Your home's roof is what protects the inside from the elements, which is why it is so important that you keep up with maintenance over the years. If not, it's possible that a leak could form and start letting water inside. These common issues could be what is causing your roof to leak.
Installing A Layover Roof
Installing a layover roof is a cheaper way of adding a new roof to a home. Instead of ripping off all the old shingles, you lay the new ones directly on top of the old ones. There is a misconception that you have even more protection for your home with this technique, but that is simply not true.
The aging shingles that make up the first layer could be hiding damage that needs to be repaired, which includes sheathing that is rotting. There is a membrane that provides waterproofing underneath your old shingles, and that can be damaged as well. In addition, the new layer of shingles have a greater chance of becoming loose, which will let moisture get trapped underneath both the new and old shingles. This is what will cause a leak.
Caulking is not a bad thing to use on a roof, but it must be in good shape to prevent leaks. It's common to use caulking with metal flashing strips that are placed around vents, chimneys, and any other item that protrudes out of a roof. If the caulking becomes old and crumbles, it will allow water to get behind the flashing and into the roof deck. Make sure that the caulking is still in good shape, and replace it if it goes bad. This will help prevent roof leaks.
Tar Roof Repairs
When a quick fix needs to be made to a roof, tar is often used to plug the leak. It is smeared on the part of the roof that is leaking and is designed to cover the hole in the roofing material. Tar can also be used an alternative to flashing. Similar to old caulking, tar can deteriorate quickly. If you have a part of your roof that uses tar for a repair job, make sure you monitor it for deterioration.
Patching in new shingles is an acceptable roof repair technique, but only if done correctly. Shingles must overlap, meaning they're installed from the bottom of the roof to the top. If individual shingles are being replaced in the middle of the roof, they must be installed exactly like the old one. Look for shingles that were patched the wrong way, with the overlap happening in a way that allows water to collect along the seam and let water into the roof.
Once you know the cause of a leak, contact a roofing company to repair the damage that was caused.