The problems in this property were so bad the owner couldn't believe he didn't have severe structural problems.  A look at the way the property was set up and how it was used by the tenants certainly threw doubt on this presumption...
 

Client(s)  Mr B

Property  Cheshire

Instructions    To inspect the property and provide an opinion on areas of dampness to several of the internal walls.
   
Background    The client owns the property, which is currently let to a family of two adults and one infant.  According to the tenant, they noticed problems with dampness almost immediately after moving in, approximately one year ago.  Since then, and despite some remedial efforts, the problems have become progressively worse. 

Recently, a chartered surveyor examined the property and his conclusions seemed to be that condensation was at the root of the problems.  My client now requires an independent assessment in order to verify this.

Disclosures    I am not aware of any affiliation, financial or otherwise, with the client or the property.
   
Limitations    Limited to the instructions

Restrictions    The survey was non-invasive.

Date of Survey    2nd September 2008

Weather    Fine, sunny.  The weather during the summer months has been quite wet, and Relative Humidities have been higher than normal for long periods.  Although not the genesis of the perceived problems, these latter conditions will have had a significant effect upon them.
     
Viewing Orientation    Unless otherwise stated, all observations are made as if looking towards the house from the front.

Type of Property    Purpose built flat, c1970’s or early 1980’s, with accommodation is on the ground floor only.  There is sealed unit double-glazing in [unvented] PVCu frames, and the property benefits from gas-fired central heating.

External Observations    The flat is situated such that its front elevation faces in a southerly direction, and it is the central building of three, similar, conjoined units. The whole are staggered such that the front elevation of the unit to the left is slightly behind this property, whilst that to the right is slightly in front.  This arrangement has a detrimental affect on the property’s ability to benefit from sunshine, and a look at Google Earth using the postcode as a reference will show this clearly. The only elevation that will receive effective sunshine is the front one, and except for perhaps very early in the morning, the other two will be in permanent shadow. The effects of this on internal conditions in the flat will be significant.

There is a clearly visible damp proofing course (dpc) in the brick, cavity walls and there are no high ground levels that would compromise this.  Even if there were, unless they were blocked with masonry* or other permeable materials, the cavities would not allow dampness to affect the internal walls. 

*Although there is anecdotal evidence that workmanship at the time of construction was poor, and debris was allowed to fall into the cavities, the condition of the brickwork below the dpc, vis-à-vis that above it, would indicate that this is not actually so.

It should also be noted at this point that as far as I can tell, cavity wall insulation has been installed in this building. However, the materials used in this process require agrément certificates, which ensure that although the process does bridge the cavities, the materials used do not allow the passage of moisture.

    I also understand that further anecdotal evidence suggests a watercourse or faulty drain may be causing water to flow beneath the property.  Again, even if this were so, the inherent damp proofing measures included in modern houses should deal comfortably with such a problem. In addition, there are no physical indicators that it is happening.

    Other than to note again the shaded aspect of the rear and gable elevations, externally, there are no other factors that would influence this report.

Internal Observations    Access to the property is via a shared entrance hall; from there a side door leads into the internal lobby of the property itself.

    The accommodation consists of a living room at the front; a kitchen at the side; and a bathroom and double bedroom at the rear. The bedroom, which is to the rear corner, also has a gable elevation. I understand that all members of the family share this room for sleeping.

    Ventilation does not seem to have been considered at the time the property was constructed: the windows do not have trickle vents; the only fireplace is blocked and uses an electric fire; and neither the bathroom nor the kitchen have extractor fans. 

    The floors are solid throughout, and in those areas I inspected there are vinyl tiles on top of a sand and cement screeding.

    The external walls are plastered blockwork and some of the internal dividing walls are constructed from timber studding and plasterboards.  Gypsum plaster has been used throughout.

    Living Room: The lintol over the window in this room has been badly affected by mould colonies.  This mould is of the species Aspergillus Niger, which is invariably associated with condensation.

    The rear wall, which divides this room from the kitchen, is badly discoloured.  The discolouration is not uniform and affects those areas that coincide with electrical appliances on the other side of the wall, in the kitchen.

The staining and distress on the wall exactly mirror the position
of the appliances in the kitchen.

  Moisture meter readings taken from the walls were ambiguous inasmuch as their pattern indicated that moisture could be present from two sources: condensation and rising dampness. However, I concluded that the latter is unlikely and that dampness at the lower levels of the walls results from a severe case of ‘wall/floor junction’ effect.  This occurs because the lower reaches of the wall are usually the coldest, and thus condensation occurs readily in these areas.  In this property, it is particularly severe.

The meter readings also indicated that despite the Aspergillus on the lintol, the walls in the front half of this room are not as badly afflicted as those towards the rear, and that the problem affecting the lintol is the result of cold bridging across the lintol itself.
 
    In places, the moisture content of the skirting boards was above the level at which rot could occur, although this is not yet happening. Again, this only applies to the rear half of the room.

Kitchen: This room contains the following appliances: a refrigerator; a freezer; an oven and hob; and a washing machine.  This latter is of the washer/dryer type and I could not find any venting system for it.  It seems to exhaust directly into the space beneath the worktops.

