Worked on an older Chicago home the other day- brick on all 4 sides. Nice brick on the front, common brick on the other 3 sides.
It has been tuckpointed at some point in the past… well, more like skim coated with something as the tuckpointing is only 1/4 inch deep at best. That stuff sticks well to the brick.
I had to repair a few areas where the mortar had come out of the brick joints.
Didn’t need a grinder because the existing white mortar could be scraped out with a screwdriver.
When I wetted the repair area to keep the new mortar from drying out too quickly, the water disappeared into the brick like a sponge. That was neat to watch.
Has the existing mortar failed due to porous brick and many years of freeze/thaw cycles?
What would it take to repair properly? Is a proper repair possible without tearing down the walls?
Would a water based masonry sealer help at this point to slow further damage?
Thanks
Replies
sounds like lime mortar possible. There are others here who know better than I.
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Should be some interesting comments.
Pop tuckpointed Grandmas house in downstate IL about 15 years ago on house my grandpa built in 1910. Pretty sure it was lime mortar.
Pop said most of the place he dug out to the center of the brick to tuckpoint, and this was on the interior basement walls.
Have never looked into the deterioration mechanisms, will be interested in the answers also.
Might be old lime mortar with no portland in the mix.
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I recently had to redo a small retaining wall for my momma that I put up about 6 or 7 years ago. Used high psi decorative concrete paving stones and a bag of quickcrete's premixed mortar (from HD).
Over the past coupla winters, the snow plow had knocked this wall off kilter, so in taking it down, I was shocked to discover the mortar had turned to greyish sand. All I could figger was the movement of the moisture had caused the protland component to leach out.
Anyone got a better figger?
portland does not leach out, it enters a chemical reaction that makes it one with the other clean components.I have had lousy results with quickrete brand. I think they use a bare minimum of portland and so I add a shovelful to each bag when I have to use it.
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Typical mix in Chicago is 1 1 6. Thats one part portland, one part masons cement, and six parts sand. Have used this many times for tuckpointing and never failed
what you have is lime mortar...
it's very soft like 250psi... but the brick it bonds is also very soft usually wood fired and only hard on the outside... you'll find the bricks that face the weather to be a better brick than the center rows and the brick that faces the inside will be better than the center but not as good as the outside...
You'll also notice that you have no expansion joints...and no weep holes... these old brick walls move ad lime mortar is "self healing" it will crack and move but with a little moisture it will "self heal"
here is what you don't want to do... tuck point it with a standard portland mix.. it's way too hard... harder than the brick... when everything contracts and expands it will bust the faces off the brick... it will no longer self heal... and you will have moisture problems...
yes your brick sucked water like it was drink'n it... you can spray the wall and water never makes it to the ground... it will suck it all in... that tells you it'll expand a ton in a freeze.
you never want to seal this brick or paint it... that traps the moisture in the brick... the paint won't last and you'll have spalling of the brick face... you will also have mold problems inside that you never had before...
you need to clean the joints... hose the wall down alot... and tuckpoint with lime puddy or lime mortar... now this is the correct way.... but i don't live where we have much freeze thaw.. so i make a very weak mortar i mix my portland 25% portland to 75% lime... then i mix that mixture with my sand 1 part portland/lime to 5-6 parts fine white sand... it's a weak mortar that is easy to work with... i tuckpoint with a grout bag... so i add liquid dish soap to the mix so it'll slide out of the bag... the lime already makes it very plastic...
I did 24,000 sf of surface area with this mix... the last time i tuck pointed... not hard just alot of time...
p
Thanks for the info and insight
So, the person that tuckpointed the house over 15 years ago with the much harder mortar probably did something wrong?
The original material is white, and the surface material is a dark grey, but much harder than the original stuff.
Yes, I noticed no expansion joints or weep holes.
No sealing, even with the water based products that supposedly let water out of the brick?
Edited 10/7/2009 6:45 am ET by danski0224
"you never want to seal this brick or paint it.."Kind of like this. It is a little hard to see in the pic but the brick is painted and somebody went to a lot of trouble to paint all the mortar lines white. This building is in China Town in Manhattan.
I'm surprised that no one thus far hasn't offered this..
that's exactly what mortar does if it freezes before it sets..
Maybe they were tuck pointing too late in the fall or too early in the spring..
I'm not going to disagree with the Lime consensus, but perhaps
it's it could be a bad mix, poor installation.
It can be white colored from drying to quickly, especially
if the joints are very shallow (like a 1/4 inch). Also more
likely with very porous brick like you described.
This particular mistake turns the mud to powder, so it could
also be the culprit.
You say it stuck to the brick faces very well? Could it have been
a wet mix that was smeared on? That coupled with drying to fast will
defiantly turn out like you described.
But, in answer to the real question- Just point it properly and
all will be well. No need to worry from what you've said.
PS
Sealer will not help, but could useful AFTER it is fixed.
What ponytl describes is dead-on correct. I've had this very same conversation with many old time bricklayers and restoration professionals in the chicago area, and they say it drives them nuts how many handy types look for the hardest mortar mix they can find. The idea is the mortar is supposed to give before the brick does, and tuck pointing every 10 or 20 years or so is just routine maintenance on these old brick buildings.
I don't know much about how sealing the brick effects it, but I say if it's aint broke don't fix it. The building has stood for 80 or 100 years without sealer, and with proper maintenance it will stand another 100 more, and occasionally need tuckpointed.~ Ted W ~
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