Mould under Edwardian tiles in hallway

[The Globetrotter]

Hi all,

I'm new to the forum. I did do a search before posting but I couldn't find anything really relevant to my problem. This is a very long post, and I apologise for this, but I thought it would be better to give as much information as possible upfront to save everybody's time.

I live in a mid-terraced Edwardian house in North London, built approx. 1905. Bought about three years ago, the previous owners had disrespected it for decades. In particular, some of the lovely original geometric tiles in the hallway were destroyed to lay a supply pipe for a radiator. Don't make me think about it...

Anyway. Just after we bought, we had the house almost completely gutted and redone: replumbing, rewiring, replastering and redecorating throughout. The house has suspended floors throughout except for the hallway which is solid (I'm sure, I have the pictures from when the house was stripped). The top floor has new parquet floors, whereas for the ground floor we chose to restore the original floorboards. Underneath them the builders laid a rockwool insulation layer and nothing else, which means that about 30cm below the rockwool is plain earth, honeycomb walls and joists (which were inspected and sprayed). Front and back patios redone to a high standard. The front one in particular was lowered to well below the DPC, as per building regs. Lots of air bricks (four at the front, four at the back, another three in the side wall). Front door replaced. We got a specialist tiler in to try and restore the hallway tiles as much as possible (this was obviously before the problem began). Double glazing throughout. The front of the house was re-pointed and pebble-dashed. Fascia, gutters and a substantial part of the roof were redone. The whole project was executed without cutting corners: architect, building control, planning control, FENSA, Part P, gas certificate: you name it, we have it (yes, we spent a fortune. We'll need another lifetime to pay off the mortgage).

Anyway, the problem. The house smells of mould. It sticks to the clothes and is driving me mad. It is particularly strong in the hallway and in the third bedroom which is just up the stairs (I presume this is due to stack effect, as a window is partly open all the time in that bedroom. Paradoxically this seems to make things worse as it's sucking rubbish air upstairs). We had three surveyors in, two of whom were mould/damp specialists but all they could come up with is that the house is now airtight so this is a condensation/humidity problem: "Just fit an air vent and stop cooking vegetables/rice/pasta." Now, the house is a bit damp, I'm not denying this, but I'm sure this is not the source of the smell. We have a dehumidifier on 24/7 in the kitchen because that's where we hang out clothes (and obviously that's also where we cook). Makes no difference to the smell. I have windows open all the time even in winter, my wife is freezing and threatens to divorce me every second day, all to no avail. The neighbours have even higher humidity and no smell whatsoever. I got another specialist over to search for a leak. Sophisticated machines and measurements (and another pile of cash): no leaks. The front door is brand new so I'm pretty sure there's no water ingress from there. There is no visible mould (and there's no wallpaper that could mask it). There are no damp patches on the walls (a little bit of condensation in the master bedroom on winter mornings, but that room is the only one with no smell!). Walls look and feel dry.

We are by now convinced that the smell originates from under the tiles, particularly from the section next to the front door, where the tiles have clear salt (or possibly mould) patches, as per pictures attached. At some point we laid an underlay, tightly taped to the skirting boards and with a plastic sheet on top (to try and insulate as much as possible). We left it in place for a couple of months in summer. When we took it off, the tiles in that section were wet. Proper wet, not just a bit damp. But curiously, they don't smell anything (and I have a very good sense of smell, which makes things worse). Some of the tiles sound hollow when you tap on them, but to be honest this seems to be randomly spread and is not confined to the section near the door. We have a cupboard under the stairs, which is also smelly. Not the same smell, not mouldy. It's the same cellar-y smell coming from under the floorboards as explained below.

Back to the main smell, it's an erratic one. It tends to be worse a day or two after a strong rainfall but this is not necessarily the case. For example we've had some good weather in London over the past few weeks but the smell is now pretty strong. And it's november so it's not that hot (evaporation was another strong suspect). On some days it's almost non-discernible (not too often to be honest), on others it's unbearable.

We also thought that maybe the smell was coming from under the floorboards. Sadly, the original builders used brads to secure them which means they don't squeak but also that lifting them without damaging them is almost impossible. There is one that is screwed in (don't know why) so I lifted that one. The earth is dry. There is a smell under there but it's a different one, it reminds me of a cellar and is the same one coming from the under-stairs cupboard. It's not a mouldy smell.

