Smell when windows are opened I'M DESPERATE :(

[Carp76]

Hi I'm new here and hoping someone can please help with an ongoing problem we have with a smell coming from under our house. This may be long and I apologise in advance.
The smell is predominantly in our kitchen, and it ONLY occurs when a window or door is opened, however any window or door will cause it to appear. It's as though when the house seal is "broken" the smell is being pulled up through holes in the floor. We do know that there are several large holes in the floors, kind of under the floorboards mainly around radiators and the boiler but also under our bath. When my husband went under the house (large crawlspace) to take a look, he could see the bottom of our bath. The smell is similar to the VERY musty smell our house had when we first bought it but that smell gradually disappeared as we removed old carpets and redecorated, but it's not exactly that smell. We had our cavity walls insulated earlier in the year, and my husband checked all the underhouse airbricks at the weekend and discovered most of them blocked, so he has now cleared them. I had expected this would help but so far, no difference. He now plans to block up the large holes and seal around them. He discovered no leaks or dead animals (and we did n't expect to either as the smellisn't like those smells. The smell goes away more or less straight away after closing a window or door so this is why I am certain the smell is being sucked/pulled up. (And why we thought reopening the airbricks would help, my husband thought perhaps we need to give it some more time for the stagnant air to dissapate but I'm not hopeful). This has been going on for a good number of months, and I'm certain it's getting worse as in the past we would have had the odd occasion of opening the door/window and not smelling it too strongly, but it happens every single time now. I no longer have visitors to the house because of the smell.
Any views, advice or general musings on this problem would be very very much appreciated. P.s. it's a detached 2 storey. I have searched EXTENSIVELY online to try to get to the bottom of this. Thank you so much for reading.

 

[Burnerman]

Does your house have an earth floor, by any chance? If so, then you can expect a musty smell down there, but there's no reason whatever for holes through the floor boards and under the bath for example.....these need to be filled.
The air bricks must be clear, and any outside land must be lower than the damp course membrane (if there is one). The membrane will often be the same level as the bottom of the air bricks. The more air that can circulate within the crawl space the better!
A photo or two would be nice if you can manage it.
John

 

[footprints]

You seem to have tried most things so I'm afraid it's clutching at straws time!

Is it possible you have no water trap on the sink and air is passing up from the outside gully? How about putting something strong smelling in the sub floor area, oil of cloves, peppermint oil, sliced onions or garlic perhaps to see if the windows are in fact drawing from under floor as you suspect.

Sorry that's all I can suggest, but a least garlic would keep the cellar free of vampires!

Do please let us know if you do sort it out.

Regards,
footprints

 

[Carp76]

Hi John thank you for replying. It's not an earth floor, looks most likely to
be concrete. Yes we will definitely get the holes all sealed up, am I right in thinking that it can't be "too" sealed? I don't know much about the damp proof course, what should I be checking/looking for? I will try to post some pics but won't get back under the house til the weekend. Do you mind giving me your thoughts on my theory about the window sucking up the air from under the floor? The oddest thing is that we aren't aware of anything that could have changed in order for this to start. Thanks again for replying, it is appreciated. Pamela

 

[foxhole]

Could be a broken or leaking drain, my external drain has a hole thru to the inside which previous owner fed drain off for the heating system, the idea being he could empty the system directly into a drain . unfortunately when the drain backed up occasionally the 'grey water' from sinks and bath overflows thru the hole under our floor boards and caused a musty smell whenever the front door was opened [thru draft]. Have blocked this now but took a while to figure out as was intermittent.

 

[Burnerman]

The large crawl space could be a real boon here - at least if there are drainage issues they should be easy enough to spot!
Can I ask how old the house is? Older properties actually had earth floors, sometimes covered with all sorts of builders rubbish and dust, but more modern ones were built on a concrete 'raft'......do try to ascertain which you have. On both types, the inner walls are supported on sleeper walls, with a damp course, under the floor. If you have a solid concrete raft there's no need for any smell.
You can make the floors as air tight as possible - so long as there is a good draught underneath. Therefore tight fitting skirtings etc are recommended.
Your theory about opening windows and allowing the pong in is spot on.....plugging the floor holes will soon get rid of that.
Its also worth trying to spot any exit holes for drains, and inlet holes for water and electricity - sometimes these are left in ducts that aren't sealed, and in come the mice and bairns......
It would be a good idea, with such a crawl space, that timbers are checked for dampness at the same time - damp testers are less than £20 from Toolstation and similar.
John

 

[JohnD]

there is a fair chance that you have a leaking pipe or drain causing the damp - examine especiallu under the kitchen and bathroom, and external walls where there is a drain or gulley outside.

do you have a water meter? does the bubble stop?

 

[Bosswhite]

My moneys on some sort of Drainage problem !!

 

[HERTS P&D]

Check manholes and have a cctv survey carried out.

Shame you live so far.

Andy

 

[Carp76]

Hi again and thanks for all the replies! You have all given me lots of possibilities and suggestions and lots of hope! I will try to answer your questions over the next few days (re. construction, sink traps, damp proofing etc) and hopefully post some pics after the weekend. Things happen sloooowly here with little'uns around...

But I WILL be back as your advice is invaluable.
Thanks again.

Ps Our house is around 30ish years old.

 

[Burnerman]

30 years old building = concrete raft for sure.
Its go to be worth a look where any toilet outlets come through the timber floor and disappear into the raft - just for cracks etc.
Although we can't be sure the smell is actually from a damp source, it is the strongest possibility.
John

 

[jj4091]

I have seen this problem when the cavity has not been filled with concrete to within 6 inches of the d.p.c, as it should be, & the bottom of the cavity(possibly 18 inches deep or more) then fills up with foul water & causes the symptoms you describe. I would guess it would be made worse by loose fill cavity wall insulation being installed later as it would stop it drying out.
It may be worth asking your home insurer if they would cover the cost of further investigation by professionals.