Roofing Over Tg Sheathing

If conditions are right new shingles laid over old shingles can be just as attractive and durable as shingles laid on bare sheathing.

Roofing over tg sheathing.

Roof sheathing basics the skeleton of a roof is formed with rafters or trusses generally spaced 16 inches or 24 inches apart from the center of one rafter to the center of the next. As more and more layers of the roofing kept being added there was a minimal chance that any water was going to be able to work its way through your roofing deck. The fully adhered membrane wrapped down over the cut back roof deck to tie into the wall water control layer and air control layer photograph 11. Product may vary by store.

Installation is easier than for a tear off job because you can use the existing shingles as guides for laying the new ones. Once this roofing material started to wear out composition shingles began being applied over the original sheathing. To stabilize the rafters support the roofing material and hold the entire roof together roof sheathing is installed. Add the thickness of the true fascia 15 16 in in this case.

When the roofing material wore out new composition shingles would be applied over the original roofing system. Starting with how to place the first row of sheathing we cover fastening methods the use of h clips stagg. If your roof was not a low slope roof if it was say a roof with a 4 in 12 pitch you could install metal roofing over purlins with roofing underlayment asphalt felt under the purlins and above the roof sheathing. The most common uses are as sheathing in walls flooring and roof decking.

Roof sheathing attaches to the surface of the rafters or trusses to form the structural skin of the roof. It spans the rafters to support the roofing and in the case of panel sheathing such as plywood or osb it acts as a diaphragm with the walls to resist horizontal loads. On the gable ends this was pretty easy. It is common to find older homes with 3 or 4 layers of roofing over the original roof.

Measure from the edge of the plywood outside of the wall over to whatever the overhang will be and square a line up to indicate the end of the truss tail. This type of roof has a secondary layer the roofing underlayment to catch drips and an air space to allow the drips to evaporate. Osb is a material with high mechanical properties that make it particularly suitable for load bearing applications in construction. One of the keys to over roofing is to tie the air control layer of the roof assembly to the air control layer of the wall assembly.

As more layers of roofing were added there would be little chance that water would work its way through to the roof deck. We go in depth on how to install roof sheathing.