High humidity and condensation

achtunglady

sorry to hijack the thread, but i have a bedroom that has wallpaper peeling off the wall, a black mouldy corner of the ceiling and was wondering what the difference was between condensation and damp?

The room is noticably colder than the rest of the rooms in the property a few degrees colder even with heating on and there seems to be a draft from the double glazing as i can see the curtains moving when theres a gust. I plan to get a dehumidifier to try and draw out the water.

dadsarmy

2Sheds wrote: »

What I can never understand with condensation is why we get it and the neighbours don't get a drop?!
We'd have the bedroom windows totally soaked from top to bottom, neighbours either side nothing whatsoever!


but why did we suffer (until the drimaster) with condensation and the neighbours don't

Perhaps there are more people in your house?

Your neighbours doors are open for longer and therefore more air changes?

.....................................

We use a rubber squeege thing in the shower cubicle after showering plus mop up with a cloth.

Never let the kettle boil away.

Keep an eye on the cooking.

I live in a 3 storey terrace that sort of breathes through the open velux vent at the top room.

On several new houses in a terrace where I live the extractor fan pvc flexible ducting for the upstairs bathroom and en-suite shower room terminates in the space above the soffit and under the tiles. There are no roof vent tiles or grilles for the ducting to connect to the soffit itself. The vent is therefore terminating inside the loft void. The only vents on the soffit are the standard trickle ventilation slots all the way along the soffit. I have mentioned this to the owners and but no one is interested to learn their roof timber could be at risk. Ours does have the correct soffit grills fitted by the way.


Oriiginally the house builder fitted a 4.2 metre flexible duct to a axial fan that is only capable of up to 1. 5 metres of ducting! When I questioned the site foreman why the back draught shutter on the external wall for the cloakroom fan did not open when the axial type fan was switched on he said "it does not have to open" Thanks site foreman :T I quoted building control and type of fans needed and they changed all three of my fans with the correct centrifugal type fans several days later.


Later I -

The cloakroom fan - I have replaced one 3.6metre flexible hose with solid 100mm pvc pipe.

The bathroom fan I have replaced most of the 4.2metre flexible hose with solid 100mm pvc pipe.

The ensuite fan I have replaced most of the 4.2metre flexible hose with solid 100mm pvc pipe.


For a good selection of extractor ducting/back draught shutters/etc etc at good prices google BES

skiTTish

Is loft insulation a major contributing factor to condensation then ?
Our last house we had a terrible damp/condensation problem ,we had those positive pressure fans (bloody awful things blowing cold air and keeping you awake with the noise all night )and roof vents and still we had mould and damp ,the house had cavity wall insulation and lots of loft insulation.
Our new house ( which we bought mainly to get away from the damp issues ) had no cavity wall insulation and a few millimeters of loft insulation and its as dry as a bone even though our lifestyle hasn't changed ( same amount of showering/drying clothes /kettle boiling ) etc .On noticing how poor the roof insulation was ,I ordered some more insulation ( being delivered next week ) Im now beginning to think maybe its not such a good idea?

David_Aldred

Hi SkiTTish,
I think from the above people will note that altering the way a property was originally built and designed to function has consequences. So in answer to your question if you make the loft void colder by laying insulation upon the ceiling without considering whether the ventilation to that loft void will consequentially require improving, then yes the risk of condensation occurring within the loft void on the cold side of that insulation will increase.

Well built older housing stock that remains as it was originally designed to function with draughty windows and doors, breathable external walls, clear cavities where applicable, fireplaces in constant use for open coal / wood fires to four or more flues, breathable flag / tiled floors, little if any loft insulation and no roofing felt under the slates / tiles such that wind blew through the roof covering tend not to suffer musty odours and chronic mould with unhealthy side effects. That is not to say they were not cold to live in and ice would be upon the inside of the single glazed windows in winter and drain outwards through drainge channels in the base of the frames if provided when it melted. The outside path l/ driveway levels will have been well below the level of the damp proof course and these paths / drives will have been well draining stone flags / stones sloping away from the property.

