BUILDING SURVEY REPORT for 18th 19th and 20th century building in Hong Kong

BUILDING SURVEY REPORT

April, 2012

Consultant:

CMM Conservation Consultant Inc.

HERIOT WATT UNIVERSITY School of the Built Environment – MSc/PgDip in Construction Management & Surveying

Module: D31BX Building and Contextual Investigation

P. 2 / 24 Student: Mak Chi Man (H00118235) Assessment: 2012 (Assignment2)

TABLE OF CONTENT

ITEM DESCRIPTION PAGE


1.0 INTRODUCTION

1.1 Instructions 4

2.0 BUILDING TYPE 1: 18th Century

2.1 Description of Property 5

2.2 Common defects and typical locations 6

2.3 Suitable investigative approach for defect 7

2.4 Pro’s and Con’s of investigative technique 7

2.5 Suggested repairs intervention 8













5.0 CONCLUSIONS & RECOMMENDATIONS

5.1 Conclusions 19

5.2 Recommendations 20

6.0 PERSONAL REFLECTION 22

7.0 REFERENCE 24

APPENDICE








1.0 INTRODUCTION

1.1 Instructions

CMM Conservation Consultant Inc. was employed by TF Properties Ltd. to conduct

building survey and advise on common defects identified associated with the

architectural 3 periods (18th century, 19th Century and 20th Century building).

Suitable non-destructive and destructive techniques will be proposed to identify the

defects. Pros and cons of the proposed technique will be discussed. The most suitable

repair and remedial work to such defects will be proposed and adopted.

At the end of this report, a summary of the survey and recommendation will be made

for the “due diligence”. Hence the investment option will be concluded.




2.0 BUILDING TYPE 1: 18th CENTURY

2.1 Description of Property

Nga Tsin Wai Tsuen Walled Village gatehouse was situated at the said village located

at the turning corner of Kai Tak River with Tung Lung Road and Tung Kwong Road

on both sides, San Po Kong, Kowloon, Hong Kong. Nga Tsin Wai Village is a walled

village established by three clans, Chan clan, Lee clan and Ng clan.

It is believed that the Walled Village was built in Ming Dynasty. In the early Qing

Dynasty, the Qing government forced the population to withdraw inland about 17

miles from the coast to stop their collusion with the Ming loyalist Cheng chenggong

in Taiwan. Members of three clans returned to Kowloon City and rebuilt their village

in the 2nd year of Yongzheng era (1724) in the Qing Dynasty. The gatehouse at the

entrance of village with the entire village surrounded by moat and a drawbridge for

access, reflecting the high security system it once possessed.

The Gatehouse and Tin Hau Temple are the most outstanding buildings of the village.

Their location along the central axial lane, which is the main access of the entire

village, reflected their significance.

The Gatehouse is a one-hall two-storey building of one jian in width. The entrance

wall is very thick, of around 1.3 meter thick for security reason. It has a granite door

surround.




Walled village is a kind of traditional building which is completely surrounded by

thick defensive walls, protecting the residents from the attack of wild animals and

enemies. Usually, people living in the walled village are extended families or clans

sharing the same surname. Gatehouse is usually constructed for security aspect of the

clans. Walled villages can be found in mainland China and Hong Kong. Nga Tsin Wai

Village in San Po Kong is the one of the few walled villages left in the urban built-up

areas of Hong Kong.

2.2 Common defects and typical locations

The structure of the gatehouse was made from granite and masonry with paint finish

on plastered substrate. Some loosen plaster found at the lowest outer corner of the

semi-circular archway.

It found that a crack developed at outer boundary edge of wall of the gatehouse. It is

the party wall to neighbor building. It seems some plaster work have been applied

before to cover the crack, however it could not successfully terminate the crack

development.

Some painting had been peeled off and showed sign of dampness problem over the

exterior wall.




2.3 Suitable investigative approach for defect

The loosen plaster should be tested by hammer tapping to identify whether the plaster

was broken by external forces or by the inferior deterioration such as plaster

workmanship or material failure.

