# Will hammering from basement waterproofing crack our plaster?



## csabr (Mar 3, 2010)

We need to have waterproofing done in our basement, and we were told they need to break up the concrete to put in a sump and drain tile.  Our house was built in the 50s and had plaster walls on the ground floor.  Is there danger that the jack hammering they have to do in the basement will crack out plaster?


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## Cork-Guy (Mar 3, 2010)

There is a slight chance it might; you could try doing it with a sledge hammer to minimize the vibrations, however that would be one hell of a task! Do you have support beams in your basement going into the concert itself?


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## mudmixer (Mar 3, 2010)

If they cut or score the edges of the removal area, that will minimize or eliminate the need for for a jackhammer. When I did my interior drain tile myself, I hired a man with a good saw to cut the line and make the diagonal cuts at the corners. Once you have the edges scored deeply and can get a hole started, a jackhammer is not needed if you want to use a sledge and break it into manageable sized chunks.

Much depends on what you specified when asking for a quotation and what was proposed.

Dick


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## MaFoundationFix (Mar 4, 2010)

It is very unlikely that jackhammering the basement slab will cause any damage in the walls on the main floor.

Here's why. It is very likely that your basement walls are resting on a footing. The floor slab is poured once the walls are in place. The floor slab in this case is not connected to the walls. It may be lying right up against the walls but the vibrations from a jackhammer are quickly absorbed by the soil below the floor and would never, in this case, reach the top of the foundation walls to an extent that might cause damage.

If your basement is monolithic there is a higher risk. A monolithic foundation is one that is constructed to incorporate the floor slab into the stability and structure of your home. In this case, a large void is dug around the perimeter where the foundation walls are going to be erected.

The floor slab is poured and a where the voids are the concrete is much thicker than the inner parts of the basement floor. This thick area of cement is what holds up the foundation walls. 

Jackhammering the perimeter of a basement with a monolithic foundation is NOT recommended and can undermine the structural integrity of your home and definitely cause damage on all floors of the home.

I am going to use your question and my answer as a post on my blog. Thanks for the idea! Massachusetts Foundation Repair Co | Wet Basement Waterproofing


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