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yep its that time of year again, we're just in the process of redecorating our bedroom, pulled up the carpet and the underlay's wet, with mould starting to accumulate on skirting behind drawers and under bed..
had this problem a few years ago, with clothes going green in drawers under the bed, so got our builder to stick us a couple of airbricks in. To our dismay we found the airbricks were always wet and mould growing around them. id have thought that was the place where youd be least likely to find that!
we also bought a decent dehumidifier and use that elsewhere to dry clothes (at the other end of the house in utlity room, so this wont contribute to the bedroom problem)
wifes wanting to buy a fancy £250ish dehumidifier and stick it in the hallway. my response is, theres no condensation in the hallway, its our bedroom and the lads that are worst (outside north facing wall). these are just off the hallway, she says if we leave the doors open itll be the best solution.
i say..... ill ask on here 🙂
ive just taken the covers off the airbricks and hoovered them out, they were a little clogged with dust.
id also guess that a small dehumidifier that fits under a bed may be the best way forwards, one in each bedroom. she says these dont exist.
whats the most important consideration here, dehumidifying, or air movement?
we're also about to build some new wardrobes, but im wary of mould growing behind them over the months/years. would a blast of air from a fan maybe every week or so behind them prevent this? will a dehumidifier in the room (or hallway) pull moist air from behind wardrobes or not powerful enough?
dont even get me started on the bathroom, crap extractor fan, radiator going rusty grrrrr......
so many questions, i hope you have all the answers 😀
thanks
I'd look at the a loft based positive displacement wotsit.
Start here;
https://singletrackmag.com/forum/topic/positive-pressure-ventilation-loft-units-which/
and more;
http://singletrackmag.com/forum/topic/nuaire-drimaster-heat-experiences
Dehumidifiers are a [partial] solution to a problem caused by lack of air movement. Solve the latter and you [hopefully] won't need the former.
Do your windows open?
had this problem a few years ago, with clothes going green in drawers under the bed, so got our builder to stick us a couple of airbricks in
The thing is that those drawers are under the two of you and you're giving off moisture - unless the drawers were open they wouldn't get much air circulation.
a problem caused by lack of air movement. Solve the latter and you [hopefully] won’t need the former.
so would a fan be more beneficial than a dehumidifier?
Do your windows open?
yes, and we do open them, we have trickle vents when closed, and often have them on the security vent setting where theyre just slightly open.
I suspect that with that much moisture you have a water ingress problem rather than a condensation problem. Take a look at what's immediately outside, and what condition gutters and downpipes are in, also drain gulleys etc.
Have you got cavity wall insulation?
I would recommend PPV as above over dehumidifier any day, but does sound odd how damp it is
I suspect that with that much moisture you have a water ingress problem rather than a condensation problem. Take a look at what’s immediately outside, and what condition gutters and downpipes are in, also drain gulleys etc.
I would agree with this.
We identified three issues:
- drip from a gutter join splashing a wall
- crack in render between extension and old house
- the sh*te building materials, narrow cavity and lack of any insulation in part of the extension
Sorting these solved half our damp/mould issues.
We also have a decent dehumidifier. This gets moved around the house depending on where hasn't had it or where the window condensation is forming. For reference, we have 5 of us in very small semi, so condensation build up even with vents etc overnight can be a problem.
I suspect that with that much moisture you have a water ingress problem rather than a condensation problem. Take a look at what’s immediately outside, and what condition gutters and downpipes are in, also drain gulleys etc.
builder checked this all over and said it was defo condensation. there is no sign of damp on any walls (which i would expect from a guttering/drainpipe prob), just the floor and mould at low lying levels.
there are no water pipes under the property, we checked that too and also looked at the water meter with everything turned off to see if it was still moving. it wasnt.
yes we have cavity wall insulation which i am told can contribute, seems a fine balancing act between keeping warm and getting damp :-/
Could you experiment with the dehumidifier you do have in the utility room and run it in the bedroom during the day? I've run a dehumidifier in two houses now - actually in one house, and an outhouse office - and we have one in the cellar and they do make a difference, but as per the poster above, if you're sure there's not a leak, I'd look at one of the Drimaster, loft-housed things.
I'd also bear in mind that most dehumidifiers make a low hum or worse, while in operation, so you may not want one on when you're in the bedroom, which in turn is when you're creating the most moisture.
Do you have extractor fans in the bathroom and kitchen btw, it all helps?
I’d look at the a loft based positive displacement wotsit
A friend of mine had one of these, rated it except for said it was always chilly in the house.
