Another issue is that when you add in the second layer it can add extra weight to your roof.
2 layers roof shingles.
This will force you to replace your roof earlier than expected.
On most flat roofs such as epdm tpo or modified it is perfectly acceptable to two layers of roofing.
Asphalt shingles come in two major types 3 tab and architectural.
For many years it was acceptable to put even the third layer.
If you are putting a layer of asphalt shingles over an existing layer of asphalt shingles on to a 3 4 inch deck or a plank deck then you should be using 1 1 2 inch nails.
Two layers is the maximum in most areas but some building codes allow only one.
Most cities and towns allow a maximum of two layers of shingles says chad muth president of muth company roofing in westerville ohio.
The second layer of shingles will trap heat which can result in the decomposition of both roof layers.
Here is a video on how we lay a second layer of asphalt shingles over existing asphalt shingles.
If your decking is less than 3 4 inch then a 1 1 2 inch nail will suffice.
Roofers will have to work harder and longer to remove two layers of shingles later making the savings only temporary.
Hope you like it.
For example towns in climates with heavy hailstorm activity or significant ice dam problems may not allow multiple roofing layers.
This is especially true if you ve overlayed your new shingles on top of warped shingles.
Asphalt shingles typically can have one more layer added over the top two roofs total.
Steep sloped roof products such as tile slate metal and shakes only allow one layer.
Saving on the initial shingle installation doesn t solve the long term cost of adding a second layer of shingles.
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.
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 the structure can support the added weight a typical 20 square 2 000 square foot reroof will cost at least 1 000 less than a tear off job.
Two layers of shingles trap more heat which in turn damages the shingles and shortens the life span of the roof.
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.