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Paul Sharlow
Crumbling Mortared Rock foundation

My wife and I own a farmhouse built in 1880 in Central New York (Pompey, just south of Syracuse). We recently had the basement closed cell foam insulated. Shortly thereafter, we realized on the outside of the house, the joints between the rock foundation have deteriorated. I watched the video of Tom Silva from August of 2014, wherein he shows how to clean out and re- point a foundation from the inside and recommends the use of Type S Masonry Mortar (Quickrete) mixed with bonding agent. Can I use this same product on the outside? I am reading alot about the need to use a lime mortar as was used in 1880 because the modern concrete mixes will block in moisture and cause more of a problem. Is the Type S Masonry Mortar mixed with boding agent appropriate to point the outside?

Clarence
Re: Crumbling Mortared Rock foundation

Your best bet would be to get an analysis of the existing mortar.
Most soil testing labs should be able to do it.
Type S mortar is not a good choice.
You should use a lime based mortar.
There are pre mixes you can order or get from the local masons supply.
Check with some of the following.
U.S. Heritage Group.
Cathedral Stone Products, Inc.
Edison Coatings, Inc.
A. W. Cooks also has a special mix for Historical repointing.
If you can't get mortar from one of the above you could make your own using the follow.
1 Part White Portland
2 Parts Type S Hydrated Lime
9 Parts sand.
For reference see if you can find Preservation Briefs # 2 Repointing Mortar Joints in Historic Masonry Buildings also check Preservation Briefs # 22 it also gives some mixes to be used.
Not sure of the spelling on this one Gouchy Lime also it could be Lime works. They sell a hydraulic lime mix for repointing.
I have used A.W. Cooks , Cathedral Stone and the 1-2-9 mix all worked very well.

Paul Sharlow
Re: Crumbling Mortared Rock foundation
Clarence wrote:

Your best bet would be to get an analysis of the existing mortar.
Most soil testing labs should be able to do it.
Type S mortar is not a good choice.
You should use a lime based mortar.
There are pre mixes you can order or get from the local masons supply.
Check with some of the following.
U.S. Heritage Group.
Cathedral Stone Products, Inc.
Edison Coatings, Inc.
A. W. Cooks also has a special mix for Historical repointing.
If you can't get mortar from one of the above you could make your own using the follow.
1 Part White Portland
2 Parts Type S Hydrated Lime
9 Parts sand.
For reference see if you can find Preservation Briefs # 2 Repointing Mortar Joints in Historic Masonry Buildings also check Preservation Briefs # 22 it also gives some mixes to be used.
Not sure of the spelling on this one Gouchy Lime also it could be Lime works. They sell a hydraulic lime mix for repointing.
I have used A.W. Cooks , Cathedral Stone and the 1-2-9 mix all worked very well.

If I use the 1-2-9 mix do I need any bonding agent? Do I have to do it during a period of long dry weather, or am I ok to go ahead and do it now in the fall chilly damp weather?

Clarence
Re: Crumbling Mortared Rock foundation

Do not use bonding agent.
Cool and damp weather is ok as long as the temp. is not below 40 and will not be lower than 40 for about 48 hrs.

Paul Sharlow
Re: Crumbling Mortared Rock foundation

Great, thanks so much for the knowledge!!

Paul Sharlow
Re: Crumbling Mortared Rock foundation

Just to make sure: Our local Hardware store sells the following:

1- Minute Man Type S Hydrated Lime
2- Portland Cement Type I/II
3-Quikrete Premium Play Sand

Is the Portland Cement Type OK?

Clarence
Re: Crumbling Mortared Rock foundation

Type s Lime ls ok.
White portland Type I is ok.
Play Sand ? see if you can find baged sand that state it is washed, the play sand will have clay content in it also may have tree trigs in it.

Paul Sharlow
Re: Crumbling Mortared Rock foundation

I do see they sell "washed". Thanks again!

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