happy new year,

i need to get a 40mm shower waste through a 7x2 inch floor joist. it is the last joist against the wall. i want to make a hole through the centre of the joist 660mm from the end of it, the total length is 3m will this be ok does anyine know?

thankyou

as a rule your hole can be up to 25% of the joist depth - (so ok to circa 44mm on 7" joist) but the acceptable zone for drilling a hole is usually taken as between 25% and 40% of its SPAN from the supoorting walls- ie. as an example a 3 metre span joist (not total length but span) should only be drilled between 750mm and 1200mm from the closest support.... sounds like you want your hole slightly inbound of this zone ? are you able to change the 660mm ?

i can move it into that zone and maintain a fall, cheers for the advice scotty