How To Install Chimney Flashing

Before you begin working, you may want to ask someone in your family, a friend or a neighbor to help you. It is a good idea to have another person assist you at least in holding the ladder steady when you climb up to your roof. They can also hand you materials or tools that you might need while working.

If you just moved into a new house or just had one built from scratch, you may have to install chimney flashing. Likewise, if you already have flashing up on your roof but it has been there for many years and is suffering from severe wear and tear, you may have to replace it with new materials. Flashing and roof shingles typically will have to be replaced after about 25 to 40 years.

Before you start this project, you should know that installing chimney flashing is an advanced job. It is not recommended for individuals who have never done it before, or for those with minor do-it-yourself skills. So, make sure you know exactly what you are doing. If you are a novice, talk to people close to you or to your neighbors. If one of them has had experience doing this type of job, you can ask them to do it for you while you assist them.

Make a trip to your local home improvement store to obtain your new flashing and any tools you feel you might need that you don't already have at home. Then, when you're ready to go ahead with the job, you will have to remove all your old flashing on the roof. A chisel will come handy in removing it as well as the cement on the roof that is holding it into place. You may want to use a safety harness to keep yourself secure before climbing your ladder to get to the roof. Even if you have someone holding the ladder below, this is a good precautionary step to take.

Find the slope on your roof and label the area. Use a square to create a line from the mark to determine the run area where the flashing will be installed. Next, cut a piece of base flashing in a 45-degree angle so that it can bend to fit flush with the roof. Lay down the strips of metal flashing to the base of the chimney, and apply strips of waterproof barrier around it. Make sure to overlay the strips so that they can shed any water that runs onto your roof. Apply waterproof membrane to the back portion of the chimney in addition for added protection.

Install the flashing piece by piece, starting from the chimney's base and around to cover the shingles. Apply caulk beads in each corner piece to keep it further secured in place. Also, install roofing nails to hold the flashing to the roof.

The next thing you will have to do is to seal the sides of the chimney under the shingles and flashing. Use extra caution when sealing overlapping pieces in a manner that will enable water to be diverted from the top of the shingles. Nail the saddle with more waterproof membrane, and cut the shingles appropriately, with a portion of the flashing still exposed.

Apply extra caulking to the flashing cap. This is to ensure the entire assembly will stay completely snug and will not be disturbed by extreme weather, such as heavy winds, rain and snowstorms. After all, the main idea is to keep your home waterproof and free of leakage. Should you find the flashing to still be a bit loose after the application, you can tighten it with a small plastic shim that can be wedged within.

Make sure to cut grooves into the mortar joints in the chimney to seal up the flashing cap. Allow this to extend to both corners. Use a grinder and a diamond blade to do this, and be sure to wear earplugs, a dust mask and goggles as protection for your hearing, lungs and eyes. When you are done, you can apply a coat of paint on the new flashing, as this will help its endurance. Avoid painting over the nails holding it into place.