Now let's do some home improvements with the best of intentions and look at the consequences:

You decide to have a new driveway / path so we will lay a new non permeable concrete / tarmac one on top of the old flags so the level of the path encroaches upon the damp proof course and we will slope those paths towards the house because there is a handy drain there - oops rainwater now bears against the house walls and permeates into the sub floor void beneath the supsended timber floor whereupon it evaporates up into the property and causes low level dampness misdiagnosed as dpc failure by a contractor. This moisture evaporating up from the sub floor void raises the relative humidity within rooms and with it the risk of condensation / mould growth.

The outside walls look a bit tatty so we will re-point the breathable lime mortar the house was built with, with a hard dense cement mortar. The consequence is evaporation outwards through the mortar beds is drastically reduced and the bricks stay wetter for longer and suffer freeze / thaw damage along with increase dampness internally. Or we can render in a hard dense cement render that does an even better job of stopping evaporation outwards and when it cracks and fails it will pull the outer face of the brick with it.

How about some double glazing to stop all that nasty ice on the windows. These are air tight and oops you forget to mention to ask for trickle vents on the window frames so they really are air tight.

That roof looks a bit tired what you need is to strip it off and lay a new roofing felt with new battens and we will take the slates away (so we can sell them) and put concrete tiles back. Oops you forgot to request a breathable roofing felt and now air movement through the loft has dropped dramatically. The heavier concrete tiles start to make the roof sag.

Those coal / wood fires are a lot of work but they do provide 2-5 air changes to rooms which you haven't really considered when you decide to block them up apart from the one in the lounge and fit a gas fire to that one. The heat from the coal fires is no longer there to keep the hearths dry and the chimney breast becomes damp and a moisture resevoir with that loose fill behind the fire back - next door does the same on a party wall - now with redundant chimney breasts on both sides of the party wall you have a really nice moisture resevoir in this area and as the moisture evaporates from the wall it brings with it sulphates from the soot that disrupt the plaster. Perhaps it is rising damp in this area - that nice damp-proofing contractor said he could put you a chemical dpc in this area and inject through the entire depth of both back to back chimney breasts - oh was that a pig flying past the window. The chimney stack brickwork above roof level that was once dry becomes constantly wet without a lead dpc at the roof / stack interface this moisture permeates down into areas below.

Those breathable tile floors to kitchen and hallway are looking a bit tired - lets take them up and lay a concrete floor with a damp proof membrane but oops we forgot to seal the damp proof membrane into the damp proof course and because the replacement floor isn't breathable any more it causes dampness to concentrate in an attempt to emerge at the floor / wall joint directly under skirting / plaster / base of stairs etc. Again let's misdiagnose this as dpc failure and have another damp proof course and with it a hard dense replacement plaster that stops evaporation from the wall at this level - oh dear the next door neighbour's side of the party wall has suddenly become more damp just after we plastered on our side - perhaps they need misdiagnosis to have another damp proof course on their side. I'll recommend that nice damp proofing contractor we have become so friendly with.

How about an extension / conservatory on the back of the property with a nice concrete floor - oops you have put your new concrete floor infront of the vents that used to provide ventilation to the sub floor voids beneath timber floors and in effect blocked them up. This has raised the moisture content in the timber floors to above the threshold of decay and they are rotting / dampness is emerging up from these floors into the rooms raising the relative humidty / condensation / mould problems.

What about some insulation and draught proofing - let's attempt to fill the cavity wall with insulation but oh no there are voids to it and the condensate is increasing the corrosion of the cavity wall ties. With the draught proofing the house is really sealed up well though - no more draughts - aren't you lucky.

Let's put in some cavity wall ties and - well fancy that, the debris from the drillings when they put the wall ties in is sat upon the cavity wall insulation and bridging the cavity causing damp spots to appear on the walls.