Moved into a new home in October and had constant wet windows to start with, window opening didn't do very much as occurred mainly overnight, I think its mainly down to an under heated upstairs but clothes are dried upstairs on a horse too. As a temp fix We got a 12 Litre Dehumidifier and run it by drying clothes and also put it on for a few hours everynight on the landing with the doors open, has fixed it for us for now.
if there isnt a leak, then the moisture in the air that is condensing will be coming from the bathroom, the kitchen or from you. decent extractors in the bathroom/kitchen and a PPV unit in the loft will fix the problem.
I only notice the cold air from my PPV if I stand directly below it at the top of the stairs. its made a massive difference to the house and how it feels. damp air isn't good for you either and costs more to heat.
I suspect that with that much moisture you have a water ingress problem rather than a condensation problem.
I know the guy said it wasn't, but it does sound like a LOT of water.
I would have a look around looking for holes as well.
Over various propeties blah blah blah, I have seen:
A drip from a gutter end cap on wrong.
Holes in the wall adding moisture into the cavity.
Cracks in render.
Gaps around drains outside next to the house.
A leak in the tiles round a shower tray leading to water and damp creeping under the floor to a cupboard.
A shower leak running along a pipe out of sight to another point.
A house with cheap pebble dashing covering up the air bricks.
The 'smelly pipe' that went through the roof letting water in and it running down. agin into the cavity and then along the base of a wall.
Another property was completely fine as I lived there, but it got really bad with the next person.
The place had excellent windows etc. But they refused to open them.
They would do a lot of vigorous boiling type cooking, had four people in a two bed flat,all had hot long showers with the window shut.
Always had the heating right up.
Caused a lot of damp and mould issues.
Drying your washing indoors creates an awful lot of moisture in a house.
Can be all sorts of things.
I got a secondhand dehumidifier, it'll do at least 7 litres a day (will need emptying every 8 hours if we have washing in the house) and will dry a whole rack of washing in 12 hours. At the same time it has prevented any mildew/mould growing in the colder corners of the room.
You don't need them in the damp room itself, you can run it on the hallway and the dryer air near the dehumidifier supposedly will encourage air movement as the house stays evenly humid.
If I could be bothered, ours can be plumbed with a flexible pipe so it never needs emptying.
We've got a drimaster - they're great - cost nothing to run, very quiet, and our flat never smells of cooking etc due to the constant fresh air. Automatically shuts off in summer when the loft gets too warm. It does leave the hallway slightly colder, but it's cheaper to heat dry air than humid air. A dehumidifier just helps temporarily deal with the problem, a drimaster (for us, and for my parents in their old cottage) eliminates 95% of the damp. If you're worried about cold air, think they do one with a heater built in.
Has nobody mentioned an extractor fan? Do you have them in kitchen and bathrooms? That would be my no 1 place to start.
In residential kitchens we normally fit an external routed fan over the hob, plus a humidstat one on the wall.
edit - I see your bathroom one is dreadful, sort that out. Condensation spreads out so this could be part of your issue in the bedroom.
If the bathroom hole is only 100mm then get a centrifigal jobby, they are excellent, this blauberg one is our current fave as its 123m3 per hour. Its sucks like a good un.
https://www.blauberg.co.uk/en/blauberg-force-centrifugal-residential-fan-100mm-timer?
Which way do joists run, you could be getting joist end damp/rot on them caused by cavity insulation being soaked and up against them, this will cause you a world of pain if it is the case, get a floor board up and check.
Are you heating the room enough?
If you have the windows open a lot then the heat may be going straight out leaving cold walls for the condensation.
Thought about internal wall insulation?
Cynical -al I am half with you - insulation is another one, if the walls are cold, then they will cause condensation.
However open windows are good, not bad, we get horrific condensation in rooms where the tenants have lots of heating but no ventilation, eg they close the trickle vents and tape up the brick vents....
Do you have extractor fans in the bathroom and kitchen btw, it all helps?
we do but theyre next to useless, token jobbies. ive watched steam near the bathroom one laugh in its face, and the kitchen one is one of those cooker hoods with a filter that doesnt lead to the outside.
If the bathroom hole is only 100mm then get a centrifigal jobby, they are excellent, this blauberg one is our current fave as its 123m3 per hour. Its sucks like a good un.
https://www.blauberg.co.uk/en/blauberg-force-centrifugal-residential-fan-100mm-timer?/blockquote >looks interesting, ill have to have a measure up of the hole weve got at present. its to an outside wall but just under the soffits. i assume all id need to supplement it would be a bit of plastic pipe?
get a floor board up and check.
no floorboards, we're in a bungalow with concrete and floor tiles.
im leaning with the extractors ^^^ at the minute, maybe a small dehumidifier under the bed if they exist? anyone know of any, or is my wife right? (as usual)
thanks
However open windows are good, not bad, we get horrific condensation in rooms where the tenants have lots of heating but no ventilation, eg they close the trickle vents and tape up the brick vents…
It's a balance...
