Data loggers
In conclusion from the data logger
- During the period under investigation the surface relative humidity near the bathroom (green line) is high, peaking at 100%RH and risking condensation on the coldest surfaces. Relative humidity is above the mould risk of 85%RH and at risk of condensation.
- The surface relative humidity is calculated considering the temperature difference between the data logger and cold surface at the time of the survey – this is an approximation and illustrative. You can check the difference more accurately with a laser thermometer on a cold night to update the “interface”user input” tab in the spreadsheet.
- For each -1°C the relative humidity will be about 5%RH higher. The effect increases as the temperature difference between inside and outside increases such as when it’s cold.
- It is interesting that your internal dew point is fair stable compared to the outside and the example property, demonstrating insufficient ventilation.
- The example property dew point is in fact from my house, where I run a dehumidifier to maintain a healthy environment and reduce the need for and cost of heating.
- Overall, there are clear signs of condensation being the root cause for much of the damp. Data loggers will be useful for ongoing monitoring following the implementation of my recommended actions. Working from home results in more cooking and more respiration. The energy crisis has resulted in people turning down the heat in unoccupied rooms and closing vents and windows. Risk of condensation can be reduced with a 20L+ dehumidifier.
Evidence & Illustrations
Hygroscopic, or water loving salts, are benign like grease stains. They don’t cause mould, dust mites or rot and are rarely result staining. They can be considered decorative spoiling. The simplest solution is to paint an impermeable layer, such as an oil based paint or vinyl backed lining paper, but any impermeable layer (non-water based) will work, including dry lining and indeed damp proofer’s slurry – although I don’t advocate it, see below.
The colour of the damp band results from hygroscopic salts trapping soot during the coal fired industrial revolution. Most hygroscopic salts are found near chimneys, spreading horizontally along about 1M off the ground. However they also travel vertically up the chimney. The movement of hygroscopic salts has not been studied scientifically, but it appears to be causes by a sweet spot between slow evaporation at the base of a wall and too rapid evaporation further up, likewise up a chimney breast – a “Goldilocks” band, not too wet not too dry.
Rising damp proofing contractors and their association will claim that they are primarily as a result of rising damp. It is true that ground water the source of water in rising damp contains hygroscopic salts, but a vast majority in houses comes from historic burning of coal and from equine urine. Being a Victorian property close to a park, you are at risk of historically high levels of hygroscopic salts, as is evident looking around the house and street.
During a lockdown pause in surveying in May 2020, brought to the attention of the Property Care Association “PCA”, the association of damp proofer and self appointed qualifier of damp surveys (I am qualified but choose not to be a member) some errors in their guidance of hygroscopic salts, see YouTube video link. In response the PCA published updated guidance on “Hygroscopic salts and Rising Dampness”. The PCA writes:
“The salt contamination problem is dealt with by removing the salt contaminated plaster and replastering witha salt resisting plaster mix. It should be noted that removal of plaster does not remove the salt accumulatedwithin the wall itself near the apex of rise. There is no economic method of removing this salt and this is thereason special plastering is used for walls affected by rising dampness”.https://www.property-care.org/write/MediaUploads/Professionals/Documents/Guidance-Document_Hygroscopic-Salts-and-Rising-Dampness-Meta-Tags.pdf
I fundamentally disagree with the PCA and have told the head of the PCA by phone and in writing. My reasons include:
- Their recommended salt resisting plaster (“also known as “slurry”) is destructive (hacking off large sections of plaster from walls, skirting boards and radiators), disruptive (often a week of work and dust, leaving an decorated uneven patch of plaster), expensive and over engineering a problem, when the solution is as simple as painting an oil based primer such as Zinsser B.I.N. Zinsser is readily available, may be applied by anyone and only need be applied to the damp patch with about 300mm overlap (two coats, refresh if required). £20 for a better invisible solution, compared to an estimated £2,000 for replacing plaster, for the patch in question.
- PCA’s method often does work, however, as water is applied, it is inevitably some salts will migrate during the application. Typically damp proofers will used Zinsser as a back up solution if the “slurry” doesn’t work.
