Data loggers
In conclusion from the data loggers
- The data logger was a WiFi logger that was not connected to the internet so could not provide data. It may have collected and retained some useful and or for collecting data going forward. I’m not familiar with this brand.
- I would use wifi loggers. My preferred wifi data loggers in vacant properties are Switch bots. I would have one or two down stairs, one upstairs and one waterproof one outside. You should aim to lower the dew point below the external dew point and increase the Vapour Pressure Deficit, the greater the deficit the faster the dry time. Heat and dehumidifiersincrease the deficit, see recommendations.
See https://damp.ai/glossary/monitor-humidity-with-data-loggers/ on how to use the data logger app.
Evidence & Illustrations
You’ve been grappling with damp issues since acquiring your flat 17 years ago, despite having installed a damp proofing barrier and a French drain. Regrettably, these measures haven’t curbed the problem, which has escalated, leaving a pronounced musty smell in the less ventilated, smaller bedroom. The delay in addressing the internal dampness was due to external cracks in your Victorian building, likely caused by tree roots, which are fortunately covered by your house insurance. You were advised to repair these external cracks before any internal plastering to fix the corresponding internal cracks, to ensure a comprehensive solution.
I am not a structural engineer, but is my opinion the damp proofing treatment is more likely to have caused the structural damage, rather than a tree, as the cracking is lateral, away from the building, fairly evenly displaced, with the largest crack in the property the furtherest from the tree.
Calcium sulphate salts are frequently found as white powder or crystals on internal walls. These salts are harmless, come from building materials, typically resulting from the constant fluctuations between evaporation and condensation.
It is ore likely that the cause of internal damp was condensation, rather than water from this tap.
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.
To keep the property dry | |
|---|---|
| Protect building from movement | |
| I am not a structural engineer. However, replacing the external ground or concrete patio, with a so-called “French drain”, the shingle pit, around the bay, an invention of Mr French, is likely to have weakened the front bay, which is unlikely to have moved had it not been for this inappropriate damp proofing treatment. The bay is likely to have been pushed out by the replacement of the suspended timber floor with a concrete floor. Were it my property I would try to get planning for an extension similar to the neighbour’s side, with properly supported RSJ holding up the bay above. You will need freeholder permission, as well as neighbours, and probably insurers, but it should be in everyone’s interest to have the bay properly supported. I won’t put a cost on the work, but it is likely to be £20,000 +/- £10,000 depending on what is agreed. | |
| Fill-in external cracks | |
| Again, I’m not a structural engineer, so wouldn’t want to be prescriptive about something that could effect the structure. But I assume there needs to be some stitching of the walls and filling of cracks to stop further damage and internal damp. I would check with a structural engineer, but if agreed would fill gaps with a material that will allow movement, not to swell up with moisture, that protects the wall, possibly external acrylic caulk. The work should take no more than a day or two. However it is unlikely anyone with wish to be held accountable for failings, so it may need to be part of a larger work plan, including structural repair, involving scaffolding. Cost may be around £2,000 – £4,000 for the stitching and filling. | |
| Duct out bathroom extractor | |
| I would open up the current ducting to find out where, if anywhere it is going. I suspect nowhere. I would imagine you can either duct out nearly from the outside above the rear bedroom, across the ceiling (possibly within the ceiling) through to the bathroom. Make sure to include external flat, use rigid ducting and test out airflow to make sure it is working. It may be worth changing the fan type, see below. You should have freeholder permission as a matter of good practice, but it would be hard for the freeholder to object. | £200 |
| Duct out kitchen extractor | |
| Like the bathroom, duct out the kitchen extractor fan. It may be worth changing the hood. You should have freeholder permission as a matter of good practice, but it would be hard for the freeholder to object. | £200 |
| Replace timber door sill | |
| The timber door sill to the outside is rotten and needs replacement. There is gap under the door frame next to this wall, which needs filling in to ensure rainwater cant enter. I would also replace the seal at the base of the door and check, by spraying water that no water enters. | £300 |
| Repair roof | |
| The roof above the staircase needs repair and gutter cleared and checked to make sure it is flowing correctly. This should be a freeholder or shared cost. | £200 |
| speed drying with fan | |
| I would use a series of fans, may be 3 or 4 downstairs directed across damp walls to speed up the drying process. | £100 |
| use a dehumidifier | |
| Use 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. The current one is on the small side and needs an extension to plug it in so that it drains into the bath. I would use two a Meaco DD8L Zambezi and a PureMate 20L/Day one in each bedroom, with the doors open, but all windows closed, both draining safely into the bath. You may need to stand them on something so that the drain outlet is well above the bath. You will need about 10M of tubing about the size of a garden hose. Be sure that it can’t leak before leaving it and monitor humidity. | £500 |
| monitor improvements | |
| I would buy a Dr. Meter Wood Moisture Meter 2 in 1 Pin & Pinless Multifunctional Water Detector £23.99 to log and monitor reduction to dampness in walls. | £24 |
| heating system leaks | |
| You may wish to update the heating system and radiators, whether or not you do the system should be flushed out and pressure test as I suspect there is a leak. A leak can be found putting strong perfume into the central heating, such as by draining a little water out using the drain typically on the lowest radiator, then pouring perfume into a blead valve on the highest radiator. | £200 |
