need a new chimney?
March 6, 2008 9:06 PM   Subscribe

Looks like leaking around the chimney - roofer says it is the chimney itself, what to do?

hey all, i posted a question awhile back about my roof, finally getting around to a new one! I have water leaking down the sides of my brick chimney, and it shows up in the basement. Have inspected it from the attic several times, and it very clearly appears to come from around the chimney and then down the sides of the chimney. Over the years this seems to have caused wood sheathing planks surrounding the chimney to get quite damp and to rot. SO - i definitely figured i needed new chimney flashing - and i'm due for a new roof too. anyway, the roofer upon coming out for an estimate says this to me:

I inspected your roof today. Were you aware of the condition of the actual chimney itself? You said you thought it was the flashing that was causing the leak.

Check out the brick. This chimney needs torn down and either covered over or rebuilt to prevent your leak.

Do you use it for venting a furnace or hot water heater?

then he attaches these two pics: here and here

The chimney is for the furnace. I paid only about $50K for this house, and it is generally in good shape - i definitely do NOT want to pay a fortune for repairs up there. A new roof w/flashing was about all i had planned for in terms of a big investment around here. I had another reputable roofer up there awhile back and he inspected everything and made no mention of the need for a new chimney! he said they'd flash it and do a new roof and be good to go. Of course, the latest roofing company also does chimneys - and would be happy to do mine. He included nothing else in the email though, no estimate, no explanation of why this would cause the leak. it DOES NOT appear to be leaking from inside the chimney out, but down the sides...

The chimney looks like it may need some work - i'm no expert so can't tell - but i'm reluctant to spend big bucks, and am not sure just what he was trying to say in the email. He never explicitly said this is causing water to come in - or what it would cost - i feel a bit wary.

anyone have experience in this? How does it look to you? What sort of costs am i looking at if i do need to repair - or heaven forbid - replace the chimney...this is not something i want to do!

thanks all!
posted by Salvatorparadise to Home & Garden (6 answers total)
Blink left has expert advice. A liner for the chimney and a repointing of the bricks that need it.
posted by hortense at 9:21 PM on March 6, 2008 [1 favorite]

to add - water comes in, especially, when it snows and then sits on the roof around the chimney...when it rains like hell water comes in too - but mostly when it snows. I think it's from the snow sitting on the roof around the chimney, then it leaks in. again, this doesn't seem to indicate to me that it is coming through the actual brick!
posted by Salvatorparadise at 9:55 PM on March 6, 2008

I don't live in a climate with any significant snow, but water leaks are all about situations where water can't drain away. I would be very surprised if some flashing didn't sort this out, plus a bit of pointing to replace mortar gaps. If the existing damage is bad, well, you be the judge if it needs sorting, but flashing to prevent sitting moisture will stop it getting worse.
posted by bystander at 2:54 AM on March 7, 2008

The existing flashing is not correctly installed: Where the upper roof meets the chimney, a roof cricket should be installed. In addition, it does not look as if the flashing is shingled properly. See example here. I agree that the mortar needs to be repointed - at least - but it looks as if someone has already tried that (poorly). A chimney liner will help with the venting, but will not solve the through-brick/missing mortar water penetration. And, I think the situation is beyond re-pointing, but a masonry installer will be able to determine if the existing mortar is, indeed, crumbling. Sometimes the integrity of the mortar is totally compromised, and the bricks are sitting there via force of gravity since the mortar-brick bond is broken.

At this point, I'd suggest taking the chimney down and having it redone. It's not overly large or elaborate. Sometimes it's more expensive to repair something in place than it is to demo and rebuild. It looks as if this may be the case, but you need to have someone who's experienced in this work provide a review and estimate.

Also, since this seems to be located on the side of the house that's away from view, consider having the roofer price installation of a new, metal chimney stack and do away with the brick altogether.
posted by mightshould at 5:19 AM on March 7, 2008

Repointing of brick chimneys isn't that expensive. Call a chimney guy, get an estimate
posted by kuujjuarapik at 5:20 AM on March 7, 2008

Hi, After reading and looking I see a couple of things.

1 The chimney, If the chimney is solid, attached to itself and not "ready to fall down or be pushed over" then the outside needs tuck pointing, re crowning (the top) and a good brush on masonry sealant. The sealant will keep the repair nice and dry and can be applied by anyone with a brush. The flashing will need to removed before and replaced after, as yes it looks funky. As mightshould pointed out a roof cricket will help as you are in snow country, but if the brick pile is unstable/unsafe it needs to come down. If the brick chimney is not safe then take it down to the roof or just below the roof at a minimum. Repair The Furnace Vent (see below) then add roof jack (for the proper vent) and flashing, roof repair etc

2 "The chimney is for the furnace." In your photo the cap on top of the chimney looks like a generic wood burning masonry cap and is not normally meant to vent a gas furnace by itself. I suspect that your furnace is venting into an clay lined masonry chimney. In areas with a modern building codes the clay liner is no longer enough to vent gas burning devices. The thread Hortense linked to has some details but basically you want to line the inside to properly vent the combustion products and the moisture that condenses on the inside of your absorbent clay/brick chimney (think acid rain sort of, burn 1 cubic foot of natural gas and you can get 2 CF of water vapor). This liner will keep the absorbent clay/brick inside dry, tuck pointing and sealing will keep the outside dry. Most importantly the liner will help to keep you, in side your house from sucking fumes :( and may even help that furnace work a little better with proper drafting. The type and material for the liner will depend on what your burning, but go full length from furnace to out the roof.

Call some sweeps, fireplace installers or hvac people who can reline and repair chimneys, get 3 quotes, call references, check contractors license take dna etc etc. You could fix the roof outside etc first then reline the inside later as money allows. Gas b-vent kits are only $175 or so and you really (wiggles fingers at Salvatorparadise) want to make sure your 1994 Fraser-Johnston? is vented properly.

Also make sure your not affected by this recall

Personally I'm not sold on any brand liner, but you want UL listed kits (that match your furnaces requirements) used whole not a bunch of bits he had laying around in some truck. Some reading here and here and here
Please keep in mind that i speak generally here to the hive public, conditions and requirements in the field can change everything.
/rant off
posted by blink_left at 6:37 PM on March 7, 2008

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