Cutting a doorway in a brick and block cavity wall

[P.J.]

Hi All,

What should I use to cut this hole in 4" bricks and blocks please ? A 12" angle grinder or can I get away with a 10" ? Or is there some other method I'm missing ?

Thanks,

P.J.

 

[oilman]

You're missing an Arbortech AS160 (Tel 0800 980 99 99) I have no connection with them. You can cut the hole with much less cleaning up than a disc cutter, and it does it in a way that's not so risky for you or the building. Total job time is about 60% of that using an angle grinder.

 

[P.J.]

Thanks for that oilman - I'm looking into it but my nearest Arbortech hire centre is a fair way away.

If I was stuck with the old angle grinder approach - what size should I go for ?

Is there another method other than these 2 ?

Cheers,

P.J.

 

[oilman]

Thanks for that oilman - I'm looking into it but my nearest Arbortech hire centre is a fair way away.

I'd get a local hire centre to stock one.

If I was stuck with the old angle grinder approach - what size should I go for ?

I'd go for the Arbortech. I hate work, and I hate cleaning up even more.

Is there another method other than these 2 ?

Sledge hammer, but it's not very neat.

 

[JerryD]

We own an Arbortech 160 and it is excellent for cutting everything except brick. It will cut bricks, but it becomes too slow and tooth wear will be excessive.

What we do is use a 350mm (14") diamond bladed angle grinder for the brickwork and the Arbortech on the blockwork.

btw, there is no such thing as a 10" angle grinder, they come in the following sizes: 16", 14", 12", 9", 7", 5", 4.5" and 4"

A 12" angle grinder will just cut through the blockwork, depending how thick the old plaster is. That's why we bought a 14", it cuts nearly 5".

Is this opening to be cut on a outside wall or is it a knock-though into an extension?

 

[P.J.]

Thanks JerryD. By 10" I meant the 230mm disc (yes that's closer to 9", I should know that as a mechanical engineer! ) - thanks for advice.

The doorway is going on an outside wall. There will eventually be a utility area outside this door, but not yet. Am I missing something ?

The lintel and dpc is now in place, I just need to replace the blocks on the inner leaf above the lintel before cutting the opening.

Is there a trick to cut an accurate line with a big angle grinder ? Maybe attach a batten to the wall to cut up to or something ?

Thanks for the advice,
P.J.

 

[JerryD]

depends on 'how accurate' the cut needs to be.

For 'near enough' stuff we precut with a 5" (125mm!!) angle grinder and this forms a very visible 'line' for the Big Daddy to follow.

However if the cut is critical then I would try and use a timber guide of some sort. One difficulty with the big machines is cutting square through the wall, you may be following the line perfectly but you may be holding the grinder 'unsquare' to the face of the wall.

Some big grinders have a guide built into the dust guard, this should help keep it all straight.