French Doors reveals moisture.

[zoothorn]

Hi chaps on this section,

 

I'm having trouble understanding my situation & wonder if you can help. My new extention new french doors built by a builder, reveals work done by me ( guided by folks on here). I must assume, that both builders' & my work done correctly.

 

The difference in insulation compared to the rest of the house is vast: I have one stone cottage 1830 large room.. onto which 4 extentions built. 2 from 1980's (kitchen & bathroom extention... & an upstairs two bedrooms extention), a front porch (80's too maybe), & lastly my new extention built 2020. These 3x 80's extentions have 25mm insulation. My new extention has 120mm. The stone large shell onto which all 4 are built.. of course has none at all.

 

I have upvc windows throughout & in 6 years I've had a small ammount of black mould on all the 80's frames, even in bathroom (even having no extractor fan & a shower in). So, in my new extention I was expecting to have perhaps the same if not -less- or no black mould even due to the up-to-date materials & insulation guages. But I'm getting -far more- black mould in this newbuild & especially badly at the new doors (cill areas): so bad here the plasterboard, in only 18 months, is damaged. I cannot fathom this if I adherred to correct building procedures.

 

The house is ventilated very well: this "problem" upstairs new extention bedroom with it's french doors has it's window open fully allday, everyday (even in winter) 9am to 7pm, I even sleep in this large'ish room with the window open partially (even in winter); so it has decent if not vg ventilation. That box is firmly ticked. 
 

Do I get a specialist in? Is this a door mfr malfunction? My build technique wrong? Or, is this entirely expected-? it's frying my head trying to comprehend this dissapointing situation which there seems no (feasible) solution to. Rebuilding the whole doors/ reveals/ cill... is not feasible/ out of the question due to finances.

 

Thanks, Zoothorn.

 

 

 

 

 

 

 

 

 

 

[zoothorn]

[markc]

My first thought would be condensation from lack of ventilation but an open window is more than enough.

I am assuming you are not using a mobile gas heater because they really do cause condensation.

are there any holes in the wall or places blown water could get past the frame or be running down the cavity?

 

[JohnMo]

The mould is caused by moisture either coming in from the outside or inside trying to get out.

 

How are your wet rooms ventilated?  Do you have a good coss flow of air between rooms from dry to wet?

 

New builds tend to have quite a bit of moisture trapped in the fabric and it wants to come out.  Good ventilation by air movement is required.  An open window is great when it's windy, when air is still no ventilation, or on a rainy day you will let 100% humidity in, which will not help.

 

You mention you had no fans, assume you have now, what sort are they and how do run?

[zoothorn]

1 hour ago, markc said:

My first thought would be condensation from lack of ventilation but an open window is more than enough.

I am assuming you are not using a mobile gas heater because they really do cause condensation.

are there any holes in the wall or places blown water could get past the frame or be running down the cavity?

 

Hi markc, no the builder part well documented as being fine/ no pitfalls. The BCO knows him ( prob best  known in area) so I can rule out ventilation, & beforehand rule out any sub-par builder aspect straight up.
 

Also I detailed the chaps on here his build progress in photos, so anything below par.. they'd have been onto it.
 

Thinking further as I scrape out my rotten silicone, "cold bridging" come to mind, I think my builder mentioning it re. some other area here yrs ago. If this is what it is (& not pane moisture collecting/ what I was thinking it was up till now tbh).. if these lower areas ARE purely & solely 'cold bridging', then logic boils the cause down to -my- own hand, building the cill & reveals.

 

That's not to suggest the kind help here wasn't good... not at all/ it was fab... it must just have be -me- cutting the odd corner in order to get the job done asap. Although I did show what I was doing, photos etc, & no-one piped up with any concern.

[zoothorn]

1 hour ago, JohnMo said:

The mould is caused by moisture either coming in from the outside or inside trying to get out.

 

How are your wet rooms ventilated?  Do you have a good coss flow of air between rooms from dry to wet?

