I was cleaning my fireplace out today and noticed a couple thin cracks. One is pretty small (red) but the other seems to travel through several bricks as well as along mortar joint.

Is this a big deal that needs quick attention? Is it repairable, and if so, is it a DIY job or a pro only?

A caulking gun and a tube of refractory caulk may do it. Google how to prep it properly.

I'd leave it alone for now. That is the lining brick settling. I've far larger cracks in my fireplace but the chimney is solid.

Build a fire and forget about it.

What’s on the other side of the brick?

Those cracks can create draft or hotspots depending on what’s on the other side.

I just had my chimney company come in and do a full inspect of mine after the tornado.

If you have a chimney company, give them a call.

Never, ever fuck around with anything fire related in a home. Better to be safe.

I suspect it is not a problem... but what I need to know is the type of fireplace you have. I can't determine if that is actually firebrick which would be laid in a standard masonry chimney or a prefabricated metal fireplace and chimney.

But either way a hairline crack like that should not be a concern as long as it does not cause the masonry to get loose.

(I've inspected, swept and repaired fireplaces and chimneys for 39 years.)

You’re getting some settling. I would keep an eye on it. If it gets worse you’re going to need some helical piers if that’s an outside wall.

The only way to then fix the brick is to have a mason come out and cut out the broken bricks and replace them.

I’m going to go against the SF trust here…

First, I see two potential issues here. The first is the possibility of heat or hot gasses penetrating the firebrick to what ever is on the other side and potentially causing a fire issue. This can be relatively easy to fix by filling the cracks as best as you can with fire caulk (yes there is such a thing).

The second issue is that when solid bricks crack in a somewhat vertical nature it is an indication of settling. In a properly constructed fireplace this should never happen. Depending on the age and technique used to build the fireplace this may be a structural issue. Given that it is relatively minor at this point I would repair it as mentioned above and keep a very close eye on it. If it continues to get larger it will need to be repaired which may include tearing part of it out to assess the root cause…

quote:

Originally posted by Blume9mm:
I suspect it is not a problem... but what I need to know is the type of fireplace you have. I can't determine if that is actually firebrick which would be laid in a standard masonry chimney or a prefabricated metal fireplace and chimney.

But either way a hairline crack like that should not be a concern as long as it does not cause the masonry to get loose.

(I've inspected, swept and repaired fireplaces and chimneys for 39 years.)

Well, I don’t know what I don’t know, but it’s mostly masonry? The flue door assembly thing is metal, and there is some sort of metal panel set into the exterior brick on the outside of the chimney, but that’s it, metal-wise. The floor and walls of the “firebox” are all brick.

quote:

Originally posted by Patriot:
What’s on the other side of the brick?

Those cracks can create draft or hotspots depending on what’s on the other side.

It is an outside wall. The other side is a covered patio. The exterior of the chimney is brick all the way up. The house was built in 84.

quote:

Originally posted by Blume9mm:


(I've inspected, swept and repaired fireplaces and chimneys for 39 years.)

This just makes me smile knowing the broad range of expertise of the members in this community.

Former bricklayer here, don't worry about the hairline cracks.

If you start losing entire joints or the bricks start to separate, then its time to get concerned.

It's a masonry chimney.. and there are or at least should be a lot more bricks and masonry behind those firebrick. On top of that it is an exterior chimney and so there is nothing but 'the outside' beyond all that other masonry. The fireplace mortar folks have suggested is really a joke and won't do a thing other than make you feel better.

Now with all that said... anyone with a fireplace should have it inspected by a certified chimney sweep (CSIA.org) But as with calling any service person I would be cautious with any recommendations they make and if they are too serious get a 2nd and 3rd opinion.

My fireplace is an insert and the bricks started cracking. I bought two steel plates and had them cut to fit the bottom and back. Keeps the bad stuff away from the cracks and holds/reflects heat really well. I priced a new insert and decided that would have to wait until the thing was truly falling apart...