Cables running over floor joists

[Brolaw]

Just built a 2nd storey over an existing single storey. The previous builder run there cables over the joists as it was a flat roof before and had room between the top of the joist and the boarding because of the firings. I have removed the firings because obviously they are not needed now. I am left with all the cables running over the joists which of course is no good as i have to lay my floor boarding. All the cables are for the downstairs so to take them all out and run them all through the joist will be a right pain in the ass along with the problem that they are all plastered in, and wired up. My question really was can i notch out the joists and put galv safe plates above to protect the wires. My only other alternative is to cut one end of the wire run it through the joists then crimp them back together, but i would end up with loads of crimps under my floor boards which i don't like much.

Cheers for any comments

 

[Click-Sure]

What is the depth of the joists?

 

[Brolaw]

200 MM

 

[Brolaw]

Any one ?????????????????????????

 

[blondini]

Providing the joists are adequately sized for the span, you can notch the tops by up to an eighth of the joist depth, but only in an area between 0.1 and 0.2 of the span.
You can drill holes up to a size of a quarter of the depth of the joists, but only on the centre line and only between 0.2 and 0.4 of span. Holes can't be too close together, think it is minimum of three diameters between their centres.

 

[ban-all-sheds]

Providing the joists are adequately sized for the span, you can notch the tops by up to an eighth of the joist depth, but only in an area between 0.1 and 0.2 of the span.

0.07 and 0.25 x, actually.

You can drill holes up to a size of a quarter of the depth of the joists, but only on the centre line and only between 0.2 and 0.4 of span. Holes can't be too close together, think it is minimum of three diameters between their centres.

Between 0.25x and 0.4x.

In other words, notches must be on the top edge, near the end of the joist (but not right at the end), and holes must be on the centre line, near to the middle of the joist (but not right in the middle).

The shaded areas shown below are the acceptable ones:

 

[Taylortwocities]

If I remember, the notching & drilling stuff refers to full load bearing floor joists and not to roofing timbers. Roofing timbers have very close support tolerances and shouldnt be made into Swiss cheese.
In a roof, its better to screw support battens to the top of the roofing timbers with gaps left for the cables to pass through.

 

[ban-all-sheds]

One hopes that proper structural calculations have been done, and included with the Building Regulations submission, and that they show that what were the roof/ceiling joists are strong enough to become floor ones....

Surely if you've got one of those execrable trussed roofs (the inventor of which should be made to drink molten plutonium), then they aren't strong enough to be boarded over, so cables can just lie on the top...?