Advice please - Cold, condensation and damp problem

Spiggle

Hi,

My daughter inherited her home which was built around 1930. The external walls were cavity insulated about four or five years ago and the loft is insulated.

The ground floor has floor boards in all the rooms off the hall which is a solid floor (not sure of the material but it looks a bit like polished stone chip or similar). The kitchen also has solid floor. The first floor has two bedrooms both of which have large dormer type windows (original to the house not added later). My DD sleeps in a bedroom on the ground floor and my two granddaughters sleep in the bedrooms upstairs. The two dormer windows and the kitchen window and door were replaced with good quality double glazed units about 18 months ago. All other windows have secondary double glazing fitted by Ev*r*st about 30 years ago.

So, the downstairs bedroom is very cold and she is getting condensation running down the walls. None of the walls are papered just painted plaster. The radiator is ridiculously under the window but that's symbolic of when the CH was fitted.

Both my GDs bedrooms are suffering similar condensation runs down the walls, they are also just painted plaster.

I have advised that at the least the external walls and preferably all walls are papered with warmaline/polystyrene insulation and then papered over. Would this be sufficient for these rooms do you think? As the ground floor bedroom has floorboards is there any other way to improve the heat and atmosphere of the room?

The bathroom was fully refitted 18 months ago and the radiator (on an internal wall) replaced with a towel rail. I really don't think this gives sufficient heat for the area. I know about the calculators for size and will use those. But as the bathroom has about a five foot circle of black mould developed above the bath/shower would changing back to a big radiator be sufficient do you think?

What do you think would be a reasonable price for someone to change it over please? If we got a large radiator to replace the towel rail and then moved the towel rail to the external wall would the extra cost of running the pipes about 10ft to the ourside wall be justified by the benefit of having two heat sources in there?

Does anyone have an opinion about putting warmaline/polystyrene insulation on the external wall of a bathroom please?

Also, my DD has been told that there is a possibility the house was built without a damp proof course (dpc). Could this be correct? If so, how could it be put right. And if there was no dpc should the house have been cavity wall insulated please?

Finally, do you have any tips for adding further insulation in boarded rooms please?

I understand about airing and open windows etc and a friend has lent my DD a dehumidifier as well. One obvious answer is to replace all the other windows but that is just way way way out of my DDs pocket at present.

Any help you can offer will be very gratefully received so thanks in advance.

Look forward to hearing from you,
Spigs

rogerblack

Condensation happens when hot, moist air hits a cold surface.
All human activities, from breathing, to cooking to ... cause some level of moisture to be emitted into the house.
This adds to the level of moisture in the air.
When the air hits a wall, and cools down, it condenses, as it can't hold that much water.

In some cases, this is unavoidable - for example in the case of single pane windows.

Now, to cavity wall insulation.

In some cases, this can work well.
In others, what happens is that the cavity - which used to carry a slow flow of outside air around the inner skin of brick in order to keep it dry, has been filled with a fluffy stuff that may initially be insulating, but does not actually let air flow, so no moisture can be removed in this way.

Any moisture condensing on the bricks has nowhere to go, and can only be removed by internal ventilation or dehumidification.

If the bricks have become waterlogged due to condensation, it may take an extremely dry atmosphere inside, for a long time to dry them out.

Lining over the wet bricks in this case could be a really bad plan, as the walls will remain wet for a long time.
It may not be a terrible idea to do this come the summer.

Paradoxical as it may seem - opening a window to air out a room for a few minutes a day may considerably improve things.

Close all the doors into the kitchen when cooking, and open the windows. Cover pots, and turn them down when they boil, so they simmer.

As will turning the heating up so that it warms the walls.

Dehumidification alone is pointless unless you reduce the humidity significantly, as you're still going to get condensation on the walls.
Significantly probably means a dehumidifier per room.

Try turning up the heating, and airing out all of the rooms once a day.

An IR thermometer http://www.dealextreme.com/p/1-2-lcd-non-contact-digital-infrared-thermometer-with-laser-sight-50-c-380-c-904435754 - for example (have one, works well) can be very useful for this.

Turn the heating fully on for a bit, and go round the walls, finding the cold spots.

A humidity meter like http://www.dealextreme.com/p/3-8-lcd-indoor-outdoor-digital-humidity-hygrometer-and-thermometer-1-aaa-37636 will also be useful - there are of course many other vendors.

http://en.wikipedia.org/wiki/Dew_point - lets you use the two above to work out if you'll get condensation.
http://en.wikipedia.org/wiki/File:Dewpoint-RH.svg

is a graph that lets you work out if you will get condensation.

For example - say the coldest wall is 15C.
Go to the 15C line on the left, and then move across to the right. The first line you come across is the line at which water will start condensing at 100% humidity - it's 15C.

If you have the house at 25C, you need to reduce the humidity to below about 50%, so it won't condense.

This is quite dry.

Spiggle

What a thorough answer, thank you very much rogerblack, very much appreciated.

I knew about airing the rooms daily it's very difficult to get DD's partner to realise this is the way to air it. He is unfortunately stuck in the paradox!

