When shingles laying on two roof planes approach each other in a valley weave the layers of shingles across the valley to create an integrated unbroken water barrier across the valley.
To layer on top of each other roofs invebriate.
Each part of the system contributes to protecting your home from severe weather.
For example towns in climates with heavy hailstorm activity or significant ice dam problems may not allow multiple roofing layers.
Other components such as metal panels or shingles are attached to the sheathing later.
Understanding the different layers of a roofing system is crucial to having a successful project and positive experience when hiring a roofing contractor.
It s usually a peel and stick product that adheres directly to the roof deck.
This layer covers the rafters and is beneath the shingles and membrane layers.
Sheathing is a layer used as the base of the roof.
Local codes might not allow re roofing.
Why you should not add another layer to your roof.
But contractors who spoke with angie s list say best practices call for stripping the roof down to the wood deck to inspect it before installing a new roof.
Roof deck is the roofing material that sits on top of the roof trusses.
Two layers is the maximum in most areas but some building codes allow only one.
Water shield is the next roofing layer that creates a water proof barrier where ice or water can buildup near the roof eaves.
Re roof or strip the roof down.
Once you have discovered how many layers of roof shingles are allowed the next decision you should make is whether you will have the existing shingles completely removed to make way for two or three new layers or whether you will have another layer of shingles placed on top of the existing layer.
Now you just have to decide whether to remove the existing roof shingles or recover the roof.
Apply a liberal amount of plastic roof cement at the base of any fixtures plumbing pipes or roof vents which break the plane of the roof surface.
Place the top of each starter shingle firmly against the bottom of the shingle immediately above it and even with the eaves then nail it into place.
Use 1 5 or 1 75 inch roofing nails.
Most cities and towns allow a maximum of two layers of shingles says chad muth president of muth company roofing in westerville ohio.
Here are the layers of a roof in order of application bottom to top.
A re roof might not look good on an inspection report.
Most roof decking is made from sheets of plywood.
Additionally make sure that the product you decide to use warranties this type of application.
However most building codes limit a home to only having two layers most homes can handle two layers but adding a third can greatly stress rafters and other structural parts of your home.
Other parts of the roof are nailed to this later.