Also, as alluded to previously, this room does not have mechanical ventilation, although I understand this is to be remedied in the very near future.

    Moisture meter readings from all of the accessible walls and skirting boards were similar to those obtained from the rear half of the front room.  Some of these walls also had a degree of distress and staining.   

    Bedroom: Some sections of the bedroom walls were also distressed, particularly the one dividing this room from the bathroom; however, I understand this has resulted from repairs, which were recently carried out to pipework in the bathroom.

    Garments were being dried on a clothes-horse, which had been laid upon the bed, and an oscillating fan, placed in the rear corner of the room, seems to have been used to accelerate this process.  Although it may well achieve that function, it will also distribute moist air throughout the property.

    The un-insulated section of the cold water service pipe in the cylinder cupboard had condensate on its surface.

    The bathroom is fully tiled and the walls beneath were not accessible. However, the skirting boards had a moisture content above the level at which rot could occur. Again, there are no extraction facilities in this room.

Discussion    Firstly, I understand from both the client and the tenant that this flat is the only one in the block that suffers from dampness; and if any of the internal problems were to be the result of structural defects, they would be unique to this unit.

Although I cannot rule it out completely, in my experience this is most unlikely to be the case; and other, more obvious sources of moisture should be sought before any expensive structural investigations are made.

Having examined the property I am of the opinion that the vast majority of the problems associated with dampness relate to excessive condensation; and that the pattern of the moisture found in the walls, the life-style of the occupants and the almost total lack of ventilation are entirely consistent with this phenomenon. In addition, the building’s positioning in relation to available sunlight will result in it obtaining less thermal benefit than will its neighbours. This is why the problems are more severe towards the rear, which is the shaded section of the building.

Although some of the moisture meter readings could be construed as indicating rising dampness, this condition is unlikely to be a problem, and to advocate treatment for it at the moment would be illogical. Condensation issues must be addressed before any other treatment is considered.

So that the situation can be improved it will be necessary to greatly increase the level of ventilation so that moist air, produced within the property, is removed at source.  This will require the installation of good quality extractor fans in both the kitchen and bathroom. At the same time, adequate venting for the washing machine/dryer must also be introduced, regardless of whether it is a condensing dryer or not.  It may also eventually be necessary to install passive vents into the external walls in the bedrooms, although I hope that ultimately these are not needed. I shall point you in the direction of these devices in the next section of the report.

In addition to improving ventilation, it will also be necessary to improve the tenants’ knowledge of the causes and effects condensation. I often find that once people understand it, they introduce minor lifestyle changes themselves, and relieve their problems considerably.  In particular, drying clothes in the manner employed by the tenant of this property should be strongly discouraged.

So that tenants can play their part, I have enclosed a small pamphlet, which you should ask them to read.

Conclusions    This property suffers from excessive condensation, and the reasons for this occurring are outlined above.

The tenants should be encouraged to read the enclosed pamphlet so that they gain an understanding of the problems. Minor changes in their lifestyle will be needed to help to reduce the effects of this phenomenon.

You should install good quality extractor fans in both the kitchen and bathroom.  These fans should be under the control of humidistats, which should be set to less than sixty-five percent Rh.  I have already e-mailed a recommendation for these, but you may choose any good-quality fan with a humidistat control.

I could not trace any ventilation system for the washer/tumble-dryer, and I believe this machine vents directly into the spaces beneath the work surfaces. If so, this is entirely wrong; the machine should be vented directly to the outside. To enable this there may well be a spigot at the rear of the machine, which can accept a flexible, vent pipe.  If there isn’t, a passive vent should be placed in the wall directly behind the machine’s usual position. A Passyfier™ vent would be suitable for this and you can find details at www.condensationshop.co.uk. Follow the ‘Products’ link.

It may also eventually prove necessary to install these vents into the external walls of the bedrooms; although once the fans are operational, I would hope this will not be necessary.  However, if, after a suitable period of time, you feel they will be needed, I would recommend you to install them in the rear, right-hand corner, on either of the rear or gable walls.  The literature on the website indicates the optimal positioning for them.

Because they are invariably the coldest sections of walls, condensation occurs very readily at wall/floor junctions, and this has resulted in the carpets rotting in some these areas. When they are replaced, you should choose ones that have a preponderance of natural fibres, perhaps wool or coir.  If there is to be an underlay beneath them, this too should allow the evaporation of any moisture that might form on the floor beneath. Rubber-based underlays are not particularly good at this.

Any re-decoration should be with anti-fungicide paints, and you can find details of these at www.biokilcrown.com. Follow the link from ‘Anti Condensation Products’.

The approaching winter months are particularly prone to condensation and although the effects of the above recommendations may not be immediate, they should eventually reduce the problems to manageable proportions.  However, because of its solid floors and poor thermal gain from sunlight, this property will always be susceptible to condensation, and the part that tenants play will be crucial.  Both present and future occupants should therefore be encouraged to read the enclosed pamphlet.  If you lose your copy, a replacement can be downloaded from my website.

I trust the above is satisfactory for your purposes but if you require further clarification please do not hesitate to contact me.
   
Date of Report    September  2008