# Repointing old rubble foundation



## Ron6519 (Mar 28, 2007)

A local mason's supply should be able to get you the correct mortar. They may also carry those applicators for the mortar. They look like pastry bags and you squeeze the mortar out the front. I've seen them used to fill joints in interior stone work but don't know if you could use it for the mortar you need. That stuff might be too thick to apply with the bag.
Ron


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## Tscarborough (Mar 31, 2006)

You do not want to use a portland cement based mortar on your repairs. You need a lime mortar. If you are in the United States, a supply house will have the ingredients to make what you need, but not a pre-mixed material. In the UK, they do.

Here is the way to do it, especially, if you plan on doing it a bit at a time. What you are making is lime mortar, which is hydrated lime, sand, and a material to assist set, called a gauging material. You can then use a grout bag and various small trowels to fill the joints. Oddly enough, you should make your mortar drier for bagging then you would for troweling. If made wet, the sand will compact in the tip.

Here is the way to make 1875 breathable lime mortar:

Buy Type S hydrated lime. Place in a bucket or something that will hold water. Gently add water to cover. Do not stir! Let sit for 5 to 6 days, maintaining water coverage. The prepared lime will last for months, just keep it covered with water.

When ready to use, pour off the water, stir gently, and mix with sand in a ratio of 1 part lime (by volume) with 3-5 parts C-144 (masonry) sand (by volume). You can add a small amount of either portland cement or brick dust, but it should be 1/10 to 1/4 part (by volume) of the lime. The gauging material will provide a faster initial set, while not affecting the breathable characteristics of the mortar (the less gauging material the better).

Mix well for 10-15 minutes by hand or at least 5-8 minutes in a mixer, after the mix looks ready. Let rest for another 10, then shake it up and use. Do not mix more than you will apply within a couple of hours. When mixing, add water slowly. It will appear crumbly, then when mixed enough will become buttery.


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## timp (Sep 16, 2007)

Sorry for the delaying in posting my thanks to both of you. I appreciate you taking the time to share your knowledge.

Best wishes,
Tim


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## Big Bob (Jul 27, 2007)

Great info, I will copy and past and keep in my mortar how to file.


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## Jeff DIY (Mar 30, 2009)

Is there a way to tell if you need to use porland cement or the lime mortar on a stone foundation? I need to do some re-pointing on my foundation. It's a stone foundation but the house was built in the late 1950's in the Philadelphia area. I think I read that houses earlier than 1930 or so probably used the lime mortar and later ones most likely use the portland cement. Can anyone confirm this or point me in the correct direction to possibly find out some more info?

Thanks!


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## Tscarborough (Mar 31, 2006)

Generally the lime/portland cut off was at the turn of the century into the teens.


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## Jeff DIY (Mar 30, 2009)

Tscarborough said:


> Generally the lime/portland cut off was at the turn of the century into the teens.


Thanks for the info!


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