A fan of ventilation

Over this past winter i’ve been surveying properties on a daily basis suffering from severe condensation and mould issues, both problems which have become a trend over the last decade with new regulations for insulation and glazing and exaggerated further in new builds by air tightness tests.

As of April 2006 a percentage of new builds now require air pressure testing to comply with building regulations ‘Part L’ the aim is to trace unwanted drafts and uncontrolled airflow resulting in heat loss. Unfortunately however, sealing our homes increases the potential for such issues to arise, not to mention encapsulating ourselves in an environment which does not naturally breath the indoor pollution both we and the synthetic products within our home produce.

We somehow seem to have forgotten in our strive to become more energy efficient that ventilation in occupied buildings is essential and cohabiting with our homes has completely gone out the window – or not as it maybe.

Whilst the majority of condensation and mould related issues are primarily caused by a combination of lifestyle and poor building design and construction, I am however consistently seeing another trend of poor and lazy building practices and simply bad advice.

A recent damp survey on a mid terraced property in York was a classic example.

This survey was referred to us by a previous client of our services, after the homeowner had been provided with a quotation for all new gutters, facia and soffits to repair their damp problem. Fortunately, the home owner had suspicions about the quotation and work recommended and decided to get a professional opinion.

The property is a mid terraced house in York constructed in the 1960’s under a pitched roof with un-insulated external walls constructed from 275mm cavity brickwork.

The property is fully double glazed with trickle vents installed, incorporating a working central heating system, no mechanical extraction within the kitchen and only a basic 100mm ceiling mounted fan present within the bathroom. The property has two adult occupants, who dry clothes on/infront of radiators and cook on gas.

Condensation was observed in most of the 1st floor windows and cills along with black mould forming around the perimeter of the outer wall / ceilings and airing cupboard on the first floor. Mould was also evident in random patches throughout the 1st floor ceilings and adjacent the ground floor front door opening.

Obviously the evidence presented above suggests the production of moisture in the property far outweighs the ventilation present, hence the property is holding vapour in the air creating the problem of condensation. This in turn gives rise to the conditions for mould to germinate, which was concluded with our assessment of the atmospheric conditions and temperature assessment of the building.

Looking at the property in detail and the ventilation already in place, problems were however apparent!

Trickle vents were installed, which do provide much needed background ventilation when working efficiently however, these vents had been installed retrofit after the installation of double glazed windows by the previous owners and unfortunately although open were not much use as they had been installed upside down!

Trickle vents in all windows installed upside down.

Our inspection into the roof space to look at the insulation levels and ventilation revealed the bathroom extraction fan most recently installed by the current owners contractor during refurbishment was also not entirely efficient.

Whilst the fan worked at removing some moisture vapour from the bathroom, unfortunately this was dispersed into the roof space as the bathroom installer has neglected to extend any ducting externally.

As a result severe condensation was forming on the underside of the non breathable bitumen roof felt membrane, saturating the loft insulation, electrical and structural roof timbers.

Bathroom fan not ducted resulting in
moisture from the bathroom being
displaced into the roof space.

Elevated moisture levels recorded within
the roof spars as a result of condensation
occurring due to the un-vented
bathroom fan.

In addition to the shoddy workmanship whilst installing the fan, the bathroom  contractor had disturbed the loft insulation in place, resulting in cool spots occurring on ceilings below where condensation and mould were observed, see pictures below.

Cold air intrusion as air enters the roof through the eves was also contributing to the problem cooling the ceilings perimeter.

Mould growth forming at the wall/ceiling
junction within the 1st floor bedrooms
caused by cold air intrusion from the eves
and absent/disturbed loft insulation.

Thermal image scan – highlighting absent insulation

Mould growth forming at the wall/ceiling junction within the
1st floor bedrooms caused by cold air intrusion from the eves
and absent/disturbed loft insulation.

Throughout the past year I have seen an alarming number of properties expressing such issues caused by poor building practices. The issue is not just lack of understanding or knowledge, but pure laziness by contractors.

So what is the answer?

These days were inundated with advertising from every direction with everyone and anyone claiming to be “specialists” in their field with “20 years of experience” advertising in local and national magazines. The crash in the economy has also led to many companies laying of tradesmen, which in turn has seen an influx of new business setting up by those previously employed.

Obviously when your in need of work choosing the right contractor can be daunting as no-one wants to employ the local cowboy.

My advice is simple, is your looking for a contractor check out the following;

• Ask for recommendations from previous clients, and most importantly check out these references.
• Check the companies trading history.
• Investigate their experience, whilst they maybe experienced at building walls are they experienced enough to fit your bathroom?
• Remember experience is no substitute for knowledge, they may have been doing things wrong for many years, check their qualifications and areas of expertise.
• Check out their industry accreditations and approval.
  The damp and remedial repair industry has the “Property Care Association” as its industry body, Contractors are only approved after strict vetting procedures and  comply with industry regulations. If your looking for a professional damp proofing contractor the PCA has a list of its members on their website www.property-care.org. Dryfix Preservation are full members of the PCA.
• Look for other industry accreditation such as the Government initiated TrustMark Scheme, CHAS or Guild of Master Crafts Men etc; Dryfix Preservation are Trustmark and CHAS approved.
• Finally don’t be afraid to ask questions about the work being carried out and expect an educated and knowledgeable response.

If you suspect you have a damp problem and need professional advice or repair, don’t gamble call the experts; Dryfix Preservation Ltd “Yorkshires Leading Damp & Timber Specialists” on 01904 791388 or visit our website www.dryfix.net

Russell Rafton C.S.R.T / A.Inst.SSE
Dryfix Preservation Ltd – Surveyor