2 Layer Shingle Roof

Asphalt roof shingles remain waterproof until they dry out.

2 layer shingle roof. The resulting shingle will be 1 2 the height and the same length as an uncut shingle. This is the starter row shingle. Cut enough shingles to cover the length of the lower edge of all roof planes. However i ve seen older homes that experience severe settling after a second roof is added over the first.

Apply the starter shingle so that the. 4 layer shingle roof tear off duration. That second layer of shingles won t last as long. Another issue is that when you add in the second layer it can add extra weight to your roof.

You are correct that second layers typically don t last as long as single layers. Yeah we ll say this. 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. 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.

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. Walter wilson 3 831 views 3 23 diy shingles over existing roof duration. It will drastically reduce your roof life. This will force you to replace your roof earlier than expected.

The second layer of shingles will trap heat which can result in the decomposition of both roof layers. 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. The savings you re going to see may be in the range of a modest 25. Collizaki 90 995 views 9 39 applying asphalt roof shingles bob.

So chances are if your roof already has more than one layer of roofing you re ineligible. 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. In fact the extra layer can reduce your roof s lifespan by up to 40. That in itself eats away at the savings.

Having an old layer of roof shingles under your new layer accelerates that process as the original layer holds a lot of heat.