Hi all, I am hoping someone will be able to help me. I apologise in advance for the long post but want to try and provide as much info as possible.

Have recently bought a 1900s terrace, around 5 months ago had DPC installed all around the kitchen, internal and external walls. Old kitchen had been ripped out, kitchen was then replastered and new kitchen fitted a couple of weeks after the plastering.

A month or so ago I noticed a musty smell behind fridge (against external wall). Pulled it out to find pipes soaking wet, bare plaster damp and mouldy. Cleaned it up, lagged the pipes, painted the wall incase it was absorbing moisture. Has stayed dry, but noticed more damp behind and under cupboards next to fridge (sink cupboard, under window, in corner of two external walls), pulled plinth off and its pretty manky under there, fluffy mould on concrete floor and where exposed bricks join the new plaster. Investigated further and mould in cupboards at bottom. Back of cupboards are wet from the bottom (unit is on legs a few inches above the floor) a couple of inches up. Feeling the (again bare) plaster behind the cupboard, seems dry, but the run of exposed bricks between the floor and the new plaster, where the DPC was injected, are soaking. Cleaned up at the weekend, dried, removed mould, and today they are wet again.

Had a builder round when first noticed the damp and he thinks its a ventilation problem (this did not surprise me, hood is on internal wall so just recirculates, but do always cook with kitchen window open). Had extractor fan fitted on external wall with a humidity sensor, have set it to 50% but this does not trigger until its really steamy in there.

Can anyone suggest why it is so damp at the base of the wall behind the cupboards? The floor level in the kitchen is a good foot higher than the ground outside, So I'm pretty sure its a problem inside.

If it is still a condensation problem, how can I increase ventilation even further - two extractors running and the window open doesn't seem to be doing the trick. Airbricks?

I am concerned that in hindsight, the kitchen was fitted too soon after the DPC and replastering so was not fully dry. Could this be contributing?

I honestly don't know what to do. My kitchen is brand new but looks a mess because of all of this. I am not keen on getting the firm who did the DPC back unless I know there is something wrong with what they did - I guess I will try get a couple of independent damp people round but wondered if anyone had any ideas from the info provided.

Thanks.

youve said that you have 2 extractors running...
but then said that one of them isnt an extractor, its just recirculating air and filtering out smells but not moisture from the air and the other is on a humidity sensor that doesnt open till you can hardly see your hand in front of you....
the problem is purely condensation...
the solution is to increase the ventilation... turn the humidity stat down to nothing and turn the extractor on whenever your using the kitchen...
have the hood extractor piped to outside and remember to set the lever inside it to extract as opposed to recirculate...
condensation is caused by people, so if possible, cut down the amount of moisture you put into the air as much as possible... vent the tumble drier outside for example...

_________________
http://www.peterborough-plasterer.co.uk/

Hi cw, thanks for the reply.

Your comment confirmed my thoughts I am also pretty sure it is (mainly) condensation, I'm just not sure how to ventilate more. The humidstat sensor on the extractor is now down to 40% which is the minimum setting, but I'm still having to pull the cord as soon as I see any sign of moisture. I am having the hood vented to the outside too, but this isn't being done until Monday.

No tumble dryer in there. Boiling the kettle and filling the sink with hot water both steam the window up.

Is there anything else I can do to ventilate? Have been reading about vents in the window frames as I see the newer houses on my street have them. Or airbricks under the cupboard? Or is SOME mositure part and parcel of a small kitchen? (it is VERY small)

Hopefully venting the hood outside will help, but I'm concerned that because the condensation is so localised under the sink cupboard, and it gets so wet so quickly after drying it, that there is something else wrong.

Should I do anything to insulate the walls, or cover the exposed bricks that are getting the wettest? I imagine that condensation is hitting here first because they are the coldest as they are bare bricks without even a layer of plaster to insulate.

Sorry to ask so many questions, I am grateful for any advice on this. I am hoping to let the house out from next year - relying on tenants to do their bit in terms of reducing condensation will be difficult so want to do as much as I can to help (hence the humidstat extractor rather than just a pull cord - although as it is not coming on quickly enough it probably would have been better if linked to the light )

Jo.

The thing with water vapour is that it always condenses on the nearest cold surface, or if you have the window open will move outside, where it is often colder.
How cold is your kitchen?
Is the window double glazed?

One way of solving the problem of condensation is to raise the temperature of the kitchen and maintain it at the same temperature 24/7, this will warm the walls and move the condensation some where else.
Do you have lots of condensation on your windows in the kitchen?
Another way is to open a window while and after you are cooking, this will let the water vapour move outside. It is nearly always drier and colder outside (not always) and water vapour will always move to cold or to where there is a drier patch. (Think of the shape of the clouds and how there are dry patches of blue sky between them)

Or you can use a dehumidifier, this will take the water vapour out of the air, and will keep your expensive heat indoors, there is a benefit, dry air is cheaper to heat than wet air.

We have had a rather cold winter, so one would expect the inner surface of the kitchen window to be cold, but if you use an electric kettle with an automatic turn off and only boil the amount of water you need, the window should not steam up.

It is likely that the extractor fan humidistat does not work.

Therefore it is probably best to turn it on before you start cooking or boiling a kettle. You can buy an electric kettle from Argos for about £5 that will turn off the moment it boils. Running cold water into the bowl and then adding the hot water until it is comfortably warm avoids steam from washing up.
I have found the best way to organize a kitchen, it to have a powerful extractor fan over the hob, blasting out through the wall, this deals with the cooking on the hob.
However, if the oven is elsewhere it needs its own high level extractor.

You definitely do not want to add any more ventilation to the kitchen.

Trickle vents in windows and air bricks are old fashioned technology. Their problem is that they are un controlled. When the wind blows your warm air will be sucked out, when the wind doesn't blow they do nothing.

From 2016 all new homes will have to be built to Passive House standard, this means all new homes will be made a air tight as the builders can make them. This is to save on heating costs and power. From then on all new builds will have mechanical ventilation, that can be controlled.

These wet bricks, can they be wet, because of a leak in the roof, or a gutter, or down pipe, or some other water pipe. Is it possible you have rising damp or is the rain blowing through the wall?

Have you checked the pipes in the kitchen?

Is it an exposed wall?

Is part of the garden raised up above the damp proof course?

Insulating the walls is always a good idea, as most of the heat lost from a home, is lost by conduction.

May I suggest that you buy an infrared temperature gauge. They are about £25, when you point it at anything it immediately tells you its temperature.
This will enable you to discover how cold your walls are and will therefore, indicate where water vapour will settle.
Perhaps you will also buy a combined humidistat and temperature gauge, this will enable you to check if your humidistat on the extractor fan is working and will show if the relative humidity in the kitchen is high.

This will tell you if the wet bricks are wet from condensation.

You will not be able to rely on your tenants being as kind to your home as you would be. An automatic extractor fan is best, but as we have found in social housing tenants will disable anything that they think is costing them money.