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".
DISCLAIMER:
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.
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".
DISCLAIMER:
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.
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Signing UpStep 1: A little Background on Brick and Mortar
Imagine a Brick. A hard shell on the face contains a softer core. To cut a brick, you just scratch the surface a little, and then strike it and it cracks in a (roughly) neat line. If you placed wight on one side, and had a fulcrum, it would do the same.
Now imagine your wall, a bunch of bricks with mortar in between - and possibly several tons of pressure leaning on the wall. You decide to use an angle grinder to rake out the old mortar, and then fill in new mortar. You deeply scratch a few bricks. The wind blows, the house pushes down on the wall, and ... *CRACK* - the bricks "spall" (the face pops off) or crack, and the wall is now in worse shape than before.
Begin slowly, like this Instructable, and clear and rake (there are simple tools) by hand until you feel more comfortable with what you are doing.
Now. You might think the mortar is like a glue holding the bricks in place - but it isn't... well, before 1920 or so it wasn't. After 1920, it's all super-tough hydraulic cement that doesn't move and is watertight. Before? Your wall is like self-healing limestone... if tiny cracks appear, the mortar will actually seep Calcium minerals into the crack and become even stronger. That mortar can actually flex! Those minerals are transported by water. If your mortar isn't permeable (being lime based), then that water will go into the brick - which will damage the brick (again, *CRACK*). New house? totally different rules unless it was made with a lime mortar.
So the mortar is like a somewhat movable cushion for the bricks - it absorbs stress, it flexes, it wicks moisture around the bricks that do all the lifting. If you suddenly add a section of harder mortar? That stiffer section might crack out the softer sections nearby. Mortar less permeable than the brick? Water travels through the brick.
So, how do you know? Chemical tests can tell you the exact proportions and components of your mortar and brick. These might be expensive - but you'll be sure. A simpler test that gets you in the ballpark? Take a solid piece of mortar and drop it on a poured concrete floor. *TINK* - harder, more portland cement *THUD* - more lime.
You can actually compare small amounts of each type in the hardness spectrum to compare how they sound. But honestly, you're investing in this house - get the chemical analysis done.
Also, see http://www.oldlouisville.com/circa1900/brick-structures.htm
Learn the types of Mortar: http://www.cement.org/masonry/cc_mortar_types.asp
A great resource: http://www.nps.gov/hps/tps/briefs/brief02.htm (Park service, who know a thing or two)
I'm using Type N, since I'm working in a load bearing part of the house. N is normally for above grade exterior, and is probably a little too hard/impermeable - but these walls don't have soil against them - so there is opportunity for them the breathe on both sides.
Now imagine your wall, a bunch of bricks with mortar in between - and possibly several tons of pressure leaning on the wall. You decide to use an angle grinder to rake out the old mortar, and then fill in new mortar. You deeply scratch a few bricks. The wind blows, the house pushes down on the wall, and ... *CRACK* - the bricks "spall" (the face pops off) or crack, and the wall is now in worse shape than before.
Begin slowly, like this Instructable, and clear and rake (there are simple tools) by hand until you feel more comfortable with what you are doing.
Now. You might think the mortar is like a glue holding the bricks in place - but it isn't... well, before 1920 or so it wasn't. After 1920, it's all super-tough hydraulic cement that doesn't move and is watertight. Before? Your wall is like self-healing limestone... if tiny cracks appear, the mortar will actually seep Calcium minerals into the crack and become even stronger. That mortar can actually flex! Those minerals are transported by water. If your mortar isn't permeable (being lime based), then that water will go into the brick - which will damage the brick (again, *CRACK*). New house? totally different rules unless it was made with a lime mortar.
So the mortar is like a somewhat movable cushion for the bricks - it absorbs stress, it flexes, it wicks moisture around the bricks that do all the lifting. If you suddenly add a section of harder mortar? That stiffer section might crack out the softer sections nearby. Mortar less permeable than the brick? Water travels through the brick.
So, how do you know? Chemical tests can tell you the exact proportions and components of your mortar and brick. These might be expensive - but you'll be sure. A simpler test that gets you in the ballpark? Take a solid piece of mortar and drop it on a poured concrete floor. *TINK* - harder, more portland cement *THUD* - more lime.
You can actually compare small amounts of each type in the hardness spectrum to compare how they sound. But honestly, you're investing in this house - get the chemical analysis done.
Also, see http://www.oldlouisville.com/circa1900/brick-structures.htm
Learn the types of Mortar: http://www.cement.org/masonry/cc_mortar_types.asp
A great resource: http://www.nps.gov/hps/tps/briefs/brief02.htm (Park service, who know a thing or two)
I'm using Type N, since I'm working in a load bearing part of the house. N is normally for above grade exterior, and is probably a little too hard/impermeable - but these walls don't have soil against them - so there is opportunity for them the breathe on both sides.
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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).
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.
http://upload.wikimedia.org/wikipedia/commons/5/5a/Elizabeth_convent_domed_tower_jeh.jpg
Nice to see some of my work online.
This is a more challenging angle to photograph that structure from though:
http://i.imgur.com/jvC9r.jpg
heh
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.