tying in - 73mm bricks abutting 65mm brick design

[sm_jamieson]

My extension will be built against the neighbours party wall, so visually, I will be extending the rear wall from her extension across mine. Her extension is built in the older 73mm bricks I think, My design is standard 65mm bricks and 215mm high blocks inner leaf. The design is to use wall starter plates anyway, to avoid cracking with the different foundations, so there will be some visual discontinuity there anyway. But should I just use 65mm bricks and have the join looking rather obvious, or try to use the 73mm bricks ? I'm not sure how this would fit with the inner leaf. Can you get taller blocks ? TIA, Simon.

[Chris Bacon]

They aren't 73mm bricks, they're probably 3" ones.

You can get bricks that are taller than 65mm, if you use them the job will IME look *much* better.

[sm_jamieson]

They are definitely 73mm, which is 2 7/8 ". They are listed as 73mm on various building supplies.

How would I link in with the celcon blocks, which are designed for

3x65mm + 20mm mortar ?

Simon.

[Chris Bacon]

sm [e-mail] wrote, munging the attributions:

Not if they're old bricks, although they may measure about that.

Aha!

Furfix fittings. Thick beds or adjustable ties.

[sm_jamieson]

Me's thinking, BCO would fuss about thick beds on the celcon, since this would reduce the insulation spec. I guess a real bricky just fiddles with things as he goes along. I would want to design the blocks and tie layout before hand so I know how they are going to fit. Might be tricky since outer skin beds would be higher than usual, but the ties must slope outwards rather than inwards. Cheers, Simon.

[Chris Bacon]

Won't adjustable ties do?

[sm_jamieson]

I don't know anything about these. Who manufactures these in the UK ? Sound like a good idea. Are they like miniature wall starters ? How do they attach ? Simon.

[sm_jamieson]

Aha. The magic words: "thin joint wall tie". Basically, using inner thin jointed thermalite blocks, the courses won't match. It the mass market. The description on one website said "also suitable for situations where the leafs don't course".

Helical wall ties hammered into the thermalite. Don't know how strong these are considering the previous posts on fixing into thermalite. But I guess they must be OK.

Cheers, Simon.

[Phil L]

You just get normal ties and normal blocks, this is something that brickies have to contend with every day, they just bend the ties up or down to reach the course of brickwork, this is normal procedure and the BCO will have seen it thousands of times. They'll look like this after it's built: _ ___ ____/

OR: ____ \____

Where the / or \ is the cavity.

[dg]

A properly constructed cavity wall should have the ties at 90 degrees vertically and horizontally to the face of the wall. Bending the ties is not good practice, and if they are angled to the inner leaf, then moisture can run down to the inside wall. In addition, bent ties could allow greater differential movement of the two leafs.

Its not normal practice, it is bad practice

dg

[dg]

The helical shape gives excellent pull resistance, and is not comparable to traditional fixings into aerated blocks.

dg

[Rob Morley]

When you do ASCII art use a fixed width font - if the ties really look like that it's a waste of time using them :-)

[sm_jamieson]

If so, can you get helical fixings for general use with aerated blocks ? Folks are always talking about difficulties fixing into these type of blocks. Simon.

[Phil L]

I didn't say it was good practice, only that it is common practice inthat almost all brickies do it, it's the main reason why the old galvanised 'butterfly' ties were withdrawn about ten years back and replaced by stainless steel, because they rust away where the brickie has give them a clout with his trowel bending them to fit in with the courses. I doubt the possibility of water ingress too, considering they have a dripper in the centre

[dg]

Yes.

They are available as 'nails' and can be used to fix timber skirting, frames, dado, curtain rails etc.

dg