 

New builds tend to have quite a bit of moisture trapped in the fabric and it wants to come out.  Good ventilation by air movement is required.  An open window is great when it's windy, when air is still no ventilation, or on a rainy day you will let 100% humidity in, which will not help.

 

You mention you had no fans, assume you have now, what sort are they and how do run?

Hi John,

 

Im fairly sure ventilation ruled out, my wet room even without an extractor fan has small mould in comparison (i i think a bathroom extractor fairly useless if you have a window you can just open after a shower or bath) & in all of 6 yrs living here too, & being a very small bathroom & extremely cold too.. leads me to think Im vindicated not having a fan in here.

 

If for eg this is "cold bridging".. would you know why does it only or rather the vast majority of it, appear at the lowest possible areas on the frame/ reveal general area? IE & not uniformly over all the frame edges.

 

I think I need a cold bridging expert perhaps to answer this one.

 

 

Edited September 29, 2022 by zoothorn

[Radian]

2 minutes ago, zoothorn said:

If for eg this is "cold bridging".. would you know why does it only or rather the vast majority of it, appear at the lowest possible areas on the frame/ reveal general area? IE & not uniformly over all the frame edges.

 

It may not be cold bridging in those areas per se. Cold air tends to pool and accumulate low down in corners where airflow is at a minimum. See a thermal image I took of our front door while looking for drafts:

 

 

The bottom left corner of the image matches one of your photos. The other dark blue (coldest) areas are the drafts I was looking for coming from poor sealing around the door and letterbox.

[zoothorn]

Regarding redoing these lower cill areas:

 

I just thought would the vertical corners be well served by adding strips of white plastic trim stuff?

 

Like my DG window job here; i saw it's made of a kind of firm foam inside: is this maybe designed with a little insulation in mind maybe? Perhaps this extra 1cmx 4.5cm, glued on like this on my french door edges.. might minimise this awful black goings on.

 

Just thinking on my feet tbh. Surely worth a go as it's a cheap addition Iknow how to do.

 

 

 

[zoothorn]

5 minutes ago, Radian said:

 

It may not be cold bridging in those areas per se. Cold air tends to pool and accumulate low down in corners where airflow is at a minimum. See a thermal image I took of our front door while looking for drafts:

 

 

The bottom left corner of the image matches one of your photos. The other dark blue (coldest) areas are the drafts I was looking for coming from poor sealing around the door and letterbox.

Useful eg thanks Radian. Looks pretty similar; in fact I'm surprised you didn't say "it may well be cold bridging in those areas".. I"m not quite understanding why you'd say it might -not- be with such a similar-fit eg.

 

But I'm v.much a newbie at all this build xyz you see- so many times I cannot fathom things, in fact I bet if I had a penny for every time I said "I cannot understand" summink...  I'd have £5.63.

 

zoot

[TonyT]

Get some kitchen foil, tape it to the wall, sealing all the edges with tape.

leave 23.5 hrs and remove.  See if moisture is present under the foil.

 

 

[Radian]

13 hours ago, zoothorn said:

I'm surprised you didn't say "it may well be cold bridging in those areas".. I"m not quite understanding why you'd say it might -not- be with such a similar-fit eg.

Your attention is inevitably drawn to those areas that show mould growth.  But the entire reveal, all the way to the top, may be a cold bridge and it's only the nature of cold dense air that causes it to sink down low, and pool there in the corners where it's less disturbed by general air movements in the room. Think of it like a gloop that runs down the walls and is hard to scrub out from the corners. The analogy I'm thinking of is that it's like you're trying to get tea stains out of the corners of a square cup.

 

It may be the head of the reveal that's got the bridge (i.e. treatment of the lintel) and the cold air falls evenly to the floor but is only showing up at the edges. You need a way of visualising the invisible. Do you have a non-contact IR thermometer? e.g. £13.99 on Amazon

[PeterW]

Are there trickle vents in the doors at the top ..?

 

other thought is this is damp from the cavity - @zoothorn have you got any pictures of when you did the reveals ..??

