Timber Framers Guild Forums General General Forum Questions saving the foundation of 1850's barn

Hi, we're trying to save and strengthen the foundation of our 3 story mid 1800's post and beam barn. Some of the large stones have fallen into the basement. Should we jack the barn, remove all the stones and pour a foundation which would have to be about 7' deep, or can we pour concrete up against the stones using rebar and widening the concrete at the base?
Thanks,
Bill in Mid-Coast Maine

Odds are you can shore up the existing foundation but it's impossible to say without seeing what's there. I'm guessing your fallen block is from the spans between the posts and not from under them, is this correct? Do you have a good local stone mason you can call in to take a look?

The stones, some of which are huge, are the perimeter foundation, there's a 6 foot deep basement, which the stones are tumbling into. I don't get what you mean about the spans between posts?
Thanks for your reply.

Sorry 27hrs on duty, I should have asked if the stones that have fallen into the basement were from directly below the posts or from the area between the posts? The stones directly beneath the posts are handling most of the weight so the loss of one of them is akin to a three alarm fire.

If it's just perimeter stones falling then your repair is less urgent so you can take some time and come up with the best approach. You may be able to effect repairs without lifting the barn at all.

If stones from directly below posts are missing then you want to get the shored up as quickly as possible before the barn sags out of square.

Have you checked out whether this might be a suitable application for Gunnite or Shotcrete? I don't know what (if any) difference there is between them, but both of them are 'sprayed' onto the surface and harden like concrete. I do believe it would be structural, too.

Bill, from your description, I believe the situation could present a risk of cascading failure of the foundation, increased damage to the building and a high risk of injury to workers. You should get a professional site assessment and place stabilization and safety at the top of the list of immediate concerns. You will need to understand the failure process to properly design a practical solution. Know the roles of water, mortar and stones, trees roots, soils, grade, surcharge(from the site, activities, future construction and equipment) and frozen walls, and so on, in the building system.

Take good care

Hi Bill;
The powerful forces of freezing ground water are the cause of many foundations here in the North. The best thing to do is to do enough digging that you can put a drainage system around the outside of the foundation as it is being fixed. Gutters help control ground water too. Stone foundations are a good way to go, but concrete repairs are probably more common.

Sometimes you can bank dirt up against a barn foundation to stop the inward movement, but where you say stones have fallen in, you should repair the foundation, not just stabilize it.

Jim

I'm a mason in northeastern VT and I have repaired many stone foundations. Have you considered restoring the stone? Chances are if you want to shore it up with concrete you will still need to dig for a perimeter drain and footing. if you want my help, check out my website at www.oldeworldmasonry.com ,you can contact me there or respond in this forum