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?
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.
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.
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.
Yes, I will need to take out more than one course, I know that, I didn't word it very well. My main reason for using the mortar rake is because I want to preserve as many good bricks as possible to make good the sides and this seems necessary because the opening isn't particularly large so I won't have that many left over. Plus it's less likely to disturb the course above the lintel and save a bit of work. I'll only take out as much as I need to install the lintel just to save me having to secure a larger hole if I can't fix the window straight away, that's all. I'm a DIY'er - we take our time ;-).
I was thinking of that but thought the depth may be limited on a grinder and these mortar rakes may be more efficient and more controllable.
That's still an option but I'm pretty sure the bricks are not going to knock out that easily. It's quite a new house and the mortar is strong.
Another point is, do I need to place a DPC above the cavity lintel? Some sites advise you need to, others don't even mention it. As it's only 900mm I thought I might be able to get away with it.
If you are living in the house when you do it, you will regret 'til the day you die that you used a diamond disc indoors to cut through brickwork! Any dust found by your wife in the next 10 years will be your fault, all your friends will be told, in detail, about the amount of dust you made,and your children and your children's children will annually be told the story of the day when Daddy cut through the wall. DAMHIKT.
I would have thought that with any approach there would be plenty of bricks to clean up and make good the sides etc, even having used quite a bit of welly with a club hammer to extract. The bricks will probably come out in 'clumps' which can be split down and cleaned on the floor.
Also, sure knocking the mortar off from below may bring some of the bricks in the course (to be) above the lintel off but they can go back on once cleaned - you've got a mix on to make good the sides right? Or if they are intact once the horizontal upper cut is made with say the grinder, you could just grind the mortar off carefully so none is visible at the front face.
IIRC the mortar rakes I have seen are only a couple of inches long and
8-10mm thick, I can't see how they would cut any deeper than your 9" diamond grinder blade.
I, perhaps wrongly, have always thought that the application for these tools was raking out before re-pointing. I can't see them being more efficient than a diamond blade for deep cutting applications or even controllable as you would be basically using a hand mortar milling machine with a long bit.
Never tried a mortar rake so maybe I am talking rubbish here!
If you hit 'em hard enough they will come out ;-)
Don't know about this, sorry. I have seen buildingswith DPC's above the lintels, mainly stone IIRC, although I can't remember the exact circumstances.
If by cavity lintel you mean the galvanised hat profile __|\__ type then the galavanised steel is water impermeable anyway so putting an DPC on the outer leaf does not make any sense to me ... but I'm just a punter and am just guessing!
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.
'less' being very loose here. I'd use a grinder. Either way will make more dust than you have ever seen...
Does the mortar rake reach right through? I thought it was only a couple of inches, meant to get it ready for repointing...
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.
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.
Indeed and if its red brick then you might end up with permanent stains on things like carpet 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.
Got the opening sorted, lintel installed and all re-bricked in 2 days. I ended up just drilling the mortar to get the first few bricks out and then took the rest out.
Everything went fine and the two courses just below the prop all stayed put. The biggest problem I had was working a straight level edge with the course of bricks. The brickie used to build this house was either crap or a real lazy barsteward as all the full bricks were totally out of line and the pointing thicknesses varied like hell, so I had to take more than just the half bricks out to get it sorted. But it's all good now!
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