Gap Between Roof Sheathing And Batt Insulation

Generally spray foams have to be applied by a professional.

Gap between roof sheathing and batt insulation. Ensure that proper ventilation is maintained below the roof sheathing from the soffit vents to the ridge vent at the peak of the roof. Apply a 2 inch layer of spray foam insulation r 10 to r 12 directly to the interior surface of the roof sheathing. The air impermeable insulation shall be applied in. First the easy stuff.

Vented roof sheathing. If there is a roof leak the insulation will be damaged by the water leaving you with less insulating value. The code calls for a minimum of 1 in. However it is considered good practice to leave a 1 8 gap between sheets and that is also recommended by apa but it is not required.

Let s look at stucco cladding over foam sheathing over osb sheathing. In older buildings the usual method is to install fiberglass batts or cellulose on top of the leaky ceiling with a gap of a few inches or sometimes a few feet between the top of the insulation and the roof sheathing. For best performance the airspace in the vent chute should be a minimum of 2 in. This is best accomplishing by installing baffles on the underside of the roof sheathing in between every rafter prior to installing insulation between the rafters.

Air impermeable and air permeable insulation. Actually panels marked sized for spacing simply mean that they are slightly smaller to allow for the recommended 1 8 gap see attached apa tt 055. The moisture is held in place by the insulation which allows for damage to the framing and other building components. Providing an air gap between the stucco cladding and the exterior face of the foam sheathing prevents the debacle we got with face sealed exterior insulated finish systems a k a.

Press the poly into the sealant. Unless you re bulk filling rafter bays between 2 10 or 2 8 rafters with closed cell spray foam this approach. The problem arises with moisture. Seal the gap between the bottom plate of the wall and the floor with acoustical sealant or caulk.

Use special airtight electrical boxes see photo tip 5 or seal the poly to the electrical box with acoustical sealant. Tape the seams in the poly with sheathing tape. Updated on april 8 2016. This will keep the surface warm and help minimize condensation.

There are lots of ways to insulate a low slope roof and most of them are wrong. T he problem with the insulation against the sheathing expands. You can then apply batt insulation around the foam without worrying too much about the air space.