Crack appearing at the outer boundary edge may be suspected be the structural crack

when uneven distributed load or movement applying. It is proposed to conduct glass

tell-taler survey to monitor crack movement prior remedial action to be taken.

For the painting peeled off and fungi development, the common cause is the damping

problem at this case. It is proposed to conduct visual investigation to identify the area

of damping.

2.4 Pro’s and Con’s of investigative technique

By the hammer tapping test is an easy approach to test the condition of surrounding

plastering. It help us to identify whether a continuously developed or locally formed

of the loosen plaster. It involves the experienced and trained personel belongs with

tapping rod to complete the test. By sound generated by vibration during tapping,

result obtained effectively and immediately after test. However, hammer tapping test

relies on the experience of testing personnel and sometimes be a subjective judgement.

Even though two experienced person may advise a different interpretation of the

sound and lead to a dispute.




Glass tell-taler test is the simplest and cheapest crack-monitoring device. The initial

reading records and periodically checks for deviation vertically and horizontally. But

it is limited by lack of any calibration and vulnerability to external damaging. It also

takes long time to acquire data.

Visual inspection for fungus development area is easy, direct and no special

equipment involvement. However, result is highly tolerated and rely experience and

knowledge of inspector and moderate risk on accuracy by human error.

2.5 Suggested repairs intervention

For the plaster repairing, it is suggested to ensure a sound substrate prepared. Remove

all local and surrounding defective plaster to identify the de-bonding condition. The

proprietary repair mortar is suggested to make good the plaster. For those substrate

defects identified, it is recommended to seek structural engineer’s advice to repair the

structural substrate.

Re-pointing to the crack is the primary recommendation provided that it is not as

worse as structural failure threatening. Proprietary product should be used in this case

to ensure a proper bonding to be resulted in the structure. Periodic monitoring is the

key issue to identify effectiveness of remedial work.

It is proposed to remove all existing painting and repaint with anti-mound and

anti-fungus function.






St. Joseph Chapel was located in Yim Tin Tsai Island, Sai Kung, Hong Kong. This

chapel was completed and blessed 1890. The chapel has all along been playing a

major role in defining the principal character of the Yim Tin Tsai being a Roman

Catholic community and differentiating it from the majority of the rural communities

in Sai Kung which are villages believing in traditional Chinese deities.

St. Joseph’s Chapel was the sixth chapel in the Sai Kung area. It is of the typical late

19th century rural New Territories style Roman Catholic chapel and is very well

preserved. It is believed that it was designed by an Italian priest because its

architectural style is close to Italian Romanesque.

The Chapel measures 24m x 9m which is a massive structure compared to the rest of

the buildings on the island. It is surrounded by a ram-earth wall which is still visible

nowadays.

There were colourful stained glassed on the original windows of the Chapel, but they

were replaced by ordinary glasses during the major renovations in 1948 and 1962. In

the recent refurbishment completed in April 2004, stained glasses are used on the

Chapel’s window once again.

For more than a century, St. Joseph’s Chapel has been the most prominent landmarks




of Yim Tin Tsai, signifying the influence of not only the Roman Catholics, but also

the villagers themselves in creating the character of the cultural landscape.


The old roof of the Chapel had been removed and replaced by corrugated metal sheet

panel to simulate the original pitched roof. It found some water stain appearing at the

interior wall just neighborhood of the roofing support frame. Some mould developed

and found at the structural beam of the chapel.

The structure of the St. Joseph’s Chapel was made from brickwork and masonry with

paint finish on plastered substrate. Some painting had been peeled off and cracks

could be found at the lowest corner of column.


It is quite common the joint between different materials (metal framework connected

to masonry wall) may not adhere very well and form a weak point during rainy day. If

the nail connection for corrugated sheet to metal frame not be sealed very well. Water

may come and appear through the weak point. For the suspected leakage of roof, it

may use Infrared scanning technique to identify the ingress of rainwater.

For the cracking at the bottom of column, it may be the sign of substrate deterioration




or loosing rendering. It should hammer tapping test to identify the developed

defective area.

