WONG HANG NEI GRACE v. CHOW YEW FATT AND ANOTHER

DCCJ 545/2023

[2026] HKDC 943

IN THE DISTRICT COURT OF THE

HONG KONG SPECIAL ADMINISTRATIVE REGION

CIVIL ACTION NO 545 OF 2023

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DECISION

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Introduction

1.  This is the application of the plaintiff (“P”) for leave to adduce expert evidence after a single joint expert has been appointed and an expert report has been rendered for the purpose of this case.

2.  By summons dated 7 January 2026, P seeks, inter alia, the following order:

(1)  Leave be granted to P to adduce the expert evidence on liability and quantum from Wong Koon Kou (“Mr Wong”) of Messrs Zeppelin Partners, a building surveyor, and to lodge the following expert reports with the court within 14 days:

(a)  Report by Mr Wong dated 8 June 2021 (“1^st Report”);

(b)  Supplemental Report by Mr Wong dated 2 July 2021 (“2^nd Report”); and

(c)  Report by Mr Wong dated 28 August 2023 (“3^rd Report”).

3.  Mr Pakco Chan, counsel for P, explained in his skeleton submissions that the 1^st to 3^rd Reports contain both factual and expert evidence. Insofar as the factual evidence is concerned, ie the tests, measurements, observations and photos taken by Mr Wong, no leave is required for them to be admitted as part of the evidence. The present hearing is only concerned with the opinion sections of the reports, namely, under sections 6 and 7 of the 1^st Report, section 2 of the 2^nd Report and sections 6 and 7 of the 3^rd Report.

4.  At the hearing, Mr Chan further indicated to the court that, for the purpose of this application, P is not seeking leave to call Mr Wong to give expert oral evidence at the trial.

Background

5.  This case concerns water seepage, and the facts can be briefly stated as follows.

6.  P is the owner of Unit K on the Second Floor of Step 3 (“P’s Flat”), Aegean Terrace, No 60 Sassoon Road (“Aegean Terrace”). The defendants (“Ds”) are the owners of Unit I on the Ground Floor of Step 2 (“Ds’ Flat”) of Aegean Terrace.

7.  Aegean Terrace was built on a slope such that the floor of D’s Flat is of the same level as the roof of P’s Flat. The roof above P’s Flat is divided into two portions: one portion was for P’s own use (“P’s Roof”), and another portion is Ds’ terrace (“Ds’ Terrace”). Adjacent to Ds’ Terrace is the terrace (“GH Terrace”) of Unit H on the Ground Floor of Step 2 and it is separated by a parapet wall.

8.  It is P’s case that since about 2017, water seepage was observed in the ceiling area of P’s Flat beneath Ds’ Terrace. Complaints were made to Ds in 2018, but the condition continued.

9.  P’s case is that the source of water seepage was D’s Terrace, and the cause of water seepage was the defective floor slab.

10.  Ds’ case is that they were also victims of water seepage from GH Terrace who erected a jacuzzi bath close to the parapet wall between Ds’ Terrace and GH Terrace.

11.  Ds further rely on the investigation of their own expert and aver that the source of water seepage could be the external wall, the damaged waterproof membrane (which they claim to be a common area and hence the liability of the Incorporated Owners), and/or the parapet walls between GH Terrace and Ds’ Terrace, or between Ds’ Terrace and P’s Flat Roof.

Mr Wong’s 3 reports

12.  In 2021, P engaged Mr Wong to investigate the source and cause of the water seepage. On 12 April 2021, Mr Wong took moisture content measurements and then carried out a dyed water ponding test at P’s own portion of the roof. On 15 and 30 April 2021, he took moisture content measurements and, upon inspection using a UV lamp, no sign of dyed water was observed. He then ruled out the source of water seepage to be from P’s own portion of the roof. Mr Wong then compiled the 1^st Report in which he set out his analysis of the data and made an assessment on the costs of rectification due to the water seepage.

13.  Due to heavy rain from 21 to 24 June 2021, Mr Wong was requested to revisit P’s Flat for measurement of moisture contents. He took the measurements on 24 June 2021 and compiled the 2^nd Report.

