Has anyone any tips on stopping smell seeping in from the adjoining property?

peter021072

This tends to happen every time there is warm weather, and rarely happens in the winter.  Around 7pm at weekends, my house is filled with a pungent garlic type smell which persists for hours.  Last year I got a central heating/plumbing engineer to look for any cracks in a ventilation duct between my house and the adjoining one which might be the source, but he couldn't see anything obvious.  I also asked my neighbour if the engineer could check if their ventilation duct was blocked (I suspect it is just vented into the attic). He said it was clear, although I'm not sure if he knew where to look amongst all the attic insulation.

I think it is caused by my house being 'downstream' of the prevailing wind.  When they open their windows to get the smell out the prevailing wind just blows more air in slightly pressurising it enough to push it through any cracks into mine.  I'm not completely sure though, the source could be another house, but the rooms that are most affected are the ones adjoining this house.  Last year I tried to seal any gaps between the floor and walls in my bathroom which might be an entry route, but that hasn't worked either.

Norman_Castle

Look under the bath for gaps between floorboards and where pipework goes through floors.

DRP

Some more details would be helpful I think.

What type of houses?
What’s the suspected source of the smell? Is it neighbour cooking?
what is the strongest location of the smell in your house, and where does that correspond to in the neighbour’s?
if it doesnt happen in winter, does that mean the source is the neighbours open (kitchen) window?
photos for context?

 

Rosa_Damascena

The 7pm is significant...dinner time?

tacpot12

A positive input ventilation (PIV) system might help. 

peter021072

It's a modern back to back house, but classed as a terraced. Draw a square divide it with two lines to form 4 separate squares. Each square is a separate house. My house is one of those squares on the North Western side. Hence there's effectively two adjoining walls, one at the side and one at the back. 
Yes it will be Dinner, but I only suspect it's the way the extractor fan is set up. I think the guy who renovated next door just found a duct in the wall to fit the extraction fan.  So if there's any crumbling masonry between our houses the positive pressure will push it through.  However the South West prevailing wing will have a similar effect if they open their windows.

The strongest smell is in the bathroom which has two adjoining walls, but it then spreads. I have an extractor fan in the bathroom which pushes air up into the attic, but this seems to suck in more contaminated air. It's a strange design because all the bathrooms are enclosed without any windows. Hence the extractor fan.

I sometimes use a large fan next to the window in my bedroom to push air in to create positive pressure. Another way is to open the West facing windows so the wind pushes air into my house to create positive pressure, but it gets very hot in Summer on that side.

I've long since suspected the area under the bath, it's the one area I've not sealed or checked so that's a good idea!

twopenny

Indeed it's often neglected as bath installed and forgotten about.
Gaps in floorboards, under skirting or where wall and floor sort of meet. The waste pipe is often not sealed around.
I even put insulation under my steel bath when I realised so it wasn't icy cold when I put hot water in.

peter021072

This is the best photo I could get of the pipes which run downwards from the bath on the left. These must run into a duct in my kitchen.  It seems that a floorboard is missing entirely. It's also a mess with bits of loose wood just left there!

You can just see part of the adjoining wall behind the pipes at the bottom. 

I still can't understand how the smell gets across the dividing wall though. These houses are supposed to be entirely separate, with separate pipework for each. It shouldn't be different than any adjoined house.

peter021072

Just an update. I had a new boiler installed in the Autumn. Although the heating works well, the central heating fitter left large gaps where the water pipes and fittings go (see pictures) and the smell is even worse today.

I'm reasonably sure it's coming from the adjoining kitchen/bathroom since the smell is most pungent in the adjoining rooms, but I suspect there's several points it's getting in. I'm sure if they had an extraction fan on the kitchen outside wall like most people do there would be no problem, but using an internal vent on our adjoining wall, which goes up to their attic means that vent is pressurised and will find any gaps between the houses.  It doesn't help that they think their gas central heating exhaust is their kitchen extracter! 

How would I find someone qualified to find the source and block it from my side? Someone used to ventilation systems rather than traditional central heating?



  

Simonon77

If the ducting goes out into the attic, and the smell is strongest in the bathroom, is the smell maybe coming into there from the attic through your extractor fan? it would soon spread to other areas of the house from there. If they have the same sort of setup could be they are just pumping the smell from their kitchen or bathroom into the attic space.

Often attics between attached houses aren't very well separated from each other so it would be easy for the smell to spread.

Not sure what the solution is, but I would be investigating the attic to see if there is anything obvious.

peter021072

Simonon77 said:

If the ducting goes out into the attic, and the smell is strongest in the bathroom, is the smell maybe coming into there from the attic through your extractor fan?

Yes I considered that and temporarily blocked the bathroom extractor fan to see if it improved things. It made no difference.  In fact the smell gets stronger if I have the bathroom extractor fan on because it creates negative pressure in the bathroom which sucks air in from other areas, presumably through any crack in the adjoining wall. I suppose having the bathroom extractor fan on is a partial solution assuming I don't go into the bathroom!  Unfortunately, the garlic smell was so strong yesterday it was causing my eyes to smart.

I've taped up some potential cracks around the bath side cover this morning.  As someone mentioned previously, the wall beside the bath can be an area which builders pay little attention to (see previous photos).  Unfortunately it's impossible to inspect all that wall without removing the bath. Refurnishing the bathroom might be an idea.