Persistent Leak - Chimney or Roof? - DIY Chatroom

CMoorhead · 01-07-2009, 11:00 AM

We have had a persistent leak around our chimney for the three years we've lived in our house. Before we moved in we had a new roof installed, so we figured it was the chimney's fault. So we had a new cap put on, had it re-pointed. Nothing stopped it. We had the flashing redone and re-sealed a number of times. Still, the leak persisted.

So then we had another new roof put on. The roofers found problems with the first roof around the chimney (a gap between the plywood and the chimney), so we figured we were all set. But today, the exact same leak has come back.

When the leak occurs, the chimney brick in the attic is soaked and drips onto our ceiling.

Another bit of info - apparently, this is a common leak in the houses on our street. All were built around the same time - 60 years ago. Don't know if that helps, but I figured I'd throw it in.

Can water soak through brick? Or is this water coming from another dimension?

Thanks for your help!

AaronB · 01-07-2009, 11:15 AM

Got any pics? Preferrably while the chimney is wet inside, as well as rooftop pics. This would help greatly.

Leah Frances · 01-07-2009, 11:27 AM

Are you getting any efflorescence on the brick? That's usually a good indicator when water is moving through brick.

kgphoto · 01-07-2009, 03:06 PM

Pictures of the outside of the chimney where it meets the roof and flashing on all sides will probably tell the story. Let's also see the chimney cap.

Yes water can go through the bricks, but that would not normally be the case. More then likely the flashing is done improperly and the cricket is missing in the back.

The gap in the plywood is nothing, in fact it is required to some extent.

tomstruble · 01-07-2009, 03:22 PM

i had a problem once where warm attic air was condensing on the back side of the flashing

CMoorhead · 01-07-2009, 08:44 PM

I've got no roof top pics, but here is what the chimney is doing right now:

The first pic shows how the leak presents - the brick is all soaked, except for that dry portion in the bottom right of the photo.

In the second pic, this is sort of a cubby hole in the chimney - no sure of its purpose. But water comes in and just drips onto the ceiling from there, leading to the most damage...

DUDE! · 01-07-2009, 08:52 PM

just a suggestion, when I was looking for my water leak around the chimney, I went up in the attic on a sunny day, turned off my flashlight and there was the light of day right next to the chimney, did same thing at my son's house to find daylight around the flashing, and hopefully the sourse of his roof leak., as a side note, was talking to someone had a new roof installed year before, had a leak, told him before working on the brick, to take a look with lights off, his roofer had failed to flash around the chimney.

AaronB · 01-07-2009, 10:12 PM

Some rooftop pics and a closeup of the top of the flashing, the flashing at the rear of the chimney (with the shingles lifted to expose the roofing procedures), the top of the chimney, and of the brick would be better to get an accurate assessment.

AaronB · 01-07-2009, 10:14 PM

Im especially interested in the upper corner to see which layers were installed and if they left out a critical piece of step flashing that wraps around and gets sealed to the pan in back.

Baron · 01-07-2009, 10:39 PM

It is usually the flashing installed poorly however mortar and bricks can be porous to a degree, some more than others and they can get saturated, but usually weep more than leak.

First insure the top of the chimney is water tight to the flue tiles and pitched nicely away to shed water.

Observe to see if the clay tiles are mortared neatly on the inside.

Make sure the cap is adequate to shed water.

Then its on to the flashing.

I usually ice shield around a chimney and lay it up the chimney an inch or two when I can, making sure to overlap the bottom piece over the back of the shingle below. every shingle needs to be place so flashing adequately sheds water over it. Sometimes it works out odd with the lead flashing so care to get the sequence right helps.

Make sure the lead flashing is cut in deep enough at the mortar joints and the mortar is tight at that point especially or cut in some new lead. A very small hole at a busy joint can leak worse than it shows. So any crack is suspect around chimneys.

The back of a chimney and the corners are crucial to a good job and a crick is the wisest thing to install behind a broad chimney if not all chimneys where possible. Tar should not be all over the face of the lead or the seams. If tar is used it should be used to prevent water backing up when the physical ability of the flashing being installed is showing a limitation in its overlap, but I almost never use it or need to use it when the flashing is done with care and mated into the shingles properly.

If the mortar and brick are suspect you could stucco the exterior of the chimney with a water proof stucco such as fiberglass reinforced stucco used for parging, however you would have to really like that look.

CMoorhead · 01-08-2009, 07:45 AM

Wow - thanks for all the info so far. As soon as I have roof top pics, I'll post them. But this is all good stuff to know...