| Remedial actions – estimate of costs | £1,724 |
Actions if all else fails | |
|---|---|
| consider installing a continuous flow bathroom extractor | |
| Given the challenges of a lower ground floor internal bathroom and likely occupation by tenants, I would install a continuous flow bathroom extractor fan and make sure sufficient air (say at least 10 L/S measuring with an anemometer on the external outlet). | £300 |
| seal around the bath | |
| Remove grout around cracks and regrout. Seal with silicone between a bathroom and the wall or tiles. It is best to fill a bath with water and leave it there during the curing process. Using paint masking tape with a neat say 5mm gap either side. Squirt sealant, run finger along (in glove), have toilet paper at hand, within a few minutes, maybe 10 remove the making tape – look at YouTube videos online for top tips. | £100 |
| Seal gap at base of external walls | |
| I would make sure there is a continuous line of concrete patio (or stones laid on an impermeable base close to the building). Essentially this is getting rid of the French drain which is likely to the cause, or contributory factor in the structural damage. There could be a case of an Aco drain, although the natural incline suggest water flows away from the rear wall. I would ensure that there is a plinth the whole way around the building, that is typically 1M or more of a cement based mortar at the base of the wall, and in the gap in between the plinth and patio is sealed, such as with a fillet of cement based mortar. | £1,000 |
| Consider targeted insulation | |
| Consider installing thermal insulation to exterior walls especially the stair case – in the region of £100 per sq. m. will need freeholder permission. Walls that I was not able insulate externally I would insulate internally using PIR, thermal insulating plasterboard, such as Kingspan to the ground floor and staircase, and thermal lining paper upstairs. | £10,000 |
| Consider heating the property | |
| Heat would speed up the drying process if used in conjunction with a dehumidifier and fans, with windows closed. | |
| Consider installing an Acro prop to secure the bay | |
| You should discuss this with a structural engineer, freeholder and other concerned parties. However, the bay looks like it could move further out, presumably it could be shored up with Acro props until structural works have been completed. | £500 |
| Check that the outside tap doesn’t continue to leak | |
| Optimal actions – estimate of costs | £11,900 |
I conclude that there was no evidence of rising damp, which comes from groundwater in contact with walls. the risk of groundwater is very low. there were many signs of penetrating damp, a heating system leak and excess humidity causing condensation and mould.
An exceptionally complex set of overlapping root causes, although I hope this is comprehensive, you can’t be sure of success until you have followed all the recommendations and measured moisture in walls, to assured yourself that they are drying out, over the course of about 10 months.
. 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 231020SH1400. I conclude that there was no evidence of rising damp, which comes from groundwater in contact with walls. The risk of groundwater is very low. There were many signs of penetrating damp, a heating system leak and excess humidity causing condensation and mould. 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 231020SH1400
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: Overcast with occasional sun; no rain; temperature approximately 16°C.
- :Victorian, semi-detached, rear and lower ground floor flat; unoccupied.
- :Structural damage.
- :Conversion into flats; replacement of suspended timber floor with solid floor; addition of side staircase; subsidence possibly due to a tree.
- :previously tenant, now vacant
- :Mould around property. Bathtub unexpectedly full of clean water; vapour signs throughout property; flip-flop with water residue.
- :Penetrating damp in the corner by the rear door due to a rotten wooden door sill.
- :Dampness around most walls.
- :Three significant cracks, potential for ingress and many poorly insulated surfaces.
- :There is a solid floor no need for air bricks.
- :There appears to be no sub-floor void.
- :lower ground floor flat
- :a semi-detached
- :Victorian
- :solid wall made of two brick widths (225mm)
- :There were major concerns seen externally that account for some of the internal issues.
- :Internal dampness lined up with some source of external water. Penetrating damp is part of the problem.
- :The drains are of no special concern.
- :Pressure well below 1 bar, suggesting a heating system leak; moisture and rust around ground floor radiator.
- :A leak appears to be one of the contributory sources of water.
- :Evidence of water dripping onto carpet over solid floor; damp walls nearby.
- :There was no loft.
- :There is rot in the rear timber door sill. The effect is localised.
- :I understand that despite numerous damp treatment, there has been a history of damp issues dating about at least 10 years.
- :The bathroom extractor fan does not appear to vent out. There is no externally ducted kitchen extractor 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.
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.
damp mainly at base of many internal and external walls, especially where cracked
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. Ideally the bay should be sored up
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 primary damp comes from penetrating damp, however excess vapour from insufficient ventilation has a wider impact.
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 Repair and stitch cracks per insurance and structural engineer guidelines; fill gaps accordingly; risk of ongoing dampness.
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. ” N/A
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 humidity levels post-repair.
7 Where appropriate, clearly state whether the building concerned represents a financial risk to the buyer or lender and why.
The property is subject to an insurance claim and could be the subject of a sale. In our opinion, there is no material financial risk once you have followed our recommendations, we can’t speak for the cracks.
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.
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?