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Another mortar question
Well I have been using the pre mix lime based mortar and I am about to do some repoint work. But I wanted to ask about the foundation stones. The area of the foundation that you can see from the street is all nice cut sandstone (I think). The foundation area around the house past the parts of the house that jut out (and you can't really see if you drive by the house on the street) are made of all kinds of stones, or scrap stones I guess. I am not sure if it is slate, or river stones or what. But I was wondering if it would be OK to use regular cement, or newer masonry cement on these stones?
In the basement, the foundation looks to be made of the same kind of "scrap stones". I will take a picture and post it here in a few days. I am asking since the pre mix lime mortar is pretty expensive for a 32 lb bag...I could buy 5 bags of newer mortar with potland cement for 1 bag of the lime base stuff. I wouldn't use newer mortar on my soft bricks, because I know what the outcome would be :), and it wouldn't be good in the long run.
So any info would be helpful. I want to get working on the foundation asap, since a LOT of it needs repointed. Over the years, missing downspouts have washed away a LOT of the mortar on parts of the foundation, and I want to fix it.
But if it is necessary to use lime based stuff, then thats ok too. I will just suck it up and drive on. I wish I could make my own stuff, but I haven't found anyplace around here in Ohio that sells hydrated lime. Thanks in advance!
* Picture 1 is an example of my "nice cut stones"
* Picture 2 is an example of my "scrap" stones, that have some kind of newer mortar smeared all over the front of them. I think that was done maybe 20 years ago or so.
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Replies to This Discussion
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Permalink Reply by PStewart on -
Martin -
I dont know anything about mortar so I cant help you there. But I do want to ask you about your "soft" bricks. I, too, requested that my mason use an older, softer lime based mortar for my supposed "soft" bricks in my chimneys last year. My house was built in 1888/1889.Then later I ready that by the late 1800s we really werent dealing with "soft" bricks anymore and that portland cement was already in use.
I wonder if that is true. When did bricks start getting "harder" and when did portland cement become the norm?
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Permalink Reply by Martin on -
I am surprised that you could find a mason who knew about older mortar. I need to do the same thing with my chimneys.. since they REALLY need to be repointed.
The house next door to me was built between 1907-1910 and it is also brick. If I took one of the bricks off their house and compared it to mine, I could tell the difference that their bricks are "newer" harder bricks. I could also tell their mortar is different too.
Now I don't know when exactly they started using the harder bricks.. They could have started using them in the late 1800s, but they could have still used soft bricks too.. maybe as a cheaper alternative? It could also depend on where you lived when portland cement/newer bricks became more common. I kind of wish I had never bricks since it would be a lot cheaper to repoint but you can't have everything :) I don't know if I really answered your question or not but maybe someone else on here can give us more info.
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Permalink Reply by PStewart on
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You need to understand something about masons, by the way. At least where I live, most are functioning alcoholics. When I asked at our local hardware store why it seems there is a correlation between masonry work and alcoholism, they all laughed. Everybody already knew the connection. They told it because its such hard work.
I learned to "roll" with my masons....unique...schedule. Plus the drunk saturday night phone calls to discuss issues with the chimney and what his thoughts were. He was great, even if hammered half teh time.
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Permalink Reply by Martin on
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Well glad you told me lol... Sounds interesting. I definately need mine done. I will have to see if I can find some around here first. Thanks for the heads up :)
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Permalink Reply by Sean Maher on -
Brick hardness is determined by the firing temperature. Old brick kilns resulted in bricks fired to varying degrees of hardness, depending on their position in the kiln and whether the fire was kept hot enough long enough. Good bricks were used in foundations and chimney stacks. The burnt bricks were used in out of the way places, and the softer ones used as fill on the interior. The more recent the bricks, the higher the temperature. Modern bricks are fired to very high temperatures in a modern facility, to ensure uniformity in appearance and hardness.