14.  Meanwhile, P made a complaint to the Joint Office of the Food and Environmental Hygiene Department (“FEHD”) / Buildings Department which appointed Multiple Surveyors Limited (“MSL”) to investigate the water seepage. After performing certain tests and measurements, MSL identified the source of water seepage in the ceiling of P’s Flat was water infiltration through the floor slab of D’s Terrace.

15.  Nuisance notice was issued by the FEHD to Ds on 24 June 2022 in which Ds were demanded to repair the floor slab within 28 days. According to Ds, upon receipt of the nuisance notice they did apply some waterproof material on the area of Ds’ Terrace where MSL conducted ponding tests, but they did so without admission of liability.

16.  P commenced the present action on 13 March 2023. After Ds served their Defence, P engaged Mr Wong again for assessment of damages. Mr Wong inspected P’s Flat on 23 June 2023 and compiled the 3^rd Report.

Report of the Single Joint Expert (“SJE”)

17.  Upon the joint application of P and Ds by way of a consent summons, by an order dated 24 September 2024, Madam Registrar Soong gave leave to the parties to adduce expert evidence from a building surveyor, who is a single joint expert for the parties in this action, on liability and quantum in relation the following issues:

(1)  Whether P’s premises are still suffering from water seepage problem;

(2)  The sources / cause of water seepage …

(3)  Any observation or comments about P’s suggestion that the original areas of water seepage have already ceased in particular whether the cessation or improvements of the problem was due to P’s alleged renovations / repair works that had been carried out by Ds (which Ds denied) or due to those carried out to the water channels on D’s flat roof by the management company as alleged by Ds;

(4)  If Ds’ property is identified to be the source / cause of seepage, what rectification works shall be done by Ds in order to rectify the situation;

(5)  The damage to P’s property as a result of the water seepage;

(6)  The repair works required to reinstate P’s property and the reasonable cost thereof.

18.  By a joint letter dated 10 February 2025, the parties jointly instructed Mr Lam Wai Keung, Andrew as the SJE to prepare a report on the aforesaid issues. The 1^st to 3^rd Reports of Mr Wong were provided to the SJE under items 16 to 18 of the enclosures, and MSL’s report was provided under item 21 of the enclosures.

19.  The SJE inspected the relevant properties in March 2025 and carried out several tests and analyses of data in September 2025. He then issued a report dated 25 November 2025 (“SJE Report”) in which he gave his opinions on the cause of water seepage and quantum.

P’s application

20.  P made the present application on the ground that there is a “fundamental problem” or “fundamental flaw” in the SJE Report that his opinions on both the cause of water seepage and quantum of the loss were solely based on his own tests and observations in September 2025, and he failed to consider or analyse the factual evidence for the critical record, ie 2017 to July 2022, which is the period of claim under the Statement of Claim.[1]

21.  Mr Chan argued that because of the SJE’s failure, the SJE did not consider the fluorescent dye test of the rainwater discharge / outlet pipe system of D’s Terrace in August 2018 and the ponding test result in 2022. It is said that due to the SJE’s failure, it is “plainly necessary to admit Mr Wong’s reports as expert evidence as Mr Wong’s reports would be relevant on the then situation between 2021 and 2023.” [2]

Ds’ opposition

22.  Ms Margaret Chan, counsel for Ds, set out in her submissions that Ds’ opposition to the present application is based on 5 grounds.

23.  Firstly, it is argued that contrary to what is stated in the summons, Mr Wong is not a building surveyor, but a quantity surveyor. P relies on Mr Wong’s CV which sets out a number of cases in which he served as an expert. However, a search on the Legal Reference System showed that none of the cases concerned water seepage. It is therefore submitted that P has failed to show that Mr Wong has the suitable qualifications and expertise to give evidence on liability in the present action.

24.  Secondly, Ds pointed out that Mr Wong’s 3 reports do not contain the requisite statement of truth under Order 38, rule 37A and a declaration on the code of conduct under Order 38, rule 37C of the Rules of the District Court. Ds argue that the opinion sections of Mr Wong’s 3 reports are therefore inadmissible and the application should be dismissed on this ground alone.

