Can I run waste pipes (such as from a washbasin or sink) through the wooden I-beams of my exterior wall, which will later be filled with blown-cellulose insulation (Warmcel)?

 

(I know its OK for water pipes. And only use a continuous pipe runs, so there are no inaccessible joints.)

Yep it’s fine 

1 hour ago, Dreadnaught said:

(I know its OK for water pipes. And only use a continuous pipe runs, so there are no inaccessible joints.)

have to say, if i were doing this, i'd run them sheathed in a larger pipe to avoid condensation risk, soggy paper and all...