I’ve noticed over the last couple of years that some brick is flacking or delaminating on my 50 year old ranch. For some strange reason, the builder built the chimney something like 12′ wide up the house, looks a bit odd. Regardless, the problem bricks are on the chimney portion. We bought this house a couple of years ago and have never used the chimney, although it may have been used before. Not sure if that would cause the problem.
So I imagine that replacing brick is the only option, any other ideas?
Thanks,
Bob
Replies
Your profile doesn't say where you are located, but my guess is in an area with freezing weather.
Neither did you mention where on the chimney the brick is flacking, so this is just a SWAG.
First check the flashing cap at the top. Most of the time these are built up with the same motar that the brick was laid with (wrong). They are not water/weather proof. Over tome the motar cracks and rain soaks into the top and eventually all the way don the chimmey. Durrung hard freezes the brick face can flake off from expansion. You may also get efforfescents.
The second cause may be as simple as the type of brick. As http://www.buildingscience.com points out,brick is like a hard spong. Different areas of the country manufacture brick with more local characteristic from the raw material they use. Some is more porous, softer, or harder than other. A soft faced, porous brick would tend to do what you decribe, if not sealed on a regular bases.
Since the house is 50 years old, and this just recently started, my SWAg would be to start at the top. You may also want to use a commercial sealer after correcting the problem of where/how the water is getting in.
You may also want to do a search of FHB for a recent artile on chimney cap construction.
Dave
Likely spalling, as already noted, from freezing moisture. This can happen either from moisture penetration, as already described, or from moisture from within, as with an orphaned chimney. Go to http://www.brickinfo.org/ and hit Technical Notes button. A siloxane based product is good for an external sealant.
Thanks for the input guys! Well I guess this makes sense - freezing. I am located in the Washington DC area, we certainly freeze here, but not extremely. But I see if brick gets wet & expands - perfect explanation. I gotta get up on the roof in a couple of weeks, I'll check it out then. The flaking is near the top of the chimney. So assuming I fix the cause of the problem, is it difficult or necessary to replace bricks or fill in the face?Thanks again,
Bob
If the flaking is only on the surface, it is a cosmetic issue, your call there. if the brick are broken and show signs of further deteriation you will probably want to replace them.
The site just posted will give you the information on the proper cap treatment and mix to use.
Dave
The other posters already nailed the problem. Bear in mind, though, sealing on the exterior may exacerbate the problem of spalling due to freeze/thaw cycles and mortar that is considerably harder than the brick. (I don't know if anyone mentioned that - brick should be laid with mortar that will cure at a p.s.i. much less than the brick unit).
I wouldn't seal the exterior of a chimney where the spalling is already occuring.
Along the same lines, My chimney cap is the same, plan on addressing this summer. But I have also noted that the mortar joints are also soft and hosting some fungus/algae/ growth in certain areas. not all of the mortar, just several horizontal bands are soft enough that I can dig it out wiht a pocket knife. I know I need to grind it out and redo it, but should I only repoint what's affected? The rest of the mortar is solid and shows absolutely NO signs of deterioration. If so any ideas what caused the problem and what type of mortar mix should Iuse to redo it? Any websites with guidelines on this?
Chimneys take a beating - exposed at least three sides to weather, open at the top and sometimes extremes of temp fluxuations. Areas of soft mortar show most often at the very top, at the shoulder above the firebox, and at the base. All are affects of water. Rake or grind out the affected joints and repoint with type 'N' mortar.
Check for flashing leaks, etc which may be responsible for the dampness inside the chimney.
The reason I earlier mentioned a siloxane sealant is that it supposedly will allow water vapor to exit the masonry, but it won't let liquid water penetrate from the outside. Sort of like Gortex for bricks. DW was talked into having our exterior chimney treated with siloxane by the great-great-grandson of a lightning rod salesman while I was away, and darned if it doesn't do a good job sealing the brick. It also does a good job of sealing the sidewalk where he spilled the stuff. I just wish I could have cleaned some efflorescence off the brick beforehand, as it's now kind of sealed in. See http://www.masonrymagazine.com/4-03/sealing.html.