Really *LONG* Wall ties

[Rick Dipper]

I am building a cavity wall, the oute wall is a stone/rubble wall, and it is curved, leaning and tapered. The new inner wall is straight. The effect is that at the worst point the walls are 300 mm or so apart.

I have to put will ties between these walls, which in places is easy, I use the drill in type, where you drill the existing wall, and screw in a tie, that is then put in the motar joint of the new wall.

Where the walls are 300mm apart the 100mm tiles most builders merchants sell are woefully inadequate. Today I have 3 options

1) buy longer ties 2) make longer ties 5mm stainless steel I reckon will do it. 3) the architects plan - basicly longer ties made of 6mm rebar.

Does anybody have any suggestions for option 1 ?

Option 3 means drilling 10mm holes 200mm into the stone wall pointing up 45 degrees, not only is this a nightmare job, the stones are so hard the hammer drill with just vibrate them out of the wall.

Many Thanks Rick

[G&M]

Is this a very old stone/rubble wall ? Like a barn conversion perhaps ?

If so the inner cavity wall should not be tied to it at all.

But if not please ignore the comment.

[Rick Dipper]

Yes, its a 200 year old wall, that the planners would not let me pull down. We have had to repair the top foot where the plants had attacked it, and do the usual lintel reparis. This wall is simply for decoration, and to stop the insulation blowing away. The internal block wall will support the roof.

If you have any documentation to say these should not be tied together I would be very interested. Another dicussion with the building regs man.

Many Thanks Rick

[Cicero]

============== It would appear from what you've said that the Building Regs people want the new wall tied in for the safety of this new wall rather than anything to do with the old wall. Like a previous poster I'm guessing, but it appears that this 'decorative wall' is room-height single brick construction. If so, it is probably too high to stand alone without being supported in some way either by ties or piers etc. Why don't you ask the Building Regs people for their reasons - they're usually pretty helpful.

Cic.

[G&M]

Talk to your conservation officer. He probably knows of previous cases. The old wall may not survive the change in loading and could fall down. There are numerous such cases in barn conversions - some more deliberate than others.

Also you could try SPAB

for any cases they know of.

The prefered way to do this is with a double skin internal wall and leave the outer alone. Judging by the 12" you were leaving I would have thought there was plenty of room for it anyway.

[dg]

Do you have proper engineers design specs for this?

As a cavity gets wider, walls can behave differently and there is more scope for lateral or differential movement - so it may not be just a case of using a longer tie. And as this cavity is not of uniform width, then this can give rise to other movement problems.

I don't know if these would be appropriate, but consider use of twisted steel ties which are drilled and epoxy fixed into the joints

Try

[Rick Dipper]

Thanks

This is what the architect has specified, and they look like a massive job to fit them.

Rick

[Rick Dipper]

The old wall is some 2 foot thick, the new wall is very close at the bottom edges, but the curve and taper move it about 12 inches away in the middle top. The old wall used to hold the old roof up, all on its own, so it should stay put.

Having the wall fall down now would be a mare, I have just spent 2K on maintance for it. What I am worried about is the vibrations from all the drilling knocking the stones out. The stones are VERY hard to drill.

I guess as with everying on this build, I'll give it a wiz, and see what happens.

Thanks Rick

[N. Thornton]

Drilling into old lime mortar is like drilling into cake. I wouldnt try to drill the stones.

NT

[Rick Dipper]

Sir

If I drill and fix into the mortar, what happens is that the fixing just pulls out connected to a clump of mortar.

Rick

[N. Thornton]

If you scrape the side of the stones clean (in the hole youve made) and use resin, it should bond to the stone. Have you tried that one?

But to be honest, I'd recommend taking advice from the real experts on historic structures:

NT