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spaulding of chimney bricks inside house

obx2003's picture

I am the second owner of a 42 year old home on the Outer Banks of North Carolina.  The former owner had a leak around the chimney which resulted in spaulding on the side of the brick chimney on the inside (painted) surface of the room.  The previous owner claimed to have fixed the problem.  I, in addition, have remodeled the house and there is now a new roof with new flashing at a higher level up on the chimney which should have added additional leak prevention.  I have also coated the outside of the chimney with a silicone coating.  I have done everything except put a plug in the top of the chimney.  Since I don't use the fireplace, I can do this.  Anyway, there is either a continuation of the leak or the spaulding is residual.  I have now scrapped the spaulded area (about 2 feet by 7 feet) and find the bricks very soft.  I can literally scrape a line or flake off chips of brick.  I believe that I have about 95l% of the bad material cleaned off but before I repaint do I need to coat the area with some kind of a sealer?  If so, what product?


Thanks for any help you may be able to offer.



(post #62931, reply #1 of 16)


Forget about painting the brick chimney...find out what is causing your moisture problem first...otherwise your interior work will be ruined in no time and all your efforts will be for not!

It sounds as if your chimney does not have a flue liner. Are you sure NOTHING is tied into this chimney...such as a gas furnace or gas water tank? If you are 100 % certain that the ONLY PURPOSE of this chimney is for the fireplace, which you do not plan on using ever again, then,

1. Remove the chimney bricks down below roof level, and have it properly capped off. This step will allow you to remove the existing step flashing and simply cover area with regular shingles...eliminating chance of future water penetration due to possible poor flashing job. Capping off chimney prevents water/snow from entering.

2. If worried about water creeping into old brick, have chimney stuccoed with a product such as quickcrete's surface bonding cement ( it's cement with chopped- up fiberglass in the mix for strength...when cured, it is water proof) or else have a mason repoint (tuck-point) all the mortar joints.

3. Use the above mentioned surface -bonding cement mixture on the interior side of your damaged chimney. Apply this mixture liberally, let cure, then paint over it. Use a bonding agent such as Thorobond when applying stucco so it will bind to brick more easily.

Again, unless you can find and stop the moisture infiltration first, your remodeling efforts will be ruined...plain and simple.


(post #62931, reply #2 of 16)

Hi Jack.

Me again...I mentioned "infiltration by water or snow"...

That was dumb of me since I doubt you ever get snow at the Outer banks, right? But, you do get lots of high winds, and rain from time to time, not to mention salt air?

Check and see whether the mortar joints on the exterior side of your chimney is flaky , soft or crumbly.... if so, really good chance that mortar joints are failing...especially in an environment such as that...especially if original mortar mix had too much sand and too little portland.

Would be a good idea to have professional mason come and inspect for tuck pointing.

Still, for me , number one option is to partially tear down chimney and plug (cap) it off.




(post #62931, reply #4 of 16)

Davo,  Thanks for your reply.  This is a response to both of your messages.

You are right, it rarely ever freezes or snows here on the Outer Banks but my home is on the east side of Roanoke Island (right on the Roanoke Sound) and we get a lot of wind and salt spray from the frequent "northeasters" (one is blowing right now).  Another respondant advised that I don't have spalling but do have rotten bricks.  I guess this could be true but it is only in an area of 2 feet by 7 feet just at the top of the ceiling.  I don't recall if I mentioned that when I bought the house seven years ago I noticed the defect and questioned the owner (the wife of the builder who was by then deceased) and she advised that they had had the roof area around the chinmey repaired.  Obviously it didn't work because it was still "peeling/spalling."  I addressed the defect (thinking that the previous owner had repaired the problem) and sometime thereafter it happened again.  Please note that this area is little more than a closet and we rarely ever go into the area so noting the reappearance of the problem is problematical as to when it occurred.

About four years ago I added 16 feet across the back of the house and, in so doing, erected a completely new roof over the affected area and around the chimney.  The location of the new roof was about one to three feet up on the chimney (the variation is due to roof slope) and, of course, the new roof was flashed to the chimney thus all problems should be resolved.

