flat roof query

[evilzee28]

At the moment I have a flat roof on my garage which is 10' wide & next to that is my utility room which is 5 'wide. The flat roof is covered with felt & chippings & covers both garage & utility room as one roof. The joists are 15' long & are supported by the shared wall between garage & utility room as well as being fixed at the ends. The joists are only 4" x2" & are 22" apart.

I want to take out 10' of the adjoining wall to make my garage wider. Is it better to just put bigger/thicker joists in to cover the 15' span, or do I need to put an RSJ in to support the roof where I've removed the supporting wall? (hope this makes sense). if I can put in bigger joists what sort of size would I need to support the roof?

Thanks in advance

cheers...Nige

 

[evilzee28]

Anybody?? Maybe if I re phrase it to, what size joist timbers do I need to support & span a 15' flat roof & how far apart should they be fom each other??

Thanks in advance

cheers...Nige

 

[Static]

47x220 C16 joists at 400mm centres.. for the 15' span..
Prob best to replace the existing as they are a little on the small size for the 10ft span

 

[evilzee28]

47x220 C16 joists at 400mm centres.. for the 15' span..
Prob best to replace the existing as they are a little on the small size for the 10ft span

Thanks for that, sorry for my ignorance but what does "C16" refer to?

cheers..Nige

 

[freddiemercurystwin]

http://www.trada.co.uk/faq/list/strength/

 

[evilzee28]

Thanks for the link, now I understand

cheers...Nige