Good Expert Evidence and Unfit Homes: What Harvey v Heaver Means for Landlords, Solicitors and Surveyors

The court deliberately confined itself to the present and prospective fitness of the property under section 9A. It did not determine historic disrepair, historic unfitness, damages, personal injury, Equality Act issues, or the wider factual disputes between the parties. That focus made the single joint expert’s evidence especially important.

The judge recorded that a single joint expert, Mr Paul Badham, a chartered building surveyor, had inspected, reported, answered Part 35 questions and produced photographic evidence. Neither party required him to attend for cross-examination. His evidence was therefore agreed and unchallenged, but the ultimate legal question remained for the court.

“A single joint expert, Mr. Paul Badham, a chartered building surveyor, was instructed. Counsel for the First Defendant described him as 'a very experienced expert who has seen lots of housing disrepair claims'. He reported on 20 April 2026 and answered Part 35 questions on 7 May 2026. Neither party required him to attend for cross-examination, and his evidence (including his answers to Part 35 questions) is unchallenged. The expert took 381 photographs of the Property, copies of which were also admitted in evidence. I treat his factual observations, professional conclusions and photographs as the evidence in the case, while remaining the judge of the ultimate questions of fitness for human habitation and relief.”

There was also an impressive line-up of other expert or quasi-expert material available. The papers included a surveyor’s report from Mr Thomas, a structural engineer’s report from Mr Murphy, the local authority’s HHSRS assessment, and mycological and medical reports from Dr Singh and Professor Richardson. Those reports potentially went to condition, structure, hazards, mould and health. The claimants invited the court to receive and rely on them. The landlord argued that, because a single joint expert had been directed, Mr Badham’s evidence was the only admissible expert evidence on the condition issues.

The judge did not need to resolve that dispute. That is one of the most important practical points in the case. He was able to decide present fitness on the competent, agreed and unchallenged evidence of a building surveying expert alone. He did not need to hear separate mycological or medical evidence to prove that mould is harmful, or to prove that these particular occupants had already suffered adverse health effects, before finding that the property created a risk of harm.

“I have reached my conclusions on the present condition of the Property on the single joint expert's report alone. A number of other expert and quasi-expert reports are in the papers, namely the surveyor's report of Mr. Thomas, the structural engineer's report of Mr. Murphy, the local authority's HHSRS assessment, and the mycological and medical reports of Dr Singh and Professor Richardson.”

“The single joint expert was jointly instructed on the condition of the Property, his report is agreed and unchallenged, and it is a sufficient basis for the findings I make as to present fitness.”

That passage is important for experts and lawyers alike. The expert’s role was to provide the factual and technical basis: observations, photographs, moisture readings, causes, risks, recommended works, costs and programme. The court’s role was to apply the legal test. Good expert evidence does not merely say “unfit” or “fit”; it gives the court the material it needs to decide that issue. Here, the judge used the building surveyor’s evidence to identify risk: risk from pervasive damp, risk of further mould growth, risk from a deflected and leaking ceiling, risk from damaged asbestos, and risk from other defects. That matters because the statutory test is not limited to occupants who can already prove injury. Occupants who are not presently ill can still rely on conditions that create a risk to health or safety, or conditions that seriously affect comfort and convenience.

“I have reached my conclusions on the present condition of the Property on the single joint expert's report alone”.

The judgment also shows why the questions put to an expert matter. If a party wants to argue that tenant conduct, lack of access, failure to ventilate, failure to heat, or failure to maintain something within the tenant’s responsibility caused the unfitness, that is not just a pleading point. It is usually an expert causation point. It needs to be pleaded, evidenced, and put to the expert in time.

Mr Badham’s evidence was not tentative or superficial. He did not merely record a high meter reading on a ceiling and infer that there might be a roof leak. He took readings throughout the rooms and roof spaces, identified gradients and moisture profiles, linked those readings to physical features such as defective chimneys, external walls, roof defects and valley gutters, described staining, blistered finishes, decayed timbers, a deflected and bulging ceiling, visible cracking, active water penetration, and the secondary asbestos risk created by the damaged textured coating. That is why the court could move from technical evidence about condition to legal conclusions about risk and fitness.

