Sometimes, these ventilation channels are mounted previously mentioned a layer or two of rigid foam. It’s also attainable to invest in nailbase (a style of SIP with OSB on a single side rather than two) that features built-in air flow channels between the OSB as well as rigid foam; a person brand name of those panels is Cool-Vent from Hunter Panels.
Nevertheless, I feel you will be Completely wrong regarding your asphalt felt; I doubt When the felt is impermeable to drinking water vapor. Most kinds of asphalt felt are to some degree permeable -- usually 5 perms when dry and as many as 60 perms when soaked.
I've a series of queries that include many of the subjects that you've included in these article content, but I am looking to use them in a retrofit situation. We're working on upgrading the Vitality efficiency, including extra/updating insulation, for our almost a hundred calendar year aged 2-1/two story balloon body property (stucco over lathe exterior).
two. Everytime you put in fiberglass batts, air obstacles are a great deal more important than vapor Command. You'll need a very good air barrier on each side of your fiberglass batts.
An additional Predicament I am obtaining re: Ice & Water Protect is the fact I had been looking forward to removing the freshly put asphalt felt which is presently more than the pine T&G and changing it with a distinct product, since the asphalt odor in the felt is coming from the T&G ceiling and bothering me (just in the event that I needed any evidence that that ceiling is horribly air permeable...). But then I browse inside the Grace Ice & H2o Shield set up Recommendations that "Due to its slight asphaltic odor, never utilize Grace... Ice & H2o Defend... where the membrane is subjected to interior dwelling places." So if I substitute the felt with Ice & H2o Protect or an identical asphalt-based mostly products, I'd almost certainly just be leaping within the fireplace in to the frying pan, odorwise.
You might be describing a cathedral ceiling that comes with all feasible problems. There was no attention to air sealing. The worst attainable insulation was made use of (fiberglass). Along with the roof assembly is unvented. So it is actually no shock that you're viewing condensation.
Don't forget, an insulated sloped ceiling isn’t generally a good idea. At times pop over to these guys a good previous-fashioned unconditioned attic is the best way to cap your house.
If at all possible, consist of a air flow channel over the highest within your insulation layer. The ventilation channel will deliver affordable insurance policies versus moisture Make-up, and can lower the possibility of ice damming.
A vented cathedral ceiling only makes sense If your geometry of your respective roof is straightforward. You will need a straight shot from the soffits into the ridge. That’s relatively effortless with a gable roof without any dormers or skylights, but When the geometry of your respective roof is difficult — with options like hips, valleys, and dormers — it’s impossible to guarantee air flow by way of all of your current rafter bays.
Martin, Thanks to your reply. Those content are equally incredibly educational. I am obtaining the perception that SIPs can be done well, but is usually beat in value with exterior rigid foam methods when you've suggested, with equivalent or far better overall performance (with emphasis on air-tightness).
The code restrictions on the use of air-permeable insulation amongst rafters were being created to circumvent the roof sheathing from rotting. When fiberglass batts are installed in unvented rafter bays, the batts allow for moist indoor air to reach the chilly roof sheathing.
I have a partial cathedral ceiling within the finished attic of my dwelling in zone 4 (TN). Each slope from the roof is split around in thirds by three diverse cases: knee walls within the outer thirds, "cathedral" ceiling in the center thirds, in addition to a vented "attic" in the middle third by using a ridge vent - a typical scenario with concluded attics, at least around below. I have a major difficulty in the summer with overheating. The insulation isn't Doing the job very well as it was inadequately insulated with just R-19 fiberglass batts involving the rafters with out a ventilation baffle or suitable soffit venting and only r-19 blown in the "attic House". Furthermore, my upstairs HVAC ducts are operate within the definitely very hot "attic" Place underneath the ridge. Depending on what i haved uncovered from a number of articles or blog posts listed here, my prepared Remedy should be to cathedralize all the roof, eave to ridge: install continous air-limited internet site-built two" vent channels making use of foil-faced polyiso board (as suggested in ), setting up continuous soffit vents to drastically improve the airflow from soffit to ridge, making an air-limited ceiling under the rafters, and, most of all, provide the ductwork inside the conditioned envelope.
Even though the GBA Web site previously includes quite a few articles on the topic, we continue on to acquire Recurrent questions on The simplest way to insulate a cathedral ceiling.
Irrespective of whether you decide to make it vented or unvented, get the small print proper — for the reason that every single cathedral ceiling offers options to help make big faults