Floor beams projecting into cavity

[jackhaughton]

Hello,

We are doing an extension, and the ground floor is a Forterra Jet Floor (concrete beams with polystyrene infill). The beams can only be supplied in 50mm increments, so in order to get the required span we end up with the beams projecting 40mm into the 100mm cavity at one end. Forterra say we can trim this overhang off with a disc cutter.

My question is, do we actually need to cut this off, or can it just be left sticking into the cavity? Given that it doesn't bridge the cavity, I couldn't really see the need. Would rather not cut prestressed beams if the extra length isn't causing a problem.

Thanks
Jack

 

[freddiemercurystwin]

Seems a bit crap of the beam supplier, have you tried an alternative supplier? What insulation is proposed in the cavity? I'd be less concerned if it were 100mm full fill than say 50mm Celotex. Why is its B/B anyway?

 

[^woody^]

You can cut or overhang the beams.

Or build the extension wider

 

[r896neo]

I'm intruiged what catastrophic damage or danger you are worried could arise from cutting 40mm off??

 

[chappers]

I would rather cut them off flush as this would reduce the risk of moisture in the cavity landing on their surface and seeping through the wall.

 

[^woody^]

I would rather cut them off flush as this would reduce the risk of moisture in the cavity landing on their surface and seeping through the wall.

Is it possible to reduce a zero risk into negative figures?

 

[chappers]

fair point