Toothing Brickwork

[Richard]

Hi

Im just about to start bricking up a doorway which will be a support for an RSJ after I knock some of the existing wall through to form an arch. I have been told by the structural enginner that I need to fully bond the new brickwork with the old by toothing it in. Can anybody give me some advice on how I go about doing this, do I remove every second course and lay the new brick into the gap?

Also whats the best way to make sure I get a straight line, should I use a plumb line or not bother due to the gap being so small?

Also what tool should I use to cut the bricks, I was planning on hiring an electric cutter of some kind.

Thanks!

Richard

[Alex]

Just remove the half bricks at the end of every other course, so that you can maintain the bond using full bricks.

Depending on the integrity of the wall, you may just be able to take them out with a bolster, but using a grinder will give a neater finish (but will produce more dust than you imagined possible!)

If you're doing anything more than light DIY it's almost always worth buying a cheapish grinder instead of hiring one IMHO.

Alex

[Steve]

Check with your engineer or BCO

All the houses round here with extensions that are toothed in seem to be three courses chopped out then leave three etc etc With full new bricks top and bottom of the tree courses Not as nice looking as every other brick but guess there must have been a reason for this Or there are metal channels you can bolt to the wall firfix etc

For removing the bricks you can drill out most of the mortar first then clean out with a plugging or bolster chisel, an SDS drill is great for this esp. if you have lime mortar

Steve

[Jerry Built]

Depends on his recommendation, I should ask. For maximum strength alternate courses is best, but you can go every three or four.

A piece of batten would probably be fine.

What are you cutting? To cut bricks, you can generally use the edge of your trowel, or tap around them with a bolster chisel for accuracy. If you mean to cut out the existing, stitch drilling and/or a masonry saw would be OK and not too dusty. A masonry saw is like an ordinary saw for timber but with big TC teeth.

J.B.

[Grunff]

I don't believe these give the same strength of bond as toothing in.

[Michael Mcneil]

The three courses are the same height as a concrete block.

Use a boulster on that sort of toothing, a masonry drill and cold chisel for every other course. I can't remember seeing an example of the latter not intended to match face brick.

[dg]

Why can't you use a mechanical fixing i.e. screwed on ties, wall starter, or helical rods? These would hold the new work just as well.

The problem with toothing is that you can crack the toothed bricks very easily when cutting the alternate courses. These cracks may be not be visible on the surface but will crack further later. Also it can be very hard to ensure the joints are full when you bond the new work, and so the toothed brick remains unsupported. These can defeat the intended load spreading of the bond.

Toothing tends to be frowned upon as a reliable bonding method - unless the work is monitored and properly done.

However, if the work needs to be bonded as it will be seen, then cut out with a disk cutter and avoid hammering, then make sure the joints are full or pack with slate.

You don't follow a plumbline, but follow the bond of the existing wall. This may mean spacing or cutting the new bricks to fit. If you mean horizontal line, then you use a string line stretched across the opening for each course.

dg