- Although in the current case, it is clear that there are hygroscopic salts as they can be seen on the external wall, it is not clear in every case. Hygroscopic saltsare not a source of water, but moisture in dynamic equilibrium between condensation and evaporation. Hygroscopic salts look like condensation from excess vapour. Where there is excess vapour, replacing a large section of plaster with impermeable plaster as is the case with slurry, they you are reducing the walls ability to absorb vapour, exacerbating the effects of excess vapour, increasing the risk of mould. Calcium sulphate salts are liable to crystallise on the interface of the slurry and normal plaster. You will see examples of these amongst my reports.
- While groundwater, the source of water in rising damp, contains hygroscopic salts, a vast majority of salts found on walls, such as this one, are not caused by groundwater, in this case it was a leak from a neighbour.
Calcium nitrate is the most common hygroscopic salt in houses. Hygroscopic means water loving, causing vapour to condensewhen humidity is below 100%RH. This is known as deliquescence. The critical relative humidity of calcium nitrate 46.7%RH at 30˚C. Common salt, sodium chloride is also hygroscopic causing condensation @ 75%RH. Some salts become more hygroscopic as temperature increase. Therefore, the damp patches can look worse during a summer heat wave.
Because hygroscopic salts are not a source of moisture, but are in dynamic equilibrium between heat reducing evaporation and heat releasing condensation, they don’t change the heat profile of a wall. This is not a definitive test as: 1, hygroscopic salts can be found on cold walls, and 2, a poorly insulated wall may be warm during a day time survey, but cold on a winter’s night.
Cavity membranes are for underground dwellings, to stop rainwater affecting internal walls. Cellar are better left without a vapour barrier, such as tanking or a cavity membrane to allow rain to evaporate away from soil, and out through the sub-floor air vents.
Like many interventions, there are side effects. Cavity membrane forces water up a wall increasing the risk of condensation above the damp proof course, risking rising damp like symptoms. These symptoms are mitigated by past damp proofing treatment using silicone or siloxane cream. However, it would have been better to leave the underground walls in the cellar to evaporate out rainwater through sub-floor air vents as originally intended.
Calcium sulphate salts are frequently found as white powder or crystals on internal walls. These salts are harmless, come from building materials and typically resulting from the constant fluctuations between evaporation and condensation.
Mould is growing in the bathroom. The room is an internalised outbuilding, with less insulation than elsewhere. If a bathroom is kept colder, by reducing heat there and keeping the door closed, then less vapour diffuses around the property. I would increase ventilation from the bathroom; this will have the beneficial effect of drawing warm air from the rest of the property into the bathroom.
Mould growth occurs where relative humidity exceeds 85%RH for more than six hours. Excessive humidity is usually due to insufficient ventilation, poor air circulation, and cold surfaces. Relative humidity measures the amount of vapour in the air relative to the air’s capacity to hold vapour. It is influenced by vapour pressure and temperature. As temperature rises, the air can hold more vapour. Conversely, as temperature drops, the air’s capacity to hold vapour decreases until it reaches the dew point at 100%RH, resulting in the formation of dew or condensation.
The wall was damp, as indicated by a Protimeter radio frequency damp meter. The meter measured 999REL, signifying saturated pores deep within the wall. Readings below 300REL are dry. These meters assess the extent of damp and are used to trace it to the source.
Not only do chimney suffer from hygroscopic salts but they are also more susceptible to condensation from heat loss to the outside or outside temperatures of the sub-floor void.
A brown stain is a sign that water is passing through building material. Timber such as a skirting board releases colour.
