Hi all, I'm going to be fitting a online fan in the loft to extract from my bathroom, this will involve drilling through a brick wall. As this would mean drilling whilst up a ladder im thinking of drilling from inside the loft. Would doing this give me a clean exit hole on the outside or would it blow the brick like a normal drill would.
Thanks
I did this recently from inside out using a coring bit with a guide bit.
Equipment
* safety goggles, mask (dust) and hearing protectors
* I had a vacuum cleaner going to help cut the dust down a little - not much dust to be honest but you'll need one to clean up the mess away..
* Drill
must have a safety clutch - this means if the bit bites the drill will not whip out of your hands. You'll want two hand grips. I used a 240V 850W SDS set to rotary. The SDS arbor helps without slipping. I think you were all sick of hearing about my Bosch SDS
but the clutch is a must - mine caught a couple of times.
Overkill for one hole.. but I've used it a lot:
http://www.screwfix.com/p/bosch-gbh-2-28dv-2kg-sds-plus-drill-240v/65597 - it takes about 5 seconds to put a 10mm x 50mm hole in the wall for bolting in the garage
As I said it's the clutch that's important, the weight because you need to hold it with two hands as it cores.
* I used a Ebaur coring bit with extension arbour and guide bit - basically the following - note the weight of it will be almost 2 Kg of drill bit..
http://www.screwfix.com/p/erbauer-diamond-core-drill-bit-107mm-x-150mm/28948
http://www.screwfix.com/p/diamond-core-kit-5pcs/83176
The arbor extension was enough to get through a block and brick wall easily.
Drilling:
1. select point - i drilled from my loft out, so a point was easy to locate and mark.
2. Drill a small dent to prevent things moving around
3. set up coring bit - adding the extension and guide bit,
the drill should be setup for rotation not hammer with a normal coring bit.
4. Drill initial 1" careful to set the path in a downward fashion so that any water/condensation will flow to the outside of the house. Ie the inner hole is higher than the final butter whole. After the first inch remove the guide bit incase it falls down the air gap between bricks. The dent for the guide bit stops things skitting around.
5. continue coring the inner brick/block until it gives. Extract the bit - take out the block core and leave to cool a little and ensure you're happy with the size and angle before getting to the outer bricks.
6. Reinsert and slowly start into the brick itself. You'll not need the guide bit as the hole in block will act as a guide (if you adjust the positioning you may need the guide bit until the coring bit can keep itself true - only a centimetre required but you want to remove the guide bit asap).
7. Easy does it.. and then pop as you go through the wall. The outside hole for me was perfectly round.
Installation points:
1. When you install the tube through the wall you don't want water dripping down inside the air gap. For this reason you should measure up and then seal/glue the pipe. If it's a telescopic tube the outter tube should connect to the outside, the inner tube should connect from the inside of the house. This means any water flows and will not pool at the joint only to find its way through to the air gap brick work...
2. Outside - seal the tube and brick to prevent capilary action and put a vent on the outside to stop wasps/birds etc attempting to use it..
Using rotary rather than hammer means you'll get a clean cut without exploding the back of the brickwork as you drill through. Also by not having the guide bit in, it means you will not get a single point pressure causing a blow out.. the coring bit will simply grind it's way through leaving a smooth entry and exit.
