Would you install air conditioning in a dormer loft conversion?

[Homerenos1]

We are getting a dormer loft conversion in the summer. 1930s semi-detached so will become 3 storeys.
In two minds on whether we pay extra for aircon.
Anyone who has or hasn't installed aircon and whether they regret it?

Thanks everyone, I'm sold. And the fact that it is day 1 of this heatwave and the back bedroom is already pretty uncomfortable.

Absolutely!! We have an air con unit in ours and it makes so much difference. It’s unbearable without it.

Yes I would. Ours isn't a conversion but was built with the bedrooms in the roof. The bedrooms are stifling, yesterday was 26 degrees at 10 pm. One of our neighbours put as it con in

Start with really good insulation and ventilation.

Lofts and attics are hot in summer because the sun beats down on the roof continually and the heat radiates inside. You need good ventilation on at least two sides so there will be a throughflow of air.

Yes, warm air from the house will rise up as well. So you have to provide ventilation for it to get out. Preferably high up. With constant replenishment of cooler air from the shaded side.

Roof lights let the rain in so are not suitable for ventilation.

Electricity for aircon, hours on end, day after day, will cost a lot more than opening windows.

Good insulation will reduce the amount of heat getting in and out and reduce the cost of cooling and heating. Insulation does not create heat, or cold.

This baffles me! How do you achieve good insulation and good ventilation in a loft room?

Agree. My house was built with the bedrooms in the roof. There's no "loft" space that you could insulate so really only a layer between ceiling and roof felt.

Yes - it gets so hot. Whose room will it be? If occasionally guest room might not need.

Where do you live? South of England - yes. Anywhere else probably not

Yes, I think it would be very helpful. The scale and configuration of the Dormer itself is also a factor. Neighbour has a giant one pane shop window in the sky. That's a lot of light and a lot of heat. Being honest it's not even appropriate for a Victorian terrace, albeit a large one. Many choose scaled versions more in keeping or smaller Dormers with shutters

We have ac in our bedroom and it gets run all night through the summer and hasn’t increased the electric bills that I can tell. Portable AC uses more energy.

We are about to put air to air heat pumps in all bedrooms. It will give extra heat in the winter and air con in the summer. It’s a no brainer since we have solar and batteries a c our central heating is oil (no gas in the village)

Definitely, mines like an oven and it's not lack of insulation as remember the builder complaining about how much building regs said it had to have and how it restricted the ceiling height. If I'd known i would have had it put in but I thought the insulation would be sufficient. To be fair it's not many weeks of the year though that it would be needed.

We put it in our loft conversion it’s brilliant. All the kids drag mattresses up when it’s really hot though!

We had an argument about this a few months ago. No conversion as such but dh wanted air con installed in the loft bedroom and I told him he was being ridiculous.

it was installed two weeks ago and as of yesterday i’m totally converted.

ps we are in north of England

We don't need one in ours (1930s 3 bed semi with loft conversion). It was done only a few years ago so very good insulation levels. The temperature does build up during the day in weather like this but we have 2 velux windows in the sloped roof side and windows on the opposite wall - once the sun goes down we can open them all completely to get a really strong through draft which clears out the heat in 10 minutes and it's cool before bed.

Of course when it's a heatwave I do sometimes wish I have air con but would be the same in any house , it's not hotter in the loft room.

Rigid insulating foam slabs have twice the insulating power of the same thickness of mineral wool quilt, which is what you normally insulate lofts with.

Typically it is packed between the roof timbers, and another layer fixed to the inner face (or insulated plasterboard which is a sandwich with foam).

Old or undocumented loft conversions that do not meet modern regulations need the old ceiling ripped out to do it, which is one of the reasons why it is often more expensive to rectify a non-conforming loft conversion than to build a new one from scratch. The other is the inadequate floor.

@PigletJohn thank you for this. Does this still apply to old Victorian houses that ‘need to breathe’ or are these regs more appropriate for modern houses? How is ventilation achieved please?

Ours is so hot. My office is up there and I can’t work up there. If you can afford it, yes

Please do! I didn’t and now have!

@NotDonna

If the house has a gable wall, you can put windows and ventilators in it. If not, the roofer or designer can discuss ridge vents. There are also vent tiles.

Disused chimneys can be repurposed.

I'm not keen on making holes in roofs as they can let rain in.

Yes, Yes and Yes again. We didn’t and it’s as hot as the god damn sun in the summer.
#seriouslyrookiemistake

Yes. We have air con in ours. It was worth every penny on the days we need it. You won’t regret it. You will regret not doing it at the time and then retro fitting it (voice of experience!)

We have aircon throughout the house (ducted) and we love it. It’s very quiet and energy efficient (mini heat pumps) and can also be used on a fan mode, without cooling. No regrets here.

Also include Ventilation at the eaves @NotDonna allowing cool air to travel through the void between insulation and the waterproof membrane.
Hot air then rises up and out throw the roof vents