ideas on old farm building/barn

[gareth1968]

hello all,

I hope you can give me some idea please - i have an old stone building (in France) that's probably 200 years+ old. 500mm+ walls that were built using lime, mud or anything handy as the mortar. Its been re-roofed to a very high standard and is in pretty good general condition. The building itself is 13m x 7m, the floor is earth and it has some old beams into the walls, for what was a first floor (in a story and a half fashion) but they are completely knackered. My questions are on two areas - (btw I don't at present want to renovate into another house or gite but to a large garage / workshop / studio ) I'd like to dig out the floor and replace with a concrete one with a DPC and insulate should i ever wish to ultimately convert it. That I think is quite straightforward, what i'm interested in is peoples advice on replacing the first floor - from my uneducated POV i have a few options - put a trench foundation around the internal edges of the new floor (prior to pouring the new floor) so should i wish to add a floor in then i could build up an internal supporting wall and have better insulation - challenge from my point is that the building has pretty much zero footings - i am worried that any excavation over the depth needed for the new floor will weaken the walls.. another option is to put in pad stones on top of the walls - put RSJs across and then joists between the rsjs, or finally chem bolt a wall plate on (not a real fan as i think it may strain the stone too much). Thanks for reading and anyone been in a similar situation and what did you do?

 

[RNReindeer]

Personally, I'd cut pockets for new joists. It will take a little work to make clean and tidy pockets after chopping out some stone, but easily doable.
It might be worth doing every other one, or every third one, inserting the joists and making good, then go back and insert the others.

You might need to protect the ends of the joists against damp, but my experience is that there is none or very little damp on the inner skins and so high up.

Alternatively, you'll probably find that previous beams were sat on a short piece of timber almost like a wall plate. You could mimic this by doing a couple of joists with a short piece of timber under the new joists, miss a few, then repeat. Continue to the end, then when all is made good go back and infill with the missing joists.

You will pobably find that the walls are two skins of stone with rubble infill between.

Don't forget you'll be digging out the floor to a depth of about 400-450mm.
150mm hardcore, 100mm insulation, 100mm concrete, 50mm screed.

When I did the same job I used a sand blinding (which of course was a sharp sand 'cos soft sand isn't available). What I should have done is a 50mm layer of insulation, dpm, 50mm layer of insulation.

Are you aware of this:
http://brittany.angloinfo.com/forum...of-usage-on-farm-buildings-new-law-march-2014
I suggest you talk to your marie before starting.

 

[OwainDIYer]

Another possibility is to put some vertical steel stanchions into pits or piles, and take the horizontal beams off those, like a mezzanine floor. The new structure wouldn't even touch the side walls.

Screw piles cause very little disturbance to the ground and you can get commercial mezzanine floors in ready-to-build kits of steelwork.

 

[gareth1968]

I was aware of the law change - and will need to check - as it was a previous combined house/animal shed i am hoping I will be able to change it's use - else nothing will happen, maybe I could just call it a new "animal shed with a large door
The existing beams are indeed cut unto the stone - but they are very low and do need to be moved closer to the top of the wall. I also found on another search that sometimes the french do use a padstone type method and anchor "sabots" (which look like short joist hangers to me) to the top of the wall to hold the new joists. Ideally i'd like to keep the entire downstairs open plan as it is now (the old beams span the 6 m ish gap at the mo.)

Good idea about the piles (my extension in the UK is on a piled raft and indeed was very quick and hardly any spoil)- and the steel mezzanine method, will do some research.

 

[RNReindeer]

Did you read some of the comments on that link I gave you? One of the posters wanted a workshop and garage but he changed it to a tractor store and stables to get it past planning.

I'd be very wary of hanging anything off the top of the walls, they tend to be rather fragile at the top, unless you remove a few layers of stone and replace them with cement/lime mortar.

I replaced the joists for my first floor. They were something like 225X75 at 400mm centres across 5.5 metres. I had to cut about 500mm off each one so you shouldn't have much trouble getting 6Metre joists.

I had the advantage of installing a ring beam around the top of the walls, though.

I set the joists at 400mm centres but when I bought the plaster boards they were something like 2.5 metres long. I think the green boards were a little longer, something like 2.6 metres. So when setting out your joists, check the length of the plaster boards first.

 

[gareth1968]

I did read the discussion and had posed on it as well I'm having a few beers with my mate who is a SE so i'll pick his brains too. Many thanks for the input. On your ring beam did you just span the gable ends with RSJ or similar or did you have effectively 4 walls of the same height? I suppose cutting out would't be too bad as that's whats in my house and its been good for long enough as well!

 

[RNReindeer]

I only did the two side walls with the ring beam, on the inner skin, but went well into the gable end walls with it. Because I did a complete re-roof and new lintels over windows and doors which was contiguous with the ring beam, it was not difficult.
Then it was easy to blockwork up from the ring beam, on the inner skin and redo the stone work on the outer skin, with a weak dry concrete mix between the two skins.