Foul smell soil pipe?

[Hididolee]

I am increasingly exeriencing very foul smells originally thought to be the outside sewer. This has been ruled out by the local water utility.

I now believe the smell is coming from the soil pipe.

The house was built in 1936 so would imagine original soil pipe exists.

My problem is that the soil pipe quite correctly vents to the roof of the house (and smells!). But on the ground level it is behind a wall in the middle of the kitchen as this was extended.

I now get the smells both in the bathroom and kitchen.

What is my next course of action?

I am not sure whether I have a partial blockage or cracked soil pipe. Is it a good idea to get someone in with an endoscopic camera? If so, what type of company does this?

 

[ChrisR]

Expensive type company.

Check that the top end of the pipe is open and not blocked. A smoke pellet would then be worth while. They DO stink though!