This property has internal damp despite state of the art damp proofing treatment.
Evidence & Illustrations
In conclusion, from the data loggers
- At the time of the survey there was no clear sign of condensation. But damp walls take about 9 months to dry out, there are clear risks such as insufficient extractor fans, therefore there is a risk and there could be residual damp.
Evidence & Illustrations
The property is being sold. The buyer’s surveyor had these findings:
- Main Walls (D4): High damp meter readings throughout the ground floor.
- Walls and Partitions (E3): High damp meter readings throughout the lower ground floor.
- Windows (D5): Old and rotten windows, with some cracked panes and lacking British Standard safety ratings.
- Outside Doors (D6): Rear door sill poorly profiled, leading to rot and potential water ingress.
- Ceilings (E2): Cracked ceilings with some blown/loose plaster; historic stain in the kitchen.
- Roof Coverings (D2): Defect suspected behind the parapet wall at the front, causing damage to the front wall.
The buyer’s surveyor suggested these causes:
- Main Walls (D4): The dampness is believed to be a result of a failed damp proof course and a lack of tanking. Although I can’t find an explicit diagnosis from the buyer’s surveyor, the mention of failed damp proof course suggests a root cause of damp in the wall is from rising damp, which comes from groundwater.
- Walls and Partitions (E3): High damp meter readings indicate dampness issues.
- Windows (D5): The disrepair of windows is attributed to age, rot, and lack of maintenance.
- Outside Doors (D6): The rotting of the rear door sill is due to poor profiling.
- Ceilings (E2): Cracks and loose plaster in ceilings are noted, with a historic nature of the kitchen stain.
- Roof Coverings (D2): There is likely a valley behind the parapet wall causing damage to the front wall.
The buyer’s surveyor made these recommendations:
- Main Walls (D4): Seek urgent inspection and quotes for repairs before proceeding with the purchase.
- Walls and Partitions (E3): Investigate and report on remedial work needed before exchange of contracts.
- Windows (D5): Undertake repairs and improvements soon.
- Outside Doors (D6): Get an inspection and quote for the rear door sill issue.
- Ceilings (E2): Proceed with repairs and improvements soon.
- Roof Coverings (D2): Request inspection and quote for remedial work from a reputable contractor; specialist equipment might be needed.
To keep the property dry
|Channel rainwater away from building
|Ask the freeholder to 1) Create a channel to drain water from front steps away from the mossy front wall above the bathroom, such as using an angle grinder. 2) A similar procedure is required for the area in front of the right-hand neighbours front door, in this case you should add a fillet of cement based mortar, along the wall supporting the step. 3) Any cracks to the front render should be filled with an external acrylic based caulk and painted with an impermeable paint such as Zinsser masonry paint. 4) drain the rear patio, ideally with an aco drain connected to the rear drain. It should take a workman no more than 1 -2 days plus materials say £1,000 in total. The cost should be shared.
|Ask freeholder for works programme
|Although the front parapet doesn’t affect the flat, it would normally form part of a 7 – 10 year cycle of works, with costs shared amongst leaseholders as part of normal ongoing maintenance.
|Check rainwater goods
|During a rainstorm, film and check the flow of water through all rainwater goods, including the back hopper. You could ask the top floor flat to do the same looking at the hopper and is possible the area around the parapet, use a long selfie stick if necessary.
|Seal tiles with grout
|This relates to the tiles around the socket for the heater in the shower room. There appear to be some gaps, partially filled with a sealant. It is better to use grout.
|Use shower room heater, disconnect or keep extractor running
|There will always be a risk of condensation in the shower room unless vapour is removed. Possibly the easiest solution is to install a continuous flow extractor fan into the shower room.
|Protect against window rot
|For the timber affected by window rot, sand, fill, and paint with an appropriate protective product.
|Remedial actions – estimate of costs
Actions if all else fails
|Consider installing and replacing bathroom extractor fans
|Consider installing a bathroom extractor fan with 30 minute overrun after lights are switched off.