Cold walls and indoor living humidity creation.
More heat, less internal moisture production (or better management) and insulation/ ventilation improvements where possible. As Jambo has said, it's a balance.
Given your air bricks were always wet, (cold spot) I'd say you have a problem with insufficient heat or excess humidity indoors.
If it is condensation the positive pressure ventilation is what you want. I've got it in mine and a rental property and it works miraculously. No messing about with dehumidifiers. If it's still a bit damp after a good few months get decent extractor fans put in bathroom and kitchen
Basic cold bridging going on then by the sounds of it, dew point being within the property. I'd hazard a guess there will be zero insulation under the concrete floors and down at the bottom of the wall due to mortar droppings during construction, current air outside has dropped cold, you've banged up the heating, add to that lack of air flow but warm under the bed and around the perimeter and you've got the perfect scenario. Positive pressure units can be very good at alleviating this but not always successful in the harder to reach places. I had all the same problems but really bad black mold behind wardrobes and anything up against a wall. Admittedly ive got 9 inch solid brickwork but i remedied by having every inch of plaster off and then insulated every external wall, I appreciate you may not want to do this but it is the only certain way by pushing the dew point further out.
Edit, but that won't help with the floor being cold...
Are you heating the room enough?
probably not, its generally a fairly cold house, i dont like wasting heat so heatings only on when its really cold outside, or for 2 hour sessions say every now and then.
ill take the cover off the bathroom fan and measure up, im defo leaning towards fans in the bathroom and kitchen anyway.
this PPV lark, bout £300 yep? our loft is freezing (as youd expect) so im a bit wary of pushing freezing cold air into a house thats already cold and we're trying to heat up.
didnt really get an answer to an earlier question, would a blast from a desk fan every now and then behind wardrobes/static furniture solve any issues of walls going black behind them, spores etc? or does it need to be a more holistic approach, so extractors/PPV to prevent the moisture build up in the first place?
any mileage in a small 'under the bed' dehumidifier that can run for a few hours in the mornings say? or leave bedroom doors open and bigger/betterer dehumidifier in hallway?
thanks
The last thing you want in your bed room is a dehumidifier.
I had a rental (as a tennents) where this was a solution to the fact it was on a noisy road and so the owner had blocked all the vents ....
Anyway you need to sort this or you'll end up with respiratory issues from the damp.
The last thing you want in your bed room is a dehumidifier.
why? i agree i wouldnt want it on whilst sleeping, but once up and at em, why not have one to remove the night moisture around the bed for an hour or two?
It's freezing in my loft too but the unit is in the hall and that's the only place I notice it being slightly cooler. As others have said it's easier to heat dry air than damp air but it does sound like you might want your heating on a bit more. Piv was no more than £300 fitted easily ourselves and if you're really worried about cold air you can get the one which warms the air before pushing it in. This is what I have in the rented property but in my own it's not heated. Our bedroom in the eaves is very poorly insulated and noticeably colder than the rest of the house which was where the black mould was worst as the moist air finds the coldest places to condense. Also if you're worried about running costs I would think several dehumidifiers would cost much more to run and more faff than one Piv unit. Seems silly to use something to remove moisture from the air when you could just push that moist air out of your house instead.
q's
Where are your kitchen and bathroom in relation to the problem room?
Which walls in the problem room are external?
PPS we have fitted 4 of those PPV units over the years without real success, improved extraction fixes it for us. With tenants we use humidistats on some fans to take it out of their control, as nobody leaves them on for long enough. So if you do fit better fans, make sure you train everyone at home to use them properly.
We did use to have a £200 hand held humidity meter to show tenants how the fan would improve things. The electrician would spend an hour or so running the shower for 5 mins, and then the fan and monitoring the humidity (only works with cooperative tenants). We have less problems now and I haven't needed the thing for years. Which one of you has nicked it?
Where's this stuff about an under bed dehumidifier coming from? Seems very unlikely that such a thing would exist.
I've been very pleased with our PPV - with the slight caveat that if I was doing it again I think I'd go for one which has the option of heating the air.
Our "normal" upright dehumidifier has a filter that gets clogged with dust and needs cleaning every few weeks (once a month). I'd imagine one under the bed (if it exists) would need its filter cleaning daily!
We also fitted a PPV a few years ago, it's infinitely cheaper to run than the dehumidifier was, and actually succeeds at drying out the whole house. I moved a bookcase before xmas and there wasn't a single mould spot behind it, we've been in the house 18 years and that's never happened before.
EDIT: Anyone want to buy a dehumidifier 😀
Where are your kitchen and bathroom in relation to the problem room?
