Gap Between Roof Sheathing And Batt Insulation

In addition to the air permeable insulation installed directly below the structural sheathing rigid board or sheet insulation shall be installed directly above the structural roof sheathing as specified in table r806 5 for condensation control.

Gap between roof sheathing and batt insulation.

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. First the easy stuff. Synthetic stucco photograph 8. Vented roof sheathing.

Use special airtight electrical boxes see photo tip 5 or seal the poly to the electrical box with acoustical sealant. Seal the gap between the bottom plate of the wall and the floor with acoustical sealant or caulk. Let s look at stucco cladding over foam sheathing over osb sheathing. If there is a roof leak the insulation will be damaged by the water leaving you with less insulating value.

For best performance the airspace in the vent chute should be a minimum of 2 in. Apply a 2 inch layer of spray foam insulation r 10 to r 12 directly to the interior surface of the roof sheathing. Of airspace between the top of the insulation and the back of the roof sheathing. Unless you re bulk filling rafter bays between 2 10 or 2 8 rafters with closed cell spray foam this approach.

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. Updated on april 8 2016. Press the poly into the sealant.

The problem arises with moisture. Tape the seams in the poly with sheathing tape. 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. There are lots of ways to insulate a low slope roof and most of them are wrong.

You can then apply batt insulation around the foam without worrying too much about the air space. 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. T he problem with the insulation against the sheathing expands. Generally spray foams have to be applied by a professional.

The air impermeable insulation shall be applied in. 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. This will keep the surface warm and help minimize condensation.