That in itself eats away at the savings.
Why not to add a second lkayer on a roof.
Add a layer of shingles over the newly repaired area before you install your second layer of shingles.
Doing a second layer right means a lot of prep work goes into the overlay anyway and flashing which remember is the most vulnerable point on your roof is harder to guarantee.
However this is a particularly short sighted approach once you realize that layering roofing can often void the warranty.
The second layer is also more difficult to install properly compared to new shingles.
That helps your final layer of shingles look flat with a proper installation.
Plus depending upon the size of your roof you ve added multiple tons of weight which could pose a big problem if there is significant snow accumulation.
You re essentially adding a second roof on your house and that added weight puts stress on the roof decking which is especially worrisome in our climate that gets heavy rain and snowfall.
Most people want to add another layer to their existing roof to save money.
You need to tear off the roof and install a new one.
The savings you re going to see may be in the range of a modest 25.
What to do if the old roof is not straight if the existing roof has wavy horizontal lines you can take out the waves by snapping a horizontal line 1 2 inch below the shingle bottoms of one course.
There are already two layers of shingles on your roof most building codes only allow two layers of any type of roofing on your home.
Flashing around roof penetrations and sidewalls can be compromised.
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.
Extra heat causes shingles to curl and break down much more quickly.
This will force you to replace your roof earlier than expected.
Reasons why you should not add a second layer of shingles it will shorten the lifespan of your roof the second layer of shingles will trap heat which can result in the decomposition of both roof layers.
That second layer of shingles won t last as long.
This is mostly due to the fact that a brand new roof traps much less heat than a roof with multiple layers.
This step is important because it brings the underlying surface back to a level height consistent with the rest of the roof plane.
Adds value a brand new tear off roof can add to your home s resale value and is a major selling point.
Manufacturers believe that layering the roofing diminishes the overall performance of the roof.