The lesson is not that every case needs multiple specialists. It is that a competent building surveying expert who explains the mechanism, extent, causation and likely consequences of defects can provide the evidential bridge the court needs. In this case, the judge was able to conclude that the damp and mould hazard, and the damaged asbestos/structural ceiling hazard, were each capable of making the home unfit without needing the claimant to prove a formal category 1 or category 2 hazard, and without needing to prove actual injury in the housing conditions trial.

Another mark of good expert evidence in the judgment is that Mr Badham was clear about the limits of his opinion. He identified where a matter might fall within tenant responsibility, such as closed trickle vents, filters, garden structures or maintenance issues, but he did not overstate their causal importance. He also left questions of legal responsibility to the court where the evidence did not allow him to decide them. The wood-burning stove is the clearest example: the expert identified the defect and advised that it should not be used without a HETAS registered engineer’s inspection, but recognised that whether the landlord had to replace it, remove it and make good the opening was a matter for the court. That is useful expert discipline: explain the technical issue, identify any factual uncertainty, separate tenant-like obligations from landlord defects, and avoid trespassing into the judge’s decision.

“However, the expert notes there is a dispute between the parties as to whether this is a tenant or landlord's fitting and there was no evidence before him (or me) to establish the position one way or the other. He advised that the stove should not be used without a HETAS registered engineer's inspection. He concludes 'whether the landlord is required to replace the appliance, to remove it and make good the fireplace opening' is a matter for the court.”

The judgment gives one of the clearest explanations of the amended section 10 test. The court started with the statutory wording. In deciding whether a dwelling is unfit for human habitation, regard must be had to its condition in respect of the familiar matters: repair, stability, freedom from damp, internal arrangement, natural lighting, ventilation, water supply, drainage and sanitary conveniences, facilities for preparation and cooking of food, and disposal of waste water. But for dwellings in England, section 10 now also requires regard to be had to “any prescribed hazard”.

That amendment is crucial. It means the fitness test is no longer confined to the older list of matters. It directly incorporates hazards prescribed under the Housing Act 2004 framework, including the HHSRS matters and circumstances. In this case, the relevant prescribed hazards included damp and mould growth, asbestos, structural collapse and falling elements, and domestic hygiene through rodent infestation.

Second, the addition of 'any prescribed hazard' in section 10(1) extends the matters that are relevant to the issue of fitness. Although there is clearly considerable overlap with the existing matters (e.g 'freedom from damp' and 'Damp and mould growth'), the addition addresses concerns that the list of 'matters' in section 10 was incomplete.”

The court described this as a deliberate, but partial, convergence between private law and public law housing standards. The private law claim remains a claim about fitness for human habitation under sections 9A and 10. However, the list of relevant matters now expressly includes prescribed hazards defined by reference to the Housing Act 2004 and HHSRS Regulations.

“Third, by including in the list of relevant factors 'any prescribed hazard' by reference to the terms defined in the HA 2004, there is a clear statutory intention to bring about a degree of convergence between the private law and the public law means of protecting tenants from substandard rented accommodation.”

The court then explained how the incorporation works. If one of the prescribed HHSRS matters or circumstances exists and presents any risk of harm arising from a deficiency in the dwelling, it is relevant to the court’s assessment of whether the home is reasonably suitable for occupation.

“If any of those 21 'matters and circumstances' exist and they present 'any risk of harm' within the meaning of the HA s 2(1) (above, paragraph 48), including temporary harm and harm to mental health, they are both a 'hazard' for the purposes of section 2(1) of the HA 2004 and a 'prescribed hazard' within the meaning of section 10(1) LTA 1985, as amended. Any such 'prescribed hazard' is relevant to the court's assessment of whether the property is 'so far defective in one or more of those matters that it is not reasonably suitable for occupation in that condition' and therefore unfit for human habitation under section 10(1).”

One of the most important points for practitioners is the distinction between local authority enforcement and a private law fitness claim. A local authority, when acting under the Housing Act 2004, assesses and categorises hazards. Enforcement duties and powers depend on whether there is a category 1 or category 2 hazard. But that is not the same test the court applies under section 10.

The court was clear that a tenant does not need to prove that a category 1 or category 2 hazard has been assessed as present before a court can find a home unfit. The court looks at the prescribed hazards as relevant matters within the fitness test. A local authority assessment of a category 1 or 2 hazard would be powerful evidence, but it is not a gateway requirement.