In case you were wondering, it is most definitely not a dead animal. It does not smell organic in any way, and it's been going on for a very long time now (couple of years).

I got in touch with a specialist Victorian tiler who basically said he didn't want to do the job because he was afraid of what he would find underneath and that was not his job. He could lift them but then I was on my own. Another tiler said pretty much the same. The builder who did the big job is basically unavailable, always too busy on other big jobs and doesn't have the time for small stuff (by the way, he didn't touch the hallway in any way so I can't blame him). Another surveyor? no thanks...

Now that I've bored everyone to death, this is my question: has anyone ever heard of anything like this? I searched the whole Internet but couldn't find anything, can this really be the first case in history? I'm really struggling to find someone who knows what it's all about and is willing and able to do it. Tilers say it's not their job, builders make no guarantee as to the destiny of the tiles (as you can imagine, the idea of giving up such old and glorious tiles makes me want to die now, especially after spending money to restore them). I posted to a different forum some time ago and someone replied saying that I had to dig everything up but again, I want to try and salvage the tiles if at all possible.

Does anybody have any suggestions of any type? Can anyone recommend someone who can do the whole job (whatever the job will be)? I'm frankly a bit desperate now. We can't go on smelling mould but at the same time I can't believe that tiles that have survived two world wars should perish in such an inglorious way.

Again, apologies for this overly long post. Many thanks in advance
Andy

 

[plasticpigeon]

I can't see why the tiles should cause smell, and if they don't smell then it probably isn't the tiles. How about chimneys? Do you have fireplaces or are they bricked or covered up somehow. If so are there vents in the chimney breasts, and are the pots capped with something that allows ventilation? You say you have air bricks in the side wall, is that the party wall? Could it be that the smell is coming from under the neighbours floor? Hopefully there will be a simple solution. Most things usually boil down to water ingress or lack of ventilation.

 

[worms]

I'd agree with PP on this, wet chimneys and cooler weather can lead to a downdraft into the house, bringing a damp smell with the air. What is the position with the chimneys? Are they in use? How rain-proof are any pots/caps? If they are out of use, are they vented at all or sealed off in some way?

 

[MikeG]

I'd be as certain as I can be without visiting the property that the tiles are a symptom, not a cause. Ventilation is your problem. I am a huge fan of whole house mechanical ventilation systems with heat recovery, which give a constant turnover of air in a house without losing huge amounts of heat int he process, and I'd be amazed if that wouldn't sort your problem out in a matter of weeks. Deal with your chimneys, and deal with your ventilation, and your experience of living in the house will be transformed.

 

[The Globetrotter]

Thanks everyone for the replies. I forgot one crucial piece of information: the chimneys are all gone. The previous owners had knocked off the ground floor chimney breasts only (!). We took them off from the first floor as well and got them secured as per building regs (surprisingly they accepted gallows brackets). Sorry I forgot to mention that.

As per the tiles, I appreciate that it seems unlikely, but remember that we put an underlay and when we took it off the tiles were wet, and only in that section near the door.

The air bricks under the side wall: this is a new wall because we also had the house extended into the side return so this is a brand new wall.

I considered a mechanical ventilation system but, apart from the cost, I've heard that they may inject air that smells of attic, have you heard about that? If that could solve the issue I'd be infinitely happier with that solution rather than having to lift the tiles.

Thanks all again
Andy

 

[Flyfisher]

I've read recommendations about ventilation that in 'wet rooms' (kitchens, bathrooms etc) the air should be changed seven times per hour and other rooms four times per hour. That's every 8.5 and 15 minutes respectively, which is quite a lot of air when you think about it.

 

[Zebra]

They are lovely tiles but it looks like there is a wet patch near the front door. It is solid floor under the hall but suspended everywhere else, is that right? Where is that wet patch originating from, if that's what it is?

 

[The Globetrotter]

Yes solid floor in the hallway and suspended everywhere else.

That's exactly my question: where is that wet patch coming from? There's no way I can know other than lifting the tiles but I want to avoid it as much as possible. As you say, they are lovely tiles...

 

[plasticpigeon]

I see, so nothing obvious. In my experience smells come from somewhere smelly. For example we had an intermittent pungent odour in our back room. I wondered about damp, stale food smells, something dead under the floor boards etc, but in the end I found out that it was a local stray tom cat leaving its spray on a very rotten window sill, so it got impregnated. When I found out what the smell was, which I did when I became aware of the same smell outside, it was apparent that the window sill smelled very strong. We also got some strong smells in our house when we opened the windows during a period that the neighbours turned their house into a marijuana farm!!!! I hope you find the source of the smell.

