Two Layers Of Shingles On Roof

If you don t tear off the old layer you can t examine the decking.

Two layers of shingles on roof.

In most areas building codes allow for up to two layers of shingles installed on a roof. 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. The homeowner will have two layers of shingles protecting the roof and the home is less likely to have ice dams he says. There are some advantages to roofing over existing shingles says dale richards owner of richards roofing in troy michigan.

Asphalt shingles come in two major types 3 tab and architectural. Saving on the initial shingle installation doesn t solve the long term cost of adding a second layer of shingles. 3 tabs are less expensive but also less durable have lower wind resistance and have a flatter appearance. For instance instead of just one roof on your home you now basically have two.

That s a lot of extra weight putting added stress on the roof decking. Richards also estimates that the homeowner saves at least 1 000 in costs associated with removing and properly disposing of the existing shingles. In fact the extra layer can reduce your roof s lifespan by up to 40. This will force you to replace your roof earlier than expected.

This is especially true if you ve overlayed your new shingles on top of warped shingles. Two layers of shingles trap more heat which in turn damages the shingles and shortens the life span of the roof. For a second layer to be as good as a roof tear off you would have to have sound decking no leaks and a roof with no sidewalls where flashing is needed in order to tie the tiles in to the exterior walls. As mentioned above homeowners are legally limited to two layer of roof shingles.

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. If two layers already exist you ll need to remove the old layers before installing a new layer of shingles. Therefore if you already have two layers you ll need a full tear off. The second layer of shingles will trap heat which can result in the decomposition of both roof layers.

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.