“Moreover, unlike the local authority when exercising its functions under the HA 2004 (above, paragraph 46), the court's power under section 10 does not depend upon a finding that there is a 'category 1' or 'category 2' hazard.”

“That said, a local authority assessment of a category 1 or category 2 hazard would be strong evidence of unfitness.”

This is a key message for landlords and solicitors. A defence strategy that treats HHSRS as if the claimant must prove a formal category 1 or 2 assessment risks missing the point. The question for the court is not whether the local authority has taken, or could take, enforcement action. The question is whether, considering the statutory matters and prescribed hazards, the dwelling is so defective that it is not reasonably suitable for occupation in that condition.

The court emphasised that the 2018 amendments did not replace the core fitness test. They expanded the relevant matters by adding prescribed hazards. The older authorities remain relevant because the central statutory language remains the same: the dwelling is unfit if it is so far defective in one or more relevant matters that it is not reasonably suitable for occupation in that condition.

“First, in assessing 'fitness' the same relevant matters ('repair', 'stability', 'freedom from damp' etc.) and test ('so far defective in one or more of those matters that it is not reasonably suitable for occupation in that condition') continue to apply as before the amendments, so that a property that was 'unfit' before would also be 'unfit' after. The core test in section 10 is carried over unchanged, and the older authorities on its meaning remain a reliable guide.”

The practical test is not whether the home is literally impossible to live in. Nor is it limited to cases of serious physical injury risk. A home may be unfit where conditions create a risk to health or safety, or where they have a sufficiently serious effect on comfort and convenience.

“In particular, Summers and Rendlesham remain good authority that fitness has two distinct components: premises may be not be fit if, first, the living conditions present a risk to the health or safety of the occupiers; and, second, the living conditions have a sufficiently negative effect on the occupier's comfort and convenience, even if there is no risk to health or safety. Nothing in the 2018 amendments displace that conclusion.”

That distinction matters. Fitness is a real-world assessment of whether the dwelling can be occupied for a reasonable period in its condition. It is not enough to ask whether the occupants can physically remain there. The court may consider health, safety, mental health, comfort, convenience and the cumulative effect of multiple defects.

The damp and mould findings were central. The expert found damp and mould in every habitable room and both roof spaces. Moisture readings were in the “wet” or saturated band across the property. The court connected those findings with the HHSRS Operating Guidance and noted that a dwelling should be watertight, weathertight and free of persistent dampness.

“Chapter 11 treats penetrating and rising damp, water ingress through defective rainwater goods, and dampness tracking through solid walls that lack an effective damp-proof course as core to the damp and mould hazard, and as matters of the condition of the structure. That is the mechanism the single joint expert describes and which I find: moisture entering through the defective chimneys, external walls and roof of this mid-nineteenth-century, solid-walled dwelling, the readings reaching the 'wet' or saturated band in every habitable room and both roof spaces. According to the Guidance a dwelling should be watertight, weathertight and free of persistent dampness (Appendix 1, baseline indicator 17.1). This Property is none of those things.”

The expert’s description of the mechanism was particularly important. He described moisture entering through the defective chimneys, external walls and roof, with readings reaching the wet or saturated band in every habitable room and in both roof spaces. The court treated that as a structural and building-performance problem, not simply an issue of visible surface mould. The presence of high moisture throughout the building fabric meant that the risk was continuing and systemic.

The landlord had advanced arguments about tenant behaviour, including possible lack of heating use, closed trickle vents and ordinary domestic moisture generation. The court did not say such matters could never have an impact. The point was that, on the accepted expert evidence, they were not a primary or significant cause. The defects for which the landlord was responsible were wholly or mainly responsible for the damp and mould. In other words, this was not a case where different tenant behaviour would have made the home fit: the building defects meant the property would have remained unfit anyway.

“While he cannot rule out that these failings may have contributed to the level of damp, he is clear that these are 'not ... a primary or significant cause' of the dampness and mould, given the evident defects and the construction”.

“That contention is at odds with the expert's evidence, which the First Defendant accepted”.

“I am satisfied that the damp and mould is wholly or mainly attributable to a combination of the limited thermal performance of the construction and active moisture ingress through the chimneys, external walls and roof due to defects or disrepair. These are the First Defendant's responsibility as landlord.”