 

[MikeG]

I've read recommendations about ventilation that in 'wet rooms' (kitchens, bathrooms etc) the air should be changed seven times per hour and other rooms four times per hour. That's every 8.5 and 15 minutes respectively, which is quite a lot of air when you think about it.

No, that's way too much.

 

[MikeG]

........I considered a mechanical ventilation system but, apart from the cost, I've heard that they may inject air that smells of attic, have you heard about that? If that could solve the issue I'd be infinitely happier with that solution rather than having to lift the tiles.....

Whoever told you that, Andy, doesn't understand mechanical ventilation systems. They are sealed. They have no contact with the air in the attic, or anywhere else they are placed. They bring fresh air in from the outside via a duct, and send stale air out through a different duct, passing the two airflows over a heat exchanger so that the incoming fresh air is pre-warmed by the heat from the outgoing stale air. Fresh air is distributed throughout the house, and stale air extracted from kitchens, bathrooms utilities etc. I have fitted them in every house I have been involved with for the last 25 years. They are the single biggest innovation in new houses in the last 30 or 40 years, and every new build should have one.

Imagine stepping out of a long steaming hot shower in the middle of January and being able to use the mirror without wiping it first. Imagine coming home from a three week holiday to a house smelling as fresh as the day you left. Imagine having a wet dog, but no wet dog smell. Imagine living without cold drafts from trickle vents. And imagine living without mould. As well as all that, they help distribute heat more evenly around the house. Those who suffer from hay fever and other allergies can fit fine filters which remove pollen from the air, thus giving them a sniffle-free indoor environment even on the worst pollen days. I wouldn't live in a house without one. I can't speak highly enough of them......they're a wonder-product. There is hardly a ventilation issue I can think of that they don't solve.

 

[The Globetrotter]

Whoever told you that, Andy, doesn't understand mechanical ventilation systems.

I found this in the Amazon reviews for the Nuaire Drimaster. At least a couple such reviews mention the attic smell.

Is this one of the products you were referring to?

Thanks

 

[88v8]

Welcome to the forum.

It sounds as if your house is sealed up too much. Bit of an insulation and 'draught' obsession?
There should be a modicum of air permanently coming into each room, not by opening the windows but by the simple fact that original windows aren't a sealed fit.
And then the air should be going out, up the chimneys you don't have.

As you say, you spent a fortune, but what your advisers have done is turn a Period house into a half-baked new one. All that money, to buy a Period house with no open fires. Huh.

In the kitchen, there should be and I hope after all the money you spent, is, an extractor fan near the point of steam creation, plus an air inlet, so the air flows in, then across the hob or whatever, then to the fan.
If you dry clothes in there and there is no chimney, perhaps a second fan on a humistat.
By fan, I mean an extract fan in the wall or window, not a recirculator.

All this is relevant to the general health of the house and its occupants, who without proper ventilation will be shut up with the array of household chemicals and artificial fibres etc that are responsible for the steep rise in allergies and food faddisms we see in recent years.
However, it is not relevant to your immediate problem, which is much simpler.

Tiles. Encaustic tiles do not harbour mould. They were fired in a kiln, and are very dense.
The damp patch you found by the classic plastic sheet method shows there is damp by the door.
The damp is coming up through the tiles, which are as usual bedded in cement with no dpm, and therefore will transmit whatever damp is beneath.
But the damp should not be there.
You have a leak.

So, what's adjacent?

Where does the water main come into the house, and where does it run between houses? Iron or lead?
Central heating - where do the pipes run?
Outside, is there a downpipe by the door?
Is there or was there a drain by the door?
Is there or was there a manhole near the door? It may be buried.
A stack pipe?
Is there or was there a drain - foul or fresh - running across the front of the house?
The new door, in a new frame? - is there a drip beneath the cill such that water cannot run back under the cill onto the wall?
What paving if any is outside the door, which way does it slope?
Is there or was there a porch?
Do any neighbouring houses retain an original garden and frontage layout that may give you a clue what was there?
Where are the sub-floor air vents in the front, how near to the hall? What are the vents, iron or clay?