Portland cement was indeed in use in the 19th century, but it is possible to add portions of Portland cement to lime mortar, as opposed to the modern stuff which has more Portland. The thing to really pay attention to is the ability to transfer water. Lime based mortar is permeable to water, which allows the wall and masonry to dry out when it gets when. Portland cement is not permeable, and traps water. If you see any sign of subflroescence or efflorescence on the interior or exterior of the foundation, then you need to make extra sure you use the lime mortar. In the winter water will freeze, and lime mortar is flexible, and will fail gradually while the masonry stays intact. Portland cement is not flexible, and the trapped water will cause spalling in the masonry, resulting in crushing. There is a temptation to "do it once" with very strong cement, but it will lead to the deterioration of the masonry instead. This wall in my neighborhood was repointed with Portland cement. The brick has spalled away, leaving the cement intact, and this building dates from around 1910 or so...
Garvin's "A building history of northern new england" has a great section on mortar and bricks.
http://www.amazon.com/Building-History-Northern-New-England/dp/1584...
good luck.
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Permalink Reply by Phil on -
Sean's analysis matches much of my observation. My 1895 house has fairly soft bricks, but on its inside layer (the house is structural brick rather than veneer over wood frame) the brick is softer and rougher looking, while the fireplace is much harder bricks. In the medium size PA town where I live, it is rare to see bricks from much before 1900 that are of modern hardness, and it is rare to see post-1900 bricks that are soft. The same goes for stuctural brick and brick veneer. Most pre-1900 houses here are structural 2 or 3 brick thick walls, while most 1900+ residential construction was frame with brick veneer. I wonder whether there is a connection between those 2 changes, or whether a new brick company came in right around the time that brick veneer became popular. By the way, old softer mortars were very long lasting, except around clogged downspouts, so I have never bought the idea of using portland to last longer. I am quite sure that some of the soft mortar on my house is 115 years old and still intact. I believe that this picture below shows a wall that has never been repointed.
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Permalink Reply by Martin on
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Good info! My lime mortar arrived today. I am looking forward to doing more repointing.
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Permalink Reply by Sean Maher on
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lime mortar will wear away with water. Consider it an early warning system for water infiltration and other water issues!
Mortar and paint are so-called "sacrificial" materials. They are designed to fail, and be replaced, so that the material they are protecting does not. Products that are promoted as lifetime fixes for routine maintenance are modern snake oil.
Good looking wall! Tight joints like that are also hard to get these days.
Sean
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Permalink Reply by Sean Maher on
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Here are some diagrams showing how water travels through brick. The lime mortar sheds the water, wicking it out of the brick, while the portland cement traps the water in the bricks themselves.
Sean - Attachments:
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Permalink Reply by Sean Maher on
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Good question. I don't have a definitive answer, but this is what I think:
Masonry buildings are about the material. You are supposed to look at the brick or stone, not the mortar. Mortar is kind of like a nail. You know it's there, it holds things together, but it shouldn't be the focus the of the building. Tight mortar joints require much more brick and more labor. Today, bricks are more expensive than mortar, and labor is very expensive. Thick joints equal faster assembly and less brick.
I also think that some masons may not know the way older bricks were manufactured, and assume that everything is the same as modern material. Modern cement and bricks are very, very hard and durable, and in a new wall it is perfectly fine. In an old wall the situation is quite different, and it's not always understood that the modern cement is not the correct choice for old bricks. The thinking sometimes is more cement, stronger wall.
Here is another picture, which illustrates the difference in pointing on an old wall.
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Permalink Reply by Martin on
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I wish the lime stuff as cheap as the new stuff.I try to explain to people about why I need the "special" mortar.. but most of the time they ask if I will still be living in the house long enough to see the bricks start to fail if I just bought the newer type mortar... I think the lime stuff is great and it isn't hard to use.
I think so far, at least with me, trying to explain why I do what I do with my house resto to people (esp family) has been the hardest part lol.. A lot of my own family thinks I should ummmm "shortcut" but I know better. It just makes things harder to do. But I am still hanging in there!
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