Holes in floor joists for waste pipes

[Vicdiy]

Drop through to room below and box in

It could look very ugly having a boxing in a living room!

 

[Scott_D]

It could look very ugly having a boxing in a living room!

Raised tray or boxing
Sometimes customers need to realise they have to compromise

 

[gmartine]

If you're worried about joist integrity reinforce it....3/4 ply either side to sandwich joist.

 

[SimonG]

There are a lot of the nearly flat shower trays without an upstand being installed now so I think a lot of plumbers must be running pipes through the joists.

Not this one!

 

[chris watkins]

There are a lot of the nearly flat shower trays without an upstand being installed now so I think a lot of plumbers must be running pipes through the joists.

Not this one! either

If you're worried about joist integrity reinforce it....3/4 ply either side to sandwich joist.

say the structural engineer who fully "understands bending moments"

 

[gmartine]

Not this one! either say the structural engineer who fully "understands bending moments"

I think I can recall my first year statics course at Uni...
The bending moments acting on a beam haven't changed just because it has holes drilled in it but it's ability to resist them has been compromised. Cutting holes can initiate cracks that can propagate when beams are loaded, mostly because of low tension strength perpendicular to grain of timber. Crack propagation changes the failure mechanism of beams, and fracture can occur at considerably lower than predicted loads therefore reinforcing the area to avoid it is a fairly common sense solution.

 

[SimonG]

I like that steel, but would like it maybe 12" longer on either side.

 

[gmartine]

It's pretty strong SimonG, those J bends make it effectively act like a box section of steel by increasing the stiffness no end.

 

[chris watkins]

I think I can recall my first year statics course at Uni...
The bending moments acting on a beam haven't changed just because it has holes drilled in it but it's ability to resist them has been compromised. Cutting holes can initiate cracks that can propagate when beams are loaded, mostly because of low tension strength perpendicular to grain of timber. Crack propagation changes the failure mechanism of beams, and fracture can occur at considerably lower than predicted loads therefore reinforcing the area to avoid it is a fairly common sense solution.

Great, so you could make an informed decision if you wanted to drilling holes in joists.
My point was/is, should we be encouraging those who don't have your knowledge to be cutting hole, thinking that screwing lumps of ply to each side will make things all right?

 

[gmartine]

The OP had already been given the advice on hole size and position to which I simply added that they could also reinforce the beam to which you decided to snidely take umbrage with. Report it or wind your neck in.