Damp and mould reports for disrepair files
What is in them, and what you can test.

1. Instructions and scope

1. 1.1 I am instructed to inspect the subject property and to report on the presence, extent and cause of dampness and mould growth; the matters relevant to an assessment of the property under the Housing Health and Safety Rating System; the remedial works reasonably required; and the likely period over which the conditions have existed.
2. 1.2 The substance of all material instructions, whether written or oral, is set out at Appendix C in accordance with paragraph 3.2(3) of Practice Direction 35.
3. 1.3 I have not been asked to advise on liability, on the adequacy of any notice given to the landlord, or on quantum of damages. Those are matters for the court and for the parties' legal advisers.
4. 1.4 My inspection was confined to those parts of the property to which I was given access on the day. This report should not be read as a condition survey of the whole building.

2. The expert

1. 2.1 I am Rory Thorne, principal of Vigilant Surveys, an independent damp and mould surveying practice based in Bury St Edmunds and operating across East Anglia and North London.
2. 2.2 My qualifications and relevant experience are as follows, and I state them exactly as they stand. Damp and Mould Assessor, a course delivered online by Elmhurst Energy Systems Ltd and completed on 10 July 2026, carrying 5 hours of continuing professional development. Relevant experience at the date of this report: 1 damp and mould inspection of the type described here. I carry professional indemnity insurance of £1m and public liability insurance of £5m. I set my experience out plainly rather than in general terms, because the court and the parties are entitled to weigh it, and because a certificate disclosed later would say the same thing.
3. 2.3 I have not undertaken formal training in the Housing Health and Safety Rating System, and I do not give a hazard rating in this report. Section 6 sets out the factual matters relevant to such an assessment so that a person qualified to carry it out, for example an environmental health practitioner, can do so. I take that course deliberately. An opinion offered beyond the expertise the expert can demonstrate is of no assistance to the court, and is the first thing a competent opponent will find.
4. 2.4 The table below states, for each class of opinion given in this report, the basis of my competence to give it. Where the basis is insufficient I say so and the opinion is not given.

1. 2.5 I have no commercial interest in the remedial works I recommend. Vigilant Surveys has no remediation arm, no contracting division and no referral or commission arrangement with any damp proofing, tanking or mould remediation company. I am paid a fixed fee for the survey and the report, and that fee is not contingent on the findings, on the outcome of the claim, or on any works following.
2. 2.6 I carried out the inspection and all measurements personally. No part of the inspection was delegated, and no examination or test relied on in this report was carried out by any other person.

3. Methodology, material relied upon and limitations

3.1 Sequence of inspection

• Contextual review of the dwelling and, where accessible, its exterior, noting ground levels, rainwater goods, ventilation provision and potential water sources.
• Visual inspection of wall, floor and ceiling surfaces for mould growth, staining, tide marks, salt deposits and defective finishes. All surfaces were photographed before any instrument readings were taken.
• Systematic moisture mapping of each elevation using an electrical resistance moisture meter, readings taken on a grid at multiple heights, with a baseline established on the least affected element.
• Thermal imaging to identify cold bridging, areas of surface temperature depression and concealed moisture patterns.
• Tracing of visible run marks to their point of origin.
• Moisture measurement and probe testing of accessible structural timbers.
• Measurement of internal temperature and relative humidity, and inspection of all ventilation provision.

3.2 Literature and material relied upon

In accordance with paragraph 3.2(2) of Practice Direction 35, the material relied upon in making this report is identified below. Nothing is listed here that has not in fact been relied upon.

• The Housing Health and Safety Rating System Operating Guidance current at the date of this report, being the revised guidance in force from 23 June 2026, relied on only for the description of the damp and mould growth hazard and of the matters relevant to its assessment, and not for the purpose of giving a rating.
• The manufacturer's technical documentation for the electrical resistance moisture meter used, in respect of its calibration basis and the wood moisture equivalent scale.
• The manufacturer's technical documentation for the thermal imaging camera used, in respect of emissivity settings and measurement tolerance.
• BS 8102, in respect of section 7 item 9 only, being the recommendation that any waterproofing system be designed to that standard.
• The photographs, moisture readings, thermal images and environmental measurements obtained by me at the inspection.
• The letter of instruction and the documents supplied to me by those instructing me, listed at Appendix C.

