Minimising cracking when drilling a hole in brickwork

[Paul205]

Dear all,

I need to drill some holes in some external brickwork. I need to drill a 100mm hole for an external fan and a 150mm hole for a cooker hood outlet.

The mortar is around 2 weeks old. I would appreciate any advice on whether this is more likely to crack or less likely to crack than more established mortar.

I am considering use of a hand held drill and 'diamond' core drill. I am considering using a 'patient' approach and not using a hammer action drill.

I would appreciate any thoughts and comments on how I should best reduce the possibility of cracking the mortar.

I could perhaps not use a core drill and go for the many holes to create a larger hole approach.

It would be noted that one of the holes could be a 'square hole' as the hole will be covered by the fan I am fitting so for this hole I could use an angle grinder for example.

Kind Regards





Paul

 

[Burnerman]

Core drill for sure....if you use the chain drilling method the mortar will break for certain. Don't use hammer action with the core drill, you'll need a fair bit of pressure and keep the drill head wet.
An angle grinder wouldn't work too well as you cant cut very deep.
Its a wee bit early for the mortar to be fully cured but you may get away with it!
John

 

[Paul205]

Thanks Burnerman,

I was considering the angle grinder to at least get the cut going a bit and then perhaps use a core driller later.

I would appreciate your thoughts on a dremmel with a small stone cutter just to get the initial cut through the brick??!?

I can wait a good 3 weeks before I do this, I was considering doing it now in case a 'softer' mortar may help me

Cheers





Paul

 

[Burnerman]

Paul, the core drill comes with a 10mm pilot drill bit and once that's been used, the core drill will cut through your brickwork without any problems......the amount of pressure you apply to the drill bit, the harder it will cut.
The only thing I'd recommend is that you use the hammer action to produce the pilot hole, and once that's done, the core drill takes over.
You'll be surprised at the quality of the drilled hole, I fancy.....Slightly more difficult is keeping the thing at exactly 90 deg to the wall in both planes.
Go for it!
John

 

[Norcon]

Once the core is started its always best to remove the pilot bit.

 

[Paul205]

Cheers gents, if you have any additional comments please feel free to chip in. I am looking for any ideas possible to reduce the chance of cracking. Thats my primary focus.

Perhaps a good 'brand' of core bit could be recommended



thanks

 

[Paul205]

Perhaps someone can possibly advise on whether I should drill the pilot into the brick or mortar would be helpful

 

[Burnerman]

Obviously it depends on where the finished hole needs to be, Paul, but the mortar bed will be suitable to take the pilot hole.
John

 

[Paul205]

Yeah I was just weighing up whether it would be better to drill into mortar or brick if the choice exists.

I would appreciate thoughts on a good quality core drill bit

 

[Burnerman]

I recommend you hire one, Paul......excellent quality and you only pay for the wear and tear. They supply the correct drill machine too, of course.
John