Damp foul smell from floorboards

[Dede]

Hello,

I'm a new owner of a Victorian semi detached. For the last few weeks (after the recent bout of rain) we kept smelling strong rotten egg/sulphur smell from different parts of the house. Eventually called a drains person to come out who said the main drains were bunged up and did a jet unblocking. The drain camera survey he did wasn't too alarming (some minor cracking which were planning to get fixed).

Since then the rotten egg smell around the house has gone. But we're now getting a really foul damp smell from under two of the kitchen/dining floorboards. These are against the side wall. I can see that the side path on the smother side of where we're smelling this has a permanent puddle. Could this be damp I'm smelling or still a sewer issue?

The floor is engineered wood with underfloor heating below it.

 

[IHateDamp]

Do you know how old is your property?

Is there any guttering above this area?

It might be helpful if you can work out where your internal floor level is compared to the path. If it's high then you may want to remove it from your walls.

Looks like cement render at the bottom possibly applied mistakenly to protect from damp ingress, when actually it will be trapping damp in your wall.

 

[Dede]

It might be helpful if you can work out where your internal floor level is compared to the path. If it's high then you may want to remove it from your walls.

Do you mean the floor level I see within the room? I've attached a photo to show you where the floor is compared to the wall outside. There's not guttering above. The house was built in 1900.

What should my next steps be? What sort of tradesperson should I call out?

 

[Cubist]

Are there any more air-bricks than the one shown in the diagram?

With a 1900 build date it's likely this house would have a damp course (DPC). Judging by the section of the side wall rendered in what looks like cement theres a good chance someone has bridged the DPC.

Do you know when the engineered boards were laid and whether this is directly over the old boards or were these stripped out to reveal the joists? Is there any means for you to lift some of the engineered boards so that you can inspect the sub-floor and void?

 

[Dede]

No other air bricks on the outrigger part of the house. They seem to have punched some holes in the cement render in the section to the right of the gully but not sure it goes all the way.

I believe the engineered boards were laid about 10-11 years ago when the people we bought the house from did some renovation work.

When you say "means to lift up the boards" do you mean equipment? Partner and I are novices with DIY type stuff.

 

[Cubist]

Is it safe to assume that the holes pushed through the render are near to or perhaps even directly above the drain gulley shown in the third photo in your first post? If so then the drain could perhaps be the source of the foul smell indoors. Entry paths/alleyways like that can operate as wind tunnels to drive air through the air-bricks to provide the cross flow needed beneath suspended wooden floors like yours. Are there any signs the gulley drain has become blocked and has overflowed?

Its good practice when laying a new wooden floor to provide the mean of taking up a couple of boards in strategic locations to allow access to otherwise hidden pipework or electrical cables. Sadly, some DIYers overlook this need and it can become necessary for some minor surgery to the boards to allow them to be lifted - this consists of cutting off the tongue and levering the boards out to free them from any nails or screws on the groove side. No particular lifting gear or kit is needed for this, usually just a pry-bar and a claw hammer. Do the boards run parallel to the alley or at right angles?

 

[Dede]

Is it safe to assume that the holes pushed through the render are near to or perhaps even directly above the drain gulley shown in the third photo in your first post?

Yes this is correct and thanks for your advice so far. Unfortunately I'm not confident enough to lift up floorboards myself. Should I call out the drain guys again or would it be a different tradesperson to this for us.

 

[Cubist]

Best to go out and check the drain for yourself to determine if there is a strong smell coming from it first. If no corresponding smell to what you have indoors then you should need the drain guys. If the problem persists you will probably need to general builder or joiner who can 'carefully', list some of the floorboards adjacent to the gulley in an effort to find out what's going on.

 

[IHateDamp]

If you know who installed your underfloor heating they may be best placed to investigate for you as you may have to move the piping to investigate the sub floor/insulation and then reinstate all satisfactorily.

 

[IHateDamp]

Do you mean the floor level I see within the room? I've attached a photo to show you where the floor is compared to the wall outside. There's not guttering above. The house was built in 1900.

What should my next steps be? What sort of tradesperson should I call out?

View attachment 18830

The floor level seems relatively high at this end of the building

Is the UFH heating ok ? No chance of a leak?

 

[Dede]

Best to go out and check the drain for yourself to determine if there is a strong smell coming from it first. If no corresponding smell to what you have indoors then you should need the drain guys. If the problem persists you will probably need to general builder or joiner who can 'carefully', list some of the floorboards adjacent to the gulley in an effort to find out what's going on.

Just did this. Lifted a manhole and the smell is exactly the same. So it must be a drains issue then but coming from under the floorboards.

 

[Dede]

If you know who installed your underfloor heating they may be best placed to investigate for you as you may have to move the piping to investigate the sub floor/insulation and then reinstate all satisfactorily.

Yes I think we know who installed it so if the drain chap can't help us then maybe they are the second port of call