25.  Thirdly, Ms Chan argued that there is a lack of probative value in Mr Wong’s opinions concerning the source of leakage because of the following.

(1)  For the 1^st Report, Mr Wong only conducted a water ponding test within P’s Roof and he observed no sign of fluorescence dye in the ceiling of P’s Flat. He therefore concluded that there was no leakage from the P’s Roof. But he did not stop there. In section 6 of his 1^st Report, Mr Wong commented that “in the absence of further test, water seepage through the external wall cannot be eliminated. Yet the presence of stain mark above window head and may lead to the thoughts that there are (sic) seepage through the external wall”. However, he went on to “conclusively” provide a “considered judgment” that there was water seepage from D’s Terrace and/or the joint of the external parapet wall of D’s Terrace without conducting further tests to eliminate the possibility of seepage through the external wall.

(2)  For the 2^nd Report, only visual inspection and moisture content measurements were carried out by another staff member, not Mr Wong. The opinion section stated that water seepage was worsened after heavy rainfall, and that reinforced his “considered judgment” in the 1^st Report. It is argued by Ds that the source of water seepage which could have been the external walls and defective window sealants and Mr Wong failed to consider those possibilities.

(3)  For the 3^rd Report, only visual inspection and hammer tapping test were conducted. Mr Wong simply adopted the findings of MSL without any analysis and elaboration.

26.  Fourthly, Ms Chan submitted that Mr Wong’s Reports could be admitted as factual evidence, but it is unnecessary to admit them as expert evidence. The SJE did not address the findings in Mr Wong’s Reports and MSL’s investigation results because he was not asked to do so in the Joint Letter of Instructions. If any party finds it necessary for the SJE to deal with those matters, the proper way is to seek clarifications or elaboration from the SJE rather than making the present application.

27.  Fifthly, it is noted that the opinion sections of Mr Wong’s reports do not only contain his opinion on the source of water seepage, but also his then estimates on the likely costs that would be required to repair the damage caused by the water seepage. While Ds do not seem to question Mr Wong’s qualification to give such estimates as he is a quantity surveyor, their objection is premised on the fact that those estimates are no longer valid or relevant. This is because P has already carried out certain rectification works to P’s Flat prior to the inspection of the SJE. Ds submitted that if there is any need to assess damages, the SJE can be asked to comment and assess any expenses actually incurred in such rectification works instead of relying on the estimates made by Mr Wong back in 2021 and 2023.

Relevant legal principles

28.  The relevant legal principles regarding obtaining further evidence after a SJE is appointed is set out by Recorder Lisa Wong (as she then was) in Daimler AG v Leiduck (re: expert evidence) [2014] 3 HKLRD 56 and they can be summarised as follows:

(1)  The appointment of a SJE did not bar a party from seeking leave to instruct its own expert to challenge the SJE’s evidence or aspects thereof. Leave would be granted if, on balancing all relevant considerations, it is just and accorded with the underlying objectives of the CJR: §§32-33.

(2)  The relevant factors for the court to consider the application include but are not limited to the following:

(a)  the nature of the dispute;

(b)  the number of disputes on which the expert evidence was relevant;

(c)  the reason for requiring the second report;

(d)  the amount at stake or the nature of the issues at stake;

(e)  the effect of permitting a second report on the conduct of the trial;

(f)  the delay in making the application;

(g)  the delay that might be caused in the conduct of the proceedings;

(h)  any other special features;

(i)  the overall justice to the parties;

(j)  whether the SJE’s report could be challenged by cross-examination without the need for a further report; and

(k)  whether the parties had already engaged own-party experts: §§34, 38.

(3)  With regard to the reason for requiring own-party expert evidence, additional expert evidence may be permitted where the dissatisfied party’s reasons for wishing to adduce such evidence are “not fanciful”, particularly if the other considerations also point to own-party expert evidence being appropriate: §§35-36.