Where I rely on a proposition of building science that is general knowledge within my field rather than derived from a specific published source, for example the relationship between surface temperature, relative humidity and mould germination, I state the proposition and my reasoning so that it can be tested, rather than citing a source I have not in fact consulted.

3.3 Limitations

• The survey was non-invasive. No plaster, masonry or floor coverings were opened up or removed.
• Temperature and relative humidity were recorded as spot measurements on the day of inspection. They are not a substitute for continuous data logging over a period of 14 to 28 days, which would record humidity peaks, dew point events and heating patterns. Where the pattern of internal moisture production is in issue, I recommend that logging be undertaken, and I identify below what it would and would not resolve.
• Moisture readings on masonry and plaster are comparative, expressed as wood moisture equivalent, and are not absolute moisture content. Readings on timber are directly meaningful. The basis is explained at Appendix B.
• Soluble salts within masonry conduct electricity and can elevate resistance meter readings even where the material is not currently wet. Masonry readings are therefore used to map the distribution of moisture and are interpreted alongside the visual evidence.
• No drainage survey, CCTV survey or investigation of buried services was undertaken.
• Conditions described are those observed on the day of inspection. Moisture conditions vary with season and weather, and a single inspection in dry conditions cannot confirm or exclude episodic water ingress.

4. Findings

4.1 Summary of moisture readings

4.2 Distribution and its significance

The elevated readings on the front elevation are uniform across the full height of the wall rather than forming a level band that fades with height. That distribution is strongly consistent with lateral penetration of ground moisture through an untanked retaining elevation, and materially less consistent with capillary rise through a failed damp proof course, which characteristically produces a defined tide line with readings falling above it. I did not open up the wall, undertake a drainage or CCTV survey, or investigate the external groundwater regime. My opinion on the mechanism is therefore an interpretation of the pattern of readings taken together with the visual and external evidence, and not a direct observation of the moisture pathway.

The infill panel is materially drier than the masonry surrounding it. This is evidentially useful in two ways. It establishes that the blocked opening is not the route by which the general wall moisture is entering, and it demonstrates that the instrument was not simply reading high across the whole elevation, which supports the reliability of the surrounding readings.

4.3 A discrete and separable defect

Run marks were observed originating below the former chute board, falling vertically and appearing to seep from beneath the modern infill. Streak marks of this kind indicate liquid water moving under gravity, which is a different mechanism from the general moisture migration affecting the remainder of the wall. External inspection at pavement level supports this as a credible path: the bituminous coating to the exposed head of the wall is cracked and locally debonding around the louvred vent, and the metal strip above the vent is corroded.

No active seepage was observed during the inspection, which took place in dry conditions. I am therefore unable to say whether this ingress is current or historic. I recommend observation of the internal face during or immediately after heavy rainfall before expenditure is committed to it. I draw this to the court's attention because it is the one finding capable of being resolved cheaply, and because it would be wrong to present it as established when it is not.

4.4 Ventilation

The only dedicated ventilation to the affected space was a single small airbrick, internally obstructed by dust and debris and externally partially obscured by debonded coating. In my opinion that provision appears inadequate for a space of this nature. I did not measure the free area of the airbrick, the volume of the space or the air change rate, and I put the opinion no higher than the observation supports. Inadequate ventilation allows moisture released by the damp fabric to accumulate in the air, raising relative humidity, encouraging condensation on cold surfaces, and creating the conditions in which mould establishes.

4.5 Mould

Surface mould growth was identified on the oak lintel nearest the stairs. That is consistent with the recorded timber moisture content of approximately 22%, though I did not undertake sampling or laboratory analysis and I do not identify the species or assert that the timber moisture content alone caused the growth. The extensive white deposits elsewhere are visually consistent with salt crystallisation rather than biological growth, and were not chemically analysed. The darker marks on the front elevation are, in my opinion, moisture staining. Mould growth is inhibited on heavily salt contaminated masonry, which in my opinion explains why growth is confined to the one organic, salt free surface in the space.