[zoothorn]

1 hour ago, Radian said:

Your attention is inevitably drawn to those areas that show mould growth.  But the entire reveal, all the way to the top, may be a cold bridge and it's only the nature of cold dense air that causes it to sink down low, and pool there in the corners where it's less disturbed by general air movements in the room. Think of it like a gloop that runs down the walls and is hard to scrub out from the corners. The analogy I'm thinking of is that it's like you're trying to get tea stains out of the corners of a square cup.

 

It may be the head of the reveal that's got the bridge (i.e. treatment of the lintel) and the cold air falls evenly to the floor but is only showing up at the edges. You need a way of visualising the invisible. Do you have a non-contact IR thermometer? e.g. £13.99 on Amazon

Hi Radian, that clarifies things/ great info. Tbh if I can keep on top of it, continual wiping & redoing the silicone ( even Forever White, going on tmrw/ redoing it, I just know will innevitably become blackened with mould) say every 2 years.. I'll just have to lump it.

 

I guess even if i found a cold 'source', with a gadget, the lintel area perhaps.. I can't do anything about it, I can't rebuild it, I have to live with it.

 

It's just having put so much work in, it's pretty dissapointing. And not understanding how this is so much worse (I mean honestly by a factor of 20x) than my poorly insulated majority of the house, having used all up to date materials. The rest of the house's extentions are poorly built, freezing cold (unlike this modern addition) falling -far- short of B.Regs, but minimal frame mould.

 

Maybe this is something just 'expected' with 'problematic french doors'; I just don't know what to expect you see/ I have no prior experience or reference points ( apart from Onoff's SWMBO who wipes moisture regularly from their french doors, much older tho, but an interesting bit of info).

 

Thanks, zoot

[zoothorn]

1 hour ago, PeterW said:

Are there trickle vents in the doors at the top ..?

 

other thought is this is damp from the cavity - @zoothorn have you got any pictures of when you did the reveals ..??

Hi Peter, I'll try digging out some pics good idea. No trickle vents, but as said the room is aired throughout the day  leaving the window open. 
 

Now the doors are acually being used for the first time, balcony finally on, increaces ventilation too.. albeit not open in winter.

 

I just know the local area moisture is a factor, perhaps the core reason even.. but it's impossible to explain it/ the moisture % reading doesn't neccessarily concur ( bizarre to me this), & impossible for me to consider actually how.

 

You know these 45x9mm white placcy strip trim long things? Are they purely cosmetic/ to cover wonky plaster ( just as I used it for on my new window install/ pic above), or do they have any form of minimal insulative function-? 

[Ferdinand]

My thoughts:

 

1 - I'd suggest getting a £10 min/max thermometer / humidistat off Amazon to investigate whether you have damp environments in rooms / areas of rooms.

 

2 - Are you sure that your extension is ventilating well? For example how does the air get in/out out - are there decent gaps around the doors etc? (Solution to that may be 6-8mm off the bottom of your doors)

 

3 - Try running a dehumidifier in the room with the excessive mould - if that improves it you know that damp air is part of the problem.

 

(My first reaction would be to fit a PIV loft fan, but that assumes that ventilation is this issue.)

 

F

 

 

[zoothorn]

6 minutes ago, Ferdinand said:

My thoughts:

 

1 - I'd suggest getting a £10 min/max thermometer / humidistat off Amazon to investigate whether you have damp environments in rooms / areas of rooms.

 

2 - Are you sure that your extension is ventilating well? For example how does the air get in/out out - are there decent gaps around the doors etc? (Solution to that may be 6-8mm off the bottom of your doors)

 

3 - Try running a dehumidifier in the room with the excessive mould - if that improves it you know that damp air is part of the problem.

 

(My first reaction would be to fit a PIV loft fan, but that assumes that ventilation is this issue.)

 

F

 

 

Hi Ferdinand, ventilation is more than good as said. Which is why surely cold bridging is top of the possibles, that is to me it just seems logical, esp if I have perhaps gone too thin with PIR below cill & behind reveals (but constrained with the ammount I could fit by the prior frame size/ &/or the timber area left for me: especially so the window L&R: I could only fit 10mm of insulation here or I'd be encroaching into the frame too much).