Which walls in the problem room are external?
rough diagram, not to scale and slightly wrong but you get the picture....
ive taken a few pics and unscrewed the extractor cover to have a measure....
bathroom extractor looks to be 90mm and as its too high to vent directly through brick, seems to be connected by way of tumble dryer flexi hose to the soffits.
as you can see by the outside view, the soffits are too low for it to go directly out in a straight line.
EDIT: yes i know the soffits could do with a clean 😉
EDIT: EDIT:
I’d imagine one under the bed (if it exists) would need its filter cleaning daily!
wouldnt that be a good sign that its shite that you havent breathed in?
Dehumidifiers don't work - all air carries moisture, and every hour the air change brings in more wet air, so it looks like you're drying the room, but you're not, you're maintaining the status quo at best.
Warming the fabric of the house is best. Condensation will occur on the coldest surface in the room regardless. Air movement isn't so important re condensation - except that most warming is by convection so often places with no air movement are coldest.
Usually these problems occur after double glazing, as before the single glazing was the coldest surface in the room, and after it isn't.
Best solutions
-
- don't produce any moisture in the house - short shower with window open, no boiling of food without pan lid and extract on, no drying of clothes in the house.
- warm surfaces of the house - keep the heating on.
- let air circulate under beds
- insulate surfaces esp North-facing walls internally until the windows are the coldest surface - condensation will happen on them then, and that's easy to deal with.
wouldnt that be a good sign that its shite that you havent breathed in?
The filter gets clogged with dust, not with mould/spores.
our loft is freezing (as youd expect) so im a bit wary of pushing freezing cold air into a house thats already cold and we’re trying to heat up.
The unit inlcudes a heating element.
Parent's house has used ppv for 40 years and it fixed things that extra vents, heating etc didn't touch.
Same for our house for the last 15 years.
It is cheap and simple to install. If you don't like it then easy to remove (one hole in plasterboard) and can probably sell on ebay for almost what you bought it for.
What type of external wall do you have IE cavity or brick built?
If it is brick built has it been plastered in modern gypsum plaster?
i dont like wasting heat so heatings only on when its really cold outside, or for 2 hour sessions say every now and then.
This is a likly to be a big part of your problem.
PPV may be a cheaper solution than heating it tho. I've only seen one client with a PPV device and she hated it - it was really drafty - but her home was hard to heat.
Given it's the cheapest thing to try, why not just clear out all the stuff from under the beds so air can circulate and leave the heating on 24/7 with the thermostat set appropriately rather than acting as a human thermostat and switching it on when it feels cold?
That 90mm is probably a 100mm hole, you defo want the centrifugal fan as they are better for long runs, yours looks to have one bend but its a bit of a crap route. If you can get in there, get rid of the flexy and fit rigid plastic it flows better, you could also see about exiting through the roof rather than under the soffit. Depending on your roof construction you might need a lead slate. This is a cheap assed one, I would not contemplate fitting, but it shows you what its for.
My experience is as an accounting manager for a property management and refurb company who ends up having to solve all this stuff as nobody else will take responsibility.
I deal with the complaints, instruct the contractors, and pay the bills, so my experience is purely anecdotal about what we have spent and whether the problems have returned.
I reckon the reason why extraction "does not seem to touch it" is that it has been installed badly, is a crap fan, and isn't used enough. So ppv can get around all that, however decent extraction will move more air when it is needed.
I deal with the complaints, instruct the contractors, and pay the bills, so my experience is purely anecdotal about what we have spent and whether the problems have returned.
The unit inlcudes a heating element.
which id be very scared of then, as that means itd be on 24/7 as the loft will never get warm enough to pump warm air through on its own?
What type of external wall do you have IE cavity or brick built?
If it is brick built has it been plastered in modern gypsum plaster?
yeah double brick with cavity wall insulation and bog standard plaster.
PPV may be a cheaper solution than heating it tho.
if the bumph is to be believed then id need both wouldnt i? house will be having cold air (unless heated in the loft 24/7) pumped around and the heating would be working harder to warm the house because of this?