5. Causation

1. 5.1 Three distinct causal questions arise and I answer them separately, because a single mechanism does not explain every aspect of the condition and the word "cause" is capable of being read too widely. They are: what causes the dampness in the fabric; what causes the mould growth; and what bears on the risk to health, the factual inputs for which are at section 6.
2. 5.2 In my opinion the dampness in the fabric arises from the following sources, in descending order of significance:

The mould growth is driven principally by surface conditions rather than by the sources above taken alone: moisture released into the air by the damp fabric, combined with inadequate ventilation, produces the humidity in which mould establishes on any suitable surface. The risk to health is a function of both. I do not rate it, for the reason given at paragraph 2.3. Separating the three matters in this way is deliberate. It would not be right to say that ground moisture "causes" the mould growth without also saying that ventilation and surface conditions determine whether growth occurs at all.

5.3 Occupier behaviour as a competing explanation

It is commonly advanced in claims of this kind that dampness and mould are the product of the occupier's lifestyle, in particular the drying of laundry indoors, inadequate heating or the failure to open windows. I have considered that explanation and, on the evidence recorded above, I do not accept it as the principal cause here, for three reasons.

• Condensation-driven dampness produces its highest readings on cold surfaces and in the upper corners of rooms, and characteristically leaves masonry at low level dry. The distribution recorded here is the opposite.
• Surface salting of the kind observed is deposited by moisture arriving from the ground and evaporating at the surface. It is not produced by condensation.
• The available ventilation provision appears inadequate to ventilate the space effectively, even allowing for reasonable occupier use. The only dedicated provision observed was a single airbrick, obstructed internally by debris and externally by debonded coating. I have not calculated the free area of that airbrick against the volume of the space or measured air change rates, and I do not put my opinion higher than the observation supports.

I qualify that opinion in three respects, so that the limits of it are clear.

• Occupier behaviour is capable of aggravating the conditions recorded, and the storage of goods in direct contact with the damp walls and floor, which I observed, will do so.
• My temperature and humidity measurements are spot readings taken on a single day. They do not establish the pattern of internal moisture production over time. Continuous logging over 14 to 28 days would resolve that question, and I recommend it where the point is in issue. I would expect logging to show whether humidity peaks correspond to occupation patterns, which is the evidence a contrary opinion would need.
• What logging would not do is displace the distribution and salting evidence above, which concerns moisture in the fabric rather than moisture in the air.

Subject to those qualifications, my opinion is expressed as follows. The physical evidence indicates that the underlying dampness in the fabric is principally attributable to moisture entering the structure from the ground. Occupier behaviour may have contributed to, or aggravated, surface moisture and mould growth. I do not consider the evidence available to me sufficient to attribute the underlying dampness principally to occupier behaviour, and I do not assert that occupier behaviour made no contribution to the mould growth, which would go beyond what a single non-invasive inspection can establish.

6. Matters relevant to an assessment under the Housing Health and Safety Rating System

1. 6.1 Damp and mould growth is one of the prescribed hazards under the Housing Health and Safety Rating System. The system was revised with effect from 23 June 2026, reducing the number of assessable hazards from 29 to 21, replacing the former A to J band structure with High, Medium and Low, and renaming the harm outcome classes. I refer to the hazard by name rather than by number, because the numbering changed with the revision.
2. 6.2 I do not give a hazard rating. As stated at paragraph 2.3, I have not undertaken formal training in the Housing Health and Safety Rating System, and it would not assist the court for me to offer a rating I could not sustain if it were tested. What I set out below are the factual matters recorded at my inspection which a person qualified to carry out the assessment, for example an environmental health practitioner, would need in order to do so. Where those instructing me require a rating, I recommend that a suitably qualified assessor be instructed, and I am content for this report to be provided to them.

The bracketed environmental values are completed from the inspection record in a live report. They are shown open in this specimen because the underlying matter is fictitious.

Two matters belong in this section. First, an assessment of this kind is a structured judgement rather than a calculation, and two competent assessors may reach adjacent bands on the same facts. Second, and more importantly here, declining to give a rating is not a gap in the evidence. It identifies precisely who should supply that part of it. A rating given by someone without the training to defend it would be worth less to the court than the factual record above, and would put the remainder of this report at risk by association.

7. Schedule of remedial works

The works below are those reasonably required to address the conditions recorded. Costs are indicative only, at a regional rate current at the date of the report, and are provided to assist the parties in understanding the scale of the works. They are not a formal estimate, and I am not instructed as a quantity surveyor.