 

I have to live with it. Dehumidifiers have been tried here by house after house, so much so everyone has them but no-one uses them: they extract alot, but it's like a drop in the ocean.. it makes no difference at all; everyone here house after house moans about the damp air, the green & black mould. Best eg: my kitchen sink drain board is chokka with green mould, masses of it. Scrub it clean, in weeks it returns. A modern 80's extention, no damp in kitchen. Everyone has it. Old house, new build bungalow. All our drain boards are similar. Outside, you whitewash a well ventilated wall, in months its covered in green mould in huge patches. You can't do anything about these two eg's. You just learn to live with it. It IS the environment. Regardless of a % figure on any device saying "no, the air is fairly normal". It just isn't, in this neighbourhood/ locality. This is a fact, & I can verify it with countless eg's here which tally with neighbours absolutely identically. How this absolute-factual aspect is affecting my problem with these doors though, is as impossible to figure out as it is impossible to do anything about this air 'thing'.

 

Imagine James Herbert's The Fog. It's like that, but invisible & never, ever ceases. Sounds implausible, but it is absolutely real.

[markc]

I live in an old solid walled house, no Internal or external insulation and I don’t have any problems with damp or mould. It had been empty for a year or so which meant I had to overheat it for about 18 months to get it dry and warm again but since then no problems and my bills are pretty low especially as I never think about leaving heating, lights etc etc on. … oh and TV for the cat.

[Radian]

50 minutes ago, markc said:

I had to overheat it for about 18 months to get it dry and warm again

Have you tried that @zoothorn?

[zoothorn]

50 minutes ago, markc said:

I live in an old solid walled house, no Internal or external insulation and I don’t have any problems with damp or mould. It had been empty for a year or so which meant I had to overheat it for about 18 months to get it dry and warm again but since then no problems and my bills are pretty low especially as I never think about leaving heating, lights etc etc on. … oh and TV for the cat.

Hi markc,

 

again, there's a mix up in communication/ my fault obviously.

 

I'm distinguishing absolutely/ totally/ unequivocally, between damp within a house. And damp within an area. And when I say area; not the area within the house; nor the area the house resides on ( the property area). I mean the locality. The combined area of say 200 houses, 400 perhaps. 
 

If we all share & moan about the same problems & similar strange things, & if we as a collection of different house types (some old miners cottages with modrrn additions, some 1930's, some 1960's bungalows, some new built extentions) share commonalities... then focussing on the house damp in this house, is nonsensical; it misses the point entirely; it's of no use whatsoever.

 

I do have some 'normal' damp within the old part of the house. It manifests itself in a dry grey-black area easily wiped off, in lower areas & corners of the old room (I only have 1 old room).
 

 

This is completely completely completely different

 

 

to the moisture-mould in the brand new extention french doors. It is completely different to green mould in the kitchen. Completely different to external green mould appearing on a 5m square patch, mid-way-up, on my new extention, within only 18 months since new & just painted. And completely different too, to the breath-related patches of dark mould formed very quickly in areas (of the modern bone dry sections, not in the old part of the house) adjacent to where my breath is exhaled. Next to my head on the wall (dry/ no damp/ modern addition) where I lie in the bath (like the drainbosrd green mould appearing in weeks, a dense black mould patch forms on the wall in weeks again after removing). Exactly where my breath exhales. This bathroom is modern dry, no damp. So this mould right here next to my head................... has nothing to do with house-damp-air then. It must have a cause though. If there is no damp in the room, the ONLY factor left, is the locality-air breathed. SO. There is something happening with the air, in the locality. It is proven time after time. But what is impossible to establish.

 

Distingushing between the different (4 as I count) mould types is 1st step to understanding which ( if it is related to one at all), these new doors' mould is related to. If it's cold bridging... then my count goes up 1 to 5 types here.

.

[zoothorn]

The only thing that seems to adequately describe what is possibly happening ( again this may, or may not be the cause or a contributing factor to the bizarrely early damaged state of my doors areas) is thus.

