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spalling brickwork (and what to do about it)  RSS feed

 
Tom Kozak
Posts: 91
Location: Sudbury ON, Canada
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Hi All,

My house was built with bricks in 1814. Most of those bricks are still sound but a few are badly spalling (spaling, spalding, spallding?). I do have a large supply of period bricks (from an interior wall in the basement). The worst of the bricks I will chip out and replace, but there are large areas near the foundation where ALL the bricks are spalling. I'd like to just parge coat around the whole house up to about 3 feet. Is this a good idea?

concerns/questions;
1. what kind of mortar should I use around the replacement bricks?
2. is parging spalled brick a bad idea? if not what is the pest method of doing this/best product to use?
3. is there a clear finish/sealer I can put on the entire wall after the parge coat that will let moisture in but not out?
4. should I hire a local bricklayer to have a look at the place and tell me what to do?



this is in Sudbury Ontario (we get short hot summers, long cold winters and A LOT of snow).
a friend had recomended spraying with Tompson Water Sealer but said that would only be a temporary measure and I'd have to re-do it at least once a year.
thanks
TomK
 
Ben Johansen
Posts: 88
Location: Door County, WI
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Tom, sorry about your brick woes. For mortar on a brick sparge, you're gonna want a really durable masonry cement, I'd go with type N. The problem is going to arise, however, given the uneven shape and varied moisture of the brick around this corner, of small gaps eventually forming between wall and sparge cap. You can combat this by making sure you don't cake on mortar too thick, and probably adding quite a bit of sand to your mix, maybe as much as 2:1, depending on what masons in your area recommend. For waterproofing, I'm ashamed to say that I know of no eco-friendly solution. The masons I've worked with only reach for one product for waterproofing stone: http://www.google.com/search?q=xypex+waterproofing&oq=xypex+wa&sourceid=silk&ie=UTF-8 . It forms this semipermeable layer on the painted edge, which repels a lot of moisture, but more importantly, it creates a surface wicking effect, that pulls water from within and releases it.
I really like this video, maybe it'll give you some good ideas:


Godspeed.
 
Dale Hodgins
gardener
Posts: 6784
Location: Victoria British Columbia-Canada
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I have had great success with Xypex. Contact a local mason and see what is working for them. The many freeze-thaw cycles at the beginning and end of winter, cause the spalling.(Spalding is a brand of shoe) Xypex penetrates the damaged material and forms a water proof coating. I have used it on foundation walls and to coat concrete statues that were absorbing water. By far the best high tech product I've ever tried.
 
Lisa Wintler-Cox
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I'm so sorry, what did you end up doing?

I've seen this before. Someone repointed your bricks with portland instead of lime cement. They might have also sandblasted or used a non-breathable sealant. On the upside, It looks like your mortar is in perfect condition! Of course, that's not supposed to be the way it works. I've learned that mortar is supposed to be a sacrificial element of your masonry. Houses move a lot more than we think and mortar is supposed to crack before the rocks or bricks. If they sandblasted, they removed the harder outer "fire coat" which normally keeps excess moisture out.

You really don't want to double down on the waterproofing. When your house was built, bricks were a lot softer, partly because they were fired at a lower temperatures. The lime mortar lets any moisture that's absorbed move back out of the face of the building. Google "spalling bricks."

https://www.nps.gov/tps/how-to-preserve/briefs/2-repoint-mortar-joints.htm
This video shows him shoving a lot of mortar in but that's the first step--you have to compress it next. His videos have horrible sound in places but it's good info.
https://www.youtube.com/watch?v=TGs6GhGZiso
https://www.youtube.com/watch?v=4vV5-vB4fRw&index=2&list=PLb5oz8FOCSxhcVXcfEsXHixIn-qcG_pgB
 
Bill Bradbury
pollinator
Posts: 684
Location: Richmond, Utah
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Tom Kozak wrote:Hi All,

My house was built with bricks in 1814.   Most of those bricks are still sound but a few are badly spalling (spaling, spalding, spallding?).  I do have a large supply of period bricks (from an interior wall in the basement).  The worst of the bricks I will chip out and replace, but there are large areas near the foundation where ALL the bricks are spalling.  I'd like to just parge coat around the whole house up to about 3 feet.  Is this a good idea?

NO
Tom Kozak wrote:
concerns/questions;
1.  what kind of mortar should I use around the replacement bricks?
You absolutely must use a lime based as in no OPC mortar.
Tom Kozak wrote:2.  is parging spalled brick a bad idea?  if not what is the pest method of doing this/best product to use?
You have a house that is 200 years old, is your new fix going to be better than what is already there? The real question is when did this start to be a problem? My guess is just a few years after the cement walkways were installed leaving the moisture under the sidewalk nowhere to go but through your porous lime mortared low fired clay brick and leaving a calcium salt efflorescence on the surface of the brick as evidence of it's origin.
Tom Kozak wrote:3.  is there a clear finish/sealer I can put on the entire wall after the parge coat that will let moisture in but not out?
Yes, Siloxane, but this is not necessary if you jackhammer that concrete.
Tom Kozak wrote:4.  should I hire a local bricklayer to have a look at the place and tell me what to do?



this is in Sudbury Ontario (we get short hot summers, long cold winters and A LOT of snow).
a friend had recomended spraying with Tompson Water Sealer but said that would only be a temporary measure and I'd have to re-do it at least once a year.
thanks
TomK
Yes, but make sure he has real credentials and at least 25 years experience in historic masonry. No to the water sealer, not ever!

All Blessings,
Bill
 
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