Loft joists notched and binder not attached

[JackK]

I posted this in the roofing forum but realised that this space is for questions about loft and structural matters

I removed all the old insulation from my loft and found some notching which concerns me - Would you be worried about this and how can I tell what sort of wood has been used for the joists -

Its certainly old wood and looks like hardwood but I cant tell what type

It is 100mm high and the joists are 6 metre lengths at 400mm widths

1) Can I lay 18mm plywood on top of the joists or will this cause the ceiling to crack underneath? Are the joists string enough - Span is 5M long and they are 100mm * 50mm joists at 400mm spacing

2) Is the binder meant to just lay on top of the joists or are they meant to be screwed into the joists ? Mine are just sitting (a few m off) the joists

3) On three of the joists there has been notching in the centre of the joists by about 15mm for cables - Tried to get picture of an example - Is this a real concern?

I plan to be able to go to the loft from time to time with plumber / electrician1 when I need to and I do not want the ceiling to collapse or the roof to collapse

Any help much appreciated

 

[Koolpc]

Tens of thousands of homes have notches in the timbers. Many worse than yours. You have nothing to be concerned about.

And looking at those holes in the binder, i would say they have been used to screw it down at some point.

 

[robinbanks]

Can I lay 18mm plywood on top of the joists or will this cause the ceiling to crack underneath?

Laying the ply is unlikely to crack it, but then what you store on top of the ply might!

There are rules for notching joists, and from what you say they haven't been followed but they haven't been broken by much

Try and move the wires to be above insulation if you can, or install lower rated circuit breakers if you're insulating the wires

If you're planning on replacing the insulation between the joists and boarding over you should be aware that it's a poor detail and doesn't meet modern recommendations. The joists (and there are a lot of them) bridge the insulation and aren't good insulators themselves. Modern spec calls for 270mm of insulation; this would be 100mm between the joists and 170 over the top of them, perpendicular. You could (and in your case would probably) use a rigid board of around 100mm over the top, tape the joints and then ply on top of that, giving you a good layer of insulation and a firm platform to walk on. Just remember the first point about not loading too much junk up there