Two layers of shingles trap more heat which in turn damages the shingles and shortens the life span of the roof.
Shingles roof layers.
Roofing layers from the framing to the shingles so we ll start at the bottom of the deck and work our way up through all the roofing layers until we reach the shingles and sunshine above your roof.
Here are the pros and cons.
You create them through shingle snapping or buy them directly.
This roofing layer will add even more protection against water perfectly combining with the water shield.
Saving on the initial shingle installation doesn t solve the long term cost of adding a second layer of shingles.
Most building codes allow this but is it a good idea.
Roofing underlayment is a layer of material usually synthetic or felt that adds extra protection on top of the roof deck and under the shingles.
Richards also estimates that the homeowner saves at least 1 000 in costs associated with removing and properly disposing of the existing shingles.
When it s time to replace your roof there are several factors that might lead your roofing professional to recommend adding shingles on top of your existing layers.
Framing includes the roof trusses that sit at the top of your house and support the weight of all the materials used to build your roof.
Most building codes allow up to two layers of organic or fiberglass asphalt shingles.
First of all multiple layers of shingles simply means layering a new asphalt shingle roof on top of the old one rather than stripping the roof completely to expose the sheathing and replacing it with new shingles.
You can either use special shingles called ridge shingles or cut a number of regular shingles into 3 tabbed equal pieces and bend each so they fit snugly on the roof peak and nail them into place.
3 tabs are less expensive but also less durable have lower wind resistance and have a flatter appearance.
That limit pertains to roofs with up to a 4 12 pitch.
Shingles are the element that most homeowners are familiar with as it is the layer you can see from the outside of your home and it is an important aesthetic aspect.
There are some advantages to roofing over existing shingles says dale richards owner of richards roofing in troy michigan.
The homeowner will have two layers of shingles protecting the roof and the home is less likely to have ice dams he says.
Chances are your roof structure was designed for a dead load of one layer of shingles plus extra for snow and a safety margin.
Synthetic underlayment helps repel moisture and provides protection against water infiltration.
Good quality composite shingles can weigh 350 to 450 pounds per square 100 square feet of roofing installed.
This is water resistant so moisture can pass through and water in a liquid form is blocked.
Pros to overlaying a shingle roof.
You ll need longer nails for this part as you re driving through more layers of shingles.