Never do a shingle over.
2 layer shingle roof.
That in itself eats away at the savings.
That second layer of shingles won t last as long.
Because the first layer holds a lot of heat and that can over the long haul wear out the second layer because that heat is the enemy of the asphalt shingle.
Having an old layer of roof shingles under your new layer accelerates that process as the original layer holds a lot of heat.
Yeah we ll say this.
The resulting shingle will be 1 2 the height and the same length as an uncut shingle.
If you only have a single layer of roofing currently and your home is fairly new structurally the home will probably withstand the extra weight.
So chances are if your roof already has more than one layer of roofing you re ineligible.
Another issue is that when you add in the second layer it can add extra weight to your roof.
It will drastically reduce your roof life.
The savings you re going to see may be in the range of a modest 25.
The second layer of shingles will trap heat which can result in the decomposition of both roof layers.
This is the starter row shingle.
This will force you to replace your roof earlier than expected.
Walter wilson 3 831 views 3 23 diy shingles over existing roof duration.
If you put a second layer on the second layer doesn t usually last as long as the first layer.
In fact the extra layer can reduce your roof s lifespan by up to 40.
Cut enough shingles to cover the length of the lower edge of all roof planes.
Building codes and most municipalities will usually allow you to overlay a second though never a third layer of asphalt shingles over an existing shingled roof.
It isn t uncommon to layer a second roof right over the first and then tear everything off before you put a third layer down.
Asphalt roof shingles remain waterproof until they dry out.
2 layer reroof tear off.
Apply the starter shingle so that the.
4 layer shingle roof tear off duration.
However i ve seen older homes that experience severe settling after a second roof is added over the first.