Remove internal partition on my extension. Will the flat roof stand?

[Jonny Vee]

Hi,

I got an extension with a flat roof and 47x125 trusses with an average distance of centre to centre less than 400mm and a total span of 5.36m

A the moment I have a blockwork internal partition dividing the extension into 2 rooms and would like to have one large space as per my neighbours with the same extension and cannot see any wall in the middle or any beam below the ceiling.

My question is? Will the roof stand or the trusses will deflect under the weight?

The extension is only 2.6mm wide and this is a single floor extension with standard plywood and waterproof membrane on top of it.

 

[Deleted member 174758]

Are the joists all one piece, or are they made up from two shorter joists resting atop the wall in the middle? 5 x 2in (125 x 47) seems a bit on the weedy side TBH. I'd have expected 7 x 2s (175 x 47)

 

[Jonny Vee]

Are the joists all one piece, or are they made up from two shorter joists resting atop the wall in the middle? 5 x 2in (125 x 47) seems a bit on the weedy side TBH. I'd have expected 7 x 2s (175 x 47)

They are one piece

 

[Jonny Vee]

They are all one piece and this is what they used 20 or more years ago

 

[Jonny Vee]

Structure engineer confirmed a beam is required in case this would be of any help for someone else.