Roof Blocking On Top Of Rigid

This insulation should be screwed down to the metal deck.

Roof blocking on top of rigid.

When we do complex roofs in high snow load areas like ski resorts we typically have the roof deck act as the air control layer and provide a high level of thermal resistance at the roof deck either rigid insulation directly above the roof deck or high density spray foam directly under the roof deck and then we provide an over roof creating a vented space over the top of the entire assembly. If you install just one layer you ll need to fasten the osb or plywood to the concrete slab with long tapcon screws that extend through the rigid foam. This type of insulated roof assembly limits thermal bridging through rafters. The three layers of rigid insulation have yet to be installed over the top of the roof decking at this point.

The type of roof. Install one or two layers of tongue and groove osb or plywood on top of the rigid foam. Install nailbase for cladding. Note that there was no air seal at this location originally.

Use a chalk box to snap chalk lines on the roof deck. Align the insulation boards with the chalk lines and lay them onto the deck. This is the method a friend and i did in his basement. The plywood was fastened through the rigid foam to the rafters with long screws.

Make sure there is sufficient soffit venting. I have to come clean here as well. They may extend a short distance beyond the wall to form the eaves and protect the sides of the building. Rafters rest on the top wall plate.

Install rigid insulation board in multiple layers with joints offset vertically and horizontally between adjacent layers. And roof overhang together into a beam. Rigid thermal insulation on the top of this air control layer in two layers at least with the joints off set horizontally and vertically. I resided 17 years ago over one layer of continuous rigid insulation.

Ladder style blocking provides the structure of a torsion box which ties the fascia soffit. Rigid insulation layers exterior to existing roof sheathing must provide sufficient thermal insulation r value to control condensation risk see climate specific guidance. Some are cut to fit the plate while in hasty construction they are merely laid on top of the plate and nailed in place. After installing several layers of rigid foam above the roof sheathing these workers installed plywood above the rigid foam.

Rafters are nailed to the plate not framed into it. Butt the ends of the boards up together. This air seal is pretty darn good. This coverboard is also screwed down to the metal deck.