Help with notches in new joists

[m0t]

I'm having a dormer put in at the moment and the floor joists went in today. As they were laying a cross an existing ceiling the builder cut notches in the bottom of 7 joists to allow existing cables to pass under without disturbing them.

I had thought that notching the bottom of joists wasn't allowed but the LABC website here says they are:
https://www.labc.co.uk/news/how-get-it-right-notches-holes-solid-timber-joists

Although some councils say differently on their website (mine doesn't specify).

The other problem is that these notches are right in the middle of the joists rather than in the specified area, so assuming notching the bottom is fine they aren't in the right place.

Builder says it's fine and not to worry about it as the joists are over specced.

The joists are 47x170 c24 and spanning 2.3m at 400mm centres. The span tables do suggest the joists could be much smaller.

Should I be worried?

 

[tony1851]

No; as long as they've not taken more than about 20 mm from the underside, the joists will be fine over that span.
The builder is correct regarding the spec.

 

[catlad]

Still not very wise! all he needs to do now is remember not to screw through them.

 

[tony1851]

Quite; might have been better to carefully unclip the wire(s) from the top of the joist and gently push them down the side out of the way.

 

[^woody^]

New floor joists should be laid 25mm or so above any existing celling or joists not tight on them. So that normally gives a natural gap for any existing cables.

 

[tony1851]

It makes me wonder why they have set the new joists above the existing ceiling joists, which naturally reduces headroom.
Most loft-builders try to set the new floor joists parallel to, and down between the existing ceiling joists to gain a few extra inches.

 

[m0t]

The floor joists are next to the ceiling joists, because the loft is an eaves space that’s the only way to do it and match the existing floor levels.

The cables run through the centre of the ceiling joists and then drop down under the new floor joists.