Now, after being prompted by my wife, I recognized the extent of the problem and am now addressing it.  The question is, when did the problem reappear - before, during, or after the new roof was erected?  I choose to believe that it happened before the new roof and was just not noticed by either my wife or me. 

One further "fix" that I have taken was to coat the entire outside of the chimney with a clear silicone.  This fixed a similar problem that I had with a rock chimney on my home in Hendersonville, TN some years ago.  I can only assume that the silicone has helped to some degree.  My next step will be to put a plug in the top of the chimney.  Since I don't, and never intend, to use the fireplace this will pose a problem only for the next occupant of the house.  Tearing down the chimney is not an option.  It is a major architectual element of the house.

You mentioned the possible absence of a flue liner - Yes, it does have a flue liner and there is nothing else tied into the flue - only the fireplace.

You are 100% correct in stating that I must stop the infiltration of water in order to effect permanent repairs.  I think that I have done so but one can never be sure until the problem either goes away or re manifest it self again. 

My request for help, assuming the leak has been stopped, addressed the possible use of a sealer before applying a new coat of paint.  This may not be necessary but since the bricks appear very soft in the defective area I thought that this might be appropriate.  Please correct me if I am wrong.  If I am correct then a recommendation of a specific type or manufacturer of a sealer would be appreciated.  The only concern being that I want to preserve the appearance of a painted brick wall which shows the outlines of both brick and morter joint.

Davo,  I really appreciate your taking the time to write and your advice is valuable to me in arriving at a solution.

Thanks again,



(post #62931, reply #8 of 16)

Heres a suggestion , get on a ladder and bring a hose up there and let the water run down the roof behind the chimney with out wetting the chimney itself.(prosess of elimination). If no leak is found spray one side of the chimney if possibble and see if it leaks, and keep checking the other sides one at a time in the same fashion.Now i have a question, Is there secondary aluminum step flashing underneath your lead flashing if so there should be one piece for every course beneath the lead and woven into the shingles. Next question is the lead installed correctly are there enough pieces along each side.... i have seen cases where not enough lead was installed along the sides of the chimney and no secondary flashing was there either and the chimney leaked in high wind storms, i would do these check points prior to using the hose ok. Last of all is the lead cut into the side of the chimney on each piece of lead and is it cut in an ample amount , (a half inch bend in the top of the lead can work its way out in high winds) the lead should be in atleast an inch to an inch an a half and sealed around using mortar or other methods approved for chimney use. Hope this helps......

(post #62931, reply #10 of 16)

Shavey,  Thanks for responding.

I agree that the "hose" method might be a good idea.  It could be a very good indicator since I have access to the chimney in my attic and can easily see if there is water seeping down the bricks.

As far as secondary aluminum flashing under the lead is concerned - I don't know.  I don't believe there is any alumnium or lead in the structure.  To my knowledge it is all copper and the flashing is "inleted" into the mortor.  How far, I don't know.  I'll have to contact my contractor (who remodeled the house for me) how far they encased the flashing.

Thanks again for your advice.



(post #62931, reply #11 of 16)

I've been following this thread and just wondered if that penetrating resin that is used to harden soft wood after you remove the really rotten stuff would work. The product I use is made by Minwax. Don't know if it would work on brick, but seems like it might. Then the brick could be primed and painted.

(post #62931, reply #12 of 16)

Danno,  Thanks for your note.  I don't know if your suggestion is the answer or not but I have received recommendations to use epoxy which would really seal the area.  On the other hand, one suggestion was to use a latex masonry paint to enable the affected area to "breath."  Obviously, both epoxy and your recommendation would not allow the area to "breath."  I may be faced with the "damned if you do - damned if you don't" decision and select one option and, if it doesn't work then try something else.

Thanks again.



(post #62931, reply #13 of 16)

You're welcome. You're right about the proposed answers often being mutually exclusive--and worse, at least the one I proposed, is that once you use it, there is no reversing it. I guess I would then suggest trying the seemingly least radical and most reversable idea and then working your way to those that cannot be reversed once done. I don't see, however, where breathability is an asset with bricks, but then I don't know everything! Best wishes--keep us posted on what happens.

