Best tool (hire?) to put hole for fan in wall ?

[Jethro_uk]

Want to fit an extractor fan in the corner bedroom which has an external wall.

Last but one time I needed to punch a hole in a wall, I drilled loads of smaller holes around a circle, and hit it with a hammer. Eventually I punched the plug out, but it was *****y hard work.

Last time I used my SDS chisel on rotary stop. It did the job, but fried the drill :(

Given I don't make a habit of making holes in walls (so have no need to invest in a tool) what's the best thing for the job.

It's one hole through an external (so 2-leaf) wall. About 4" (oir whatever extractor fan sizing is).

Presumably it's better to go outside->inside to reduce dust etc ?

[David]

Probably best to hire a core drill and an SDS drill to drive it.

It is a very common requirement, so I expect that most hire places will have one ready to go.

One thing - if you go Outside -> Inside then you are likely to tear up your inside wall surface as the remaining thin bit of wall is battered by a large SDS drill. A long time since I did this kind of thing, but I would guess you need to bore a guide hole all the way through and cut from surface -> cavity from both sides, taking out two cores (or more).

Cheers

Dave R

[no_spam]

+1 to what DaveR said, but make sure the drill has a clutch! The dust isn't too bad - you could probably use a water spray bottle to keep it under control but I haven't tried this.

[Jethro_uk]

Is this to prevent the drill "catching" and deciding to turn the drill rather than bit ?

[Tricky Dicky]

When core drilling the drill should not be set on hammer action. The last f an hole I drilled from the outside left a quite a neat hole in the plasterw ork, once you feel you are hitting the plaster you need to ease off the pr essure. Alternatively as already mentioned drill from both sides for the ne atest hole, the pilot drill on most core drill protrudes well in front of t he core drill so as soon as it pierces the other side you can then drill fr om that side. Having said that it is easy to slightly misalign the holes dr illing from both sides, to minimise this drill as far as you can from one s ide before changing sides.

Richard

[no_spam]

Yes, that's a bit of excitement that you don't want to have - especially if you're up a ladder.

[GB]

Yes.

[John Rumm]

That does depend a bit on the type of core drill. Wet or dry diamond cores are designed to be use with rotation only. However TCT cores tend to need hammer. (the TCT ones are lighter and shorter, so you need to stop and break out the partial core several times as you go).

IME leaving the pilot drill in can slow down the whole process - since it will not cut masonry well without hammer action. So once you have the core started, you can take it out (it also saves it vibrating lose and snagging the core).

[John Rumm]

A core drill and a dry diamond core bit.

Typically a 107mm core will let you get whatever ducting you fancy through the hole for a 100mm fan.

Yup. While not as bad as say an angle grinder, they still throw some into the air.

You can drill through first with a normal drill bit to mark the centre point on the outside.

[Dave Plowman (News)]

As with any brush type motor, they're not designed for continuous use at maximum load. Best to use in bursts, and allowed to cool down between.

[Tim Watts]

IME TCT are far far quicker through brick - but you really must go from both sides or at least do the last bit without hammer or you will blow off half the other side...

[dennis]

I have used one of these for the last two holes.

They are somewhat cheaper than a diamond core drill but you will need to chip the middle out a couple of times as they aren't deep enough to get a whole brick depth.

If you are going to do a few holes then a diamond core bit is probably better.

[Roger Mills]

Use a diamond-tipped core drill. TCT drills are cheap but not nearly so effective.

Go all the way through with a suitably sized pilot drill first, and then drill the real hole from both sides, meeting in the middle.

If the internal position is critical, start drilling the pilot hole from the inside. If it's not critical, find the approx position on the outside, and then drill through the mortar at the intersection of a horizontal and vertical mortar joint, so that the core will be spread across three bricks. It's easier to remove that way, because the core will come out in 3 pieces.

As others have said, use a drill with a clutch - particularly if working up a ladder.

[Chris Holford]

snip

Just an idea; when I did this many years ago I angled the hole so it sloped slightly downwards; the inner end was slightly higher than the outer end so that any rain getting into the hole would drain out rather than in.

[ARW]

Agreed

117mm is the usual size. This allows a 110mm soil pipe to be used as the ducting. Even 107mm is tight for flexible ducting.

Yes

Usually a pilot hole from inside to outside - most of the drilling from the outside if needed

The last few cm really should be done from the inside to reduce the risk of blowing the plaster (or the skim on dot and dab walls)