I will try nagging them again about fully airing the bedrooms during dylight hours and try to get the heating turned up higher. Thing is they have very little money and so keep the heating as low as is manageable but can't seem to see this is a false economy if they're getting all these problems.

Thank you again.

If anyone knows if it is likely a house built around 1930 could have been built with a cavity but without a dpc I would appreciate knowing. Or is there is a way to check if there is a dpc possibly?

Thanks again,
Spigs

Cardew

I would have thought that the vast majority of houses built in the last century would have a dampcourse - especially if they have cavity walls.

I am not a builder, but IMO the major issue is not the lack of heating, but the need to discover why there is such dampness in the house and that IMO is most likely to be an underlying building/structural issue.

I have a detached Centrally heated annex with single cavity walls(converted stables). It is only heated when it is occupied or there is a danger of frost damage. The temperature inside at the moment is 3.5C and humidity of 73% and there is absolutely no dampness evident. It was occupied all over the Xmas/New Year period baths showers etc and no dampness. Incidentally it was built in 1860 and has a dampcourse.

It could be that there is a problem with the dampcourse. However a word of warning here, there are a lot of cowboys operating in this field who will claim to fix the problem with a 'lifetime guarantee'.

Whilst I agree with Roger that use of a dehumidifier will not solve the underlying problem, it will most certainly improve the the situation at a far lower cost than heating the whole house. Largely heating masks a dampness problem by the warm air holding more moisture.

Anyway that is my take on the issue. I would try and find an experienced builder, without a vested interest! and get his opinion, or a structural engineer to investigate. There are also plenty of places on the internet that might offer advice - even the 'In my home -DIY' forum on MSE.

As an interim measure I would certainly invest in a dehumidifier.

albyota

rogerblack wrote: »

Condensation happens when hot, moist air hits a cold surface.
All human activities, from breathing, to cooking to ... cause some level of moisture to be emitted into the house.
This adds to the level of moisture in the air.
When the air hits a wall, and cools down, it condenses, as it can't hold that much water.

In some cases, this is unavoidable - for example in the case of single pane windows.

Now, to cavity wall insulation.

In some cases, this can work well.
In others, what happens is that the cavity - which used to carry a slow flow of outside air around the inner skin of brick in order to keep it dry, has been filled with a fluffy stuff that may initially be insulating, but does not actually let air flow, so no moisture can be removed in this way.

Any moisture condensing on the bricks has nowhere to go, and can only be removed by internal ventilation or dehumidification.

If the bricks have become waterlogged due to condensation, it may take an extremely dry atmosphere inside, for a long time to dry them out.

Lining over the wet bricks in this case could be a really bad plan, as the walls will remain wet for a long time.
It may not be a terrible idea to do this come the summer.

Paradoxical as it may seem - opening a window to air out a room for a few minutes a day may considerably improve things.

Close all the doors into the kitchen when cooking, and open the windows. Cover pots, and turn them down when they boil, so they simmer.

As will turning the heating up so that it warms the walls.

Dehumidification alone is pointless unless you reduce the humidity significantly, as you're still going to get condensation on the walls.
Significantly probably means a dehumidifier per room.

Try turning up the heating, and airing out all of the rooms once a day.

An IR thermometer http://www.dealextreme.com/p/1-2-lcd-non-contact-digital-infrared-thermometer-with-laser-sight-50-c-380-c-904435754 - for example (have one, works well) can be very useful for this.

Turn the heating fully on for a bit, and go round the walls, finding the cold spots.

A humidity meter like http://www.dealextreme.com/p/3-8-lcd-indoor-outdoor-digital-humidity-hygrometer-and-thermometer-1-aaa-37636 will also be useful - there are of course many other vendors.

http://en.wikipedia.org/wiki/Dew_point - lets you use the two above to work out if you'll get condensation.
http://en.wikipedia.org/wiki/File:Dewpoint-RH.svg

is a graph that lets you work out if you will get condensation.

For example - say the coldest wall is 15C.
Go to the 15C line on the left, and then move across to the right. The first line you come across is the line at which water will start condensing at 100% humidity - it's 15C.

If you have the house at 25C, you need to reduce the humidity to below about 50%, so it won't condense.

This is quite dry.

Good advice, Respect.......rogerblack

Spiggle

Thank you Cardew,

She has a dehumidifier on loan at the moment but I may treat her to another. Perhaps she needs to use it every day for a couple of weeks and combine this with opening the windows more. This is a constant battle for both me and her. She grew up with always having windows open but her partner is stcuk in the paradox that rogerblack mentions above. He thinks that it makes the house cold and causes the condensation rather than the other way around.

I had forgotten about the In my Home thread when I posted yesterday and have now posted in there as well but thanks for the reminder.

I couldn't see her house being built without dpc either. My bungalow is only about four or five years younger and it certainly has dpc. Hers is a semi detached and I'm sure the neighbours would have mentioned if there were damp problems in there, she has known them since she was a child herself and has a good relationship with them. This really feels to me like an airing problem in the rest of the house and an underheated and airing problem with the bathroom.

Looks like I'm going to be a nagging Mum again!

Thanks again,
Spigs