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Hi, I bought an old house last yer and am looking to address some issues with the exterior before winter.

The house was built in 1892 and has a stone foundation at ground level which has lime mortar joints and the rest of the house is what I think is soft brick. At some point, I think in the 1940's or 1950's; the house was treated to a cement stucco which is mostly in good repair, with some cracking here and there. Oh, and it's painted.

At the base of the house, however, there are some issues. a previous homeowner installed planter boxes along the front of the house with no drainage and raised the soil level about 6-8 inches above grade. I am going to empty those boxes to grade level and see if I can install some drainage while keeping the boxes in place. We have flood irrigation, so the boxes do serve some use.

As a result of the planter boxes, retaining water, some, but not all, of the stucco at the base of the house has separated from the stone foundation. It appears that the foundation was parged with lime mortar and then the coat of cement stucco was applied over that. In a perfect world, I would like to take off the cement stucco entirely, re-point and then apply lime stucco, but that isn't going to happen.

I would appreciate advice as to what mix would be most appropriate to replace the affected sections of cement stucco over the lime parge. This section is about 18" high and runs in a continuous strip along the front of the house.

Thanks
 

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Over time cement stucco will delaminate when applied over a lime based mortar in a high moisture area. For a repair mortar more suitable to the lime mortar you can use a mixture of 1 part cement - 2 parts Lime & 9 Parts sand this mixture maybe a little high in PSI than the lime mortar but better than Cement based mortar.
Also you can use a n NHL 5 type mortar this is going to cost more than the 1-2-9 mix.
If you are any where around Atlanta GA. contact A W Cook they have a premix of a Historical correct mortar called Mason Works this has a PSI of 350.
You do not want to use a mortar stronger than the mortar used for the original stone joints.
 
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