To 'tooth in' or not to 'tooth in'?

[dogfonos]

I'm currently in the early stages of planning a single-story extension to a bungalow. I assumed that the new extension walls would be 'toothed in' to existing (where the new wall continues the line of the existing) but I'm getting mixed messages as to whether that's a good idea or not.

The alternative - walls butted together using a wall tie system like Furfix - won't look very attractive but I can understand the appeal because:

(1) The building sits on heavy clay soil which has a tendency to shift a bit. Allowing for a little movement between old and new structures could be a good thing.

(2) The original brickwork is Imperial so toothing in would probably mean I have to source Imperial bricks for the extension which I guess don't come cheap.

I'd be interested to hear any views/opinions, especially if anyone has experience of toothed in walls built on heavy clay soil. Thanks.

 

[noseall]

If the walls are in plane, and you can get a decent brick and gauge match, then it always looks better toothed in. Your builder needs to consider gauge etc before deciding. Also make sure that the existing building is plumb and that there aren't any setting out quirks that could foul the return stretcher
bond at the other end. finally, your builder also need to get a decent mortar match or else it will look pants.

Some BCO's prefer you not to, rather they insist on using mechanical ties stating this deals better with differential movement betwixt the two buildings.

 

[^woody^]

There is a real possibility that the extension will settle and move, so toothing is not recommended as it will crack.

It's always more difficult to get toothing to look right too, and you have little chance of that with old imperial brickwork.

 

[dogfonos]

Thanks for your replies. Certainly an issue that divides opinion. I'll have a look at other extensions in the immediate area to see how they've been joined but I guess, ultimately, it depends on what the BCO wants.

 

[noseall]

It's always more difficult to get toothing to look right too.

Depends who is doing it.....
The join is to the right of the barrow and down pipe.
We blended two different bricks on this job. On another we used four different bricks!

Untitled

• noseall
• 13 Dec 2014
• 1

 

[eddieed]

We built an extension on our property. The extension is stepped back and therefore uses wall starters. The old part was imperial bricks and the builder specified imperial for the new part so that he could match up the mortar lines between the buildings. After about 8 courses they were about half a brick out and when the old bricks were measured it became obvious that the sizes were all over the place - hand made and fired I guess. Thankfully we have a rain water pipe running down the corner anyway so you don't see it anyway. The builder was annoyed as the imperial bricks were about a third more expensive - you also get a lot less choice in bricks! So depending on how old the bungalow is (our house is nearly 200) you may not be able to tooth in anyway!

 

[^woody^]

Depends who is doing it

That's nice.
But it's getting harder and harder to find people that care, and do work like that.

 

[mfarrow]

Eddieed, I'm assuming your builder was building up the corners first? If so why didn't he just gauge them to the existing rows using a piece of wood and a pencil and size his joints as appropriate.

Someone who built an extension in the late sixties on ours used imperial bricks like the existing, but completely screwed up their corner so ended up cutting into the existing bricks to tooth them. God knows how they got an angle grinder as I doubt they were common back then. Luckily I've hidden the mess under a new extension.

 

[Brigadier]

As bricks have next to sod all tensile strength, they will crack with minimal differential movement. Which will not be a good look.
Unless you could guarantee "no movement" between existing and new, you would run the risk of toothed-in brick cracking.