Given it’s the cheapest thing to try, why not just clear out all the stuff from under the beds so air can circulate and leave the heating on 24/7 with the thermostat set appropriately rather than acting as a human thermostat and switching it on when it feels cold?
leaving the heating on 24/7 would give me astronomical bills id say. its not the warmest house in the world :-/
That 90mm is probably a 100mm hole, you defo want the centrifugal fan as they are better for long runs, yours looks to have one bend but its a bit of a crap route. If you can get in there, get rid of the flexy and fit rigid plastic it flows better, you could also see about exiting through the roof rather than under the soffit. Depending on your roof construction you might need a lead slate. This is a cheap assed one, I would not contemplate fitting, but it shows you what its for.
ill look into this, the extractor still feels needed whether we go PPV or not, the bathroom is very damp and so's the kitchen at cooking times.
ill have to start stripping it i think and see what i can do, just dont want to take it to bits, leave the wiring dangling loose (its probs on either lighting or ring main so cant be isolated in itself), holes in the wall etc until ive got the equipment to fix it properly....
thanks
EDIT: if i bought that extractor linked above ^^^, what pipe should i be buying from the builders merchants, 100mm waste pipe or somethings?
and out of the choices (timer, humidity etc) would i be better with humidity? then itll always be on until the moisture goes?
thanks
if the bumph is to be believed then id need both wouldnt i? house will be having cold air (unless heated in the loft 24/7) pumped around and the heating would be working harder to warm the house because of this?
I should have said
PPV may be a cheaper solution than heating it sufficiently to stop the condensation
out of interest, what is your annual kwh gas usage? You are very much giving me the impression you simply won't heat your house enough to deal with this problem.
if the bumph is to be believed then id need both wouldnt i? house will be having cold air (unless heated in the loft 24/7) pumped around and the heating would be working harder to warm the house because of this?
I couldn’t decide whether to get a heated PPV 6 yrs ago when I installed. Went for one with heat, and never used the heat since.
Yes the air coming out is cool but when do you ever spend time on your landing ? If it is making it cold then turn down the fan speed.
The PPV works by driving out the damp moist air from the house. Damp moist air takes longer to heat than dry air, so no air temp may be fractionally lower with PPV running but you can heat the house quicker and more efficiently.
Your loft HAS to be dry and condensation free though or the PV won’t work.
I purchased a ppv system last year, all window condensation from Windows etc just vanished,nothing bad to say at all other than in the hallway you get a cool draft, but if that bothers you just buy one that also has a heater
https://www.i-sells.co.uk/ducting-system-100?
Or screwfix.
https://www.screwfix.com/p/manrose-round-pipe-white-100mm/15872
You can get all kinds of bends etc, use silicon to seal together. Easy to cut to length.
Also the fan should have an isolator on the wall outside the bathroom.
Also PPV systems do not have to have a heater, you might think the loft is cold, but its probably much warmer than outside.
out of interest, what is your annual kwh gas usage? You are very much giving me the impression you simply won’t heat your house enough to deal with this problem.
ooh now youre asking, who can ever decipher energy bills. just logged onto my bulb account (*cough* pm me for £50 referral code *cough) and it says estimated annual usage 10,400 kw/h. that sound about right?
you may be right about house not heated enough but im trying to keep energy bills down. you could ask my wife if she could only talk through her parka and balaclava.
seriously though, i know its the right answer but i dont understand why a warmer house leads to less condensation. i believe condensation is formed when cold air meets something warm, so by that reckoning, say if the house walls were the same temp as the outside, then condensation wouldnt form.
same with the inside of car windows in the morning..... if the air inside the car is the same temp as the air outside, whats forming the condensation? surely itd be worse if the car was warm inside! (i know its not, but its one of those things that still baffle me)
and warm air behind a wardrobe say, or under the bed, is still just air not moving isnt it? so what does the temp of the air have to do with it?
The PPV works by driving out the damp moist air from the house.
i get that its effective, i believe you all, but wouldnt the PPV need a fair bit of grunt to shift the damp air out of every small orifice, such as beneath closed doors and then through a trickle vent at other end of the room say? and even from the hallway to the other end of the house, under the doors, through another room and through even further trickle vents? and it shifts it from behind wardrobes, under the beds etc, all with closed doors?
Your loft HAS to be dry and condensation free though or the PV won’t work.
pretty sure its dry, just coooold.
you might think the loft is cold, but its probably much warmer than outside.
again, why would it be? its above the insulation layer, why wouldnt it be the same temp as outside? it certainly feels the same temp when you go up there?
Or screwfix.
Also the fan should have an isolator on the wall outside the bathroom.
Thanks, that pipe seems cheap enough, i think ill buy one of those extractors and see if i can cobble up a direct pipe vent to outside. might just be awkward placement of soffit, so id need a bend of some sort.
just looked for isolator, cant see one. thought it was a switch in the airing cupboard maybe, but when i knock it off the fan still works.
thanks for your help and advice chaps, really appreciate all the info.
EDIT: back to that extractor, just rang em and they say theres only the humidity version left, im thinking that would be the ideal one to go for rather than timer, am i right? itll run all the time the humidity is in the air and knock off when its dry? can you set the humidity level do you know?
Most humdity fans are settable. We have also used the blauberg heat recovery fans and you can plug into them with a PC to control the settings with their free software. Very good. Not cheap though.
