Picture of Repointing pre-1920 Brick in a historic home.
I live in a house originally built in the 1860's, owned by 10 or twelve folks over the years, and even was a boarding house in the 50's.  Over the years, as people got money, they expanded the house.  The last major expansion was around 1917, where a kitchen and "mother-in-law" room were added.  Sometime after 1898, someone put in two fireplaces, brick - and put some internal brick walls in the house.  I know this because I was able to find the patent for the fireplace based on some patent date info moulded into the iron.  BTW, they did all the patents once a week, so knowing the date means you have to wade through about 3000 patents. The patent was for a coal-burning fireplace you could put together with a screwdriver.  Cast Iron Ikea, as it were. But I digress.

We've been steadily working on the place for 10 years or so as money permits.  In the last few years, while trying to get a contractor to level the floors, I discovered that the brick in the basement is in serious need of repointing. The cost to hire someone, about $100 or more per square meter.  Area needing help?  all of it. I could buy a new house for the total cost. They say you have to do an "overhaul" every hundred years or so. .. well, other than occasional patch jobs by previous owners - I'm having to do it.  by hand. every few days.  'Cause I think it would collapse if I tried to do it all at once.

BUT, I discover, you can't just throw any old concrete mix in there - historic brick is SOFTER than modern brick... so just squeezing in some hydraulic cement with a caulk gun is a great way to destroy your house.

I talk to this guy, that guy, the guy who does restoration who comes to look at it, the intertubes, everywhere.  It's very simple but comes down to a few simple things.

- Mortar doesn't dry, it cures - a chemical process that requires moisture.
- Brick is hard on the outside and soft inside, so minimizing damage to the face is a must.
- Mortar isn't glue, it's a pillow for the bricks.

Since I had to piece a lot of this together on my own, I decided to make an instructable about it.

Don't say "tuckpointing" - that's the final step that is the decorative part.  the functial thing you are doing is "repointing".

I don't have building codes to follow in my area, and your area may be different.  I'm kind of on my own here regardless, and I accept the consequences of my actions.  Your area may require permits, codes, even specifically certified people.  Use them, they know what the hell they are doing.  If your house falls down, you have been warned, and you are solely responsible.
rahvin3 years ago
Civil Engineer here, I thought I would add a few comments to your rather wonderful article that I learned much about brick handling from. The first is I don't think you're describing very well how to get the mortar into the cracks. I can imagine what your doing but I don't think your words are describing it very well as some of the descriptions could be taken multiple ways. In particular I find 4 in the work-flow to be nondescript of what you are doing. I also was curious if you are pulling out all the mortar under a brick or if you are trying to leave half the brick supported, it sounded like you were removing all the loose mortar, even if it was all the mortar under the brick, which doesn't sound safe.

Finally the real reason I posted. Concrete, mortars or any lime or cement based product doesn't ever dry (well unless you're doing it wrong). As you mentioned in the article it hardens and as you mentioned in the article it's a chemical process. This chemical process takes the water and combines it with the lime/cement into a crystalline structure and hardens that structure with an exothermic process. Without water there is no reaction and if the cement/lime dry the reaction stops, the crystalline structure is incomplete and your cement will be extremely weak.

Now the key here is that you don't want the mortar to ever dry out (during the hardening phase) or you damage the end product. When casting any cement/lime based product extreme care is taken to keep the cement moistened so the reaction can complete. For example when doing sidewalks or driveways either the system is covered in moist burlap to keep the concrete moist or a chemical curing compound is used that will trap the moisture and prevent it from "drying", or losing the moisture present in the mix.

Now for the suggestion, I'd suggest that for at least 3 days after every pointing you keep the new mortar and bricks wet. It depends on the mortar's composition (when you don't have to worry about adding water) but as a general rule after the first 24 hours the reaction is far enough along that you can soak the mortar and you won't harm the water/cement ratio (this is what determines the strength of the crystalline structure that makes up the mortar). So for the first 24 hours you shouldn't do more than mist but for the next 48 hours you can actively spray the mortar without worry of damaging it. Again, as a general rule lime/cement products achieve 90% strength in 7 days and 99% strength in 30 days. The first 3 are key though, deprivation of water or freezing the mix during those days will harm the final product (sometimes very badly), after 3 days the reaction has completed enough that the reaction can finish later even if it's abruptly halted by freezing or drying out.

Your process of handling and moistening the brick is correct, but I worry you are allowing the mortar to dry out if your basement is a dry environment, particulary given that the heat generated by the reaction in a closed space can push moisture out of the mix. Oh and I concur with the previous poster, a sponge is the best possible way to remove the excess mortar and keep your brick clean, though I never had problems using a modern factory produced sponge when laying tile so I don't think a natural sponge is required but you do need a nice big one (6"x6"x12" or so, not a kitchen sponge).
pfred23 years ago
Hey pretty good you found out what is what when it comes to mortar and brick. Congratulations!

I'm not so sure if you've made the best choice of brushes though. Masons I've worked with tend to favor white wash brushes. Have you tried sponging your wall face while it was green? That should eliminate all but a haze of mortar, which would likely come off once it goes white with another damp sponging. Not a kitchen sponge either, like a big natural sponge.

Honestly I've never seen anyone squeegee a brick or block work. That step is done with a trowel. Mud get flipped back into the pan, if it doesn't just fall down the wall.

You know to sand your floor too right? As in put dry sand on the floor so the mortar that falls doesn't stick to it.

I spent over 10 years as a union laborer, so I've worked with a few masons. Done some hack masonry myself too from time to time. Even re-pointed a building on the national registry once.


Nice to see some of my work online.

This is a more challenging angle to photograph that structure from though:


bigattichouse (author)  pfred23 years ago
My floors tend to get "sanded" by the brushout - enough to knock loose while repointing... I'll keep that in mind on less damaged sections. So would you consider the white wash brushed more durable? Whatg would be better about them? I chose the ones I have since they fit the spacing and that's all... not considering anything else about them. Could you explain the de-hazing more for me? Everything I've learned is pieced together from several people's anecdotes.
Well what you're doing seems to be working for you. You know the old saw about changing horses in mid stream. I just consider the white wash brush the item I've seen masons I've worked with use. But they don't use their brushes how you're using yours so it hardly matters. They're just the brush a mason has, if he has a brush at all.

How you're cleaning your wall isn't how it is normally done either, but then again your job isn't a typical brick job today. Different horses for different courses!

If your re-pointing job is anything like the one I was involved with then each aspect of it has to be taken as uniquely as it presents itself. Just do the best you can. It isn't nearly as methodical as laying a brick wall. So no one can say this is right and that is wrong.

Just remember over hydrated mortar is weak and if you can control which mortar gets too wet then you might be able to use that to your advantage. Some truths are universal.
acghost3 years ago
Excellent tutorial on a lost art. (Especially for those of us living in older homes in need of "love")
bigattichouse (author)  acghost3 years ago