Hello,
I was reading the on site guide, kindly provided by someone here (thanks), about drilling through joists. It says holes should be drilled between 0.25 and 0.4 x the joist span and notches should be cut between 0.1 and 0.25 x joist span.
Now I am a bit confused about this. Why can you notch 0.1 x the span but not drill until 0.25 x the span? Surely if it is structurally safe to do one, it ought to be safe to do the other? I would have thought drilling a small hole is always better than notching because notching reduces the effective depth of the joist?
I notice that these limits keep the notches and the holes in different zones and that must be a good thing. Is that the reason they ask for holes to be drilled further along so that no "plant pot" drills a hole beneath a notch and seriously weakens the joist?
Why can't you drill halfway along the joist? If you can drill at a point 0.4 times the span from each end, you are pretty close to the centre already, so why is dead centre kept free? I knew from posts I had read here not to cut at the ends of joists but I never knew the centre had to be untouched. Why?
Thanks, Stephen.