Ventilation and roof lights

[BuildingNovice]

Building a rear extension with dining room and kitchen.

Ordered bifold doors for both rooms without trickle ventilation as by all accounts they are not very nice to look at.

We are installing roof lights for each room and we understand Velux have models that include trickle ventilation, so that should solve the problem.

Maybe a silly question, but do the vents in roof lights need to be closed each time it rains or are they designed not to let rain in at all.

Also, does anyone know if the 8000mm squared per habitable requirement for the surface area of the vent is fixed, and the room size therefore does not matter?

 

[DevilDamo]

Maybe a silly question, but do the vents in roof lights need to be closed each time it rains or are they designed not to let rain in at all.

You are correct with the latter. With the velux in the closed position, you can still open the "ventilation flap" to allow fresh air to circulate thus preventing rain entering the room(s).

Also, does anyone know if the 8000mm squared per habitable requirement for the surface area of the vent is fixed, and the room size therefore does not matter?

Correct. That's the minimum you need to provide regardless of room size.

 

[BuildingNovice]

I would like roof lights with a 'contemporary' look (thin black frames); does anyone know of any roof lights other than Velux that have trickle ventilation built in?

 

[Chukka63]

Fakro,but dont know if they do black.

 

[Nickam]

Have a look at:
http://www.therooflightcompany.co.uk/d/331/the_Conservation_Rooflight.html
Or:
http://www.lumenrooflight.co.uk/category.asp?category_id=66
Cheers,
Nick

 

[BuildingNovice]

I've checked with these and neither have trickle ventilation.

The rooflightco say, regarding its neo range:

Do your rooflights have trickle vents like other windows and rooflights?

The whole of our rooflight is a trickle vent, according to Building Control officers we have consulted.
This is because in their view the means of ventilation is 'controllable and secure' when a winding device is used to open it. This means that
under normal circumstances a Rooflight Company opening rooflight can be used as a trickle vent providing 'background ventilation' to a
habitable room in accordance with the requirements of the Building Regulations. In fact most of our rooflights can provide considerably
greater than the current open area requirements of the Building Regulations - 8,000 sq. mm..
Some Building Inspectors interpret the Building Regulations differently, however, and it is recommended that they be consulted on the
specific type and location of the rooflight proposed before relying upon the rooflight as a sole means of providing background ventilation to a room in a Building Regulations application.

Doesn't sound like something I want to rely on!

Not sure if any of their other ranges are different.

Lumen say their LR range do not have trickle vents.

 

[DevilDamo]

Hmmm. Well if they provide something in writing, then you can pass that onto the Building Inspector. I personally don't think our local BCO's would accept that but you never know... it may be on a case by case basis. May be worth asking your BCO the question?

 

[jeds]

Velux make conservation roof lights - and I believe they include compliant background ventilation. Fitted some recently on a listed building and the quality, finish and appearance is very impressive.

 

[simonjay]

Building a rear extension with dining room and kitchen.

Ordered bifold doors for both rooms without trickle ventilation as by all accounts they are not very nice to look at.

We are installing roof lights for each room and we understand Velux have models that include trickle ventilation, so that should solve the problem.

Maybe a silly question, but do the vents in roof lights need to be closed each time it rains or are they designed not to let rain in at all.

Also, does anyone know if the 8000mm squared per habitable requirement for the surface area of the vent is fixed, and the room size therefore does not matter?

You dont need to use trickle vents at all. Why not put in an air brick with hit and miss vent on the front ? Or windows that can be locked ajar can be used. But really, its a compromise between heating and ventilation. All vents even closed increase heat loss, unless you get some expensive trickle vents that are fairly well insulated when closed. Best is to use heat recovery ventilation but expensive. I never use trickle vents - they look awful
Simon.

 

[geraldthehamster]

[quote="simonjay";p="1533360
You dont need to use trickle vents at all. Why not put in an air brick with hit and miss vent on the front ? [/quote]

Yes, I did that, and my BCO was quite happy with the ventilation level. Then again if he was any more laid back he'd fall over.

Cheers
Richard