For the painting peeled off, it is proposed to conduct visual investigation.


Infrared scanning was a common tool to diagnose defects. It can be known as Infrared

thermography which utilizes an infrared imaging camera that can “see” and “measure”

the invisible heat energy that is emitted by the building components and produce

thermal images (called thermograms) that can identify and document a wide variety of

problems that may not be visible to the naked eye. It makes the diagnose easier

because the test can be conducted at a remote location with lease additional assistance

in terms of manpower or tools.

At the infrared scanning test, one important element is that the tested wall should have

adequate heat soak. Otherwise, no significant result can be obtained since the

temperature variety is too little to be determined. Though the thermography shows a

significant thermal difference for an area, cannot be determined as leakage. It is

because all findings should be treated as suspected defective area for further

investigation only.

By the hammer tapping test is a easy approach to identify latent defect for the

cracking wall surface. It involves just an experienced and trained personel belongs




with tapping rod to complete the test. By sound generated by vibration during tapping,

result obtained effectively and immediately after test.

However, hammer tapping test relies on the experience of testing personnel and

sometimes be a subjective judgement. Even though two experienced person may

advise a different interpretation of the sound and lead to a dispute.

Visual inspection was a simple and the easiest approach to identify simple defect. It

requires inspector with fundamental knowledge on building technology or even

though an semi-experienced person. However under visual inspection, only the top

surfaced condition can be observed. It may neglect if any latent defect underlying at

the substrate of the wall or structure.


For the roofing leakage, it should ensure the watertight at all the construction joints

especially the joints facing upward of the roofing system. It is proposed to refill all

sealant to the anchor bolt for fixing the corrugated sheet to the metal frame. Proper

sealant should be selected so that it is suitable to be used outdoor with durable and

anti-UV behavior.

For the cracking repairing at bottom of column, it is suggested to remove all local and

surrounding hallow rendering to identify the de-bonding condition. If the crack

generated simply by poor workmanship or material, proprietary repair mortar is




suggested to make good the render. For those substrate defects identified, it is

recommended to seek structural engineer’s advice to repair the structural substrate.

Proper shoring and temporary support may be involved depending on actual need.

For painting peeled off, loosing paint should be scrapped and removed until the

plastered surface. Appropriated new painting should be selected so that no harm to the

original painting. Painting colour should be carefully chosen to match the existing

one.






Stone Houses comprises a row of five continuous units, namely 31 to 35 Hau Wong

Temple New Village was located in Junction Road and at north west of Hau Wong

Temple in Kowloon City.

The Stone House are Chinese style tenement buildings and they were built on the

foundations of “Ho Ka Yuen” which literally means “The Ho Family Garden”

possibly during 1941-1945.

When the Japanese Army invaded Hong Kong in 1941, they had the ruins of Ho Ka

Yuen Housed demolished down to lower courses of bricks just above the foundations.

They divided the Ho Ka Yuen area into some eleven cottage-sites in two rows with a

courtyard between. These cottages thus occupied exactly the same site as the old Ho

Ka Yuen House and part of them formed the Stone Houses. They were mostly

two-storey pitched-roof of timber rafter, purlins and clay tiles with log joists in

Chinese style. Yet, part of those original tiles was replaced with corrugated sheets.

Internal staircase is constructed by timber.

The external load bearing walls and the internal party walls are constructed of granite

blocks, jointed with cement sand mortar and rendered with plaster on the interior.

There are concrete lintels above the door and window openings.




In 1951-1952, Stone Houses were repaired and let to newcomers fleeing the civil war

in China. Due to the urban development of Kowloon City, Stone Houses was cleared

in 2001.


There are signs of dampness at the lower portion of some external walls. The dark

colour jointing mortar indicates insufficient damp proof treatment.

In view of signs of serious water leakage to most of the roof soffit and rots on roof

joists, it is anticipated that there are detached and loosen roof tiles with defective

bedding which result in rain penetration and dilapidation of the roof structure.

However, except dampness problem, termite attack was found in timber component

due to high moisture condition.