The damp is there because something is leaking. Something in the house or something outside. Something old or something new.
All the original drainware was clay. In time, it cracks, it leaks.
It need not be a big leak. Drip drip drip drip.

Just big enough that the concrete beneath the floor is saturated and the underfloor ventilation is not dispersing the damp from the side of the concrete before it reaches the surface.
Find the leak, and you fix the mouldy smell problem.**

Ivor

** drying out takes about a year per foot thickness. Fix the leak, eventually fix the mouldy smell problem.

 

[Flyfisher]

I've read recommendations about ventilation that in 'wet rooms' (kitchens, bathrooms etc) the air should be changed seven times per hour and other rooms four times per hour. That's every 8.5 and 15 minutes respectively, which is quite a lot of air when you think about it.

No, that's way too much.

Yes, that's what I thought when I first read it. Unfortunately I can't remember my original source, but there are supporting references here:

http://www.engineeringtoolbox.com/air-change-rate-room-d_867.html
"All spaces in general - Air Change Rate = 4 (times per hour)"

http://www.vent-axia.com/files/Ventilation%20Design%20Guidelines%202.pdf
"Air Changes per Hour (ACH) . . . . Living Rooms 3-6"

'Healthy Beginnings - What is your Air Change Rate?
http://hbmag.com/what-is-your-air-change-rate/
This suggests an ACH of 4 as a minimum for all spaces.

However, this Japanese review of international standards suggests a general figure of around 0.5 ACH for domestic dwellings:
http://www.aivc.org/sites/default/files/members_area/medias/pdf/Conf/2004/2004028_Yoshino.pdf

And according to UK Building Regs Part F, table 5.1b, note (a):
the minimum ventilation rate should be not less than 0.3l/s per m2 of internal floor area

I make that equivalent to 0.43 ACH for 2.5m high rooms, so in line with that Japanese review paper, though nowhere near the other recommendations of around 4 ACH for living rooms.


All a bit confusing.

 

[noj]

Part of the confusion is that testing for airtightness is a blower test done at pressure (50pa) which gives and ACH figure which can be around 20 times above what happens in reality - subject to location/weather etc etc.

So 4 ACH at pressure should probably mean around 0.2 ish in the real world - but you can only measure it at pressure!

My head hurts

 

[malcolm]

I would expect if I put plastic sheet over my tiled floor with no damp course underneath it would become wet. That's why you shouldn't put a plastic sheet over your floor. The old farmhouse (1911) had tiled floors covered by rubber backed carpet. We lifted the carpet once and the tiles were soaking wet. So we put the carpet back down again (rented house since demolished).

I can't see the tiles causing a smell. The only route for water to get through is the gaps between the tiles so a tiny amount of ventilation should be enough to avoid a smell from the floor. Leaving the windows open would be overkill. On the other hand I agree with Ivor.

Sounds like damp somewhere though. I guess the question is how to find it. My house smells damp at the moment but we did have a significant flood a few weeks ago, and the smell is receding as the place dries out. Removing the wallpaper with the modern paint has exposed soaking wet walls so hopefully the smell will reduce further now.

I would look for things that are unable to dry out (waterproofing stopping them), or things that are being supplied with more water than they can deal with. I wonder if divide and conquer could help trace the problem - shut a door overnight and see which side is more smelly, or plastic sheet partitions overnight to see which side is more smelly. Then move the partition halfway into the smelly area the next night and assess again. A plastic sheet suspended overnight a foot above the floor would rule that in or out, and a few bits of 2x2 and some sheet would be cheaper than destructive testing. You won't smell anything if you have the sheet directly against the source as there won't be any smelly air to smell.

 

[Flyfisher]

Part of the confusion is that testing for airtightness is a blower test done at pressure (50pa) which gives and ACH figure which can be around 20 times above what happens in reality - subject to location/weather etc etc.

So 4 ACH at pressure should probably mean around 0.2 ish in the real world - but you can only measure it at pressure!

My head hurts

Ah, perhaps that explains the discrepancy. It's still confusing though because ACH itself is a very simple concept even though it could be achieved by many different means. Thus, if the figure for maintaining a healthy indoor environment is 4 ACH then surely that is the thing to focus on? If it can only be measured under pressure (fair enough) then wouldn't the 'blown' figure be expected to be higher than the 'real world' ACH, given that 4 ACH is presumably a real-world figure?

