Check with the Local Building Control Officer, they will advise on how they'd like it done. May allow your idea with a rodding eye at base of the stack, or may insist a manhole is fitted at the junction.
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local