Buttress for old barn

[welshcottage]

Hi all

As well as a garage project we have an old barn which we are stabilising, it's is reality my sound condition but roof needs tidying, so will be relaid in due course.

The walls are stone and over the 130 years or so the walls in their shallow stone foundations have moved a little but not too much, so we are tieing the corners together which should help with a simple corner pillar, which was suggest by a local builder and seems sensible.

One of the other things he said we might want to consider, ( he not doing the work we are !!) is building a buttress against the walls, again as a simple pillar about twice as wide as the wall itself, and about 2/3rd of the way up. Probably narrowing for the top 1/3.

I was considering building from breeze blocks and cover with stone and tie into the wall, any thoughts on this, depth of foundation and also concerned about disturbing the foundatatuon of the barn wall if we did down too far. Any thoughts ?

 

[theprinceofdarkness]

The houses and barns here (Wenselydale) all move down hill. That's it, the only point of disscusion is the rate they move. My house is going at about .5mm per 12 years, the barn rather faster, 1mm / 12 years. The reason is that the top soil is moving over the subsoil, so unless you underpin into the clay, you might just be slowing the rate down. I have underpinned some of the walls in the barn as the "groundstones" were above the new floor level. The existing flag floor was laid on a slope of about 6" front to back and side to side. So when I flattened the floor out, the level would have been below the bottom of the groundstones. It is dry now. What I intend to do is to put a run of piles external but close to the walls at the lowest corner, sunk well into the clay. I was thinking about 9" diam 1m deep with 4 X 8mm rebars in each. My problem is that I am undecided about if I build them to form a continuous wall, so the top soil can't move through them, then I might be trapping the ground water as well which could cause internal flooding.
Building a buttress?, If the walls are moving in one direction or are bowing outwards, then a buttress could help BUT it must has proper deep foundations and lean against the offending wall. If you just build it as a pillar against the side your barn will just slide by it. If your barn is like mine, rock and rubble, then it has a "cavity" in its centre filled with rubbish, so the most you will do is to stabilise the outer skin and the inner bit will do its own thing.
Frank

 

[welshcottage]

Thanks Frank

One wall on the lower side of the building has moved out from from the around 5-6 inches in total.

The opposite wall being relatively upright, you can see the pull as the wood that runs through the wall to support the roof has marked when it has move over time.

As the wall is moving out about it seem sensible to give it some additional support.

Having another chat with our local builde today, he suggested maybe a 30 degree foundation around a cubic meter in total with a wall projecting out angled onto the wall that pushed out bad then tied in through using steel pins or interweave the stone into the wall.

 

[theprinceofdarkness]

That sounds like a plan, but its the new foundations that will be doing the work, stopping the old ones moving. Just to support a leaning wall you can tie it across to the opposite wall with big Xs on the outside. I have seen this done on an old mill somewhere, I can't remember where though. Basically a long piece of 1" rebar had 1" studding welded to both ends, this was passed right through the building and the Xs nutted on, on the outside.
Make sure that the new foundation goes into the sub soil, 1m might not be deep enough.
Frank

 

[welshcottage]

Seen similar myself.

I like the tie together idea, the span is over 8 meters, so would be a long distance between then so this would also then need to be supported along its length. Will look into a little more though

 

[theprinceofdarkness]

Wow! you will need two rebars joined end to end
Frank

 

[stuart45]

You join them with a turnbuckle, which is used to adjust the tension. You can get the tie bars and various pattress plates from the makers.

 

[welshcottage]

Thanks both, it would be easier if their was a strong internal structure and would tie into the but alas there is not ! Thogh could be a good opportunity to build one!