Plenty of people developing vented cathedral ceilings use the interior drywall as their ceiling air barrier. The regular way for making the transition among the exterior wall air barrier and the inside ceiling air barrier is to set up a broad piece of plywood in addition to the wall's prime plate.
November eighteen, 2011 Image one of three A leaky ceiling doomed the roof sheathing. The ceiling of the ten-year-previous residence was Slash for an electrical box, and the outsized gap was under no circumstances caulked. Humidity-laden air entered the rafter bays through these cracks. If the humidity encountered cold roof sheathing, it condensed, bringing about moisture accumulation and rot. (The rubberized membrane from the Picture was applied as A brief patch for a hole within the roof, and didn't lead for the failure mechanism.) Picture Credit history: Peter Yost A leaky ceiling doomed the roof sheathing. The ceiling of the 10-calendar year-aged dwelling was Reduce for an electrical box, along with the oversized gap was under no circumstances caulked. Dampness-laden air entered the rafter bays as a result of these cracks.
Checking out the deadly pic I truly feel there may be a simple although unorthodox Remedy. The many rot from warm moist air satisfies cold Wooden is right near wherever a vented hip can have averted all and Devoid of vent chutes.
What got me began on the "air limited partitions and roof sheathing" was your posting of the exact same identify; specifically South Mountain Company's wonderful write-up within the Martha's Vineyard housing development. I saw Marc's presentation on Those people residences at BBD likewise.
Extremely handy (five*) thread. So, if you should use fiberglass insulation batts, and you simply dont have usage of spray foam or closed cell boards, see it here what do you do? I suppose The important thing is to make it unvented and add in other air-impermeable levels. I am about to insulate a completely new all-metal cathedral pitched gable roof in the Caribean. The approach would be to fill the cavity among the four" Z-purlins with R-eleven batting (vapor aspect struggling with the dwelling House). For extra heat conduction resistance we plan to roll An additional thinner (filleted?) layer of the batting over the top of your purlins (ie involving the purlins and also the sheeting).
Martin, Thank you to your reply. Those articles are both equally quite informative. I'm getting the sense that SIPs can be carried out well, but is usually defeat in selling price with exterior rigid foam programs while you've proposed, with equal or far better efficiency (with emphasis on air-tightness).
1. It's usually a nasty idea to install an HRV within an attic. HRVs need to be accessible enough to the homeowners to routinely change the filter.
I see your issue. I haven't worked with fiberboard. Can it's taped and regarded as a reputable Key air barrier?
Doug... For a few explanation I did't see your article #17. Appears like two of us a minimum of think there might be a surprisingly easy economical Answer.
To start with, could it be simple to discover no matter whether a roof is ventilated? If no soffit vents or side vents are obvious around the roof from the bottom, does that imply the roof is not really ventilated?
I am which includes a photo of the solution: spray foam held down in the top fringe of the rafters making sure that air can be drawn up from soffit vents to gable vents during the truncated attic cavity.
Indeed, it is actually Protected (Despite the fact that prior to deciding to inquire an issue about a specific roof assembly, It will be very good to know your climate zone).
If I changed click reference my venting depth to some internet site designed design, between the rafters, as in the several weblogs on this subject, my air barrier would need to changeover back again within just before it received on the sloped roof; really cumbersome within the gable partitions. Probably not certain how I would do this.
The outdated Canadian general guideline -- at the least two/three of the entire R-benefit you could try this out on the outside facet of your vapor barrier -- is really a rough-and-Completely ready way to handle this issue; It is also feasible to method the question by accomplishing a dew-position Evaluation or perhaps a WUFI Assessment.