Chimney Flashing Maintenance for Tile Roofing
If you are wondering how to stop your tile roof from leaking at the chimney flashing, it might be
as simple as cleaning the roof.
I’ve replaced a lot of tile roof chimney flashings in my career. Most often, by the time I am called
I find roofing tar smeared on the tiles. Tar on the flashing joints. Tar on the bricks. Tar everywhere.
Usually the tar is heaviest at the corners of the chimney. Three or four applications right where the
cricket or saddle flashing runs under the roof tile.
The cause of the chimney leak is usually not poor installation, at least not on older homes, but
water running over the channel flashing that is under the side tiles.
Here, at the corner of the chimney, the rain water running off the chimney cricket runs almost
horizontally towards the vertical tiles and the side channel flashing. The rain water collects tree
seedlings, leaves, and roof debris as it flows off the roof tiles. Over time this debris builds up
under the upper tiles and creates a dam next to the raised portion of the flashing. Water is then
pushed over the dammed flashing and under the field tiles. It doesn’t take long for the water to
find a small hole in the tar paper. Soon the water will cause the nails securing the tar paper,
usually galvanized steel, to rust away leaving a hole through to the wood.
If it is just a small hole, the water will slowly seep into the roof decking. Slowly but surely rotting out the roof boards, rafters, and soaking the insulation before making its way into the ceiling of the room below.
When the leak is finally noticed in the interior, the most “common” (read simple and cheap) repair
is to smear tar around the corner of the chimney up to and over the side tiles. Thereby, yep you
guessed right, making the leak worse.
So, what can you do to prevent this?
If you have just purchased an older home with a tile roof, and there are signs of interior damage and you can see roofing tar smeared around the chimney, probably not much other than replace the flashing and repair the roof deck.
If you have a new tile roof, or you have an older tile roof and you can see that the chimney
and flashings have not been tarred, hire a professional roofer to regularly clean out the debris
from under the tile flashings. It usually does not take too long and can prevent costly repair.