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Problems caused by Retrofitting

Energy efficiency retrofitting is causing huge problems for older housing stock.  It is one of the major causes of dampness issues in older housing stock.  Retrofitted moisture barriers sold as a means of keeping a building dry by incompetent Property Care Association damp salesmen - and other Chartered Surveyors - are causing interstitial condensation, thermal bridging, and moisture entrapment wherever they are used.  Better understanding of the unintended consequences of inappropriate retrofit is beginning to happen - the BRE (Building Research Establishment) has published data on this issue and clearly there is a huge problem in this country.  Our advice with retrofit is DO NOT RETROFIT unless you have a very detailed understanding of all the consequences - something that even the BRE does not fully understand yet.

The recently published Solid Wall Heat Losses - and the potential for energy saving document by the BRE clearly shows the issues here. This is the BRE summary of the 19 unintended consequences of installing Solid Walled Insulation (SWI):

Overheating (increases in temperature above 28° in the summer months) Observed through both modelling and in the field. It is recognised that overheating can be a problem in all dwellings which have received solid wall insulation. This is particularly a problem for (but not restricted to) those that have been treated with internal wall insulation as a result of decoupling of thermal mass from the dwelling.
Increased relative humidity, and associated damp and mould growth As a result of increasing air-tightness (not correctly alleviated e.g. through extract fans), increases in internal humidity can occur. This can lead to damp problems, and mould growth, with associated health problems for the occupants. The problem can be particularly associated with un-treated thermal bridges within dwellings.
Negative effect on neighbouring dwellings. There is the potential for the installation of solid wall insulation on one property to affect neighbouring dwellings. This is because the relative temperatures of the walls of the dwellings will be adjusted. As a result, moisture can condense on a neighbouring property in a place where it did not previously causing damp, mould and other problems.
Shifting of thermal bridging to new points The application of solid wall insulation can affect the internal condensation points. This can create new points which are incapable of withstanding exposure to condensation.
Increased risk of dry or wet rot to timbers. The risk of dry rot developing increases with increased levels of humidity which can occur following the installation of solid wall insulation. An increase in wet rot can be caused by high levels of moisture or humidity in timbers due to poor detailing.
Increased risk of insect attack on timbers Insect attack to timber structures is increased if the timbers are not kept dry. In older solid wall dwellings (where timbers are more prevalent) any increase in the relative humidity can lead to an increased risk of insect attack on timbers
Increased risk of dust mites, bed bugs, clothes moths and other insects within the home A number of household pests including dust mites, bed bugs and clothes moths are more active and prevalent in increased humidity which can follow the installation of solid wall insulation.
Increased Radon risk In areas of the country prone to Radon (e.g. areas of South West England) increasing airtightness following the installation of solid wall insulation could potentially result in an increase in the risk of exposure to occupants.
Rot of internal floor and roof timbers With internal insulation floor and roof joists can become significant thermal bridges unless particular care is taken. Due to increases in humidity, these thermal bridges can then rot as moisture condenses on them, causing significant structural problems.
Damage to the external wall structure, or failure of internal finishes, due to water fill and frost damage following internal insulation The application of internal wall insulation can mean that an external wall is no longer dried by heating the interior of the dwelling. As a result, moisture is not driven out of the walls, which can cause structural damage and the failure and decoupling of the internal finishes (including the internal insulation itself). One mechanism for damage is ‘frost damage’ to the brick as the water in the wall freezes. It is important to understand the physics of how solid walls perform and deal with moisture transference based on their levels of humidity.
Increased interstitial condensation An increase in humidity can result from the application of solid wall insulation, leading to condensation in interstitial spaces (such as in roof eaves etc.), or within the structure of the walls. In addition, moisture trapped in walls by closed cell insulation can result in moisture migration to the inner surfaces of the building, resulting in mould and premature decay of finishes and fittings.
Short-term reduction in air quality following installation of solid wall insulation (Formaldehyde and other VOCs) There is a risk of increased levels of toxic volatile organic compounds (VOCs) including formaldehyde from the adhesives and other substances used in insulation products. These substances can have significant short and long-term effects on the health of occupants, with many being carcinogenic.
Long-term reduction in air quality following solid wall insulation (CO, CO2 levels) A reduction in air quality over the longer term as a result of reduced levels of ventilation following solid wall insulation may occur. This may lead to increases of Carbon Monoxide and Carbon Dioxide, both of which can have short and long term effects on physical and mental health of occupants.
Aesthetics From a cultural or aesthetic point of view, the use of external wall insulation may have a significant impact on the character and vernacular of many towns and cities throughout the UK.
Property value The effect of solid wall insulation on property value is uncertain. While some value can be assigned to the lower levels of energy consumption, lower values may result from any reduction in aesthetic appeal, or reduction in internal space resulting from the works.
Daylighting Research undertaken by BRE indicates that the use of wall insulation can have a detrimental effect of internal day light factors. This has a counter factual outcome of providing insulation to reduced energy demand, with the potential for increased energy demand on lighting, and less benefit from solar gain.
Durability and maintenance and repair consequences Solid walls with no insulation applied either internally or externally are very robust and sturdy structures. The introduction of materials that are effectively air traps and less resilient to impact could potentially have an unintended consequence of an increased demand for maintenance and repair, as a result of damage or even normal usage.
Disturbance The installation of solid wall insulation has the potential for disturbing not only the occupiers but also the surrounding vicinity, with the erection of scaffolding, deliveries and other incidental activities. As a consequence, when residents understand the extent of disturbance, it may become a disincentive to having the improvement works undertaken.
Fire safety Applying solid wall insulation internally or externally may introduce a potential for increased fire risk to buildings, unless this consequence is fully considered. There are potentially significant risks of creating a fire bridge between dwellings with external wall insulation systems over several dwellings (e.g. a block of flats).

We are experts in Retrofit

If you have problems with a building that has been retrofitted, or need help and advice in designing retrofit, you should contact us.  We have expert and qualified knowledge in this field. Most architects and Chartered Surveyors have little or no understanding of the consequences of what they are proposing.  Often retrofit is specified to 'solve' problems which could be eliminated simply by better ventilation and drying of the building fabric to avoid excessive heat loss.

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