29.  While these principles are apposite to the question of whether a party should be allowed to adduce further expert evidence, one must not lose sight of the more fundamental principles relating to the admission of expert evidence in general.

30.  In particular, the threshold test for admitting expert evidence is that the proposed evidence must be both relevant and necessary, it should not be admitted simply because the court cannot rule out a possibility that the proposed expert evidence may turn out to be relevant and helpful. Further, the lack of probative value in the proposed evidence is a factor to be taken into account in the court’s exercise of case management power in furtherance of the underlying objectives of the CJR, including the need to avoid unnecessary time and costs to be spent: Shenzhen Futaihong Precision Industry Company Ltd v BYD Company Ltd [2019] 2 HKC 175 (Court of Appeal) at §§4-12.

31.  With these principles in mind, I now to turn consider the merits of the present application.

Whether leave should be granted

Qualification of Mr Wong

32.  It is now clear that Mr Wong is a quantity surveyor, not a building surveyor. What is stated in the summons is clearly a misdescription and is wrong.

33.  While there is no dispute that Mr Wong may possess the qualification to give opinions on quantum in relation to repair works (given he is a quantity surveyor), Ms Chan argued on behalf of Ds that it is questionable if Mr Wong is qualified to give evidence on the source and cause of water seepage in this case. This is because parties have already considered and agreed that a building surveyor is the most suitably qualified to assist the court on the issues on liability and quantum, and therefore directions for expert evidence were sought to appoint a building surveyor as the single joint expert.

34.  In my view, Ds’ objection in this regard is a valid one. As a matter of common knowledge, a building surveyor is one specialised in the physical, technical and structural condition of buildings, whereas a quantity surveyor focuses on the material and financial costs of construction projects. In water seepage cases, it is often a complicated exercise to identify the source(s) of water seepage. To achieve any reasonable degree of confidence in this exercise often requires a careful study of the physical and structural conditions of the relevant properties. As Mr Wong’s expertise is in the material costs of construction, it is reasonable to doubt if he is competent enough to render opinions on the source and cause of water seepage.

35.  Mr Chan cited the case of Lai Tun Yu v Ng Hung Ming as the Executor of the estate of Lau Ying Hing, Deceased & Another [2025] HKDC 2132, where the expert in question was neither a registered professional surveyor nor a member of the Hong Kong Institute of Surveyors. I held that his evidence would not be considered inadmissible solely because of his qualifications. But it should be pointed out that in that case, no objection was ever made to the appointment of that person as a party’s expert, a number of joint reports have been prepared with the other party’s experts and his qualifications were only called into question at the trial.

36.  As mentioned above, Ds through their solicitors conducted a search on the Legal Reference System and could not find a water seepage case in which Mr Wong served as an expert on liability. In response, Mr Chan belatedly attached to his supplemental submissions[3] excerpts of 4 expert reports to demonstrate that Mr Wong has served as an expert on liability and quantum in water seepage cases before the High Court and the District Court. However, for present purposes I do not think those cases take P’s position much further, as it is unclear to what extent his expert opinions were accepted by the court. The fact remains that, on paper, his expertise is not directly relevant to the issue of liability, and it is a factor which ought to be taken into account when considering whether the court should accede to P’s application.

Statement of truth and O 38 declaration

37.  Order 38, rule 37A and Order 41, rule 2 stipulate that an expert report “must” be verified by a statement of truth. Order 38, rule 37C(1) makes it clear that an expert report is not admissible unless the report contains a declaration by the expert witness that he has read the code of conduct set out in Appendix E and agrees to be bound by it, that he understands his duty to the court, and he has complied with and will continued to comply with that duty (“Declaration”).

38.  There is no dispute that Mr Wong’s 3 reports do not contain the statement of truth or the Declaration. Under Order 41A, rule 2, the court may direct that an expert report need not be verified by a statement of truth if it considers that it is just to do so in a particular case. But the court has no discretion to dispense with the expert’s Declaration under Order 38, rule 37C. Ms Chan submitted that P’s application to adduce Mr Wong’s reports should be dismissed on this ground alone.

