Our bedroom faces directly south and the house is very well insulated so that in the summer it’s always hot and hard to sleep.

We bought a portable air conditioner which worsw ok but venting it though the window isn’t ideal, even with a homemade cardboard template to stop the hot air just coming back in.

You can see where this is going…

Is it a stupid idea to drill a hole for the vent? Theres no wires or pipes where we would make the hole.

Is it as ‘easy’ as renting a big drill and the right diameter hole drill piece. Or will it end in tears, no house and/or no limbs?

Any advice welcome!

What are your walls built from?

Assuming your house is masonry construction then yes.. big drill.. right size core drill. Drill a pilot first and then drill from both sides so you aren’t going to burst out with a huge hole. Find out what insulation you have… loose fill polystyrene would be fun as it fills your bedroom.

Think about how you’re going to finish the hole. Insect guard, non return flap. Will it be a cold disaster when it’s -5 outside in Jan?

J

I have core drilled 6″ holes in 3ft thick stone walls – so anything is possible. The tools are expensive tho and when you hire you pay for the wear on the drill bit.
Why not do something about the solar gain instead?  Blinds or shutters?

What about a vent through the attic and out the roof?

We sleep in a south facing attic room and the heat is unbearable. Having a vent fitted next week into the crawl space out through the roof. Can’t wait to blast the air con then.  I work nights and currently I’m sleeping on the landing as it’s the only quiet and cool place during the day .

Do pilot a hole from inside to out then core drill but only from one direction. Usually from the inside as it won’t require being up a ladder with a snatchy grabby core drill. Plus lining up holes is an art form even for the skilled. As you approach the finish depth go nice and steady. Your grill on the outside will cover any spalling. As above make sure you are not loosefill insulation. On a final note most hired cores will be around say 150 in depth meaning you have to clean the cores out as you go to enable full depth.

Crack on and mind your wrists 😉

The 6.3kg titan drills at screwfix are almost as cheap as hireing and have enough power and a clutch to save you from broken wrists if it grabs.

I would look at going through the roof though, less messy. Go up then under the eves.

Or, get a new sealed glazed unit for your window (especially if you have a small opener at the top) with a hole cut in it (like they do for cat flaps in glazed doors) or a cheaper option would be a white UPVC infill panel.

Unless your house is rendered, or you are core drilling out in a discreet place, I would hesitate to do a large core drill as you are bound to regret it at some point and it will always be a visible scar unless you get a proper repair done with matching bricks.

PS if your house is very well insulated, it shouldn’t be getting as hot as other less insulated houses in summer.  In hot countries they will keep the rooms cool during summer with decent blinds.

When I drilled a 6″ hole through our kitchen wall I bodged a large biscuit box over the hole with the Hoover tube taped to its side to suction off the worst of the dust whilst drilling from the inside. IIRC drill & bit hire from TP was ok (ignore their www prices & go in store for a quote).

The insulation holds heat in.

The weight of insulation/decrement delay and solar gain through windows allows the heat into the house in first place.

This is why on continent you see shutters down during day, shady overhangs, heavier weight/bigger specific heat capacity materials, hidden reflective layers or light colours used in buildings.

Can you keep (thermal and white lined) curtains closed during day?

Doors closed to stop heat rising?

Etc

A 4″ core with correctly coloured grill on the front won’t look anywhere near as horrendous as putting a solid panel in one of your windows trust me. As for talk of clutches, don’t believe the hype, I’ve got a makita core specific drill and that **** will still grab.

On a final note id never send anything up through the roof unless it was a last resort. So much harder to create proper water tightness once a roof is complete. Decktights etc need flashing in correctly so if there is a horizontal option I would always take that.

A 4″ core with correctly coloured grill on the front won’t look anywhere near as horrendous as putting a solid panel in one of your windows

This.  Same sort of thing as used to stick a vent in for a tumble dryer, cooker extractor, etc.  Once done no one would give it a second glance

Is it as ‘easy’ as renting a big drill and the right diameter hole drill piece. Or will it end in tears, no house and/or no limbs?

Just make sure you hire a core drill with a clutch. I learnt the hard way and nearly broke my hand the first time I tried a core drill bit in a normal SDS drill. Ripped the drill out my hand, span round 15 times wrapping the main lead around the drill (and unplugging itself) and smacked the back of my hand at about 500 rpm!

Very lucky to just get some bruised fingers…

[url=https://flic.kr/p/dQp1mQ]Ouch. Drill caught using holesaw and whipped out my hand at 300rpm![/url] by Ben Freeman, on Flickr

I now have a nice Bosch SDS with a clutch….

I vent my bathroom through the soffit board. So extraction fan in ceiling, flexible pipe to soffit. No holes in walls required, almost invisible, no idea if there’s any reason why I shouldn’t but it’s been fine for 10 years.

Can’t see why aircon exhaust couldn’t go the same way.

Thanks everyone, really helpful advice, esp about the clutch drill and pilot hole.

My insulation is foam balls (:)) so I expect they’ll go everywhere, I’ll have my trusty Henry on standby.

Will go for the wall hole rather than the ceiling option as it means the run of pipe from the AC unit will be v short (and so less heat leaking back into the room).  It’s a rear facing room and I’ve got a guard thing so it doesn’t look like an escape hole from a WWII prison movie.

I’ll gird my loins (and my wrists) and crack on, hopefully this Monday.  Will report back.

The insulation holds heat in.

The weight of insulation/decrement delay and solar gain through windows allows the heat into the house in first place.

This is why on continent you see shutters down during day, shady overhangs, heavier weight/bigger specific heat capacity materials, hidden reflective layers or light colours used in buildings.

Can you keep (thermal and white lined) curtains closed during day?

If you close the curtains inside the windows doesn’t the UV penetrate the glass, reflect back from the curtains but then fail to get back through the glass as reflected light? Greenhouse effect? That’s why they have external shutters in hot countries. I ask as I have a similar problem and I close the curtains when I think it’s going to be a hot day, but I’m not sure if I’m doing anything effective.

I vent my bathroom through the soffit board. So extraction fan in ceiling, flexible pipe to soffit. No holes in walls required, almost invisible, no idea if there’s any reason why I shouldn’t but it’s been fine for 10 years.

I was wondering the other day why this isn’t done more often, was even going to look if a boiler flue could be done this way to (I suspect not though as I guess you can’t guarantee all fumes are going external).

We use a flexible tumble dryer extension pipe which hangs out of the window by about a foot so no hot air coming back. We have the air con on the landing with the pipe extending into the bathroom and out the window.

I’ve put all my vents through the soffits, as suggested they are almost invisible. However, I have large soffits and it’s a bungalow so easy choice to make 🙂

If you really need a/c do it properly with an external condenser e.g. link

Shutting curtains with top panel open so that hot air trapped behind the curtain can escape makes a massive difference.

If you have an attic, open the loft hatch – it’s a big win too, especially of the attic is properly vented.

If you’ve got foam ball insulation what’s going to stop it emptying from the top all the way down to the hole? Vent into roof and out through the soffit  (using straight pipe where possible) sounds a lot less messy!

what’s going to stop it emptying from the top all the way down to the hole?

friction.

Don’t do it, buy a split system air conditioner if you really need it. Or solar control glazing:better window openings/external shutters