 

Although the humidity percentage taken here may read similarly to an average area, or even very slightly above average ( as it does), something else is playing a factor that this  figure is not showing. 
 

If mrs. miggins in her new bungalow gets the exact same drainboard green mould spring to life in ridiculous fashion, repeatedly, without any let up all year... as I do here. And if both our kitchens are dry. And if the tap water isn't any "different" to normal water ( the only other possible contributing factor producing this green extravaganza). Then the only thing linking me & mrs.miggins... is the air.

 

Now, if this air has a similar moisture content to normal let's say, or nothing pinging out as higher than average, then something this percentage figure ----doesn't show---- MUST be at play.

 

My only possible theory, is that for some reason, the air here is a particularly good CONDUIT for carrying, (or, particularly good at aiding the development of) MOULD SPORES. It must be something within the air that a " normal" figure for eg of " 72% " just doesn't explain. This is the only possible explanation for all the catalogue of mould happenings in our part of the world here, 6m east of the irish sea, in very hilly west wales, in a bowl of steep-sided fir forests, where plants grows unusually almost weirdly-well. And my hunch has been from day 1, & has never changed, that it's a "perfect storm" of factors including topography, sea air.

 

It is known, for eg, that we have here in this locality, a UNIQUE flora mould type. I've bumped into the nerdiest nerds on planet earth here whilst hiking, excited by a patch of green on a farm gate. Come all this way, to witness this unique incredibleness. Gives my theory wings doesn't it.

[JohnMo]

You need damp or humid air for mould to form and grow.

 

Damp could be cold bridging, as previously described and or relative humidity at it or above 70% for prolonged periods.

 

You should aim to have a relative humidity in house of around 50%.  If your house is colder than outside the relative humidity will be higher inside than outside.  As the cold air cannot carry as much moisture.

 

A warm well ventilated house should not have the physical environment to support mould growth.

 

The need for mechanical or stack ventilation is written in to building regs for a good reason.

 

Question how is your house heated?

[dpmiller]

what temperature is the room kept at?

[Onoff]

3 hours ago, zoothorn said:

It must be something within the air that a " normal" figure for eg of " 72% " just doesn't explain.

 

A figure of 72% internal humidity explains everything. 

 

https://www.oxford.gov.uk/info/20271/guidance_for_private_tenants/1129/preventing_damp_and_mould#:~:text=A good range of indoor,minimise or control dust mites.

[Radian]

If your house is nominally at 20^oC with an RH of 73% then the dew point is 15^oC.

At 50% RH, the dew point drops to 9^oC which is much less likely to occur indoors.

 

Even though your room thermostat might be giving you 20^oC, 15^oC is the sort of temperature that you would find low down around doors and skirtings, and also on poorly insulated walls and...

 

...Draining boards often sit atop kitchen cupboards, the insides of which don't benefit from the general air circulation outside. They also sit on outside walls where the drainage outlets are located. Even if these are well sealed around wall penetrations, the air inside the pipe can be the same temperature as the outside air and similar in the case of the cold water pipes. Lots going on under sinks. But draining boards (especially stainless steel ones) are a great place to mirror the thermal goings on. For sure, yours and you neighbours are all developing a thin layer of condensation and feeding your localities special fungi.

 

Edited September 30, 2022 by Radian

[Ferdinand]

29 minutes ago, Onoff said:

 

A figure of 72% internal humidity explains everything. 

 

https://www.oxford.gov.uk/info/20271/guidance_for_private_tenants/1129/preventing_damp_and_mould#:~:text=A good range of indoor,minimise or control dust mites.

 

That was a for instance as I read it.

Which was why I mentioned a min/max humidistat to find out.

 

I couldn't live somewhere with 72 - I would be coughing all day. Had a Ts bungalow with that problem, and condensation etc. Too many total people + dogs, and too little ventilation. Fitted trickle vents with removed closure flaps and a PIV fan, and it did it.

 

But if genuinely something like 72 in the entire area, I would have to move house or seal it and maintain a low dampness zone inside.