Should an Old Roof Be Removed Before Re-roofing?

Weather Considerations

• The environment you live in plays a part in whether you should place new shingles over an old layer of shingles. A water protection membrane is essential on a roof in climates where alternating hot and cold winter temperatures create conditions where ice dams form. If you live in a climate like that and lack a water protection membrane, you need to remove the old roof entirely and install a new one that will protect your house from damage in the event of an ice dam.

Layers

• One important consideration when deciding to put down a new roof over top of old roofing is whether this process has been done before. If a house is old enough, it is possible that someone has already had the same idea that you've had and shingled over an existing roof. If that is the case, you should not roof over it again. The weight of three layers of shingles is too much for most houses.

Condition of the Roof

• This is where a problem emerges with the idea of roofing over existing material. Usually, the only reason you would put new shingles on a house is if there was damage to the old roof. Shingling over a damaged roof is not a good idea. This preserves the problem and can even make it worse. Also, without removing the old shingles, you can't inspect the condition of the structure under the roofing, which may need repairs or treatment. If there are problems there, the added weight of another layer of roofing will be problematic.

Inspection

• Ultimately, there are situations where you might be able to roof over existing shingles. It is difficult for the standard homeowner to evaluate this on his own. The absolute best approach to take is to hire a roofing professional to evaluate your existing roof. He should be able to tell you if it is safe to shingle over your existing roof. Stick to the advice of the professionals, and you should end up with a reliable roof.