If your home's roof is getting a bit old, the materials may not be as waterproof as they should be. Asphalt shingles can get brittle and actually shrink over time, and there may be tiny tears to the flashing or roofing paper underneath that can allow in moisture and water leaks. If the damage to the roof is not very severe or the tiles and shingles are not very old, you might consider some options for adding waterproofing to the roof rather than having it replaced altogether. This waterproofing usually involves a type of coating that is put right over the current tiles and which then provides an added layer of protection. Note a few of these options so you can discuss these with a roofing contractor as needed.

Built-up tar

Tar is a good choice for adding as much waterproofing as you want; it's referred to as built-up because you can add a number of layers for extra waterproofing and protection. Tar is usually applied over the roof with a type of mop and it hardens and becomes thick. However, it's somewhat difficult to install and usually needs to be done by a contractor who specializes in applying hot tar. You also want to take into consideration the weight of added tar on your roof and ensure your home can support that weight.

Rubber

Like tar, rubber coatings can be mopped or spread onto a roof. This layer is very thin so it may not provide quite a much protection as tar, but this thinness also means it's very lightweight. For older homes which cannot support many more layers of weight on the roof, rubber can be a good choice. Many rubber coatings need to be melted with a torch, and this too is best done by a contractor who specializes in this work.

Liquid

Liquid coatings may be the easiest to install and some homeowners might be able to add their own liquid coating to a roof. They may be brushed on just like a paint and they seep into the cracks and crevices between asphalt tiles and other such roofing materials, providing more waterproofing coverage than many other options.

Liquid coatings are also good for when you already have a coating of waterproofing over the roof, as they easily cling to any such material. The liquid coatings are usually very affordable and available at most home improvement stores, or you can have a contractor actually spray the coating over the roof for a faster and easier installation.