Old Stone Foundation Repair - Sister Wall? Lime?

tcook555 · 08-21-2011, 09:23 AM

Good morning everyone... I recently bought an old New England Farmhouse that I traced back to at least 1820. The foundation has a variety of "issues" that I want to address right away and I am looking for helpful advice/suggestions from anyone who wishes to chime in on this thread. My main concern are the bowed walls (pics attached). As you can see, I don't think the walls are a MAJOR problem right now, but I don't want them to be any problem at all-- I want them taken care of! First I'll be installing drainage around the house to help draw the water away from the foundation. But what to do about the walls after that?? It is my understanding that simply repointing these walls with mortar will HELP but will not provide a long term solution. I'm thinking of pouring a sister wall along the inside instead.

Here are my questions:
1. Is repointing a worthy consideration?

2. Will a sister wall, properly formed with rebar, prevent the bowed walls from caving in? (remember, this is in conjunction with drainage which will be installed beforehand.)

3. If so, can I use the modern-day cement that all the local suppliers deliver?? These walls are 200 years old and made from stone and from the information I've read so far, cement will actually damage the stones unless it is mixed with lime.

Thanks in advance for any information!!!

CyFree · 08-26-2011, 12:33 PM

I suggest you do not touch these walls, or the soil around them before you have a foundation repair company or a structural engineer have a look at it.

Although I agree that you need to provide better drainage, digging out the foundations with walls that are already bowing might not be the best course of action here. Not only it can compromise the structural integrity, but it can also make the subsequent step in your plan, which would be stabilizing the foundation walls, much more difficult and expensive.

You would be digging soil that's quite compact (settling since 1820 I assume) to expose the walls and then back filling it with lose, fluff soil that will take other 200 years to become that packed. It will be like a sponge, soaking up rain, expanding and contracting, causing wall movement, and resulting hydrostatic pressure pushing against the walls.

There are several options to stabilize, strengthen, and in some cases even straight up bowing basement walls, including wall braces, wall anchors, helical anchors and fiber reinforcement systems. Likewise, there are other ways to improve foundation drainage that do not involve digging out the basement.
Please call a few specialists (not general contractors), and get expert opinions before you do anything.