|Consider using a dehumidifier
|Maintain relative humidity, especially at night when it’s cold outside, with a dehumidifier such as PureMate 20L/Day Portable & Compact Dehumidifier with 6.5 Litre (£179.99 Refrigerant), Duux Bora Smart Dehumidifier (DXDH02UK £300 Refrigerant) or Meaco DD8L Zambezi (£260 Desiccant – best for colder environments) – Which! Best buys. There are plenty of alternatives available. I choose a dehumidifier based on daily and tank capacity, low noise, whether it has a pipe out, and ease of programmable functions over other considerations such as weight and aesthetics. The technology is old and easy to manufacture. So if these brands are not available, you are sure to find another alternative. Evaluate based on daily capacity (20L minimum) and whether it has a continuous pipe out (use this to drip into a sink when away in winter).
|Consider installing a kitchen extractor
|The main issue to getting ducting out the extractor fan. Ideally it should be using rigid ducting (not flexible as the ridges create eddies slowing air speed), as short as possible with as few bends. It can go up the chimney but would then need to be run for longer to account for the possibility of vapour travelling back down.
|Reduce the absorption of moisture from solid floor
|To reduce the absorption of moisture up from a solid floor, ask a general builder to carefully remove skirting board from the wall, ensuring there are no cables or pipes, carefully cut back the lowest 10mm or so of plaster back to brick at the base of the wall (perhaps with an angle grinder), run a 10mm thick bead of thixotropic cream, such as DryZone by Safeguard, along the brick to reduce absorption (ignore Safeguard’s claims about using the cream for rising damp). Then replace the skirting board. I don’t advocate drilling holes and injecting a thixotropic or any other type of rising damp treatment.
|Replace damp proofing DryRods
|To improve the effectiveness of the damp proofing DryRods, instruct a general builder to replace the current rods with new DryRods. I would screw into each and lever each out, such as with a claw hammer. 3 packs of 10 should be ample (I didn’t count).
|Paint mist coat
|Paint mist coat to any paintwork that has lifted off the plaster wall to ensure adhesion to the unpainted plaster, e.g. bathroom front wall and upstairs living room.
|Optimal actions – estimate of costs
I conclude that penetrating damp exacerbated by past condensation.
Front shows rainwater penetration, rear ponding causes moisture.
. By taking a root cause approach, rather than a focus on blocking the symptoms of damp the savings are likely to be around £4,000. This contrasts with typical damp proofing contractor recommendations such as chemical treatment for rising damp and untargeted ventilation, such as PIV systems.
Flood risk: Low risk See Flood Risk (note most flood risk is not from groundwater).
Sub-soil rocks: Rocks with essentially no groundwater 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 231211SH1200. I conclude that penetrating damp exacerbated by past condensation.. 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.
Site visit 231211SH1200
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.
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: Your buyer’s RICS homebuyers identified a potential damp issue.
- Damp treatment: Despite the low risk of rising damp, there has been an attempt at chemical treatment against rising damp. Rising damp treatment is normally a sign of insufficient ventilation. The walls have been drilled into by about 200mm and injected with damp proofing chemicals. In theory the chemicals are absorbed into the brick pores reducing the bricks ability to absorb moisture. Walls are replaced with damp proofers slurry. This can cause problems with absorption imbalance, resulting in increased condensation on other walls or vapour becoming absorbed and trapped behind the slurry. There was evidence of surface condensation in areas probably not treated with replacement plaster but no evidence of trapped vapour. The solution is through ventilation and humidity control.
- Weather: Overcast and dry.
- Property: Ground and lower ground floor flat in Victorian terraced house.
- Background: Property being sold, recently surveyed with standard findings.
- Changes: Conversion into flats, heating off in lower front middle room, no bathroom extractor.
- Occupancy: Occupied by a couple.
- Mould & notes: Condensation signs, past mould, no longer an issue.
- Primary damp concern: Suspected rising damp at wall bases.
- Other damp concerns: Parapet concerns, no top floor access.
- Compounding: Solid floor amplifying condensation.
- Tenure: Ground and lower ground floor flat.
- Attachment: Terraced.
- Build: Victorian.
- Walls: 9-inch thickness.
- Exterior comment: Ponding signs to rear patio, water traces from stairs and front right-hand neighbour’s door.
- Penetrating damp assessment: Signs of penetrating damp.
