Thread: Cracks in Fireplace

House 1948, addition where fireplace is built 19??. Cracks are in the brick above the ends of the lintle. Both cracks are only slightly larger at the bottom than the top. No noticable vertical displacement. No cracks observed inside the firebox walls. Unable to view firebox floor as gas logs installed with mineral wool and vermiculite for ember effect. Right side of fireplace is on CMU's that are on there sides, does not look like there is footing under the CMU's.

I think this is one for SE. What do you think?

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Originally Posted by Vern Heiler

Right side of fireplace is on CMU's that are on there sides, does not look like there is footing under the CMU's.

You sure that the right side of the fireplace is on the CMUs? That looks like the hearth extension to me. It sure matches up pretty close visually to the first photo showing the brick hearth extension from the top side.

Id say its been like that for a long time.

Best

Ron

Actually I think it is under the clean-out, located at deck level. I think the hearth extension is infront of and to the left of the CMU"s.

I just can't come up with a good reason for the location of the cracks. Its like there is or was horizontal pressure pushing out from the top of the opening of the fireplace?

Originally Posted by Ron Bibler

Id say its been like that for a long time.

Best

Ron

I tend to agree, but don't want to buy a fireplace and chimney!

Originally Posted by Vern Heiler

I tend to agree, but don't want to buy a fireplace and chimney!

You ID it. now defur it to a contractor.

Best

Ron

Just pondering here. Could this have been caused by too hot of fire too fast. Not warming up the brick before throughing on a wheelbarrel of split pine?

Originally Posted by Vern Heiler

Its like there is or was horizontal pressure pushing out from the top of the opening of the fireplace?

Originally Posted by Vern Heiler

Just pondering here. Could this have been caused by too hot of fire too fast. Not warming up the brick before throughing on a wheelbarrel of split pine?

Steel angle not large enough for the span/load. The steel angle bows downward toward the center, the load crack vertically through the brick near the ends?

Hi Vern i don't think heat had anything to do with the cracks. Concrete and Brick work is like glass it will bend and then bend a bit more and then crack. Its just what concrete and brick work will do. If you look at most interior windows inside or out or if you look at stucco just about every window will have cracks at the upper corners. Your fire place has cracks at the upper corners. No big deal its what brick work likes to do...
As Jerry stated on his post ? hard to say...

Hope this helps

Best

Ron

Originally Posted by Ron Bibler

Hi Vern i don't think heat had anything to do with the cracks. Concrete and Brick work is like glass it will bend and then bend a bit more and then crack. Its just what concrete and brick work will do. If you look at most interior windows inside or out or if you look at stucco just about every window will have cracks at the upper corners. Your fire place has cracks at the upper corners. No big deal its what brick work likes to do...
As Jerry stated on his post ? hard to say...

Hope this helps

Best

Ron

Ron,

I know it's very easy to give flippant advice such as you just did, but ANY crack in a fireplace has a potential to be a "big deal".

I would recommend a Level 2 Inspection by a CSIA Certified Chimney Sweep or a FIRE Certified Inspector.

This could be an overfire issue, a settlement issue, a lintel issue, etc...

Get a professional in there to find out WHY this happened.

Bart Ogden
Wichita, KS

Thanks for the flippant advice Bart. If you had only look at the complete post you would SEE. (well maybe you would)... That i did give him that very advise... but you only look at the last part of this post and steps in it.........He wanted to understand why the fire place has cracks.
did you help with that NO...you did not you only gave some flippant advice.

Jerry peck gave the same sound info as i did ( ya wack job )

Name calling first thing on a Monday. its gonna be some week...

Best

Ron

Originally Posted by Bart Ogden

Ron,

I know it's very easy to give flippant advice such as you just did, but ANY crack in a fireplace has a potential to be a "big deal".

I would recommend a Level 2 Inspection by a CSIA Certified Chimney Sweep or a FIRE Certified Inspector.

This could be an overfire issue, a settlement issue, a lintel issue, etc...

Get a professional in there to find out WHY this happened.

Bart Ogden
Wichita, KS

I agree that it is more than likely nothing but some settling that has taken place over time.

Saying that I always suggest a certified professional for further evaluation foir the sake of the flue having no cracks.

