New build insulation failure

base of each wall is losing considerable heat. Mould grows where there is excess vapour and low temperature. There is insufficient ventilation, especially from the family bathroom but also from the ensuite bathroom

I improved the ensuite overrun by extending the overrun from about 30 seconds to 30 minutes and improved the flow rate of both bathroom extractor fans. By taking a root cause approach, rather than a focus on blocking the symptoms of damp the savings are likely to be around £10,000. This contrasts with typical damp proofing contractor recommendations such as chemical treatment for rising damp and untargeted ventilation, such as PIV systems.

Flood risk: No risk See Flood Risk (note most flood risk is not from groundwater).
Sub-soil rocks: Near low productive aquifer with intergranular flow See British Geological Survey.
Therefore risk of Rising Damp: highly unlikely, see explanation by Dr Robyn Pender of Historic England.

I confirm that I inspected the property on 240110SH1000. I conclude that there is clearly a design or build defect, that is both for insulation at the base of the wall and building regulations for ventilation. All buildings can be exposed to unvented vapour and external dampness to some degree. You will mitigate the risk of damp if you follow all our recommendations. This report is intended to be read in full including supplementary links in this report. Observations and opinions must not be taken in isolation. Given the right weather conditions almost any house can be affected by rain. Like any building, you need to be aware of the risks of damp arising in the future and should plan a programme of monitoring, prevention and maintenance accordingly. Damp Surveys Ltd reports are designed to provide you with an informed, independent expert opinion as to the cause of dampness in the property, together with any recommendations for further investigation or remedial work. We do not warrant any findings in this report unless we enter into a separate warranty agreement with you.

The survey was conducted during daylight hours. Damp will be more noticeable at night and when the weather is colder and more humid. Gutters are more likely to fail when full of leaves and during periods of prolonged rain and adverse wind. We make best endeavours but cannot guarantee being able to identify all forms of damp, rot and insect infestation affecting the property.

We carried out a careful and thorough inspection of as much of the property as was accessible. However, when a full inspection is not possible, we make a professional judgement regarding the likelihood of a defect being present. In certain circumstances, this may lead to a recommendation for further action to open up an area for additional investigation. We were unable to inspect the entire roof, all the guttering, and some of the drains. Similarly, inspection of woodwork or other parts of the structure that were covered, unexposed, poorly lit or inaccessible such as in the loft, cellar, or sub-floor void was not possible, and therefore we are unable to assert that such parts of the property are free from defect. There were no obvious signs of damp resulting from these limitations

Negligence claims must be made within 90 days of the damp survey site visit. Clients must make best endeavours to monitor humidity and temperature on a damp wall and the closest source of humidity, by purchasing and placing two data loggers for example the Smart Hygrometer measuring humidity on the wall and nearest source of vapour, before and after following our recommendations. These data loggers have sufficient memory capacity to store 90 days of data.

This report is for the sole use of the client (named on the invoice, but omitted here for anonymity) for whom the survey was undertaken and can only be relied upon for 90 days from the survey date. Unless expressly stated otherwise in this report, nothing in this report confers or is intended to confer any rights on any third party pursuant to the Contracts (Rights of Third Parties) Act 1999.

Simon Hichens

Site visit 240110SH1000

Simon Hichens BSc Chemistry RICS Qualified Expert Witness (Chartered Surveyors)
PCA Certificated Surveyor of Dampness & Timber in Buildings (Property Care Association)
Damp Surveys Ltd, 119 Longton Ave London SE26 6RF Reg. 10977488 (England & Wales)
Founder of damp.aï & Member of the Society for the Protection of Ancient Buildings (SPAB)

Our damp surveys are designed to provide a holistic diagnosis that identifies and deals with causes rather than a focus on symptoms. Symptoms will disappear over time, once damp is stopped at source. We look for risks of dampness, but unless moisture is present, we can’t guarantee to identify all risks of future moisture. Our reports:

• identify root cause(s) of major unwanted dampness within the property,
• identify major symptoms of unwanted dampness,
• identify major structural damage caused by dampness,
• recommend actions and estimated costs to stop damp at source and mitigate its effects,
• recognise that treating damp is often a staged approach, treating obvious causes first.

Understanding damp

For survey purposes, damp is defined as unwanted water. Water brings life. We need it. Unfortunately, fungus and insects also thrive in water. While a damp wall can cause decorative spoiling, it is not moisture, but the life it brings that causes the greatest concern in the home environment. FACT: vapour causes 85% of residential damp problems.

Independence and Methodology

Our only income is through damp survey fees. We are independent of contractors and never profit from remedial work. We do not receive or pay any fees or other inducements. Our motivation is peace of mind and practical, durable solutions. We use an array of equipment to identify the root cause of damp within walls. Our damp surveys follow guidance from RICS, Historic England and PCA joint position statement and support RICS’s highest standard, level 3 “Home Survey Standard” (HSS).

During the survey we assess likelihood of rising damp*, mainswater leak, penetrating damp, condensation, timber rot and woodworm. We profile the damp patches and consider the likely sources of dampness and test ventilation against building regulations requirements. We consider changes to the property and factors just before the first sighting of damp.

