Your program will get the job done high-quality, as long as the layer of rigid foam along with your roof sheathing has an R-value of at least R-20. In case you are working with XPS, you may need no less than 4 inches of foam. If you are utilizing polyisocyanurate, you need a minimum of 3 inches of froth.
If possible, incorporate a air flow channel previously mentioned the highest of the insulation layer. The air flow channel will present low cost coverage towards moisture Create-up, and may lessen the prospect of ice damming.
If you decide not to increase the rigid foam in excess of the elements of your roof that have a conventional vented attic, your builder (or an architect) can think of a trim depth that you choose to could possibly Dwell with.
At last (I promise this is my previous topic). Relating to my fiberglass batts: Will the struggling with that comes with it retard the drying out course of action which i described above (does it subject what facet I set it on inside the purlin cavity?
Chuck- Google "reclaimed foam." There are a number of sellers of reclaimed foam in MA. You are going to preserve a bundle and assistance the Earth besides.
As I defined inside the article on this web site, you can't use fluffy (air-permeable) insulation within an unvented roof assembly Until you include rigid foam or spray foam over the fluffy insulation.
Back again to your vent strategy. I actually think venting a roof that is airsealed in the interior properly and designed with no vent chutes is quite possibly The easiest way to Create cathedral ceilings.
The for a longer time you wait around to set up rigid foam earlier mentioned your roof sheathing just after your rafter bays are stuffed with fluffy insulation, the bigger the chance that your roof sheathing will accumulate dampness. A couple of years should be no issue, but I would not stretch the exercise much farther than that.
Concerning installation: When it's been properly put in in Europe for quite some time, we've just gotten the material, and so we look forward to finding it with a career internet site soon and really installing it - and naturally, reporting back again the way it went.
BTW, for the foam type, I am leaning toward XPS because 1) I hold the perception that ISO is to some degree fragile, for example if it will get in any way wet, and a couple of) the possibility of lasting outgassing with ISO. Ideally any these kinds of outgassing would go upwards and outwards as opposed to downwards into the home interior, but the prospect that it will outgas into the inside seriously problems me.
I really have to surprise When the failure while in the photo would've occured In the event the hip and ridge was vented and everything else the same?
If we're going to put some insulation previously mentioned the ceiling, then I would like to place The many insulation earlier mentioned the ceiling, and steer clear of the Charge and headache of a different decreased ceiling. Meaning a Develop-up of eight", using XPS. If we Create up the roof line higher than the cathedral ceiling of the relatives room by eight", we presumably will need to create up the rest of the adjoining gable roof also.
Set up rigid foam insulation previously mentioned the roof sheathing and air-permeable insulation in between the rafters. Such a assembly is built to dry to the interior, Therefore the assembly really should never include things like an inside polyethylene vapor barrier. If you decide on this process, it’s attainable (even though not necessary) to put in vent channels in between the best on the rigid foam and the best layer of roof sheathing by putting in a series of parallel 2x4s — a single over Every rafter — extending from soffit to ridge. (To find out more on this method, see How to set up Rigid Foam In addition great post to read to Roof Sheathing.)
I'm opening up my household and installing cathedral ceilings, I just needed to verify my strategy because I acquired next ideas reading Increasingly more about it. My first conclusion was to go with a vented roof method and R38C batts. I browse a good deal about the different procedures and it continue to appears to me this is the best. Livint in Atlanta GA We've to cope with both hot humid summers and cold winters, so humidity Regulate is an issue, This is why I feel the vented strategy is the greatest. Anyhow, I am all the way down to the rafters and roofdecking and furred out the existing 2x6 with six" metallic studs, so I have about 11.five" for insulation. Mt system was to create a continual ventilation beneath the roofdeck, my problem goes to to make use of baffles, xps board Develop baffles or insect display screen nailed at furring strips to site link permit to the airspace.