39.  Ds through their solicitors pointed out this issue in their affirmation in opposition dated 31 March 2026.[4] But P did not deal with this whether in the affirmation in reply dated 23 April 2026 or Mr Chan’s skeleton submissions. It was only mentioned in Mr Chan’s supplemental submissions that Mr Wong would provide the requisite statement of truth and Declaration once leave to adduce his 3 reports is granted by the court.

40.  At the hearing, Mr Chan submitted that the lack of statement of truth and declaration is a defect that could be rectified retrospectively. However, no authority was cited in support of this proposition. The only authority before the court is Hing Yip Holdings (Hong Kong) Ltd v Cellmark China Ltd [2020] 3 HKLRD 821, a case cited by Ms Chan, where the plaintiff applied to exclude the reports of the 2^nd defendant’s expert on the ground that they did not contain any signed statement of truth nor Declaration. Mimmie Chan J dismissed the application and allowed the 2^nd defendant to rely on the expert reports, subject to the expert’s signing and filing the statement of truth and Declaration before he continued to give evidence at trial. Mr Chan therefore submitted that the omission of the Declaration was a formality which could be rectified retrospectively.

41.  In considering this issue it is important to bear in mind the purpose of the requirement under Order 38, rule 37C. As Mimmie Chan J said in Hing Yip Holdings at §5, the purpose is to remind the expert preparing the report that his duty to assist the court overrides any obligation to the person from whom he has received instructions. As such, the requirement is not one of formality. Rather, it goes to directing the mind of the expert to act impartially and independently when he/she is preparing the expert report and, if and when he/she comes across any matter which is against the client’s case, the expert is fully aware that he/she has an overriding duty to assist the court and must act accordingly.

42.  Thus, in my view, whether the absence of the Declaration can be rectified retrospectively depends on whether the purpose of the rule is satisfied. This in turn depends on the circumstances under which the Declaration was omitted. For instance, if an expert received the code of conduct upon instruction, agreed to be bound by it, and complied with his/her duty to the court when preparing the evidence, the omission may be deemed inadvertent, and no real prejudice was caused. Under such circumstances, it would be appropriate to allow the defect to be rectified retrospectively.

43.  It seems to me that Hing Yip Holdings is an example of such a case. As rightly pointed out by Ms Chan, the learned judge allowed the 2^nd defendant to rely on the “defective” expert reports on the grounds that (1) the application to exclude those reports was only made during trial when the expert was called to give oral evidence, (2) the expert did sign a statement of truth and the Declaration in the joint report, and (3) there was no real prejudice to the plaintiff. I also note that in that case, the reports in question were prepared after the commencement of the proceedings and the final report was dated shortly after the joint report. When the expert was cross-examined, he did confirm that he had read the code of conduct at the time when he was appointed as the defendant’s expert, and that he knew he had to comply with the rules of the court. These facts are clearly distinguishable from the present ones.

44.  Here, the 1^st and 2^nd Reports were prepared nearly two years before the commencement of this action. There is no suggestion that Mr Wong was given a copy of the code of conduct prior to his engagement, as required under Order 38, rule 37B. Furthermore, no evidence shows that when preparing his reports, he intended for them to be adduced as expert evidence, or that he recognised his overriding duty to assist the court impartially and independently. Mr Wong’s current willingness to sign a Declaration—should the court grant P’s application—is far from satisfying the core purpose of Order 38, rule 37C. As such, I do not think the absence of the Declaration can be rectified retrospectively in the circumstances of this case.

45.  Therefore, I agree with Ms Chan’s submission that P’s application to adduce Mr Wong’s reports should be dismissed on this ground alone.

Reason for the 3 reports and necessity

46.  If I am wrong in the above discussion, it seems to me that this application is in any event misconceived and should be dismissed. This is because granting leave to P to adduce Mr Wong’s 3 reports would not address the so-called “fundamental flaw” of the SJE Report.

