Tuck Pointing Pre-1930 brick house - okay to use a latex binder?


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Old 07-23-10, 12:26 PM
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Tuck Pointing Pre-1930 brick house - okay to use a latex binder?

Need to tuck-point the mortar in my parent's home. I've read that you're supposed to use a flexible mortar mix (type n or less) to tuck-point the mortar in older homes.

Is it okay to use a latex binder in place of water for a tuck-pointing job?

I've done some tile work & used a latex binder in other mortar mixes and found it works well. Just concerned how it will work on older brick...
 
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Old 07-23-10, 02:07 PM
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First you need to make sure that it is portland cement mortar and not lime mortar you are tucking over. Even then, you will probably not want to use a bonder. You want soft mortar to tuck with.
 
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Old 07-26-10, 03:33 AM
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tuck pointing

In a pre 1930's home it is safe to assume that the mortar is a lime mix. You will notice that I specifically stated "mortar" and not cement. You are on the right track with type "N", but you want a lime mortar blend to match the existing.
You don't state where the house is located or how extensive the job is. Do you know how deep the joints need to be cleaned out?
Tuck pointing is usually done in stages. The joint is cleaned of all failing mortar, cleaned with a wet brush, allowed to dry a bit and then the tuck pointing process begins. We typically proceed in thirds. Tuck a third of the depth and allow it to set overnight, ( since i have no idea as to the scope of work required on this project I will assume that you are repairing the entire house.), wet the joint the following morning...damp not enough water to cause the mortar to run out of the joint..and repeat until the joint is full.
Good luck
Vince
 
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Old 07-26-10, 12:05 PM
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You would be safer using a 1900 date to assume it was lime mortar, but you should check regardless. I have seen brick laid in the 1880s with portland cement mortar out in podunk South Texas towns, and there are buildings being constructed today with lime mortars.
 
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Old 07-26-10, 12:18 PM
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The whole idea for using a lime mortar is that in type N it is more forgiving than a type n masonry cement. The lime allows some movement in the joint and any microscopic cracks are "self healing", which alleviates some of the cracking in the joints. I would not use a latex binder additive in this situation.
 
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Old 07-26-10, 12:52 PM
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This is what happens when you tuckpoint over lime mortar with portland mortar. This church was built in 1870 and lasted until the 1980s with the original lime mortar. In the early 80s it was tucked with a hard portland mortar. As you can see, the joints are beginning to fail as the moisture behind the portland erodes the old lime mortar from beneath the hard tuckpointing. It is a shame, since it will most likely not be fixed and the building will not see it's third century.



 
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Old 07-27-10, 08:08 AM
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Great post Tscarborough! Shows the problem exactly. A picture worth a thousand words.
 
 

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