Humidity levels very high

[shappaeye]

We have recently bought an old house, probably around 100 years old.

The humidity in all the rooms ranges from 70-90% continuously.

We bought dehumidifiers for each room which extract, on average, about 10 litres of water every 2-3 days.

The dehumids bring down the humidity to about 55-65%.

Once they are off it goes back up.

We have been running the dehumds for about 2 years now and the water extracted hasnt decreased.

There is one corner of the house which is visibly wet but apart from that corner the walls are bone dry.

The roof is sound and the attic is dry.

The walls are made of big stones and dirt like mortar (it is an old house!). The walls are rendered.

We had a builder round who pointed out the front wall is porous and needs re-rendering.

Just looking for any other suggestions that we may have missed, I dont expect to cure it over night. Its an old building with central heating and a wood burner in the front room.

Thanks in advance.

 

[KenGMac]

shappaeye, Hi.

Apologies if this reply and its suggestions have been implemented previously.

If you and your family get rid of any "free moisture" when it occurs then there is a possibility that your high moisture readings may drop?

"Free moisture" or "Free water" is best described as Steam! simply put cooking. showering, a Bath Etc. can result in higher than wanted humidity levels.

If you can please consider the following.

1/. Install an extractor fan above the cooker that will remove the steam from cooking to the external of the property.
2/. If possible [dependant on the layout in your Kitchen] when cooking keep the door to the rest of the house CLOSED, simply to prevent this "steam- free water"
3/. If there is no possibility of an externally ventilated extractor fan once steam is produced, cooking Pasta, Potatoes. Rice Etc. open a window or the rear door. All of the above to get rid of "Free Water"

Bathroom.

1/. As above install or make use of an extractor. The fan should have a run on facility. that is once the light is switched off the fan runs on for some time to evacuate all the steam
2/. If there is no extractor, then open a window BEFORE you leave the room, do NOT leave the bathroom door open to the rest of the Property, this will reduce the "free water" escaping into the rest of the property.

General.

1/. If fitted keep the "trickle vents" on the windows open in the Bedrooms, important because when asleep we all breath out substantial volumes of moisture.


Hopefully, I hope you can see where I am going? the bottom line is evacuate the dreaded " free Water"

Ken

 

[shappaeye]

Thanks for the reply Ken.

We have implemented all those features.

We have an extractor fan and hood for the cooker which is vented outside.

We keep the door closed when cooking and showering (we dont shower in the kitchen!).

We have a powerful extractor fan in the bathroom.

All the windows have trickel vents and have done for over 2 years now.

Basically without the dehumds running the sofa and bedding feel damp and wet and the humid monitors read 80-90% all the time.

 

[joe-90]

It sounds like your floors that need sorting. They will wick up water for ever and a day if they have no membrane.

 

[shappaeye]

Thanks Joe.

The ground floor appears bone dry. I have no idea if thats relevant at all!

 

[joe-90]

The moisture is coming from somewhere. The usual culprit is it rises from the earth, through the floor and into the room where it condenses and causes damp. It won't necessarily feel damp.

 

[shappaeye]

Thanks Joe.

I have been told Sovereign K11 is good stuff for 'sealing' floors, etc.

Any recommendations? Or is this a job for the professionals?

 

[joe-90]

Do it yourself. If it doesn't work you'll have to dig it up anyway.

 

[jeds]

A standard dehumidifier will extract water for ever in a situation like this but unfortunately won't solve anything. You need to eliminate excessive moisture sources first. I'd have a proper survey done by an experienced surveyor. Not a timber and damp company - search out a local chartered surveyor. You'll have to pay but at least the report will not be biased.

You could also consider a positive input ventilation unit. (PIV) The units in the links below are good ones. These run constantly and cost nothing to operate. They are silent so you don't know they're there. The benefit over a standard dehumidifier (apart from running cost and noise) is that these push any moisture outwards instead of drawing it inwards. The slight increase in pressure reduces condensation dramatically and in most cases eliminates it completely.

http://www.nuaire.co.uk/products/ca...ositive-input-ventilation-piv/drimaster-heat/

http://www.rhldirect.com/store/warm-air-dehumidifier-whole-house-fan/

 

[KenGMac]

shappaeye

A couple of other musings?

Have you checked for a fractured water main, you mention that in one area of the house it appears wet? or is their any drainage in this area that may be causing this problem?

I have a home that was built Circa 1822, lathe and plaster walls externally and large Sand stone masonry, not rendered. it is sited on a Sea front Promenade so it has high Humidity levels to deal with even when it is not raining up here in Scotland, where it sometimes does

On the wall in this office of mine there is one of these Multi-function clocks on the dial the Hygrometer [can not guarantee its accuracy] is reading just over 50% right now. A couple of years ago we had a new C/Heating boiler fitted, the standard "condensing type" and since then the moisture readings have dropped from a fairly constant 65% + / 70 % to what we have now. Just a thought but how old is your C/heating system? At the same time we had a cooker hood installed vented to Atmosphere.

We have the ground floor of a converted villa, all the floors are T+G sanded boards, no carpets to speak of so there is a slow leakage of dampness from the Solumn into the house. the ceilings are 3.8 M high with no trickle venting on the windows, they just leak air in the gale force winds, with the wind off the Sea we have plenty of "Natural" ventilation [too much at times]

It has take about a Year for the humidity levels to drop from 65 + to the now acceptable 50+ but we have not had a lot of rain in the same period?

Hope this gives some further ideas on your problem?

Ken

 

[shappaeye]

Hi Ken,

I called our local water supplier out last year and they checked the main in and around our property and found the pressure was good.

I have humidity sensors in every room to monitor rise and falls. During dampish weather they generally go from 70-90% if the dehumids are left off.

During the summer we tend to have the doors open and of course the outside humidity is a lot lower so therefore the house will be inside too.

I am looking into buying a PIV system to circulate air, at 300 quid I am willing to try anything to try and win a battle or 2 against the humidity.

We have been running dehumids now for nearly 2 years on and off and they still drag a lot of moisture out, 10 litres every 2 days if they are left to run.

We hardly use the central heating system at all since we got a wood burner in the living room.

The central heating system is about 4 years old and is serviced every year. The previous owners had the system put in and is not very old.

 

[TinoMclaren]

shappaeye

This is most certainly penetrating damp. Rising damp has been proven to be a fallacy so ignore any advice you may get from suspicious DPC injection salesmen.

You say your brickwork are stones which are rendered, this will allow moisture to travel into and out of the house ( if render is lime).

If you have a cement based render then your in trouble as this wont allow any moisture inside your house out and you are then relying on air circulation, which in winter is hard as we close our windows.

PIV may help you, but also look at heat MHRV which renews all the air in your house a few times a day efficiently, reducing RH and stopping mold growth.

You need to google and read but as an example I have just installed MHRV and reduced RH to a constant 45 - 55% (from 70-90) in a cement rendered solid wall property. It doesnt have to be expensive, especially if you DIY (pipework £200 ish, MHRV unit £700 ish) and you get lower heating bills (moist air is more expensive to heat than clean air).

Houses are meant to have fresh air in them, either the old fashioned natural way (through the walls ) or as it is now done extensively in Europe with GB following slowly, via mechanical intervention.