How about some loft insulation to that roof void but no we do not do roof ventilation - nothing to do with us but this inslation will cut your heating costs.

How about a couple of en-suites to your bedrooms - can't beat having a shower in your bedroom morning and night while chatting to your partner in the bedroom with the en-suite door open.

Kids have left home - your health has deteriorated and isn't too good - you have got a chesty cough and have constant headaches, I am sure all this mould isn't helping. You don't want to be in a draught so keep the windows shut and folk don't visit much these day with all these musty odours. Can't think the last time there was a busy household here with the front and back doors banging in and out. You can't understand where all this chronic mould is coming from on your clothes / shoes / blinds it's awful.

Statistically 70% of dampness is due to condensation in one form or another and mould growth is associated with this form of dampness.

Yes we need to insulate our homes and conserve energy - only a fool would disagree with that but if you are going to alter the way a property was originally designed to function please think it through as to what the consequences will be and how you will address those consequences in a manner that is sympathetic to the way that property was originally designed.

Kindest regards to all, David Aldred independent dampness and timber surveyor.

ixwood

good advice all round.

[Deleted User]

I bought a B&Q dehumidifier and even though i switch it on normal it never switches itself off. My flat has got high humidity but i cant leave the dehumidifier running constantly as im out at work all day and i cannot leave my windows on a open/locked latch as its a downstairs flat. Im a bit worried that if i left it running when im not there it wouldnt switch itself over to the bucket full mode and turn itself off and keep running and therefore the bucket would overfill. What else can i do to get the humidity down. Its worse when i get home from work and have had the storage heater on as no air is circulatiing. Sometimes it feels like a hot house. Just to add its a 1970s built ground floor flat with new pvc windows (ive got to fit trickle vents on these), the bathroom has no window but an extractor fitted and i have a north facing wall which is doesnt have cavity wall insulation (as i thought this may make the situation worse) running the length of the flat. I have 3 external walls, 2 of which have large windows.

Swipe

coralred wrote: »

I bought a B&Q dehumidifier and even though i switch it on normal it never switches itself off.

All dehumidifiers should switch themselves off when the bucket becomes full. Even on the dampest of days my dehumidifier takes at least a couple of days for the bucket to become full. So if you are still worried just make sure you empty it every day.

[Deleted User]

The problem is the bucket gets full within a 6 to 8 hour period. Its never turned itself off other than when the bucket gets full. Its never taken two days to get full so i would like to know how i can solve the humidity levels in my flat.

dampdaveski

David_Aldred wrote: »

Hi SkiTTish,
- oops rainwater now bears against the house walls and permeates into the sub floor void beneath the supsended timber floor whereupon it evaporates up into the property and causes low level dampness misdiagnosed as dpc failure by a contractor.
Perhaps it is rising damp in this area - that nice damp-proofing contractor said he could put you a chemical dpc in this area and inject through the entire depth of both back to back chimney breasts - oh was that a pig flying past the window.

. Again let's misdiagnose this as dpc failure and have another damp proof course and with it a hard dense replacement plaster that stops evaporation from the wall at this level - oh dear the next door neighbour's side of the party wall has suddenly become more damp just after we plastered on our side - perhaps they need misdiagnosis to have another damp proof course on their side. I'll recommend that nice damp proofing contractor we have become so friendly with.



Kindest regards to all, David Aldred independent dampness and timber surveyor.

Hi David,
Whilst the damproofing industry has a very bad reputation, (and with very good reason). Just remember that there are good contractors out there, I'M ONE OF THEM! I don't mis sell anything! I actually go out to a job and look for a reason NOT to install a DPC. I provide solutions for people, whether it's DPC works, ventilation equipment, mould treatments or just plain free advice.
Another valid point is that I choose to remain anonymous on this site, it's not me that is selling anything on here, though your name and business are on every thread??

ixwood

I think you've got the wrong end of the stick. I read it as a a rant on shoddy damp companies, not you.