(post #62931, reply #14 of 16)

Danno,  Thanks for your comments. I agree totally with your suggestion.



(post #62931, reply #3 of 16)

jack... your bricks are not spalling.. spalling is when they get wet and freeze.. your bricks are rotten.. they are the wrong kind of bricks

someone built your chimney with soft bricks instead of fire hardened..

if you put a metal cap on and let them dry for about a year you might be able to stucco the exterior with a cement or modified stucco.. but more than likely.. you should tear it down

repointing it will give you a temporary fix

Mike Smith   Rhode Island : Design / Build / Repair / Restore

Mike Smith   Rhode Island : Design / Build / Repair / Restore

(post #62931, reply #5 of 16)

Mike,  Thanks for your reply.  I will probably follow your directions.  I think that a cap may be my best solution.  Tearing the chimney down is not an option.

Thanks again,




(post #62931, reply #6 of 16)

jack... in the period your house was built... a lot of chimneys were built with the wrong brick..

there is "soft brick " and " hard brick".. some well meaning people use the wrong brick..thinking "brick is brick"

 soft brick will crumble under repeated soaking ...

a lot of times soft brick is included in "used brick".... it cleans easier than hard brick ..

 if it is soft   or "rotten"  you could possibly harden it with an epoxy.

 also.. if it is used brick it may have intermixed hard and soft.. a good mason can remove just the rotten bricks and lay up new ones.. with a good match, you won't tell the old from the  new..

 if it is all rotten.. then tear down and rebuild is probably the only option

Mike Smith   Rhode Island : Design / Build / Repair / Restore

Mike Smith   Rhode Island : Design / Build / Repair / Restore

(post #62931, reply #7 of 16)

I suspect that rain/salt spray is running down inside the chimney liner, then when it hits the corbel it soaks into the brickwork. [Many times the liner doesn't extend through the corbel]

The salt will give the same effect as efflorescence when it dries out to the air and it can, in fact, produce spalling of the bricks.

I'd try capping off the flue if pulling it down to the roof-line isn't an option.

(post #62931, reply #9 of 16)

Mike,  ROGER your last.  Good advice.  I know that there is no used brick but there could be some soft bricks mixed in with the rest.  There is no way that I can now determine if soft material was used but I would think that the contractor (the best on the beach at that time) would use the best materials he could find in the construction of his own home.  He built and lived in it for 20 plus years until he died.

I like the idea of epoxy and I will explore that option.


Thanks again,



(post #62931, reply #15 of 16)

agreeing with mike smith,

bricks, or stone have to be at least as hard as the mortar used or they will spall, flake a thin veneer off, in the case of some sandstones, and  won't stand up to repeated freezing/ thawing cycles. i generally use type s or in some cases type m hydraulic mortars because of the strength, and water repellency, though i sometimes question the actual degree of water repellancy without adding admixtures. in my experience, i have repaired a chimney where some previous mason had done a clean looking tuckpointing job on 19th century brick. the effect was the same,,,, severe spalling. luckily we found some of the original brick in the cellar, where most old time builders hid scrap materials, and  after replacing the damaged bricks and re-tuckpointing with a soft lime mortar the problem was solved.  this is pretty common and if you don't want to replace all the bricks i'd look into trying the type of mortar that should have, and probably was used on the original job. mortar with portland cement in it was not very prevalent in some areas of the south years back, but then again it depends on how far back and what region.

good luck

j. jordan

(post #62931, reply #16 of 16)

J. Jordan Builders,  Thanks for your note.  I have quite a bit of information and it seems that most of it is along the same lines that you suggest.  Replacing the bricks is not an option however as they are in the middle of the chimney and in the ceiling of the first floor.  There is, of course, no freezing in the location of the problem.  I think that my best approach is to actually plug the flue to prevent water entry, let the bricks dry out for an extended period, then apply a latex mortor paint and hope for the best.  If that doesn't work then you can expect me back on the forum asking for more advice.

Thanks again.