On 26/06/2019 18:33, DerbyBorn wrote:

the regs tells me that in a 20cm Joist the max hole can be 32mm I
need to pass a pipe of 42mm diameter!

Reinforce the joist by bolting metal plates to both sides?


Or bolt it to the wall.


Access would be very destructive.


So not as simple as just lifting the boards either side of the hole then:-(



--
Adam