We have an exposed brick chimney running through our 3rd floor flat. The mortar between the bricks seems to be very “sandy”; it’s constantly sifting down onto the floor, and you can dig it out with your finger easily. We’ve been told there’s no significant structural or safety issue (there are two terra-cotta lined flues inside the brick), but we want to stop the sifting and any further deterioration, at least on the exposed portion. I suspect it’s caused by the chimney getting wet above the roof (we’re the top floor), so maybe sealing the chimney above the roofline is in order, but is there something we can spray (brushing will just sweep out the joints, I’m afraid) that would harden or at least stabilize the mortar? We don’t want to change the color, so it needs to be clear.
Thanks
Bill
Replies
What about really wet epoxy? Maybe even the stuff you use to consolidate rotted wood?
Seems like I was just talking to someone about a similar problem--can't remember what they did though! I know an architect once told me how a school he built had mortar where the kids were just digging it out from the brick walls with pencils--turned out the mortar dried out before it cured (walls were laid up on a very hot day (several days?)) and he just had someone go and mist the mortar and it cured. That's probably not your problem though since it's an older house.
Thanks, Danno- yes the house was built in 1903.
Edited 6/22/2007 4:46 pm ET by PGproject
Do not apply any sealants or resins to the mortar or brick surfaces, you will create problems for the future. With a property this age will it be lime mortar? If the mortar is coming out between the brick it needs to be cut out then repointed - with care so that the mortar cures properly, thus sealing the surface naturally and curing the problem. It is fairly easy to get the mortar colour the same by analysing the mix and using a comparable sand. Sand and cements do vary in colour and this affects the colour of the mortar. This method will not be as fast as using a mastic gun but it is a tried and proven technology and it looks better.
What problems in the future?I REALLY want to avoid hauling buckets of mortar up the three flights of carpeted stairs in the common hall.
If you put something into or on to the brick or mortar surface which renders it impervious to moisture that may 'cure' the dampness but cause difficulties later if you need to repoint the brickwork or do a more extensive repair. I had a conversation recently with a slater who could not understand why a cement filet was not sticking to a chimney, until he realised that the chimney had previously been coated with a silicon spray and the cement could not bond properly with the stonework.
The chimney is probably crying out for some attention after a lack of routine maintenance over the years.
For the indoor portion, I'm not going for "imperviousness", just want to stick the sandy mortar in place- so far, I like the idea of the wood hardener- could be applied w/ a pump-type sprayer...
My point is that if you put anything other than mortar between the bricks you may affect what can be done in the future. A little hassle now will produce a good looking job, and it will last longer.