Here adjustable from 60-90% https://blaubergventilatoren.de/en/product/force-100\
Instructions https://blaubergventilatoren.de/en/product/force-100#downloads
Edit - note there is a force 100 and a force 100max - make sure you get the max.
https://blaubergventilatoren.de/en/product/force-max-100
Am i right in saying your problem isn't the walls as such, you stated where the damp was, it's all at low level, as I explained reckon you're getting cold bridging up through the floor and around the low level perimeter which may be as I explained full of mortar droppings from construction and therefore breaking the cavity. Was the cavity wall insulation blown in afterwards,if so it may not be down to that level hence the damp at skirting level.
This is an excellent point ^^^^^^^^^^^^^^^
Have had exactly this.
Am i right in saying your problem isn’t the walls as such, you stated where the damp was, it’s all at low level,
in the bedroom yes. it was green clothes in drawers under the bed, skirting boards, around air bricks. nothing on walls. maybe a little in window reveals too.
you’re getting cold bridging up through the floor and around the low level perimeter which may be as I explained full of mortar droppings from construction and therefore breaking the cavity. Was the cavity wall insulation blown in afterwards,if so it may not be down to that level hence the damp at skirting level.
not exactly sure what you mean, but ill try and answer. if you mean was the CWI a retrofit, then yes. it was my parents house and i remember them drilling holes in the wall and filling it in when i were a lad. so its maybe 40 years old now?
ok, lets say the CWI isnt down to floor level, and theres mortar droppings at the bottom. what can i do about this, nothing? just deal with the results rather than the cause?
good investigative work that man 🙂
EDIT:
Edit – note there is a force 100 and a force 100max – make sure you get the max.
https://blaubergventilatoren.de/en/product/force-max-100
just rang em and they said they dont sell the max, and google doesnt throw up any for sale either. whats the difference, why should i get the max, and do you know who sells it?
He means that something might be bridging across the cavity, either a cold bridge, or damp into the room.
Get one of those usb bendy cameras or one you can plug into you phone for a tenner, drill a hole and have a look.
It took three goes of wrigthyson describing it before any of us listened, apologies that man.
Get one of those usb bendy cameras or one you can plug into you phone for a tenner, drill a hole and have a look.
can certainly get one if need be, lets assume youre right and thats the problem......whats the answer? deal with it or fix it?
btw, i edited my last post as you were typing, blauberg max info ^^^
The max is the 123m3, the non max is only 98m3. We did get them from somewhere in france, but now we buy from the blauberg uk too. I'll dig it out, havent bought a max for a few months.
We fixed it by taking out a few bricks and vaccuming the gap and smashing up the mortar snots that were bridging.
Can also be caused by cavity wall insulation I have heard.
i dont understand why a warmer house leads to less condensation. i believe condensation is formed when cold air meets something warm
It's because you've got it completely round the wrong way.
Condensation is formed when water vapour cools and turns to water on a cold object(or, air).
You have lots of water vapour in your warm indoors air. Where it's touching your cold walls, it's condensing into liquid. If you make your walls warmer by adding more heat, once you get above dew point, condensation can't form.
The max is the 123m3, the non max is only 98m3.
sorry, bit confused. the first one you linked to (which isnt a max) also states 123m3.
We fixed it by taking out a few bricks and vaccuming the gap and smashing up the mortar snots that were bridging.
Can also be caused by cavity wall insulation I have heard.
again apologies, are we saying then that CWI is a bad thing if it can cause this? i was thinking the ideal answer would be to get rid of broken mortar and fit more insulation in there, but maybe not?
thanks for the science behind it scienceofficer 🙂
Cavity wall insulation can sometimes cause a problem by retaining moisture that penetrates through the exterior leaf wall. The point of the cavity is to allow moisture to drain down the cavity face of the exterior wall and either go to ground of be fed back out through the block work via a cavity tray located above a wall opening.
If theres a bunch of blown glass fibre or foam holding onto the water, it can bridge into the inner leaf, and also suck heat out of the building like you wouldn't believe. It also corrodes your wall ties.
It's recommended that exposed southwesterly facing walls in the UK shouldn't receive CWI because of this.
I love it when someone explains it! Cheers SO.
My apologies, I forgot the difference between the force and the forcemax. That blauberg uk site is just wrong to say 123m3, its only the max that is 123m3. Misprint I think. on the blauberg.de site its hows force100=98m3, forcemax100=123m3.
The point of the cavity is to allow moisture to drain down the cavity face of the exterior wall
Well the cavity is there primarily for insulation (heat moves better through a solid than air, so the air in the cavity is there for insulation) but ^ this also.
