Structural survey trial pits

[Drellingore]

Gah, I never know the right subforum to put posts in

I've got to dig some trial pits for a structural survey of an old Atcost concrete-and-asbestos barn. They'll need to be right up against one of the posts and one of the walls.

 

A couple of naïve questions:

 

1. I'm guessing the intention is that I need to dig deep enough to get under the footings, to show how deep they really are?
2. What kind of tools/equipment would people use for this?

 

I recently dug a 2m deep pit to establish where the water table wasn't for the Environment Agency, and I figured it'd be good exercise to do it by hand with a spade and pickaxe, and it would give me an appreciation of how long these things take. Neither I nor my back particularly want to repeat the experience!

 

I'm guessing what equipment to use will depend on how deep the footings are, which I won't know until I start digging. I'm guessing mini-excavators would be inappropriate to use so close to a building?

[saveasteading]

An atcost footing for a farm building won't be very deep or very big.

 

I'd expect to have found it by 3 ft.

 If really needs to be dug by hand or with  a small machine, eg 2 ton.

 

Often the post was just dropped into a socket in the footing, and packed in, or even  supported in the hole while concrete was packed around it...like a fence post.

So it could all be a  bit fragile. Hence be gentle.

 

I recommend a fencing crow bar/ excavating bar or a spade for an sds drill if you have one. 

 

Then yes, stop digging at the bottom of the concrete.

[Temp]

If it was me one sneeze and the digger bucket would go right through the asbestos sheeting 😞

[saveasteading]

On the subject of atcost and similar, In case anyone is interested. There used to be a thriving trade in second hand concrete portals  of which atcost was best known. 

A farmer would sell one"as seen", then the buyer commissioned a contractor to move it.

They stripped the asbestos cladding in strict order so it could be reused, then the concrete or steel rails. And the rafters.

Then they cut off the columns at slab level.

In its new location it became lower as the columns were reduced. They were dropped into recesses in concrete pads and packed into place.

Then reassembly with new fixings like abu simbel  all in order. Every new hook bolt went in an existing hole.

A building might be moved several times and become ever lower.

 

They were worth much less already disassembled as there  was uncertainty as to it going back together.

Broken asbestos cladding was legally buried on a farm.....and can be an expensive discovery.

[Drellingore]

Thanks folks! I've hired a concrete breaker for tomorrow, and that'll help get through whatever is under the surface. The farmer that used to live on the site said that the posts were concreted in 3' deep.
 

Quote

On the subject of atcost and similar, In case anyone is interested. There used to be a thriving trade in second hand concrete portals  of which atcost was best known. 

 

Thanks for that. Do you know where I might be able to find any online communities for this sort of thing? It's not the first time I've heard it - a neighbour of the site mentioned that he'd heard of it happening before. I did an online search, and also phoned the company that now own the Atcost brand, but they weren't aware of anything. If a couple of people have mentioned this sort of thing, I'm sure there must be something to it.

[saveasteading]

I was offered the atcost brand but declined, as it was only if value if wanting farm work.

 

I think ask a farmer for contacts or find a farmers weekly.

[George]

Shed builders will often need to take an old shed down first. They do hold a reasonable amount of value.

[saveasteading]

12 minutes ago, George said:

They do hold a reasonable amount of value

I don't agree. The chance of having some wrong bits is a risk. Also somebody else's bodges with the cladding. I always settle for being removed free of charge and I think that is realistic. Not if there us asbestos though.

 

One existing client wanted another shed. They had  a steel one the right size dismantled elsewhere for reuse. I quoted but also gave a much cheaper price for an all new one. Client wasn't best pleased and got 3 more quotes, all higher than mine for the reused one.

No apology but a fifth job so hey-ho.

 

That doesn't mean it had no value, but it wasn't a lot.

 

On balance, steel sheds go for scrap. Concrete frames crush nicely.  Asbestos cladding.....ahhh well, even farmers have constraints now. Hence building it again can be the cheapest solution.

 

Farm buildings have no safety factors and are allowed to leak and be draughty.

 

[George]

56 minutes ago, saveasteading said:

That doesn't mean it had no value, but it wasn't a lot.

I don't think we disagree. I count that as reasonable.

 

 

[Gus Potter]

On 04/07/2023 at 18:54, saveasteading said:

On the subject of atcost and similar, In case anyone is interested.

Invaluable knowledge disseminated. Thanks for that.

[Gus Potter]

On 10/07/2023 at 11:42, George said:

Shed builders will often need to take an old shed down first. They do hold a reasonable amount of value.

Yes I think they do but from that value you need to take of the cost of an SE assement.

 

I have surveyed some steel portals.. with a view to extracting extra capacity, say by adding an extension or a mezzanine floor. Have had reasonable results but.. you need to be very careful. You need to get yourself there and examine it in detail.

 

I would be very wary about trying to reuse a concrete frame.. there are not just issues around strength but bar cover. When these things were made there was often no quality assurance.. if you don't know how the thing was cast and how well then how do you justify it will perform?

 

Last man on the job gets the blame!

 

Now if you are an SE make sure you take a micrometer to measure the flange and web thickness as for a while folk were passing off Chinese steel as BS sections. They look the same but the web and flange thickness is thinner and the steel grade who knows?

 

For all.. if you are doing things that require steel box sections for example then there are two fundamental types; hot finished and cold formed. The cold formed tend to be cheaper.. but don't do the job.

 

If you are going to buy something second hand then you need to really do your research.