I draw attention to item 9. A full waterproofing system is the appropriate remedy only if a drier environment is required for the intended use. If the space remains in its present use, the proportionate objective may be the control and management of moisture rather than the complete elimination of moisture from the below ground structure. I do not say the structure is incapable of being waterproofed; item 9 exists precisely because it is. Items 1 to 5 appear to me to achieve a material improvement at a small fraction of that cost, though I have not carried out a comparative costing and I am not instructed as a quantity surveyor. An expert who recommends the most extensive works available without addressing proportionality is not assisting the court.

8. Range of opinion

1. 8.1 In accordance with paragraph 3.2(6) of Practice Direction 35, where there is a range of opinion on the matters dealt with in this report I summarise it and give reasons for my own view.
2. 8.2 On the mechanism of moisture ingress. In my experience of this field it is commonly asserted, in reports prepared by remedial treatment contractors, that dampness presenting in this way is attributable to a failed damp proof course and that chemical injection is the appropriate remedy. I identify it as a view encountered in practice rather than as a proposition drawn from published literature, and where such a report exists in the papers I identify it by author and date. I do not share that view here. Injection addresses capillary rise through a wall, and the distribution recorded, uniform to full height on an earth retaining elevation, is not that of capillary rise. I record the alternative view because it will very likely be encountered.
3. 8.3 On the significance of the suspected ingress path. It is open to another expert, on the same evidence, to conclude that the run marks predate the infill works and are historic. I have not excluded that possibility and have recommended the observation that would settle it.
4. 8.4 On occupier behaviour. The contrary view is addressed at section 5.3 above.

9. Summary of conclusions

1. 9.1 The property exhibits widespread dampness which is, in the main, characteristic of an untanked below ground structure of its age rather than the consequence of a recent building failure.
2. 9.2 Two findings merit specific action: a suspected rainwater ingress at the redundant opening, which should be confirmed or excluded by observation in wet weather, and the apparently inadequate ventilation, which on the evidence available to me is the most straightforward and apparently proportionate improvement identified, and the one most relevant to mould risk.
3. 9.3 Mould growth is present but limited in extent, and its distribution is explained by the surfaces available to support it rather than by the absence of moisture elsewhere.
4. 9.4 In my opinion occupier behaviour is an aggravating factor and not the cause of the conditions recorded.
5. 9.5 The accessible structural timbers I inspected were serviceable at the date of inspection. The accessible oak lintels showed no evidence requiring immediate intervention, and periodic monitoring is in my opinion appropriate. I did not inspect concealed or inaccessible timbers and express no opinion on them.

10. Expert's declaration

11. Statement of truth

A. Appendix A: Photographic schedule

Each photograph is numbered, dated and cross-referenced to the paragraph of the report in which it is discussed. Photographs are presented unedited save for cropping and, where a photograph is a thermal image, the temperature scale is shown. Visible-light and thermal images of the same elevation are presented as a pair so that the two can be compared directly.

B. Appendix B: Note on moisture meter readings

Readings in this report were taken with an electrical resistance (pin type) moisture meter. These instruments measure electrical conductance between two pins and are calibrated for timber. On timber the displayed percentage is a direct measure of moisture content: below approximately 16% is dry, 16 to 20% is damp, and above 20% the timber becomes vulnerable to fungal decay.

On masonry, plaster and other non-timber materials the instrument cannot give a true moisture percentage. Readings are expressed as wood moisture equivalent and are meaningful only as comparative values, showing which areas are wetter than others relative to a baseline. In addition, soluble salts within masonry conduct electricity and can produce high readings even where the material is not currently wet.

For these reasons the masonry readings in this report are used to map the distribution of moisture, and are interpreted alongside the visual evidence and the thermal imagery, rather than being treated as absolute measurements. Where a conclusion depends on a masonry reading alone, I say so.

C. Appendix C: Substance of instructions

The substance of all material instructions received, whether written or oral, on the basis of which this report was written, is reproduced here in full, together with the date of each. In a live report this appendix contains the letter of instruction and a note of any material oral instruction.

Vigilant Surveys · independent damp and mould surveying · no remediation arm, no contractor ties
07791 178 870 · surveys@vigilantsurveys.co.uk · vigilantsurveys.co.uk

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