Do not make any hasty decisions that you'll regret. If essential, notify your roofer to stop all work on this project until finally this issue is solved (assuming, of course, that your roof sheathing is guarded by asphalt felt or an analogous underlayment.)
I'd personally include to Martin's list of materials for rafter vent channnels, fiberboard sheathing. I take advantage of I joists for vented cathedral ceilings and staple one/two" fiberboard to The underside of the highest cord on the I joists. It might be ripped over a table noticed and installs swiftly, fiberboard does Possess a large perm score and should enable tiny quantities of dampness to pass through in the vent Area.
I reside in northern Vermont, and I haven't got ample working experience with air con to answer your dilemma about condensation on interior ducts.
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If you want to build a ventilated insulated sloped roof assembly, pick a form of air flow baffle which might be put in in an airtight fashion. Internet site-created baffles are finest.
It's a code violation to set up an air-permeable insulation like fiberglass batts concerning unvented rafters. It is also a bad idea, simply because humidity can accumulate on the roof sheathing if you try this process, and you may end up having sheathing rot.
Back for the vent concept. I really Imagine venting a roof which is airsealed in the interior effectively and crafted without the need of vent chutes is potentially the best way to Establish cathedral ceilings.
The best Answer is to deal with the specific situation from over, by including a substantial level of rigid foam higher than your present roof sheathing. You could build up the layers yourself, of you can buy SIPs or nailbase panels.
one. It's always a foul thought to set up an HRV in an attic. HRVs should be available adequate to the homeowners to routinely change the filter.
Code will not appear to apply since it's grandfathered in. It looks like I need to redo the corridor ceiling.
Martin, because of your outstanding and well timed tips, we at the moment are headed towards a solution of rigid foam about the outside on the ceiling. Thank you for pointing me During this new and enhanced route. We remain Doing the job out some information, including...
The Continued plan is to set up it (from The within of the home) concerning the similar time the drywall is set up. I'll instruct my crew to make sure there won't be any air pockets within the purlin cavities & no air stream to the latter.
"The regular roof air flow necessity Employed in setting up codes and asphalt roofing companies calls for one square foot of "Internet free ventilation area" for every three hundred sq. toes of ceiling region (attic floor spot) when vents are evenly divided — fifty percent of them significant on the roof within the ridge, gable, or maybe a high roof, and 50 % small about the roof in the eaves.
Many people creating vented cathedral ceilings use the inside drywall as their ceiling air barrier. The conventional way to make the changeover between the exterior wall air barrier and the interior ceiling air barrier is to setup a broad piece of plywood in addition to the wall's top plate.