I note white efflorescent salts on the front wall, this is a sign that water has overflowed the rainwater goods at some tie in the past. It appears to be repaired, but make sure there is no ongoing gutter leak, by checking during a heavy rainstorm or soon after.Post navigation
To keep the property dry | |
|---|---|
| Cover hygroscopic salts | |
| The simplest, cheapest and in my opinion the best is using 2 coats of Zinsser BIN Cover Stain, a solvent-based, primer-sealer. For each patch, it takes about 1 hour and costs around £15 plus any labour if required, the great thing with Zinsser is it is easy strip off and reapply. For significant areas consider painting a coat of gloss paint sandwiched between two layers of Zinsser BIN Cover Stain, and ideally paint all sections of wall affected, as like icebergs, there can be more hidden just below the surface. Most homeowner would be able attempt this. It will take a general builder a few hours, and so should be considered as part of a larger project. | £25 |
| Reduce vapour from cooking | |
| Cook with tops on pots and pans to reduce the production of vapour from cooking by 80%. | |
| Target vapour from bathroom | |
| TIP: Keep the bathroom door closed with the fan running or window open until the humidity from the shower has subsided – typically at least 30 mins after the last shower. | |
| Target vapour from clothes drying | |
| Use a tumble dryer (like a heat pump), dry in a vented room with the door closed (possibly a bathroom with the extractor running or window open), or use a powerful dehumidifier. Don’t dry clothes in an unventilated room, such as the annex. | |
| Direct a fan onto the leak to speed up the drying process. | |
| Remove mould | |
| Consider sanding down mould where dry, and removing it with either bleach or anti-mould foam. I personally use HG Mould Remover Foam Spray, but imagine there is no major difference between brands. | £50 |
| Remedial actions – estimate of costs | £75 |
Actions if all else fails | |
|---|---|
| Consider replacing the bathroom extractor | |
| In my opinion, the optimal fans are ones that are targeted, with the fan located near the shower head (without being so close that water sprays onto it), removing vapour during and for at least 30 minutes after taking a shower or bath (which typically produces slightly less vapour). Ideally the fan should be separately wired up with an overrun. Installing the overrun can account for a majority of the cost. Consider installing a continuous flow extractor fan such as Brookvent Airstream DMEV 100 HT (Continuous Running Extractor Fan with Humidistat Timer). Note a continuous flow fan will expel warm air, thereby increasing heating cost by about £120 p.a. but this may be a small price to pay. You can use an isolator to manually turn off the fan when the property is sufficiently ventilated, but the risk is it is left off. | £300 |
| 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. | £500 |
| Use 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 daily and tank capacity, low noise, whether it has a pipe out and easy 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). | £180 |
| Optimal actions – estimate of costs | £980 |
I conclude that there were hygroscopic salts absorbing moisture from the air and causing a form of condensation at normal levels of relative humidity. there is no evidence of rising damp, as confirmed by normal humidity levels in the subfloor void and british geological s.
Hygroscopic salts were released into the wall when your neighbours leak cause water to dissolve these salts already in the bricks, seen on external walls. Defective bathroom fan, drying clothes internally, and the absence of a kitchen extractor fan contributing to additional condensation.
I stopped the leak behind the washing machine. By taking a root cause approach, rather than a focus on blocking the symptoms of damp the savings are likely to be around £20,000. 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: Rocks with essentially no groundwater See British Geological Survey.
Therefore risk of Rising Dampremote possibility, see explanation by Dr Robyn Pender of Historic England.
I confirm that I inspected the property on . I conclude that There were hygroscopic salts absorbing moisture from the air and causing a form of condensation at normal levels of relative humidity. There is no evidence of rising damp, as confirmed by normal humidity levels in the subfloor void and British Geological Survey data indicating no ground water bearing rocks below the property.. 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
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.
- Weather: cool, dry overcast
- Property: A ground floor flat in a Victorian terraced house situated close to a park.
- Background: The property lost its buyer following a damp survey recommending rising damp proofing treatment from a contractor
- 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.
- Changes: neighbour’s leak, releasing hygroscopic salts into the walls, conversion into flat, working from home following, Covid, past damp proofing treatment including cavity membrane
- Occupancy: a couple who often work from home
- Notes: Maintain dew point close to external temperatures, especially during the sale period or before the next survey. Hygroscopic salts will remain, but condensation-related dampness should dissipate over time.
