damp problem

[dormantmould]

hi all

i am writing about an ongoing problem with a 2 bedroom ground floor maisonette with concrete floors and ceiling and double glazing and cavity walls. it was built around 1979 and i own the leasehold.

whenever i have lived at the property or its been empty i have not had the problem, it's only when other people live there and create condensation. however, i don't believe it is solely condensation causing the problem, i think there is something much more serious.

basically the rear of the property faces north, and the back garden is higher than the front as the maisonettes are built on a slope. with my untrained eye i cannot see a damp proof course. i would expect to see a plastic black sheet or something like that but cannot see it along any of the outside walls.

the recurring problem is mould which initially starts in the back corners (both bedrooms) and then expands to cover the whole outside walls. when one previous tenant reported it and vacated the property for a few days i had to go in and clean black mould off almost top to bottom.

i had the bedrooms carpetted a few years ago and between tenants found the underlay had also got mouldy and damp so i had to take it up and get rid of it. i've had builders look and one fitted air bricks along the outside wall and found a lot of debris in the cavity (higher than it should have been) and removed as much as he could whilst fitting the air bricks.

before that i enquired about cavity wall insulation and they refused to fit it due to the roof tiles not overlapping the wall enough. i checked the lease and found the neighbour above is responsible for the roof and he kindly had the problem fixed so now the tiles are ok and there shouldnt be any problem with the roof.

my current tenant reported mould appearing in the corners of the bedrooms, so i bought them a big dehumidifier, which definitely helps, but the mould keeps growing and they are now having to spray mould cleaner, but i know it's going to come back, it always does. to make it worse my tenant is pregnant.

i have had a friend dig out a channel along the back wall in case the garden is too high and water is saturating the bricks, but the problem is still happening after this. i really don't know what to do next, this is really testing my patience and i need a final solution.

as i said its definitely not just down to condensation, but i am sure the first sign of condensation is triggering the mould growth and starting it off. any advice is much welcomed. the only thing i can think of is to check there is a damp proof course (i dont know anything about this though) and whether is it doing its job or not. i have heard things about injecting a damp course but that it can be costly and why shouldnt a 35 year old property need this?

it's a leasehold and the fact i am supposed to own the lease (a right to occupy the space between the walls) means i'm not 100% sure on whether the freeholder has any responsibilities. the lease says i am responsible for foundations and each leaseholder has to arrange their own buildings insurance. anyway thanks for any replies.

 

[Flyboytim]

There is a different attitude between (many) tenants and that of owner-occupiers. The former often do not do anything about symptoms, like damp and condensation until there is a problem like mould, and then it is the landlord who has to deal with it.

Tenants often disbelieve that the problem is of their own making, expecting the landlord to furnish them with a dry property that stays dry.

It is a winter problem often set off by intermittent central heating, in which people to come home to a cold house and blast the heating on, then turn it off at bedtime, and repeat the process in the morning throughout the cold months. It is a false economy to heat a house like this.

Magically, by about April or May, the damp problem resolves itself, as the heating is left off more as the outside temperatures grow warmer.

The condensation is forgotten until October or November, when it begins again.

If CH radiators did what is written on the packaging they came in, and just radiated out heat, there would be very few condensation problems in homes.

However, radiators primarily convect heat, in a very limited pattern throughout the room, leading to cold corners near skirtings, windows and behind furniture and in cupboards.

Once these cold surfaces come into contact with air that has warmed and picked up moisture, condensation can occur.

Once a wall has become damp through condensation it becomes even more difficult to warm up and a condensation cycle then ensues, each time the heating is switched on.

The provision of fans to move air around the room, independently of the convected heat will defeat condensation by bringing surface temperatures close to that of the air in the room.

Unheated fans of less than 100W power can make the difference, and by regulating the pattern of heating thermostatically during the day so that the differences between cool and high temperatures is less than the dew point for indoor humidity obtained at the higher temperature, condensation can be eliminated.

