Condensation Bedroom Windows

g33k0ut

As someone who has been on a similar journey over the past 8 years(!) and benefitted from threads such as this, I wanted to throw in my experiences should they help others searching out solutions.

We have a 1930s solid wall detached house. When we first moved in we had a bit of a nightmare to be honest - humidity readings in the range 60% to 80%, external walls very cold to touch, certain fabrics and clothes noticeably ‘damp’ feeling, musty smells in rooms and cupboards, thick black mould on various surfaces and very heavy window condensation in the winter. It was so bad at times our smoke alarms would even be triggered by the high humidity!

Always struck me as a confusing issue. We moved here from a 1980s-built semi-detached house. We didn’t change any of our behaviour in terms of cooking / washing / drying / showering / breathing, but it was clear the 1980s place had no issues whatsoever, whilst the 1930s place did.

We did loads of things to try and resolve the problem over a number of years. Improved extraction in the bathroom and kitchen, fitted additional air bricks to ventilate under the floors, replaced windows to include trickle vents (and used them!), opened the windows often, fitted more powerful radiators to replace weaker single panel ones, fitted foam-backed plasterboard to some of the more mould-prone walls and improved insulation in the loft space. We also purchased a dehumidifier, run on it’s own humidistat, which essentially ran non-stop all winter.

All of above definitely addressed the more extreme humidity levels in the house. However we were still sat squarely around the low 60% humidity level in winter and still suffered with all the issues mentioned above to some degree.

I eventually decided to buy a PIV system. Fitted it myself (I’m an enthusiast amateur, not a tradesman!) and cost about £400 all in. The benefits are clear and I’m of the opinion that the PIV has contributed the most of anything we did. I’d even go as far to call it the cure we needed all along. If I did it all again, a PIV is the first thing I would buy.

From the second the PIV was turned on, the landing area under the ceiling diffuser smelt fresher. After a few days that fresher smell spread around the entire house and the air felt noticably better throughout. Painted walls now feel chalkier and warmer to the touch. Fabrics and bedsheets feel dry. The windows barely mist up at all, even in this current spell of cold weather. The house seems to ‘feel’ warmer at a given temperature, appears to hold that heat longer and takes less time to warm up than it used to. Humidity levels now measure in the low to mid 40s, which is a dramatic improvement. In fact the humidity is so good now that running the old dehumdifier makes the house perhaps too dry, so we’ve been able to stop using that entirely.

So, tl;dr - I’m a big fan of positive input ventilation. At least in our case it’s a solution we needed all along and I will consider fitting one in any future house.

Shimmyhill

We had the PIV installed on weds and early impressions are very positive, windows kept shut overnight and dehumidifier not being used and barely any condensation - only very small amounts on the north facing bay windows with all other windows clear!

Given the bathroom extractor is faulty (new one arriving Monday) and not even had it a week it is performing well, not sure if they take a while to be fully efficient at what they do but even on first morning the improvement was stunning.

Maybe not snake oil after all!

saintscouple

Well we had a visit from Airtech a few days ago to see how the humidistat fans are performing and they sent in a report, extracts which i have copied below.
They say bathroom one is ok, yet there is mould forming on the kitchen window and the fan isn't strong enough to lift the louvres of the external vent. No mention of the black mould forming on the back door. And still insist on passive vents with no reference at all to my concerns they can only be fitted above our beds, and no mention on the PIV unit i've repeatedly asked consideration for.
Airtech are a joke, only interested in the data from their humidistat fans and remain oblivious to evidence of mould and other factors. They give the impression they have stock to shift and thus present data which quantifies the need for that stock.
I have asked my housing association that if i get a different recognised condensation / mould specialist in to conduct a report, will they recognise and action upon their findings.

no1catman

I did see a 'cure' for mould on silicone on youtube.
It suggested, folding and refolding a kitchen paper towel sheet, till its less than an inch, half is best. Lay it firmly over the effected area, then pour thick bleach over it.
The bleach should soak into the folded sheet, and act as a constant layer over the problem mold.
Leave for 12 hours, before removing when the mold should be clear.

No, can't say I've tried it - Partner can't stand the smell of bleach!!

DaftyDuck

Many moulds love the after effects of bleach - they thrive on it. It will temporarily remove the surface evidence but, despite all the views to the contrary, it will normally return... with vengeance!

poadb

PIV seems to be the only way to go.

You must remember that warm air holds more moisture. And moist air takes longer to heat.
When heating of this moist air occurs, the moisture will condensate on the coldest surface.

If ventilation isn't helping, the PIV will. It pushes in dry air, forcing the moist air out. Constantly.

The result is dry air taking less time to warm, with no or little moisture left to condensate on cold surfaces.

I'm currently looking into installers as I don't trust myself in these types of DIY projects.

Herongull

You said you tried a second hand dehumidifier that was noisy and didn't collect a lot of moisture. Given how humid your house is, this is telling me that the dehumidifier wasn't working or not working properly.

If you get put a dehumidifier in a humid house, it will certainly collect loads of moisture - that is what dehumidifiers do. The decent one's are pretty energy efficient and quiet.

A decent dehumidifier is far far cheaper than having your heating on at night. Turning it up to 22 degrees is also environmentally unfriendly as well as wasteful.

Turn the heating off at night and get a warm duvet and set the temperature to around 18 degrees during the day and get a decent dehumidifier

See the which article on dehumidifiers https://www.which.co.uk/reviews/dehumidifiers/article/how-to-buy-the-best-dehumidifier

If you sign up for the £1 which trial you can find out which ones are the best buys.

The reduction in your heating bill will easily pay for the dehumidifier within a few months. Having your heating on at 21 to 22 degrees all the time must be ridiculously expensive.

The dehumidifier may not solve the cause of the humidity but at least it will be constantly removing the water from the air and providing the solution to the problem.