Some cavity insulation materials are better than others with regards to transferal of moisture and just because you've got cavity insulation does not mean that you're going to have problems.
Saxedpunk, it's not a bad thing per se but it can cause problems as highlighted above. Good luck with getting it sorted.
No. The cavity originated as a weather deflecting face. It's effectively two walls built very close together and the outer is there to protect the inner.
In most cavities there is significant movement of air - you can feel the breeze quite easily. Thermal performance is not exactly great from this, it's just better than a wet, cold wall that bleeds moisture through due to wind pressure.
More latterly in modern times its been regarded as an opportunity to retrofit thermal performance to a building where none was previously considered, and now modern houses have an enormous cavity to provide space for insulation and maintain a space between that and the exterior wall so the water doesn't bridge across.
Anyway, we're still talking about the same thing.
We don't really know enough about ex-punks building to do anything other than give pointers.
i believe condensation is formed when cold air meets something warm
As above, that is backwards. IF you heat the room (and thus walls) condensation won't form on them (but possibly will on the windows).
You have lots of water vapour in your warm indoors air. Where it’s touching your cold walls, it’s condensing into liquid. If you make your walls warmer by adding more heat, once you get above dew point, condensation can’t form.
I’d say it easier to reduce the humidity of the air, which lowers the dew point temperature it will condense, than to raise the temperature of the walls above the dew point of damp air.
Eg. 55% RH air at 18 deg has a dew point of 8.8 degC
75% RH air at 18degC has a dew point of 13.5 degC
Before fitting a PPV unit, humidity levels in our house were always up around 75-80%, now they are 55-60%.
Same for me Jambo.
wouldnt the PPV need a fair bit of grunt to shift the damp air out of every small orifice, such as beneath closed doors
It works though. I used to get mould in corners, behind chest of draw and water would stream down windows and bedroom wall now nothing, dry as a bone even on the windows. It works even with internal doors closed as they are not air tight so we can be sleeping in bedroom with door closed all night and wake up with no condensation.
The theory behind PPV systems is that they only have to have a slightly higher pressure than outside, so the inside air is being forced out of every orifice. I do not doubt it works.
I don't agree with the "extra heating" principle mentioned above several times. Extra heat means warmer air, warmer air holds more moisture, if you have a cold bridge then you'll make the problem worse once that warmer air hits the cold point.
I'd start with two investigations:
1. Why is your air so damp? It's been mentioned several times above , are you excessively drying clothes in the house without getting rid of the moisture properly, is your kitchen vented, does your bathroom vent correctly etc. Is the spin on your washing machine broken so that your clothes are excessively wet.
2. You mentioned that the moisture is being found at floor level, specifically the underlay is wet and mold is under the bed and appearing on skirting board. Humid air is lighter than dry air and therefore "should" rise, that's why mold often appears in the top corners of outside walls first. So why are you seeing it at floor level? I would lift the carpet and underlay and get some floor boards exposed. Then tape small pieces of tin foil to the floor boards (without the foil bridging a join). Now observe for a few more days, does the condensation appear on top of the foil? If so you have condensation and you need to work out why the floor is so cold, does it remain wet under the foil? Then you have damp from under the floorboards. I would also certainly lift some floorboards and have a look underneath to see if you can see some moisture or venting issues.
I would definetly be getting into the floor space, if your underlay is wet you'll only have a couple of years before the boards are rotten anyway. (I'm assuming you have floorboards and not a concrete floor because of the airbricks).
Good luck!
We have had similar problems in previous houses. Our solutions have included:
1. insulation of a North wall, lost a couple of inches but made a big difference to that room, have also just put foam board behind draws etc.. so warm (moist) air does not hit cold hard surface.
2. putting in good fans in bathroom and kitchen (biggest impact and put new good fans in to any house we are involved in),
3. dehumidifier moving around the house as required (this didn’t seem to need much to make a difference).
4. When weather is good, opening up the house, giving lots of air a chance to blow across it.
5. Log burner also has made a big difference to the house, guessing it sucks air out rather than the positive pressure fans pushing it out.
A few of the above have sorted in each place.
He said he doesn't have floor boards but concrete
I would still do the foil test on the concrete floor, I did it in my cellar and you can see the issue within a day.
I don’t agree with the “extra heating” principle mentioned above several times. Extra heat means warmer air, warmer air holds more moisture, if you have a cold bridge then you’ll make the problem worse once that warmer air hits the cold point.
i like that answer, it means i dont have to put the heating on more than i do already 😀
1. Why is your air so damp? It’s been mentioned several times above , are you excessively drying clothes in the house without getting rid of the moisture properly, is your kitchen vented, does your bathroom vent correctly etc. Is the spin on your washing machine broken so that your clothes are excessively wet.
no, we dry clothes usually by my favourite method of hanging near a decent dehumidifier in the utility room. seems to be a constant battle with my wife who likes the 'lazy' (to me anyway) option of tumble drying (one of those without a vent, condensing?).
we have new windows around the house, kitchen does get steamy when cooking so we open the windows a bit. im defo going to go for a fan in there now tho.
washing machine fine, clothes not excessively wet.