A cooler, drier house cost less to heat comfortably than a cold and damp house.

 

[pinenot]

The problem appears to be tenants solely and surely, as you say the problem is not raised when either yourself occupies or it's empty. As per the last reply, tenants can simply use and abuse and pass any problem to the landlord, in this case you.
As you are renting out a home to private tenants, for by your statuary obligations you obviously want the property to be user friendly and at the same time low maintenance i.e. of problems like this. Here's something I picked up -

Condensation.

Condensation is by far the most common cause of dampness in buildings,
probably accounting for the majority of damp problems reported. It affects both old and new buildings, but it appears to be a significant problem where the building has been modernised.
Condensation is directly associated with mould growth. It is this that the occupier sees first, and it gives an indication of the potential scale of the problem. The mould is usually found on decorative surfaces, especially wallpapers, where it can cause severe and permanent spoiling. In many cases, the mould and its spores ('seeds') give rise to complaints about health, and cause the "musty" odour frequently associated with a damp house.
The obvious places for condensation to occur are on cold walls, windows, and floors, but it can also occur in roof spaces and in sub-floor areas where there is a timber suspended floor; in the latter case, it can lead to dry rot or wet rot developing in floor timbers.
The Cause.
It is a fact that warm air can hold more water as vapour than cool air.
Condensation is caused when moisture-laden air comes into contact with a cold surface - the air is cooled to the point where it can no longer hold its burden of water vapour. At this point, known as the "dew-point," water begins to drop out of the air, and is seen as condensation on surfaces. On impervious surfaces such as glass and gloss paint, beads or a film of water collect. On permeable surfaces such as wallpaper and porous plaster, the condensing water is absorbed into the material. Therefore, the problem is not always initially obvious.

Identification -

Condensation is very much a seasonal problem, occurring during the colder months - October to April. During the summer, the problem is seen to go away.
During the winter, ventilation of the house is usually low (due to windows and doors being closed, draught-proofing takes place). This allows build up of water
vapour in the house, which, in some cases is sufficient to cause condensation. This condensation becomes apparent from the following symptoms:
Water droplets form on cold, impervious surfaces such as glass and paint.
Slightly damp wallpaper (often not noticed).
Development of moulds, usually black mould.
In some cases, condensation may be long term, but intermittent, forming only at certain times of the day or night. In these cases, the only sign of condensation
may be mould growth, as the moisture may have evaporated by the time moisture measurements are taken.
Condensation on Window, mould caused by condensation.

How Condensation Occurs -

One should be aware that the problem can occur well away from the site of most water vapour production. E.g. water vapour produced in the kitchen may diffuse through the house into a cold bedroom where it will condense on cold walls.

Confirmation -

If one wishes to confirm that there is a condensation risk, then a Humiditect card
can be affixed to the surface where condensation is suspected for 7 days (due
to the intermittent nature of the problem). Spots of colour printed on the card will
gradually bleed depending on the severity of the problem.

Control of Condensation -

The control of condensation is based on two very simple primary measures, supported by a number of secondary measures.

Primary Measure 1 - Improve Ventilation,
This will sweep away the internal moisture-laden air and replace it with drier air from the outside (yes, external air is drier than internal air most of the year!)
Mechanical ventilation such as Humidistat Fans and the PPF9 Positive Pressure System should be considered.

Primary Measure 2 - Improve Heating,
Coupled with ventilation, heating should be set or applied to give a low-level
background heat. This will ensure no rapid changes to the environment, and will
facilitate slight warming of wall surfaces over a period of time, thus reducing the
risk of condensation.

Secondary Measures
Remove excess moisture sources - e.g. paraffin heaters, indoor drying of clothes.
Insulate cold surfaces.
Prevent possible water penetration.
Install a dehumidifier.
Use an anti-mould paint.

Hope you can gain something useful with this...pinenot

 

[dormantmould]

Thanks for the 2 replies, they have made me think, and I am starting to think that condensation is the main cause of the problem.

