PC Paul wrote:
AlexW wrote:

wrote:

Hi,

I'm about to create a new window opening with a 900mm lintel into a
cavity wall.

Rather than start banging away I'm looking to use the 10mm mortar
rake bits from screwfix attached to a grinder to remove the top
layer of bricks and install the lintel first.

To make the cuts on the internal wall I'm going to use a 9 inch
grinder with diamond blade.

For the exterior brick work I'm looking to make it good by cutting
half bricks and mortaring them in the alternate courses.
That's presuming the the mortar comes cleanly off the full length
bricks and the courses are pretty regimental in the first place. An
alternative was to cut with a bricksaw and make good with a render
coat but not sure how to finish the render coat neatly around the
opening without some kind of frame..

Anyone got any other suggestions or advice I should take on board?


I really am no expert here (Caveat DIYer)...


Very ditto for me..


Why remove the single course of bricks first? Sure you'll have a nice
lintel shape aperture if it does /not/ collapse. But even a single
course removed will mean its unsupported above - may as well take the
whole lot out. You could support the above courses with a strong boy
or two to avoid collapse either way. Or let the bricks loose and
rebuild later.


That row of bricks are only effectively supporting a triangle of bricks
above them. I would remove a single row (and others below if they want to
come too..) and get the lintel in, to minimise the time they are unsupported
for. Especially since the rest of the opening will be being bludgeoned about
and the shocks could loosen the mortar.

If lucky the above bricks might not come down, if they corbell well.

You have essentially cut the mortar above and at the sides, I would have
thought that very little shock will be transmitted to the courses above
I think, nor will it take long to get the bricks out. No harm in doing
it this way though.



For a lintel of 900mm won't you need to take more than one course out
and put some padstones on?

As for the mortar rake, why not just cut out a line in the mortar with
the grinder (less dust as the blade is thinner) or a stone cutter.
Clean the remaining mortar off with a bolster etc.


'less' being very loose here. I'd use a grinder. Either way will make more
dust than you have ever seen...

Indeed and if its red brick then you might end up with permanent stains
on things like carpet etc.


Does the mortar rake reach right through? I thought it was only a couple of
inches, meant to get it ready for repointing...


Why not use a petrol powered stone cutter/"stihl" saw to cut either
side and then bang bricks out with a club hammer as they will no
longer be attached ... feeding water onto the blade will reduce the
dust and these are much better for this sort of thing, IMO.

I seem to remember the new windows in our house (18" thick random
stone) walls being cut this way.


The problem doing this with bricks is that they aren't solid all the way
through, so you'd end up with voids and holes. Sadly you do have to take out
the full bricks and replace them with halves, with all the attendant mortar
matching etc.

Depends on the brick, I think, even modern ones. Trimmed up a door
opening (single brick) this way ... no holes in mine!

I think from the OP that the OP was replacing alternate half brick
alternate courses, so I was assuming he would be slicing down a mortar
joint on alternat courses to acheive this. If this is the case the cut
half bricks will be easier to remove than just taking is out brick by
brick from below the lintel.


Good luck!



Yes this sounds like a bit of fun anyway.