- Primary damp concern: A persistent damp patch on an internal wall, following a leak from the neighbour
- Other damp concerns: damp and calcium sulphate blistering around light switches, a brown stain on the wall near the washing machine
- Compounding: heat loss from poor insulation
- Concern: Your buyer’s RICS homebuyers identified potential rising damp.
- Sub-floor humidity: The sub-floor had normal levels of relative humidity.
- Exterior comment: There were no major concerns seen externally that would account for internal issues.
- Penetrating damp assessment: The exterior appeared to be OK from a damp perspective. There are no obvious signs of significant penetrating damp.
- Drains: The drains are of no special concern.
- Leak signs: No suspicion of a mains water leak
- Leak assessment: There are no obvious signs of a significant mains or wastewater leak.
- Loft: There was no loft.
- Timber assessment: There are no suspicions of significant timber decay.
- Last dry: The primary concern started last year after the neighbour reported a leak.
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.
RICS, PCA, HISTORIC ENGLAND JPS REPORT
RICS (Royal Institute of Chartered Surveyors), Historic England (a public trust protecting sites of historic interest) and the Property Care Association (an association of mainly damp proofers) set out a Joint Position Statement (JPS), in September 2022 – see below.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
In addition to the content typically included in a professional and impartial survey report (e.g. client, surveyor and property details; limitations and exclusions), the report should include the following information:1 A summary of the surveyor’s observations, including an Assessment of Significance.
Primary dampness was hygroscopic salts released by a leak on the neighbour’s side of a party wall
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. Improve ventilation and check the leak has stopped behind the washing machine
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.
The risk of ongoing high humidity, are condensation, mould and dust mites, easily mitigated with ventilation and dehumidification.
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 Use Zinsser B.I.N. to block the hygroscopic salts and ventilation to stop condensation, aim to bring the dew point down to close to external dew points.
5 The client should be provided with alternative options for which each 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. ” No alternatives required or appropriate.
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. Monitor visually and with a radio damp meter and data loggers, see recommendations.
7 Where appropriate, clearly state whether the building concerned represents a financial risk to the buyer or lender and why.
The property was subject of a sale which has fallen through following an inappropriate survey. In our opinion, there is no material financial risk once you have followed our recommendations.
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.
| Question and Answers |
|---|
| Q: Would the general builders you’ve listed here be appropriate for getting our fan replaced, or did you have someone else in mind who might be able to do that? |
| A:I am independent of builders. I note competent general builder who have worked for clients. They should be able to replace fans previously installed. A new fan installation typically request an electricians as it needs new cabling, one from the main and one from the light switch. Make sure that the fan is correctly set with the overrun to 30 minutes, the default setting is normally inadequate and rarely changed by installers. |
| Q: Also, as discussed, if you did have any recommendations for specific 2L capacity dehumidifiers, we’d certainly appreciate your advice. |
| A:Try a 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 daily and tank capacity, low noise, whether it has a pipe out and easy 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). |
Relevant examples of properties with similar damp issues: electric-sockets
[mwai_chatbot_v2 id=”default”]Ask A.I. about your report, in the “Type your message” you could ask:
What does the damp report say are the main causes of damp and main actions to stop damp?
¿Qué dice el informe de humedad sobre las principales causas de la humedad y las principales acciones para detenerla?
潮湿报告说什么是潮湿的主要原因和防止潮湿的主要措施？
नमी की रिपोर्ट के अनुसार नमी के मुख्य कारण और नमी को रोकने के लिए मुख्य कार्य क्या हैं?
Que dit le rapport sur l’humidité concernant les principales causes de l’humidité et les principales actions pour l’arrêter?
Was sagt der Feuchtigkeitsbericht über die Hauptursachen von Feuchtigkeit und die Hauptmaßnahmen zur Bekämpfung von Feuchtigkeit?
Что говорится в отчете о влажности о основных причинах влажности и основных действиях по ее устранению?
Cosa dice il rapporto sull’umidità riguardo le principali cause dell’umidità e le principali azioni per fermarla?