The judgment is therefore a useful reminder that tenant lifestyle arguments need evidence. Normal domestic activities produce moisture. The question is whether the dwelling is capable of coping with normal occupation. Where building defects, poor thermal performance, moisture ingress or inadequate ventilation are the real drivers, the issue is unlikely to be answered by telling tenants to open windows or use heating differently.

The visible mould was described by the expert as generally light with localised moderate areas. The landlord relied on that. But the court did not treat the visible mould on one inspection day as the whole picture. The high moisture readings, seasonal worsening, and continuing risk of mould development all mattered.

“I accept that the mould observed on inspection was at the lighter end. But that goes to the severity and extent of one hazard on one day, not to the overall question of fitness, which must be considered in the round and over a reasonable period of time (Rendlesham, [68]). The finding must therefore be read with two other matters in mind. First, the moisture readings are so high that there is a continuing and substantial risk of further mould developing in all the habitable spaces. Secondly, the expert notes that internal conditions in autumn and winter would probably be less favourable”.

This is a point tenants and advisers should not miss. The court did not require the claimants to wait until mould growth became severe before they could be heard. The visible mould being “light” did not defeat the claim because the physical conditions created a real and substantial risk that it would develop and spread, particularly in colder months. The danger lay not only in what could be seen on the day of inspection, but in what the expert evidence showed the building was likely to do over a reasonable period of occupation.

“In conclusion, in my judgment, even if the mould in its present state is no more than minor there is a real and substantial risk that the mould will develop and spread given the damp conditions, particularly in winter.”

This is a particularly important evidential point. Fitness is not a snapshot test divorced from the building’s condition and likely performance over time. If the physical conditions create a continuing and substantial risk, that can support a finding of unfitness even if the visible manifestation is less severe on the day of inspection.

The judgment also gives helpful guidance on section 9A(3). A landlord is not liable for unfitness if the unfitness is wholly or mainly attributable to the tenant’s own breach of covenant. But the court described that as a high threshold. A tenant’s conduct being a contributing factor is not enough if it is only secondary.

“The s 9A(3) question concerns the attribution of responsibility for the premises being in an unfit state. Where the dwelling has become unfit for reasons 'wholly or mainly' attributable to a breach of the tenant's own obligations – including any express duty and the implied duty to use the premises in a tenant-like manner - the landlord is not liable under the implied covenant. The threshold is a high one, however: tenant default that is a real but secondary cause of 'unfitness' does not meet it.”

“So, for example, condensation mould wholly or mainly the result of the tenant's own failure to ventilate or heat the dwelling will defeat the claim; but the same mould, if mainly attributable to a defect that is the landlord's responsibility, such as inadequate insulation or the absence of effective ventilation, will not, even if the tenant's use of the dwelling has played some part in it.”

For landlords, that means tenant conduct arguments must be properly evidenced and must go to main causation. It is not enough to identify something the tenant could have done better, such as opening a trickle vent, using heating differently or managing day-to-day moisture. If the landlord’s defects are wholly or mainly responsible for the unfitness, section 9A(3) will not assist even if tenant conduct played some part. For claimant solicitors, it is a reminder to scrutinise whether the alleged tenant default is really the cause of unfitness or merely a secondary factor. For experts, it underlines the importance of clear causation evidence.

The court found that the property was unfit individually and cumulatively by reference to several statutory matters and prescribed hazards. Damp and mould was the most serious failing and was enough on its own. The court also considered asbestos in a damaged ceiling, structural collapse and falling elements, rodent infestation, drainage and sanitary conveniences, and heating issues relevant to damp and cold.

“Standing back, I am satisfied from my findings based on the single joint expert's report at paragraphs 12-33, above, that the Property is, as at the date I made my order (25 June 2026), unfit for human habitation. It is so far defective in several of the matters to which section 10(1) directs attention that it is not reasonably suitable for occupation in its present condition. Those matters include freedom from damp, repair, drainage and sanitary conveniences and a number of the hazards prescribed under section 2 of the HA 2004 and listed in Schedule 1 to the HHSRS Regulations, as amended, namely damp and mould growth, asbestos, structural collapse and falling elements (engaged by the deflected and bulging ceiling to Bedroom 1) and domestic hygiene (engaged by the rodent infestation). Each is incorporated into the fitness standard as a prescribed hazard.”

