Max span of flat roof

[daz3770]

hi there,

I am thinking of having a new extention built. I want to keep the inside final plaster board flat with no joists showing. The width is 7m. I want to extend out as far as possible (max 7m) I have looked around the net and found that C16 75mm x 225mm timber will span about 5m.

Can anyone tell me if there is timber capable of spaning further than this or is there any other methord? Price will be a factor as the timber methord is the most cost effective.

Kind regards

 

[Deluks]

You'll need an engineered timber joist, google parallam. Can be done in steel as well, but I'm not sure which will be cheaper. A structural engineer will be able to advise on best option.

 

[aconnor2]

the timbers your talking about will span up to about 6 m at 400 centers according to trada
but I joists will go further look on the finnforest web site for finn joists they span over 7m don't know about cost though

 

[masona]

Have a look at TJI joist, there're light and very strong and span a long way too