Putting a 150mm wide hole in a 530mm thick wall

RoyMi6

RoyMi6

RoyMi6

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I'm an avid DIYer and after 2 years or so of doing 2 bathrooms and one room I'm becoming quite the dab hand at it all.

However, I'm at the point where I need to put a 150mm wide hole in an external wall for the extractor hood (currently no external vent in the room) and it's simply something I've never done before.

It's a victorian house so the walls are stone built and roughly 530mm thick.

I figure the two options are either a diamond core bit, or stitch drilling with a regular masonry bits.

I don't have an SDS drill, or any appropriate bits for either option.

Looking at the costs of hiring a diamond core bit (which seem to be a max length of about 320mm) with associated drill seems like it will cost me in the region of £120 given that I'll need to do it at a weekend and likely need it for at least 2 days - because literally everything I do always takes at least double the amount of time I predict... which means I'll probably take 4 days... but then if I predict 4 days I can absolutely guarantee it will take 8 days...

Aaaaaanyway...

Other option, as I see it, is I could probably make long term use of a regular SDS drill, and combined with one or two bits would likely only cost me the same as hiring something specialist.

As I see it, the biggest challenge with hiring diamond coring bits is lining up both holes as I'll need to drill from both sides - obviously a pilot hole will help mitigate this though, but that means buying/renting drill bits for this purpose as well.

With stitching (with a newly purchased SDS drill and bits) it's keeping everything aligned and level as I put 10 or so holes through the wall...

Anyone got any advice or experience with either/both options? Any pointers, recommendations for drills/bits or alternative methods?

Thanks in advance.
 
Got a friendly plumber/heating engineer that you know/have used? They will make short work of putting the hole in, will cost less than renting/buying the bits yourself and as its something they do often (for boiler installed), it will be easy and they will have the bits.

Have done one ourselves before, but we already had a good SDS and simply purchased the core drill.. Cheap one from Screwfix, it was dead by the time we had done 1 hole (following instructions to the letter) so it went back and they gave a full refund.

Pilot hole first, all the way though. tilted slightly from inside to out (so any water that gets into the pipe runs out).


cheesyboy said:
If you're using a SDS, make sure it's got a clutch. Or you'll break your wrists when it sticks.
Click to expand...

This, 1000x this. They shouldn't be allowed to sell SDS without a clutch IMO!
 
I'll be following this as i'll also be doing similar for an extractor. Our walls will be similar thickness, but i assume that a pilot hold and then drill from either side should do it.

The price of the core bits is pretty extortionate though. Might follow @samcat 's experience and buy the cheapest from screwfix and hope it's knackered after one job :p
 
Marvt74 said:
I'll be following this as i'll also be doing similar for an extractor. Our walls will be similar thickness, but i assume that a pilot hold and then drill from either side should do it.

The price of the core bits is pretty extortionate though. Might follow @samcat 's experience and buy the cheapest from screwfix and hope it's knackered after one job :p
Click to expand...

Their should always be drilling from outside in first (AFTER pilot hole), 25mm or so. This prevents the bricks chipping off and looking rubbish.

Be VERY aware that EVEN a clutched SDS can kick. This can be VERY scary if you are up high on a ladder. Better to have scaffolding/platform.

For a 100mm vent you probably want 106mm core.

SDS set to DRILL, NOT HAMMER.

Link to a good previous discussion on this matter:
https://forums.overclockers.co.uk/posts/27306895/
 
@RoyMi6 that is a fairly sizable hole to drill. It will probably be cheaper to get someone in to do it than buying all the equipment. You will need a decent 152mm core bit plus possibly a couple of extension bars. And a good sds drill but note you don't want hammer action on.

Cheap core bits are a false economy, and from my experience they only seem to be effective with hammer action which causes all sorts of issues Inc damage.

You are probably looking at £200-£250 of tools if buying to do this right. Not to mention the health and safety risk. Most builders/electricians I know won't do at height drilling like this without a platform or secured ladder + assistance.
 
Old stone wall
SDS drill and long bits/chisel bits too
DO NOT try a core drill.Chances are if you hire one you will break it and they will charge you for a new bit
and core drills are not really meant to be used in stone walls,mainly concrete/blocks and bricks
Just my opinion(been in the trade for many years now)

Core bits and diamond core bits are 2 different categories and methods of use.No hammer with diamond bits.Hammer with TCT core bits
EDIT
if it is old stone victorian etc be prepared to have a large hole you have to patch,especially if there is a large stone in there
 
152mm is probably a bit big for a lot of normal range sds drills, i stitch drill, best way is say drill 6mm holes as close as you can at say 150mm circle. Then follow that with a larger size and it will break the core free then, say 10mm bit.
152mm you really need a core drill. Ive done 52mm through engineered brick and that took ages with my makita.

Or pay someone to do, pretty sure it wouldnt bee that much.
 
Good luck, did this with our old house for a combi flue hired a large drill and core bit and it didn't touch it! Ended up using the core bit just to make a nice hole in the render and then worked our way through with hammer and chisel, bear in mind if yours is anything like ours the stone was all shapes which was sending drill bits off in all directions and the centre is filled with loose scalping's which fall down as you clear through.
 
I did this recently for my bathroom. Like you I have a Victorian house and the bricks are three solid courses thick and made of the hardest substance known to man, even drilling a regular hole is really hard work. It took my plumber a good 2 hrs to drill the hole. (He had a team of 3 employees doing 15 minutes each until it was done)
Good luck!
 
I did this in my last place - turned out to be cheaper to get a specialist company to do it than it would have been for the cost of the hire for the drill and bits, plus less chance of injury!
 
I didn't read the rest of the thread so forgive me if things changed!

Don't whatever you do use an SDS. Go an hire a specialised core drill. They are far superior to a standard SDS even SDS MAX for doing that one job ~ drilling a core. You can hire the core bit with it. A Diamond 152mm core bit is a bit of a monster and together with the drill it's a hefty weight so it can be difficult holding it level. I use a pocket level on the barrel of the core bit frequently to make sure. The core drill will come with a big handle, use it or you will break your wrists. It is best to drill a pilot hole all the way through the wall and drill through one layer of brick from the inside and the other from the outside. You can do both from the inside though if need be. Believe me a 152mm hole is a monster when you are drilling it and you really need the right equipment or you are going to hurt someone. Most likely yourself. Make sure you wear protective gear, especially on your feet. And switch the power to the drill off before you retract the core.
 
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