• Rising damp concern: the owners were worried about rising damp
• Damp treatment: the property is a new build, and therefore would be expected to be damp proofed with a DPC, which there was evidence of. That said rising damp is not the root cause of dampness here, so the DPC would not be relevant.
• Weather: inclement
• Property: new build flat on the ground floor
• Background: the property was apparently built for key workers, and I understand part of the specifications were that it should be insulated to a much higher level than otherwise required, certainly much better than any property build prior to 1970, yet insulation is one of the worse that we have seen recently, clearly there is a design, material or build defect.
• Changes: none
• Occupancy: young family
• Mould & notes: there is mould across the property, particularly in the master bedroom
• Primary damp concern: dampness across the base of the property walls
• Compounding: the ventilation as not been installed and set up correctly.
• Airbricks: not relevant as there is a solid floor, yet there appear to be airbrick covers.
• Sub-floor humidity: Not relevant as solid floor.
• Tenure: ground floor flat
• Attachment: detached building
• Build: new build
• Walls: presumably cavity walls with insulation
• Exterior comment: there are no defects to the exterior
• Penetrating damp assessment: there is no sign of penetrating damp
• Drains: there are no signs of drain defects
• Leak signs: No suspicion of a mains water leak
• Leak assessment: There are no obvious signs of a significant mains or wastewater leak.
• Floor: solid floor
• Loft: there is no loft
• Timber assessment: there is no damage to structural timber
• Last dry: I understand these problems have developed almost immediately after buying the property, new
• Ventilation assessment: the overrun on the fans was insufficient, and the family bathroom extractor fan has no overrun, with insufficient speed due to the length of ducting, running at about half the Building Regulations required rate of 15 l/s

RICS, PCA, HISTORIC ENGLAND JPS REPORT

There has long been disagreement about the causes of damp amongst surveyors. Historic England surveyors represent one extreme. They typically do not believe rising damp is a likely cause of internal dampness and rarely recommend altering walls to alleviate damp. By contrast PCA surveyors typically recommend rising damp treatment whenever they see dampness at the base of a wall and often recommend altering a building. RICS surveyors tend to be somewhere near the centre of these extremes. However, unlike Historic England and PCA surveyors, they rarely specialise in damp and often refer issues to PCA surveyors. We and most other independent surveyors are more closely aligned with Historic England’s position except that we are perhaps more pragmatic. For example, if a hole in the wall is the optimum way of solving internal dampness, then we will recommend it, but not otherwise.

JPS questions and answers

1 A summary of the surveyor’s observations, including an Assessment of Significance.

there is dampness and mould at the base of walls

2 The importance of regular building maintenance and how a lack of even basic maintenance can lead to problems arising. This is especially important and relevant to roofs, gutters, hidden gutters, rainwater disposal and changes in external ground levels.

As is common with all buildings, gutters and other rainwater goods should be checked twice annually, ideally during or soon after a rainstorm, for evidence of overflow and rain not being dispersed properly from the property. You should also check that there is no flow of water flow during periods of absence for signs of a leak, for instance, by note the number on the mains water meter outside your house. the bathroom extractor fan has been poorly maintained by the Builder

3 An impartial diagnosis of the damp problem, which should be clearly explained and laid out systematically to communicate the relevant risks to the reader.

poor insulation and insufficient ventilation

4 Where recommendations for the repair and recovery of moisture-affected structures are stated, the solutions should be clearly explained and prioritised as appropriate.

The solutions are explained in the Recommendations section. The primary recommendation is The builder should return to solve the insulation issues. This may require additional wall insulation. If so, the builder will have to make sure that there are no resulting thermal bridges. Consider replacing the family bathroom extractor fan with a continuous flow extractor fan to overcome the speed loss due to the length of ducting

5 The client should be provided with alternative options for which each recommendation should include advantages and disadvantages and the relevant cost and time implications.

This question is primarily directed at PCA damp proofers, to encourage them to consider methods that address the source of water not just the symptoms, such as by hacking off plaster and replacing it with slurry. You can sometimes take this damp proofing approach with short-term success. However, water will eventually find its way through. Furthermore, treatment is disruptive resulting in high cost and a poor finish, with no worthwhile guarantee of success. It likely to lower the value of the property. In our opinion you are better off trying to stop the water at its source, as we recommend. ”

6 Where monitoring and staged interventions are appropriate or beneficial, the client should be informed of the reasons for these options, together with the likely cost and time implications of such recovery strategies.

Properties should be monitored for humidity and temperature using data loggers, see datalogger section of this report. The cost of data loggers is currently less than £20 for two, aim to keep the dew point, as shown on the app screen of each logger (bottom centre on the SensorBlue), within 3°C of the external temperature, especially at night (use ventilation and/or dehumidification to reduce the internal dew point – measure external conditions or refer to weather forecasts for night-time temperatures, such as BBC Weather – a short explanation is; that this will make sure the relative humidity of all surfaces will be below the mould point even if poorly insulated). We also suggest noting values monthly using a multi-functional radio wave and conductance damp meter costing about £24 to monitor and map damp patches on internal walls. This way you can monitoring the dry progress, which typically takes 1 month per 25mm thickness of walls and more if coated. This helps determine if the root cause has been fixed or there is an additional or new source of water, and therefore more actions are required. Ideally this should be started before or soon after starting our recommendations and for about a year, repeating monthly to check progress.

7 Where appropriate, clearly state whether the building concerned represents a financial risk to the buyer or lender and why.

8 Any conflicts of interest should be clearly stated.

There is no conflict of interest. We never profit from our recommendations.

As a background, although we charge a fee for undertaking damp surveys, profit is not our primary motivator. We are motivated to:

• solve damp problems in properties,
• encourage clients to spend money wisely for the protection of the property and, where possible to lower the environmental impact,
• stop or at least play our part to reduce the over-diagnosis of rising damp and so called “damp proofing” treatment by replacing plaster with chemicals and slurry, rather than dealing with the root cause.