It seems if one particular were being to use dense pack cellulose within a vented cathedral ceiling the vent channel content needs to be rigid adequate to resist the tension.
November eighteen, 2011 Image 1 of three A leaky ceiling doomed the roof sheathing. The ceiling of the 10-yr-old residence was Reduce for an electrical box, along with the outsized gap was by no means caulked. Humidity-laden air entered the rafter bays by these cracks. In the event the moisture encountered chilly roof sheathing, it condensed, resulting in dampness accumulation and rot. (The rubberized membrane during the Picture was made use of as A short lived patch for any hole in the roof, and did not add for the failure system.) Image Credit history: Peter Yost A leaky ceiling doomed the roof sheathing. The ceiling of this ten-yr-outdated dwelling was Slice for an electrical box, plus the outsized gap was never ever caulked. Moisture-laden air entered the rafter bays as a result of these cracks.
I utilised to work like a roofer, and roofs that are fully protected with Ice & Water Shield make me anxious. I see this sort of style as lazy and possibly problematic.
This article will discuss insulated sloped roofs. The approaches explained listed here can be used to build an insulated cathedral ceiling above an incredible place, a section of sloped roof previously mentioned a kneewall, or any identical section of insulated sloped roof.
Thank you, Martin and Stephen. The good news is we have been in a very circumstance where by we will pause and reconsider, as the new felt has actually been put, However they have not started off putting in shingles however. I will talk about the problem Along with the contractor yet again. I may be able to get him to reconsider.
I might include to Martin's list of resources for rafter vent channnels, fiberboard sheathing. I use I joists for vented cathedral ceilings and staple one/2" fiberboard to the bottom of the highest cord in the I joists. It can be ripped over a desk noticed and installs rapidly, fiberboard does Have a very high perm rating and could let little amounts of moisture to go through in to the vent House.
I have constructed dense-packed unventilated roof assemblies numerous situations with out challenge. Of course I have never torn into them possibly. I would like to see here extra samples of failures in These types of assemblies if they're out there.
Does it make sense to spray and cut and cobble four inch closed mobile foam/board on underside of sheathing accompanied by fiberglass Within the bays and one inch of eps/iso beneath the rafter (to halt thermal bridging) ahead of ending with drywall? Will I make a vapor sandwich and superior leave the final EPS and take the thermal bridging?
I concur with you: I might love to see more information on this issue. I'm not aware of any failures which have transpired in appropriately dense-packed unventilated rafter bays.
Martin, owing to your great and well timed tips, we are now headed towards a solution of rigid foam in excess of the outside of the ceiling. Thanks for pointing me With this new and enhanced direction. We remain Doing work out some information, which include...
I am knowledgeable about that tactic and have employed it on past double partitions with flat ceiling/ truss roof assemblies. Labored beautifully.
If you want to use just one variety of insulation in unvented rafter bays, you're limited to spray polyurethane foam. A further likelihood, obviously, is to make your roof with structural insulated panels (SIPs).
If a constructing inspector insists that you put in some type of inside “vapor barrier,†you are able to often put in a smart vapor retarder like MemBrain to satisfy your inspector.
A. I concur. In gentle of your odor issue, I do not believe my suggestion to make use of Ice & Water Protect was a fantastic one -- so I withdraw it.