Brick chimney leaking into fireplace
We have a brick fireplace at the end of our family room. Outside the bricks start at ground level and rise upwards about 25 feet. Inside are two flues. One that has a metal liner inside the tile for the basement gas-fired water heater and the other a 13" square tile flue for the fireplace.
Water leaks into my brick fireplace during an extended period of heavy rain. Water drips from the back of the lintel into the firebox area, and it also saturates the bricks that make up the interior fireplace surround. During a recent 24 hr drenching rain we collected about 10 gallons of water that had dripped into the firebox.
After the surround bricks dry out (it can take a couple of weeks) they are coated with heavy salt deposits. There are also salt deposits on the exterior, chimney bricks, but they are lighter than the interior. The flue has a chimney cap (steel cover supported by a steel screen). The shed roof that abuts the chimney has a cricket against the chimney. The chimney flashing was redone when the roof was replaced 2 years ago and it looks to be well done and well sealed. Four years ago a mason repointed the bricks of the top, ca. 8 ft of the chimney, reset the top three courses, and replaced the mortar cap. The next year he came back and sealed some hairline cracks in the morter cap with silicone caulk.
None of these things seem to have had any great effect. We're still having the problem. Yesterday I have a chimney repair company look at the chimney and they recommended treating the exterior bricks with a water repellant. They claimed that the water was being absorbed by the interior bricks and leaking into the flue.
That doesn't make sense to me. I could see that the exterior bricks could absorb water, but don't see any reason why that water would want to seep out of the bricks and drip at a high rate into the firbox. It seems more likely that there is a leak in the top of the chimney near the mortar cap and the water is dripping down the chimney and into the fireplace. But the repair person looked at the mortar cap and claimed it was ok...and then went on to recommend a plastic sealant for it, as well???
He did say that some of the mortar was missing from between the flue tiles. But that there was not enough to be of concern.
Any suggestions? Water repellent seems, at best, like a bandaid. More likely it is a way for the chimney repair person to generate the highest profit in the least time. I'm looking to get the real problem corrected.
By the way, I tried to use a hose to locate the problem, but didn't see a leak. In the rain it takes many hours for leaks to develop, and I can't afford to spend several hours at each spot waiting for a leak to develop before moving on to the next spot.