drilling a 107 mm hole through tile/brick for vent - help

[glider2]

Hi,

I'd like to install an extractor fan in our 1st floor flat's bathroom. For this I would need to drill a hole through a tile and bricks of a total thickness of 300mm and a diameter of 107 mm.

From what I've seen on these forums and a chat I had at the local hire shop it looks like a rotary diamond core bit on a clutched drill and a pilot bit is the way forward. I have a few questions though:

- how do I cope with drilling through the tile and without cracking it?

- I have no experience with drilling to such depth and I really don't want to mess this up given the complications of making it right if I do. How hard is it to do this for the week-end DIYer?

- is breakout damage on the external side of the wall a potential issue?

- 300 mm is quite deep. Are their core bits that can handle this depth without being stopped in their tracks by the remaining debris?

Thanks.

 

[Softus]

- how do I cope with drilling through the tile and without cracking it?

If the tile is properly stuck on then it's unlikely to crack because you won't be using hammer action. However, if the tile is smaller than 107mm in either dimension then it might.

- I have no experience with drilling to such depth and I really don't want to mess this up given the complications of making it right if I do. How hard is it to do this for the week-end DIYer?

Easier than you think. The hardest part is keeping the core horizontal. If you drill the hole slightly off then you can easily cold chisel off some more.

- is breakout damage on the external side of the wall a potential issue?

Yes, a bit; hence after drilling the pilot hole I would cut about 1" deep from the outside and do the rest from the inside. Unless the wall is too high, then you have no choice. Again, because you'll be drilling without hammer action you can ease off the applied force as it's about to break through.

- 300 mm is quite deep. Are their core bits that can handle this depth without being stopped in their tracks by the remaining debris?

No. You have to clear the core regularly. You'll suss out how regular it needs to be when you have a huge lump jammed inside.