The reason I think something else may be contributing is because I have lived in other properties with other people. In these other properties, despite careless living by the occupants, steamed up windows for example, there was never any sign of mould. I guess this could be down to better ventilation, timber rather than concrete construction for example?

I just feel like the property has a very low tolerance, compared with other buildings. I hope that makes sense!

There are a couple of things I know may help, the tenants dry their clothes inside, previous tenants used a condensing drier. I rented it unfurnished, as I didn't want to be responsible for white goods for example. Would it be in my interests to supply a condensing drier to the new tenants?

The other thing is kitchen ventilation. The bathroom has a decent fan which comes on with the bathroom light. However, the kitchen has no ventilation except for opening the window. I did try and get this done but the kitchen fitter couldn't do it because it was not easy to drill a hole out of the kitchen. The window takes up the full width of the external wall, and above the window, there are tiles on the outside, and an outlet would affect the appearance of the property.

Finally, the heating. It's a combi boiler with rads all turned on fully. The way I left it for them was basically having the timer on 'always on' but control the heating with a thermostat dial. So all they needed to do was turn it to, say, 20 degrees when they are in, and down to say 12-15 at night or when they go out. However, I noticed they had changed it to the timed setting on the boiler, so basically they are turning it off completely at times instead of just turning it down at the thermostat. Why people mess about like this I dont know, I think they think its costing money by leaving it on even if the thermostat hasn't kicked in.

So , all in all, frustrating and I'm sure anyone else who is a landlord here knows how hard it is to try and tell people how to live, when it's them that pay the bills, but me that suffers the consequences of their lifestyle!

 

[pinenot]

Here in lies the perils of being a landlord. Basically your rental value should reflect costs like this that you may incur from one tenant to an other and the basic conditions of contract i.e. your tenant agreement, should lay down basics that will help prevent this sort of thing...pinenot

 

[Flyboytim]

Almost airtight homes are becoming common. Every window and door has seals, frames are fixed with silicone sealants, heating systems have sealed boilers with balanced flues, and floors have laminate locking flooring with an underfloor membrane.

OK, that is the reason why condensation is so likely - warm moist air is trapped inside, and some areas of the house have colder surfaces for water to condense upon.

Winter 2013-2014 has been exceptionally wet, with some places with almost 2 months of daily rainfall and temperatures well above 5 deg C.

Even extractors (which have to suck air into the house from somewhere!) and ventilation through open windows would not allow significant moisture out of houses under these conditions, without near saturated air entering.

Air movement is not necessarily ventilation. As well as supplying a vacuum cleaner at the onset of the tenancy, supply a couple of straightforward desk-type fans. They are not expensive unless you try to buy them during a heatwave. Advise that they may be used in summer to make rooms more comfortable, and in winter to move air around any areas that may become damp through condensation, including corners, wardrobes, behind furniture etc.

Consider electrical storage heating rather than GCH for rental properties, since this gives continuous warmth, and less chance of abuse by the tenants. It also frees the property up from an annual gas safety check and hiked up fees from Gas Safe engineers for repairs or installation. There is also less chance of explosion, and it should deter the growing of certain houseplants which do not like dry heat Make sure that butane/propane heaters are disallowed.

Condensation is one thing, Mould growth is another.

Mould will not grow to a problem extent on surfaces that are cleaned regularly with cleaners that are basically biocidal - we used to call them disinfectants, now they may be antibacterial surface cleaners.

Make cleaning surfaces (windows, frames, tiles and grout etc) to prevent build-up of dirt, mould a condition of the lease.

Give the tenants a handbook how to go about cleaning and make sure they know that excessive dirt is not "normal wear and tear" and will be charged for unreasonable quantities in the cleanup at the end of the tenancy, and during the term of the tenancy if an inspection shows that cleaning has not been carried out to a reasonable level. This could include carpets, upholstery and kitchen and bathroom fixtures.

Above all, make it easy for tenants to contact you or your managing agent about problems, and be available to advise and fix anything that needs doing promptly.