47.  As noted above, P now founds her application on the SJE’s failure to consider or analyse the factual evidence and test results from 2017 to July 2022. As the relevant reports were already attached to the joint letter of instructions, the natural and more appropriate remedy for this alleged “fundamental flaw” is to seek further opinions or clarifications from the SJE on such factual evidence and test results. This was suggested in Ds’ affirmation in opposition but was ignored by P. Alternatively, as Mr Chan has rightly pointed out, the factual evidence in the 3 reports (ie the tests, measurements, observations and photos taken by Mr Wong) is already admitted as part of the factual evidence. It would be open to P’s counsel to cross-examine the SJE or challenge his opinion based on such factual evidence. In any event, adducing the opinion sections of Mr Wong’s 3 reports as expert evidence will not solve the problem – the situation remains that there is an alleged lack of analysis from the SJE on the factual evidence and test results from the period in question.

48.  Mr Chan in his supplemental submissions argued that P cannot seek further clarification or opinions from the SJE. This is because due to certain mistake or oversight of the parties, when they sought directions from the court to appoint a SJE by way of a consent summons, they omitted to include a direction for the SJE to comment on the past factual evidence and test results. Given the expert directions as they are, the SJE could not further expand or clarify his opinion on what the source or cause of water seepage was, as this would be outside his scope of instruction and the scope of the court’s order.

49.  I cannot accept such an argument. There is nothing to prevent the parties from seeking further directions from the court for the SJE to expand his opinion and to cover the previous test results. While the parties would incur additional costs in seeking such directions and instructing the SJE, it is difficult to see how P’s current application offers a more cost-effective alternative. Most importantly, P’s application completely fails to address the SJE’s alleged lack of analysis.

50.  Regarding Mr Wong’s opinions on quantum in the 1^st and 3^rd Reports, the issue is now academic as P has already carried out rectification works to her premises. I agree with Ds’ submissions that if damages must be assessed, the SJE can be directed to review and assess the expenses actually incurred, rather than relying on the speculative estimates made by Mr Wong in 2021 and 2023.

51.  Mr Chan argued that Mr Wong’s estimates could assist in the apportionment of quantum if the court ultimately finds multiple sources of water seepage. I cannot accept this submission. Mr Wong’s estimates contain no apportionment, and his “considered judgment” was that the Ds’ Terrace was the sole source of water seepage. Consequently, it is difficult to see how his estimates would assist the court in apportioning quantum.

52.  In conclusion, I am not persuaded that the reason for adducing the 3 reports of Mr Wong is “not fanciful”. Further or alternatively, I am not satisfied that it is necessary to adduce the opinion sections of the 3 reports as expert opinion.

53.  For completeness, I have also considered the remaining factors set out in Daimler AG, but I do not find that any of them materially affect the merits of the present application.

Disposition

54.  In view of the foregoing discussion, this application should be dismissed.

55.  At the hearing, Ms Chan indicated that should the court dismiss the application, Ds would be amenable to discussing and agreeing on a set of directions for the SJE to comment on the historical factual evidence and test results. I trust that the parties will act sensibly and exercise their best endeavours to conduct this case in an expedient and cost-effective manner.

56.  As regards costs, Mr Chan argued that the current situation was caused by a mistake on the part of both parties when they sought the expert directions by consent. Hence, he proposed that if the court is not with P in this application, there should be no order as to costs.

57.  I cannot accept this submission. P made no attempt to discuss with Ds on how to address the alleged lack of analysis in the SJE Report before issuing this application. Even after Ds indicated in their affirmation in opposition that P could have requested a joint letter to the SJE to seek clarification, P ignored this proposal and persisted with the present application, which is misconceived in any event. Under these circumstances, I see no reason why costs should not follow the event.

58.  Ds filed a statement of costs for summary assessment. Mr Chan commented that the amount stated is excessive and the court should only allow half of the sum being claimed.[5] Using a broadbrush approach and having regard to the nature of the application, I take the view that a sum of HK$80,000 is appropriate.

59.  I make the following orders:

(1)  P’s application is dismissed;

(2)  P do forthwith pay Ds the costs of and incidental to this application, with certificate for counsel, summarily assessed at HK$80,000.

60.  I thank counsel for their assistance.