Loft bedroom - how many windows needed for good 'air flow'?

[cunningplan101]

If you have converted your loft into a bedroom, how many windows do you have in it? Counting dormers and veluxes. If you have more than one, do you think the second window makes a big difference?

I've read in the lessons learned thread that converted loft rooms can be quite hot and stuffy in the Summer, so posters recommended lots of insulation and ensuring you have 'air flow'. Is this mainly achievable by having more than one window? Or could a second window actually make it more stuffy, because more light so more heat?

Could one dormer window be enough, or is it asking for trouble?

And has anyone experienced the heat/stuffiness problem with a recent (last few years) conversion? I'm wondering if insulation building regs might have been increased? Does anyone who has avoided this problem remember how much insulation they used?

Reason I ask is that we're converting our loft and have only been allowed two windows by the council (conservation area), so wondering whether I need to put both in the bedroom or could have a dormer in the loft and a velux in the hallway to light both spaces?

Thank you!

[PigletJohn]

it is best to have a vent or opening window in each room, and at least one at each end/side of the loft so that any wind will blow in one and out the other.

Provided there is a high-level vent, such as a Velux, and a lower one, convection currents will cause hot air to rise out of the higher one.

Windows with no trickle vent will only ventilate if they are open.

Ordinary lofts get intolerably hot in sunshine because it beats down on the tiles. Your insulation on the slope will reduce this, between the plasterboard and the tiles, but it will still be a lot more heat than you would provide to the conversion on a cold frosty night.

I suppose that if you had solar panels on the south side, they would prevent the sun reaching the tiles.

[fluffygreentail]

Hmm, interesting. We have just had a quote for a loft conversion with a master bedroom and en suite. The dormer at the has a window obviously but on the front of the roof, there is no window. There will be a window in the en suite.

I was thinking the above would be adequate because there would be two windows and I want to avoid a window at the front basically above our heads where the bed has to go as we live on a kind of busy road and I did not want to be bothered by extra noise.

So, Piglet, you think two windows in the bedroom is the best way.

[PigletJohn]

if not windows, you could have vents. Either cut into a gable wall like airbricks, or there are vent tiles (often used above bathrooms) and ridge vents. You might have to consult a roofer though. Your architect or designer should know, or be able to look it up.