I cannot remember when I have checked with a client in the past where a crack in the brick face had any affect on the flue. Hence "I really don't think it is anything" As far as what Ron said I would have to agree, "you ID the concern and make your opinion for further evaluation" (oops, I did not just say further eval)" and you are done with it. I know how some disagree strongly with that choice of words)

Now obviously when I see cracks inside the firebox the fire brick needs repair and it is also deferred to a certified professional.

As far as deferring anything to any trade, once deferred, I am done with it. Other than normal follow up as one should do verbally to any client if they want future work.

This is just my opinion based on the limited information. The damage on the face does not appear to be settlement or lack of support. Usually this results in a series of step or angled cracks (again meeting hypothesis, over time).

However, imagine that the damper was closed or the flue was obstructed, and the heat rolled out and up the face of this fireplace. This would heat the entire center section of the face. This section would expand rapidly starting at the fireplace opening and working its way up. Note the almost vertical cracks through bricks and mortar. You cannot have this type damage without a section of brickwork performing the same yet different from the adjoining material. The outer portion of the face not located directly under this heat source will not expand as fast and will allow heat to migrate into the masonry mass. That front face directly above the fireplace will be thinner and cannot distribute the heat as fast.

Vic and others were correct on recommending further evaluation. When dealing with gas logs, the risk of personal injury becomes more likely with a malfunctioning fireplace. An educated specialist needs to review and calculate the system to ensure several things.

1) Is this a vented or unvented gas log set?
2) Was the damper closed during operation with the gas logs set?
3) If so, why was the damper allowed to be closed during operation?
4) Is the flue to fireplace ratio proper for the required draft?
5) Are there any obstructions within the fireplace or chimney flue system?
6) And much more…

It appears that this fireplace was located outdoors within a patio area of screened room or some strange application (maybe a remodel) as indicated by the underfloor photograph. I noticed the steps up to the house in the underfloor area. Are those steps for the rats? Do you know the history of this section of the dwelling?

Fuel for Thought...

Originally Posted by Dale W. Feb

This is just my opinion based on the limited information. The damage on the face does not appear to be settlement or lack of support. Usually this results in a series of step or angled cracks (again meeting hypothesis, over time).

However, imagine that the damper was closed or the flue was obstructed, and the heat rolled out and up the face of this fireplace. This would heat the entire center section of the face. This section would expand rapidly starting at the fireplace opening and working its way up. Note the almost vertical cracks through bricks and mortar. You cannot have this type damage without a section of brickwork performing the same yet different from the adjoining material. The outer portion of the face not located directly under this heat source will not expand as fast and will allow heat to migrate into the masonry mass. That front face directly above the fireplace will be thinner and cannot distribute the heat as fast.

Vic and others were correct on recommending further evaluation. When dealing with gas logs, the risk of personal injury becomes more likely with a malfunctioning fireplace. An educated specialist needs to review and calculate the system to ensure several things.

1) Is this a vented or unvented gas log set?
2) Was the damper closed during operation with the gas logs set?
3) If so, why was the damper allowed to be closed during operation?
4) Is the flue to fireplace ratio proper for the required draft?
5) Are there any obstructions within the fireplace or chimney flue system?
6) And much more…

It appears that this fireplace was located outdoors within a patio area of screened room or some strange application (maybe a remodel) as indicated by the underfloor photograph. I noticed the steps up to the house in the underfloor area. Are those steps for the rats? Do you know the history of this section of the dwelling?

Fuel for Thought...

They built a deck over the entry stairs. The fireplace is inside.

Originally Posted by Ted Menelly

They built a deck over the entry stairs. The fireplace is inside.

Close! The addition (one of many) was built over a concrete patio. I think the blocks on there sides line-up with the right side of the fireplace. Not sure, didn't do any measuring. I turned it over to SE cause Vern don't buy no fireplaces!

I'm not an expert on chimneys by any measure. But what I do know is that the cracks appear to be from lateral thrust. I'm guessing that this is a masonry chimney without a liner or one which the flue liner that has failed. Either way, moisture has found its way into the masonry of the smoke chamber above the firebox. The source could be condensation forming by the lower burn temperature of a gas fireplace (compared to a wood burning one).
A missing rain cap or wind driven rain. Once the brickwork is wet it's subject to thaw/freeze cycle and before long insto-presto Cracks!

Anyways, that's my guess but I'm still new at this.
Besides, as an Inspector I'm not going to put that into my report. I'm simply going to defect it and refer the chimney to the specialist. Because I don't wanna buy the chimney either.