prerequisite Employed in building codes and asphalt roofing producers calls for 1 square foot of "Web free ventilation area" For each and every three hundred square toes of ceiling area (attic flooring area) when vents are evenly divided — 50 percent of these high within the roof with the ridge, gable, or a high roof, and 50 percent lower around the roof for the eaves.
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In the final summary it reads: "When you are using fluffy insulation, you would like two air barriers: one particular underneath the insulation, and a person higher than the insulation.
Put in rigid foam insulation higher than the roof sheathing and air-permeable insulation amongst the rafters. This type of assembly is created to dry to the inside, Hence the assembly really should never involve an interior polyethylene vapor news barrier. If you choose this technique, it’s feasible (though not required) to put in vent channels among the best in the rigid foam and the top layer of roof sheathing by setting up a series of parallel 2x4s — 1 previously mentioned Each and every rafter — extending from soffit to ridge. (For more info on this solution, see How to set up Rigid Foam On Top of Roof Sheathing.)