“I am satisfied that, individually and collectively, those matters render the Property not capable of occupation for a reasonable period without risk to the health or safety of the Claimants. I am also satisfied that, regardless of risk, those matters render the Property not capable of occupation for a reasonable period without the undue inconvenience or discomfort of the Claimants.”

On damp, the language was particularly strong.

“The levels of damp throughout the habitable parts of the house, recorded at paragraph 17 above, are, frankly, deplorable.”

“The damp is so widespread and pervasive that it not only compromises the comfort and convenience of the Claimants but is a risk to their health, including mental health, and a 'prescribed hazard' within the meaning of section 10(1) LTA 1985 for the reasons I give at paragraphs 22-23, above. In my judgment the extent and degree of the damp are sufficient to make the Property unfit without the need to consider any of the other relevant factors.”

The court’s approach to asbestos and structural movement followed the same evidential logic. The judge did not need a formal HHSRS category score to recognise the risk. The building surveyor’s evidence identified a deflected, cracked and bulging ceiling above a bed, active water penetration, decayed timbers above, and damaged asbestos-containing textured coating. Those facts were enough for the court to draw the legal conclusion that the asbestos hazard was sufficient, on its own, to render the property unfit until repaired or replaced.

“Bedroom 1 (the main bedroom): readings of 713 to 228 (pinless) in a descending gradient from the wall/ceiling junction down the wall with mould growth and staining, indicative of moisture ingress tracking from the central valley gutter junction above and condensation; readings of 999 (pinless) and flaking paint and blistered decorations, with staining to the head of the window, consistent with 'significant moisture saturation'. The ceiling to Bedroom 1, the main bedroom, is deflected and bulging as a result of moisture ingress with decayed timbers above which require cutting out with additional structural support where required”.

“Several videos of this crack were taken by the First Claimant during the evenings of 1st, 4th and 7th December 2025. I watched the video, taken on 1 December 2025, which showed visible ingress of water from the roof space above to the extent that water droplets were collecting and dripping every 10 seconds or so onto the floor below.”

The asbestos finding is also significant because the court treated the damaged asbestos coating to a cracked, deflected, leaking ceiling as a health, safety and mental health risk capable of rendering the property unfit on its own.

“A deflecting, cracked and bulging ceiling, carrying a damaged asbestos coating, above a bed, with water actively penetrating it, is an obvious and constant source of anxiety. Furthermore, the asbestos fibres thereby exposed are a not negligible risk: 'there is no threshold safe lower limit of exposure to asbestos' (above, paragraph 26). The asbestos therefore constitutes a risk to safety and to health, including mental health, and is a hazard that is sufficient, on its own, to render the Property unfit until it has been repaired or replaced.”

The court declared a breach of the section 9A covenant and ordered specific performance of identified remedial works. The power to order specific performance is expressly contained in section 9A(5), and the court was satisfied that damages would not be an adequate remedy because the claimants needed a habitable home.

“There is nothing oppressive or unjust in requiring the First Defendant to do that which the statute obliges her to do. Damages would not be an adequate remedy here: the Claimants need a habitable home and an award of damages would not secure the works. Specific performance is the appropriate remedy, and this is a proper case for such an order.”

However, the court refused the application for an order requiring the landlord to provide or fund temporary alternative accommodation on the evidence before it. That refusal was not a finding that a decant was unnecessary. The court held that the evidence did not establish the necessary entitlement at this stage, especially where the expert did not say vacant possession was required and issues about the occupiers’ vulnerabilities were for the remitted proceedings.

The central message of Harvey v Heaver is that fitness for human habitation is a practical, evidence-led assessment. The 2018 Act did not discard the older fitness test, but it did expand it by expressly incorporating prescribed HHSRS hazards into section 10. The court does not need a formal category 1 or category 2 finding. It must look at the condition of the home, the relevant statutory matters, any prescribed hazards, the risks to health or safety, and the impact on comfort and convenience, then decide whether the dwelling is reasonably suitable for occupation in that condition.

“Taking those matters individually and collectively I am satisfied the Property is not reasonably suitable for occupation and is unfit for human habitation as at 25 June 2026.”

Full judgement available here: Harvey & Ors v Heaver & Anor [2026] EWHC 1671 (KB) (03 July 2026) with thanks to the British and Irish Legal Information Institute (BAILII).