Flatroof Joist Opening for Roof Windows

[hankmarvin]

Hi,

I have 225 x 75 joists, 5.8m span.

I wasn't planning on any roof windows but after getting the first deck on it is rather dark and when some changes are made to exisiting house the existing livingroom will get a bit darker so I'm planning a roof window in new extension towards livingroom end wall opening.


Window people said that a 300mm x 1500mm unit would weigh about 40kg, do you think two joists bolted together each side of the window would be enough? Roof is 400mm centers, particular size I was looking at would need 500mm gap.

Window http://www.ebay.co.uk/itm/331071308...49&var=540269236576&ssPageName=STRK:MEBIDX:IT

U-Values seem good, look good, bigger and cheaper than a velux fixed dome, they are rather tempting.


Any thoughts re joists would be great!


Thanks a lot
Hank

 

[hankmarvin]

Any opinions?

 

[catlad]

5.8m is a large span for timber, how solid does the roof feel to walk on? I would think two joists bolted together would be enough.

 

[hankmarvin]

with two sets of noggins its really solid(was quite surprised actually once it was complete), first deck is on and it feels fine, not bouncy/wobbly etc. Just need to undo some of the work to create the opening.

I think two each side should be fine but waiting on BC who are being painfully slow.

 

[hankmarvin]

Finally got answers from building control.
Having the joists at 500mm centres for the skylight is fine they said, just extra noggins at each end of skylight. Ok to proceed