WDR Roofing Company Austin - Roof Repair & Replacement
Austin, TX, USA
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I've presently insulated the steep sides of my unvented mansard roof with 6" fiberglass (and I had it inspected), do you propose I rip that out and use spray or board foam? I have gotten conflicting info on regardless of whether to treat it as being a wall or perhaps a roof.
We are already recently setting up loads of closed mobile foam on to the roof sheathing with wonderful success. However I wonder When you have listened to about what happens when the inevitable roof leak takes place?
Your proposed assembly is usually a code violation. If you want an unvented roof assembly, you must maintain the roof sheathing warm with spray foam or rigid foam. Cellulose insulation is classified being an air-permeable insulation and cannot be Utilized in such a roof assembly.
We actually Will not know if these roofs have correct vent channels, or what sort of vent baffles (if any) were applied to keep up the air flow hole among the top on the fiberglass insulation along with the underside with the roof sheathing.
It appears if a single have been to use dense pack cellulose within a vented cathedral ceiling the vent channel product need to be rigid enough to withstand the force.
Section D: Possibly notch the dealt with 2x4 spacers for fitting 1x4's horizontally throughout them in an effort to ...Portion E: Set up metallic roof in excess of this.
Evidently, from time to time you might want to plan ahead to be sure that your rafters are sized sufficiently to allow for insulation and venting. For more info on acceptable approaches to insulate reduced-slope roofs, see this short article: Insulating Reduced-Slope Residential Roofs.
Our cooler mornings may possibly make the inside of my metallic roof sheeting to sweat somewhat considering that It'll be in touch with the warmer unvented fiberglass-insulated purlin "cavity" underneath. When our very hot Caribbean sunshine starts to kick in I want this humidity to dry and/or diffuse out of this cavity, in the gypsum sheeting, into your cathedral residing Place beneath, to then be blown outside of my 4x3 gable window. A vapor barrier would totally retard this method.
I suspect that Bill Rose is true: these failures require moisture that is carried by relocating air. They are not diffusion failures. When the rafter bays genuinely are correctly dense-packed -- a large if -- the possibility of air movement roofing company augusta ga is rather reduced.
Nevertheless, I feel you will be wrong about your asphalt felt; I doubt In the event the felt is impermeable to h2o vapor. Most different types of asphalt felt are rather permeable -- typically five perms when click now dry and up to 60 perms when damp.
Builders resolve this issue by furring down or scabbing on further framing down below the rafters to deepen the rafter bays.
In the ultimate summary it reads: "In case you are using fluffy insulation, you will need two air barriers: one particular beneath the insulation, and just one above the insulation.
Install closed-cell spray foam towards the underside of your roof sheathing, and no other style of insulation. Be certain that the thickness of the spray foam is sufficient to satisfy minimum code requirements. Bear in mind that open up-mobile spray foam is risky in all weather zones, and if open up-mobile spray foam is set up in this location in a chilly local climate, the underside in the cured foam need to be coated with gypsum drywall that is painted with vapor-retarder paint. Vapor-retarder paint is ineffective here whether it is sprayed straight around the cured foam.