Roof lantern sizing

[Detta Walker]

Hi

 

I'm planning a roof-light for my kitchen as part of the extension. 

The back extension is 2 storey on the right (with bedroom 4 above the dining room) and the kitchen extension is single storey with a roof lantern on the flat roof.

The external dimensions of the kitchen single storey extension is 2.5mx5m, internal is 4.5m by 2.2m) (although bearing in mind that the room is connected to the kitchen itself as we'll have a steels over to break through that wall). 

 

I'm trying to select the roof light I want but it's difficult to find on the manufacturers website how much space needs to be next to the rooflight (so what's the minimum space between the existing wall and the end of the roof on either side for the roof light? The "parapet wall" is 400mm. So that means there is 2500mm-400mm=2100mm of roof space left to accommodate the width of the roof lantern. I would have thought I'd need somewhere around 300mm of space between the wall and the actual roof lantern and similar distance to the parapet wall, leaving me with a potential roof lantern width of up to 1500mm - is that assumption right? are there any minimum required distances? 

 

Hi,

[George]

- Will you need to access around the lantern for maintenance? 

- Consider the u-value of the lantern - it is likely much, much lower than the roof build up. if it's a very high percentage then the roof may be leaking a lot of heat

- Conversely, consider how much solar gain you'll get in summer

- Installation and laying the roof will be difficult with only 300mm to play with

 

 

 

 

 

[Detta Walker]

Hi George - thank you for your response. My answers:

Q1 - not sure? What kind of maintenance is required? Cleaning it? We can do that from the window above I'd imagine but I guess you'd need to be able to stand next to it.

Q2 - I was going to get double glazed ones so it doesn't leak much heat. My concern is that if it is too narrow, it will look flimsy. 

P3 - the light is on the north side of the house - so it wont heat up much during summer.

P4 - what would you say is the minimum width required to lay the flat roof?