My head hurts as well!

 

[The Globetrotter]

Hi all, thanks for your replies.

Ivor
In the kitchen there is an extractor fan with a 6 inch pipe plus trickle vents on the French doors. Trickle vents in the living room as well.

Leak: yes that's what I thought as well, and I called an expert just for that. He said positively no leaks anywhere.

There is one general stopcock in the front patio, not in front of the hallway (in front of the bay not too far from the hall). From there, one pipe with no junctions runs all the way to the boiler cabinet in the kitchen. From there, a manifold system distributes everything (hot/cold water and heating) to the rest of the house. There is a radiator in the hallway, the pipes to which run behind the skirtings. That was one of the suspects but again, the inspector said there were no leaks, and that pipe is well away from the wet section anyway, the latter being between the rad and the door so downstream from the pipe.

Outside, there is a downpipe by the door that goes into the ground, runs buried under the patio and eventually on to the pavement. This was done recently (about 10 months ago) i.e. about three years after the initial big job. Previously the downpipe shoe was a few inches above the patio, just outside the house, letting water out directly on the patio, between the hall and the bay, very close to the house. There was green mould on the stones around the area where the water was landing. The whole patio was since destroyed and rebuilt. It's now got gravel on the patio proper (permeable as per building regs) and stones on the path to the front door. It slopes away from the house. Reading your comment about the drying out taking one year per foot thickness gives me hope that that donwpipe layout was the root cause and that now the problem will slowly sort itself out. However, when the builders destroyed the original patio, the ground didn't appear to be soaked (but then again I wasn't there all the time). Manhole by the door I would rule out because it would have come up during the excavations.

There is a porch, with proper gutters.

The vents are not underneath the hall because it's solid. There are four of them in the front, the closest being around 400mm from the hall. All the vents are clay.

There shouldn't be a drain in the front, drains and sewers run along the back.

Malcom
Nice suggestion about the divide and conquer approach. I'll try that. I also agree with your remark that if you put the sheet directly against the source you won't smell anything.

Thanks again
Andy

 

[The Globetrotter]

Hi all, thanks for your replies.

Ivor
In the kitchen there is an extractor fan with a 6 inch pipe plus trickle vents on the French doors. Trickle vents in the living room as well.

Leak: yes that's what I thought as well, and I called an expert just for that. He said positively no leaks anywhere.

There is one general stopcock in the front patio, not in front of the hallway (in front of the bay not too far from the hall). From there, one pipe with no junctions runs all the way to the boiler cabinet in the kitchen. From there, a manifold system distributes everything (hot/cold water and heating) to the rest of the house. There is a radiator in the hallway, the pipes to which run behind the skirtings. That was one of the suspects but again, the inspector said there were no leaks, and that pipe is well away from the wet section anyway, the latter being between the rad and the door so downstream from the pipe.

Outside, there is a downpipe by the door that goes into the ground, runs buried under the patio and eventually on to the pavement. This was done recently (about 10 months ago) i.e. about three years after the initial big job. Previously the downpipe shoe was a few inches above the patio, just outside the house, letting water out directly on the patio, between the hall and the bay, very close to the house. There was green mould on the stones around the area where the water was landing. The whole patio was since destroyed and rebuilt. It's now got gravel on the patio proper (permeable as per building regs) and stones on the path to the front door. It slopes away from the house. Reading your comment about the drying out taking one year per foot thickness gives me hope that that donwpipe layout was the root cause and that now the problem will slowly sort itself out. However, when the builders destroyed the original patio, the ground didn't appear to be soaked (but then again I wasn't there all the time). Manhole by the door I would rule out because it would have come up during the excavations.

There is a porch, with proper gutters.

The vents are not underneath the hall because it's solid. There are four of them in the front, the closest being around 400mm from the hall. All the vents are clay.

There shouldn't be a drain in the front, drains and sewers run along the back.

Malcom
Nice suggestion about the divide and conquer approach. I'll try that. I also agree with your remark that if you put the sheet directly against the source you won't smell anything.

Thanks again
Andy

 

[The Globetrotter]

One last point I forgot to mention: when we came back from a two week holiday last summer, the house had a strong chemical smell of wet paint/plaster, as if it had just been redecorated. After several hours with all the windows wide open, the smell reverted to the usual mouldy one.

Walls were bone dry. Last decorated over 3 years before.