Maximum thickness of mortar bed joint.

[davidmiller]

Hello. I seem to remember that 30mm is the thickest a bed joint can be (for building regs).
Having googled it I call only find anything that states it in Imperial measurements which seems odd. And they state it at three quarters of an inch. Anyone know?
This is to correct an uneven foundation on the first course. Cheers

 

[SpecialK]

How thick do you need it to be? You could use some more concrete, cut some bits of block down or pack it out with something suitable?

 

[noseall]

Hello. I seem to remember that 30mm is the thickest a bed joint can be (for building regs).
Having googled it I call only find anything that states it in Imperial measurements which seems odd. And they state it at three quarters of an inch. Anyone know?
This is to correct an uneven foundation on the first course. Cheers

I'm not sure there is a limit. Rather, practicality supersedes, in that large beds are both ugly and difficult to work with.

 

[Nige F]

Christmas Joints ...................cuz you always have a big joint @ Christmas

 

[Ivor Windybottom]

I had the same issue. I used concrete common bricks sliced in half lengthways with a 9" diamond blade for the first course, did the job. I suppose there'd be a 40mm-ish bed next to them, where I was stepping to/from a full brick or nothing, so don't know if officially correct.

Also you can use commons as brick-on-edge to give 1.5 courses (in place of 2), may be a better alternative if there's enough space as you may need to widen out. Best used crossways ideally. Obviously needs to be at least as wide or wider than the standard courses above, so layout may dictate whether you can or can't do this.

Don't use any old rubbish, e.g. paving slabs, roof tiles. It's going to support the entire building, so it has to be something of a known standard with a specified load rating.

 

[^woody^]

30mm with 6:1 or 3:1 mortar?
Soft building sand or sharp sand?
I suspect the crushing strength will have something to do with it.

There is no such dimension for a single joint - joints are based on an average depth over several courses, and DPC joints are double.

You would normally pick a corner up over several courses, not a monster joint.

Or use tiles, brick on edge or a split brick.

 

[catlad]

You could use some slate which would also act as a dpc.

 

[davidmiller]

Thanks people. I'll probably use a few different ways as it's a bit uneven as well as generally being 30mm out of gauge.
With regards to some is these points below

30mm with 6:1 or 3:1 mortar?
Soft building sand or sharp sand?
I suspect the crushing strength will have something to do with it.

There is no such dimension for a single joint - joints are based on an average depth over several courses, and DPC joints are double.

You would normally pick a corner up over several courses, not a monster joint.

Or use tiles, brick on edge or a split brick.

I'll use 3:1 as it's below dpc.
As for getting back on gauge gradually I agree. But I'd like to do the first course in concrete blocks to save time and bending down. That will get me to about finished ground level and the first course of bricks may be visible. So I need to get it in one hit I suspect. (On the outside wall). Cheers.

 

[bsr]

When I've needed to build up a bed I've used a sharp sand mortar for the first course - doesn't slump and stronger than a soft sand mortar.