DIY Doctor UK DIY Forums

Our house has a conservatory built onto it. Standing in the conservatory, looking at the kitchen door, you have the kitchen sink downpipe on the left (boxed in) and the bathroom wc & sink (boxed in) to the right. Bothe sets of pipes go underneath the consevatory floor. We don't know where, as we have only been there for a few months and the conservatory was built 3 years ago.
The problem is that the kitchen sink water drains very slowly and the washing machine backflows into the kitchen sink on some cycles. When we use the kitchen sink, we would get a foul smell coming into the house.
This is only coming from the dining room through the floorboards, as it is next to the kitchen.
I have checked under the dining room floorboards and could not see any signs of water pooling there, so the smell must be coming rom elsewhere.

We decided to lift the laminates in the conservatory inbetween the two sets of boxed pipes at the kitchen door, in the hope of inspecting what goes on underneath. Unfortunately we have only managed to lift two as when we did, we found the underlay & what I assume to be cement boards, to be wet. That area must have been like that for some time, as the underlay has mould/fungus on it. It seems that it might only be the area between the kitchen downpipe & bathroom downpipe.
We are uncertain as to what constructionmethods were used to build the conservatory, but it has brick wall, so I assume that it is on a concrete foundation.

Could it be that there is a blockage in the drain that allows the water to overspill and cause the smell, as well as the moisture in the underlay/laminates & cement boards?

Hi all,
Just to let you know that the problem might be solved. We lifted the laminates, chipped away a bit of the cement-board to reveal the metal plate over the drain. After taking this off, we stuck a rod down the shaft and pulled it back up...to our surprize.

When we pulled the rod back up, a plastic rubble bag came along with it, and a big one at that. We assume that the dogy builder whom worked for the conservatory company, obviously thought that such a big bag would disappear if you stick it down a drain outlet and cover it up.

This was the cause of the water pushing back up into the kitchen sink, because it had no other place to go after the water filled the drainage pipes.

So in conclusion, a drainage / plumbing problem is not always as obvious at it might seem & check up on your builder / plumber when they install something at your house. Better even, ask them, no tell them that you want to take photos whilst they install anything of their handywork.
If they are not up to it, then they obviously know that their dodgy work will be evidence against them.