(I’m assuming you have floorboards and not a concrete floor because of the airbricks).
as has been mentioned its concrete and tile. airbricks are above skirting level. was going to say id lift the carpet but we're about to have a new one laid and dont want to mess it up. would foil on top of the carpet instead still prove the same, itd be wet on top if it was condensation?
EDIT: after typing that i thought, no, if it was condensation on top of foil on top of carpet, itd just evaporate wouldnt it.....
putting in good fans in bathroom and kitchen (biggest impact and put new good fans in to any house we are involved in),
if i can source and fit decent fans i agree, this will make the biggest difference to us in bathroom and kitchen areas.
as i cant find the above recommended fan for sale, anyone care to link to an equally as good fan? 100mm diameter and 120ish m3 air extraction?
i still havent ruled out PPV too, sounds like it really would make a difference, but im leaning on the side of seeing if the extractors work first, mainly cos of running costs. i dont like the thought of something else drawing constant energy to run the pump.
thanks
Decent bathroom fan with humidistat hard wired sorted our condensation issues. It kicks in at all random times not just when we shower. Has taken our average humidity level down to 55-60% from 75%+
Our heating is set to 18° 24/7 this helps too.
I'll reiterate an earlier point once again. Under the bed is stale unmoved but warm air, your resperation and heat when lay in bed will further increase the effects. The floor is of solid construction, it will no doubt be straight on to hardcore with (hopefully) a simple membrane but likely no insulation. Is this floor cold to the touch, if hazard a guess it's very cold, it's the same cold bridging effect. In modern construction we now insulate under solid floors and also around the perimeter where it abutts the external walls. All stuff that wasn't regs when your bungalow was constructed.
On another note is the whole house tiled then carpeted?
i still havent ruled out PPV too, sounds like it really would make a difference, but im leaning on the side of seeing if the extractors work first, mainly cos of running costs. i dont like the thought of something else drawing constant energy to run the pump.
I can't remember the exact figures, but I think it was estimated to cost about 30-40 quid a year to run the PPV. £3-ish a month for a dry house seemed worth it to me.
Do you have anything that measures humidity? A cheap clock and weather station with a humidity reading, while possibly not super accurate, might be a handy guide to helping you understand what you do that might be contributing to the moisture, and also to see the affect of changes you make.
Do your Windows condensate loads, or a little, or not at all?
I'm just thinking, is very high humidity the problem (I'd expect condensation in many places, especially windows)? If not, then it maybe points more to cold bridging at the spots where you do have problems.
This one'll shift 170m^3/he but looks quite big.
https://www.fastlec.co.uk/11946-vortice-quadro-medio-t-surface-centrifugal-fan.html
Just Google centrifugal fan and have a look through the options. We had a really effective Manrose one in our old bathroom but it was ceiling mounted and looks like it would be too big for your current mounting.
In the kitchen, you really need an extractor right near the cooker, rather than on an external wall (although that will be better than nothing.
My parents only have an extract on the outside wall and the level of condensation is pretty high. You can see all the steamy air coming out of the kitchen! I've been trying to persuade them to get a ppv system for the last few yrs.
Have you thought of selling and buying a smaller more energy efficient home? What’s the point of living there if you have to sit there with layers and layers of warm clothing on in attempt to feel comfortable?
Have you thought of selling and buying a smaller more energy efficient home?
To be fair a pretty over the top suggestion. What's a house move cost these days, what with all the fees, moving costs, solicitors etc, you could remedy the situation with that money.
As I said previously I went all in on my own 3 bed and did a full renovation to allievate some of the problems mentioned above. I appreciate it all costs but in my mind it is money well spent long term if you plan on staying. I'd even consider a remortgage if I hadn't got the cash rather than keep fighting the core of the problems.
That vortice fan looks good.
Its funny how this stuff goes. I asked around the office for the RH meter and the first thing that happened is I get three reports of properties with condensation or damp issues.
So to that end I am going to get the Vortice one in and test it. You have to be cautious as we used to get the manrose CF200H but the built in RH meter was rubbish, it either stayed on forever or never came on. Which, I am reminded by our electrical contractor, is why we bought the RH meter in the first place. The blauberg one was super accurate and works like a charm. However the flow rate on that Voritce has me chomping, watch this space.