WDR Roofing Company Austin - Roof Repair & Replacement
Austin, TX, USA
Your plan will work great, as long as being the layer of rigid foam along with your roof sheathing has an R-worth of at least R-20. When you are using XPS, you'll need at least four inches of froth. If you are using polyisocyanurate, you'll need at least 3 inches of foam.
On an unrelated matter: The Cold Weather Housing Investigation Middle has created a video (under) displaying just one method of creating an insulated cathedral ceiling. The method shown while in the video is particularly suitable for builders in climates topic to ice dams.
Here's what you wrote: "I realize that there isn't any caulk/sealant among the side of the beam along with the put the place the drywall butts versus it, so there is a small air hole there. My memory is that fiberglass insulation was used. There is undoubtedly no vent from the roof."
The first vent baffles to strike the market — the traditional Suitable-Vent of your nineteen seventies and ’80s — were being affordable, flimsy merchandise fabricated from slender polystyrene. Polystyrene baffles have many disadvantages: staying slim and flexible, they will’t resist the pressures from dense-packed cellulose or blown-in fiberglass; they don’t ventilate your complete width of the rafter bay; and as normally installed, they permit air to leak out the very best in the insulated assembly.
We actually Never know if these roofs have appropriate vent channels, or what sort of vent baffles (if any) ended up utilised to keep up the ventilation gap involving the top in the fiberglass insulation as well as the underside in the roof sheathing.
Ideal on! Venting the slope safeguards the sheathing from remaining caught in between two vapor barriers/retarders and provides the h2o a spot to go when You will find there's leak....a method I will start using quickly. Thank you very much Martin.
Leak prone areas like valleys, chimneys and skylights have ice & water protect membrane installed for additional protection and satisfaction.
You might be appropriate that such a roof assembly will never dry to the inside. But it is not alleged to. I would tape the polyiso -- the tape will not likely result in any problems.
Inside the roofing company aberdeen absence of an airtight ceiling, roof ventilation can do a lot more harm than her comment is here very good, considering the fact that air click this motion in rafter bays can inspire indoor air to leak by means of ceiling cracks.
Occasionally, these air flow channels are put in previously mentioned a layer or two of rigid foam. It’s also doable to buy nailbase (a kind of SIP with OSB on one facet in lieu of two) that incorporates integrated air flow channels among the OSB plus the rigid foam; 1 model of these panels is Great-Vent from Hunter Panels.
two. I feel your proposed depth could well be challenging to Establish. How simple could it be to harmony around the rafters as you install the membrane, presumably with staples, after which you can install the 2x2 spacers, presumably with nails or screws, all without putting a foot among the rafters? I wouldn’t want to get it done.
Like Doug's structure, the main target is on making a high perm layer for drying to the outside, that will however allow venting while blocking wind washing within the fluffy things.
Outstanding posting and dialogue. I have a matter about an current unvented attic assembly. The rafters are 2x4's and also the bays amongst them are totally filled with shut cell spray foam. I wish to add two 1in layers of polyiso to the interior of attic after which include with a vapor open up membrane to airseal the assembly.
The roof was shingles on t&g pine decking. Insulation was right up towards that pine decking because seventy seven and is particularly 2014. Things seems like it absolutely was put in yesterday. Not a bad place everywhere, no roof vents totally unvented roof.