- Drains: Drains running freely.
- Leak signs: No leak signs.
- Leak assessment: No apparent leaks.
- Floor: Solid.
- Loft: n/a.
- Timber assessment: No rot in structural timber. Minor rot to rear door.
- Last dry: Past damp-proofing suggests common historical condensation issues.
- Ventilation assessment: Front bathroom lacks extractor, rear needs improved fan.
W.H.O. indoor air quality guidelines
“Management of moisture requires proper control of temperature and ventilation to avoid excess humidity, condensation on surfaces and excess moisture in materials. Ventilation should be distributed effectively throughout spaces, and stagnant air zones should be avoided.”
FACT: Houses contain 30 – 40 litres of water as vapour typically. Each day, each occupant adds on average about 1.5 litres as follows:
- Each shower results in 1/2L condensing (each additional shower in a series won’t add as much as the first, so long as the door is kept closed)
- Vapour from drying clothes releases about ½ litre per day if dried indoors
- Respiration releases about ¾ litre per day (of which ¼ l at night)
- Cooking produces about ¼ litre per day per person
- Unvented vapour can cause condensation, mould and allergenic dust mites. The simple rule for keeping your property dry and mould free is;
- Vent out as much vapour as produced, each and every day!
- Central heating and double-glazing reduce background ventilation. To overcome this you should use mechanical extractors. Where properties are rented, consider using monitoring devices (such as a Govee WIFI hygrometer) and if necessary, install continuous flow extractors, but beware there can be a thermal cost caused by continuous heat lost.
FACTS about Condensation and Mould
- FACT: warm air holds more water vapour than cold air. The warmer it is, the more air’s capacity to hold water vapour. Conversely the colder it is, the less capacity, until air cannot hold any more vapour. We call that the dew point or 100%RH. As soon air reaches capacity, condensation will form on the coldest surfaces.
- FACT: Mould and dust mites
- FACT: Mould only grows when air is humid for long periods. In the occupied home environment, it is 6 hours over 85% RH. For properties that are unoccupied for long periods, it is 75% RH for many days of consistent and high humidity. Avoid allowing the surface relative humidity of cold walls to exceed 85% RH by ventilating, dehumidifying, insulating, and ensuring airflow, particularly in cold corners, base of walls and ceilings, eaves, and cold window and door reveals.
- FACT: Dust mites are microscopic insects that can cause allergies. They grow in similar conditions to mould. So ventilate more to avoid allergies.
- FACT: Health concerns: There are no health and safety issues from damp noted. It is in the occupier’s interests to keep a property properly ventilated or dehumidified and temperatures above the dew and mould points throughout the property, thereby reducing the health risk associated with dust mites, bacteria, protozoans, as well as decorative spoiling caused by mould.
TIPS To Stay Condensation and Mould Free
- TIP: Reduce the production of vapour at source:
- TIP: Keep bathroom extractor fans running, or window open for at least 30 minutes.
- TIP: Keep bathroom doors closed at all times, and bathroom windows open safely.
- TIP: When filling the bath, run the cold water first then add the hot.
- TIP: Dry clothes outside, in a dryer, in a closed room with a dehumidifier or window open, never on radiators or heated rail without a door closed and a means of removing the vapour.
- TIP: Cook with tops on pots and pans, avoiding excessive boiling.
- TIP: Keep the kitchen door closed and extractor fan on where possible.
- TIP:Mechanical vents are best, but if you only have passive vents, such as a whole in the wall or chimney, then vents open with space for air to move, insulate where possible.
- TIP: Keep trickle vents open or alternatively, open windows on safety locks.
- TIP: Stop mould forming:
* Maintain external wall temperatures above 12°C, with low background heating.
* Declutter leaving space for warm air to circulate around cold surfaces.
* Where possible, avoid placing wardrobes and furniture against external walls.
* Avoid overfilling wardrobes and cupboards as it restricts air circulation.
* Use dehumidifiers or small wardrobe dehumidifying bags and replace regularly.
* Wipe mould and condensation off walls and clothes as soon as it appears.
- TIP: Monitor relative humidity
* We recommend monitoring temperature and relative humidity with a data logger to see what is happening.