That s a lot of extra weight putting added stress on the roof decking.
2 layers of shingles shed roof.
Usually this number is two meaning that if your roof already has two layers you won t have the option of installing a metal roof over shingles until you ve removed at least one of the layers.
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The second layer of shingles will trap heat which can result in the decomposition of both roof layers.
In most areas building codes allow for up to two layers of shingles installed on a roof.
Also two layers of shingles are going to attract a lot more heat than just one layer which can lead to the shingles prematurely deteriorating.
If two layers already exist you ll need to remove the old layers before installing a new layer of shingles.
Roofers will have to work harder and longer to remove two layers of shingles later making the savings only temporary.
If you re peeling off two or more layers of shingles even a small section will be heavy.
This is especially true if you ve overlayed your new shingles on top of warped shingles.
Any more than two layers of shingles can be too much for the roof to handle even if the local building codes don t outlaw it.
In fact the extra layer can reduce your roof s lifespan by up to 40.
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.
Disadvantages to a roof recover.
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.
For instance instead of just one roof on your home you now basically have two.
Saving on the initial shingle installation doesn t solve the long term cost of adding a second layer of shingles.
Two layers of shingles trap more heat which in turn damages the shingles and shortens the life span of the roof.
Richards also estimates that the homeowner saves at least 1 000 in costs associated with removing and properly disposing of the existing shingles.
Reasons why you should not add a second layer of shingles it will shorten the lifespan of your roof.
The homeowner will have two layers of shingles protecting the roof and the home is less likely to have ice dams he says.
Having multiple layers of shingles is going to make your roof hotter because the heat gets trapped between the layers which could mean premature aging of the shingles.
This will force you to replace your roof earlier than expected.
You may have to pull the shingles apart to make them light enough to carry.