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Brick Foundation


Jim Katen
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I have a friend who lives in Philadelphia and he has some concerns about the brick foundation under his 100+ year old house. He's noticed that the mortar wash has popped off in spots and he's concerned about places where the mortar between the bricks is loose and reverting to sand.

After reviewing the pictures he sent, I don't see anything all that alarming. If those pictures were of a house in my corner of the country, I could tell him that the foundation was 12-16" thick and that the small amount of mortar decay wasn't really a concern, especially if gravity were the only force acting on it. I'd probably tell him to invest his resources in addressing the water entry issues that are the source of the problems that I see in the pictures. If the house were on the west coast, I'd probably also warn him that a brick foundation, in any condition, is more likely to suffer damage during an earthquake than a cast concrete one. Lastly, I'd tell him that, if any of the bricks are actually loose, he could hire a mason to re-set them using lime-based mortar, *not* portland cement-based mortar.

However, his house isn't in my part of the country. For those of you who know Philadelphia housing stock:

Do you see anything alarming in the photos?

Aside from addressing the water-entry issue, would you advise him to follow any particular course of action?

Is the advice that I laid out, above, applicable to a house in Philadelphia?

If you work in Philadelphia (Kibbel?) do you know of a good mason who knows his mortar?

- Jim Katen, Oregon

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Based on the photos, I have brick in worse shape in my Saratoga Springs NY house and I have not designed any repairs as of yet. The mortar in the photos looks pretty good. Someone from Philly or NYC may have another opinion. We have brick foundations all over the Connecticut market in big cities. This would not have been called out as problematic except where water entry was a concern.

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Your advice is spot on. The earth in Philly doesn't move, it only vibrates from traffic. The lime based mortar works well for for that reason and many others.

The only mason I recommend is Andy DeGruchy, but he doesn't touch jobs under $8k.

He can supply the correct mortar needed for your friends repointing though from DeGruchy Limeworks.

It looks like very little work is needed. Repointing is only necessary for any spots that has missing mortar in the joints to a depth greater than 3/8". The joint prep should include raking the missing spots to a depth of 2.5 times the width of the joint and repoint with a natural hydraulic lime mortar. Some folks want to keep raking 'till they hit "solid" mortar. This isn't solid cement mortar. The bedding mortar is supposed to be that way.

If the brick foundation is coated with a lime wash and he wants to renew it, thats fine. If it's an elastomeric type "waterproofing" paint on there, let it all flake off, the sooner the better.

If this is a friend of the great and powerful Katen, he's welcome to contact me directly for advice (although I'll only go down there for the 5 figure inspection fees now). bill(at)historicbldgs.com 610-346-7880.

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