No Gap Between Roof Sheathing Panels

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.

No gap between roof sheathing panels.

The recommended maximum gap between roof sheathing boards for low quality 3 tab shingles is 1 4 inch. Avoid butting osb panels tightly leave a 3 mm 1 8 inch gap between the osb panels to allow for expansion. Roof trusses must be dry when sheathing a roof with osb to prevent mold growth in the roof and coverage gaps as the trusses dry and shrink. Apa recommends a 1 8 inch space between panel edge and end joints.

Lay sheets in rows with the long edge horizontal to the roof bottom. Plywood and oriented strand board osb like all wood products will expand or shrink slightly with changes in moisture content. What h clips do h clips provide additional stiffness between bearing points for the unsupported edges of wood panel plywood or osb roof sheathing along with the necessary 1 8 gap for expansion as shown below illustrated on a bag of simpson h clips. That can mean costly time consuming callbacks.

When you sandwich the layers so there is no air gap you only get the insulation value of the closed foam in the prodex material. The minimum osb panel size is 24 inches in any direction and each sheet end must rest on a rafter. Unless you provide a small gap between the exterior face of the osb and the back surface of the foam sheathing to provide for some hygric redistribution. It doesn t mean that panel edge clips h clips are required although there are types of clips that will help with properly spacing the panels.

Stagger the panels over the roof with 2 supports between panel ends. Provide a 1 8 inch gap. Not always required but a good idea. If asphalt shingles are installed over sheathing with gaps exceeding 1 4 inch over time these gaps may telegraph through and become visible.

Sometimes plywood or osb was installed right on top of the boards. Some older h clips do not provide a built in gap. 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.