Propping a rubble wall for lintel?

[gsportgeorge]

Hi,
We are in the process of buying an old stone built house, and one of the first jobs we want to do is knock a large opening through a structural internal wall.
Since we dont own the house yet I havent been able to chip away plaster to look at the wall but I suspect it is a random rubble construction (it is a good 14-18 inches thick including plaster).

The plan is to open a hole 10 feet wide and install a suitable lintel.

I WILL seek expert advice as required (ie. structural engineer) but I WANT to do as much of the work as possible myself and to check calculations etc.

Can anyone advise as to the correct method to prop this kind of wall? I am assuming I need to clamp plates around the wall to hold it together above where the lintel will go, and prop these? Knock out inside this (we dont need the lintel to be very close to the ceiling), cast padstones in place with shuttering, install lintel as normal...?

Any advice/suggestions gratefully received.

Also any sources of figures to use for floor loadings etc for doing the calculations would help too..

George

 

[breezer]

as you said

seek expert advice as required

this is a diy forum, we can not see it and are not structural engineers

 

[shaggy]

Be nice to see a pic though?

 

[gsportgeorge]

A picture of the wall at present would consist of some rather natty 60s wallpaper

All I am looking for is anecdotal information on ways to tackle propping such a wall. If it comes to it I can work something out that will do the job, but it is likely to be overkill. If there is an existing simple method in use then I might as well try to find out about it dont you think?

This is the sort of thing I thought:-

The red area is what we want to knock through and the plate above and bolts would be clamped round the wall to provide something solid to prop to....

G.

 

[shaggy]

That's a good diagram George and an interesting idea. I've got a lot of brickwork experience but no experience of working with stone although I did find this link. The guy wants to make a hole in a stone wall and the recommendation is to make a series of holes and pass 4×4 needles through. This is no different in principle to supporting brickwork except the needles would be closer together because you don't benefit from the arching action of the brick bond.
I'm wondering if, with your method, you may have a problem building from the new beam to the underside of the wall that is clamped?

 

[gsportgeorge]

Thanks for the reply shaggy.

I have since been told that the conventional way to deal with this problem is to drill a series of holes and "pressure inject a concrete slurry" to bind everything together.

This seems logical, so my current thinking is to do this (subject to the opinions of building regs, structural engineer etc.).
Cant seem to find anywhere that hires such equipment but the materials themselves seem to be available and I can always make a simple hand pumped injector mechanism.

I would then use a core drill to put numerous holes through just above where the beams will sit and use some big steel tubes as needles. Calculations suggest that these need to be pretty hefty due to weight of wall above.

Does anyone know of places that hire more substantial props and tree-heads to support larger loads without having to have a forest of props in the way of the hole?

4 super props would handle the load but I need something almost equivilent to the final UBs (loading is around 60kN/m, 3m span, 2off 3.8m long 254x146x31kg UBs) to spread the support to the needles... real shame I cant use the UBs themselves

G.

 

[shaggy]

That's interesting to me George, so if you can post any pics as the job progresses it would be good to see it. As I said, I've got no experience of stone so I might learn something myself.

 

[gsportgeorge]

As I said originally we are still in the nerve wracking purchase stages but assuming everything goes through OK my plan is to Blog the whole ordeal... I mean experience...

Still looking for information on padstones and tree-heads... though the way steel prices are it might be worth "investing" in some extra steel for the tree and sell it on after the job...

G.

 

[jbonding]

after youve dealt with BCO and found out what lintel or steel size you need mark out the steel on the wall and mark out pad stones with a felt tip.get six acros 3 on either side supported on scaffold planks, floor and ceiling, remember your not supporting the wall your supporting the ceiling and floors above. cut out with a grinder on both sides and knock out what you cant get out with a bolster chisel. lay your pad stones on both sides, use concrete bricks or a kerb stone broke into two or three, then lay your piece of steel on top on a bed of morter and use slate to pack up to get level,fill all the joints with morter leave till morter sets remove acros now youve got the choice when you want to knock through.

 

[gsportgeorge]

....get six acros 3 on either side .... floor and ceiling, remember your not supporting the wall your supporting the ceiling and floors above....

Thanks for replying... but...

There is a 6 meter height, of foot-thick stone wall above the lintel... weighing around 16tons for the total width of the lintel..... I think I should prop the wall and let that support the piddling weight of the floors (say a ton and a half) ... I also think I should be using more than 6 acro's that should only have to support 1.5 tons each.....

 

[trogo]

On the offchance gsportgeorge completed the task how did you get on? I am about to embark on exactly the same task.

 

[tony1851]

He's probably sold the house by now!

 

[^woody^]

..... or lying under a pile of rubble

 

[HERTS P&D]

His ex-wife got the house and he had to move to a bedsit. Should of listened to his mother and never married that gold digger.

Andy