Spalling concrete with rusty bars exposed at the soffit is found at some reinforced

concrete beams on 1/F.


It is effective approach to identify the latent source and pathway of water leakage

pattern by ultrasonic moisture test. It is a kind of moisture detection technique which

the detect pointer not just detect the surface moisture content, but also 25mm, 50mm,




75mm or 100mm inward from surface. We may capture the simulated pattern at each

depth layer hence chase the weak point causing the leakage.

To diagnose the termite attack of roof timber structure, the primary method is the

visual inspection, hammer tapping and even touching by hand. Insect attacks show

normally typical features, such as galleries on or in the wood developed by termites or

holes made by beetles, and so on. In the case, live adult insects, pupae, larvae or eggs

are found, the insect attack can be judged as progressive.

For the spalling concrete at interior, it may be the sign of substrate deterioration or

loosing rendering. It should hammer tapping test to identify the developed defective

area.


Before ultrasonic moisture test, a pre-determined and evenly distributed grid line (or

marked as dot) will be marked on the wall. Each reading coming from moisture detect

pointer in different depth would be input to the computer to generate a comprehensive

simulated the water pattern for accurate judgement for leakage point. However, the

process is very time-consuming and costly.

Visual inspection for termite attack is easy, direct and without involvement of special

equipment. However, the result is very depending on the experience and knowledge

of inspector and moderate risk on accuracy by human error. The judgement, should




also include whether the timber degradation is progressive or not. It is very important

but sometimes hard to be classified.

However, hammer tapping test relies on the experience of testing personnel and

sometimes be a subjective judgement. Even though two experienced person may

advise a different interpretation of the sound and lead to a dispute.


For the dampness of wall , it should ensure the watertight from the exterior rendering

with least gaps between roofing system and window frames. It is proposed to

re-render by proprietary waterproofing render instead of ordinary cement/sand render

to enhance durability with waterproof behavior.

To mitigate the termite attack and maintain stability of the structure, it is suggested to

employ professional pest control contractor to apply control method to the defective

area. It is aim to mitigate the root cause to prevent termite attack spread for further

damage. Periodic inspection is needed to continuously monitor the development of

termite. After the termite mitigation, strengthening action may be taken and seek

structural engineer’s advice is recommended. The termite mitigation is just a passive

action to control the growth of termite. It is most important to cure completely for

moisture accumulation such as leakage problem and humidity control.

For the cracking repairing soffit of 1/F decking, it is suggested to remove all local and




surrounding loosen concrete. De-rusting is an important process to avoid degrading of

substrate. Proprietary repair mortar is suggested to make good the substrate. For those

serious structural damage, it is recommended to seek structural engineer’s advice to

strengthen the structure. Proper shoring and temporary support may be involved

depending on actual need.




5.0 CONCLUSION AND RECOMMENDATIONS

5.1 Conclusion

3 different architectural period properties namely Gatehouse of Nga Tsin Wai Village,

St. Joseph’s Chapel and Stone Houses are selected and intended to purchase. Brief of

properties’ historical background, architectural features, building material and

decorative elements are assessed and described for general reviewing.

Defects are identified for those building. Leakage and damping problem are most

commonly found from those properties. They appears mainly at the roof structure and

external wall. Secondly, spalling concrete and loosen plaster are also the similar

symptom from those 3 different architectural period of building.

Destructive and non-destructive tests are discussed. Among them, it is commonly and

primarily to conduct visual inspection since its quick and inexpensive approach to

identify the defects which is an important approach for universal condition required

different skill and knowledge of inspector. Ultrasonic moisture test and infrared

scanning are proposed for detection of leakage and seepage problem. In various

situation, Pros and Cons behind each approach discussed and concluded.

The simplest and effective repair method proposed for those properties. or those

serious structural damage, it is recommended to seek structural engineer’s advice to

strengthen the structure. Proper shoring and temporary support may be involved

depending on actual need.




This report revealed the defect and repairing necessities for the selected properties. It

form a basic overview and help to adopt resolution for future investment.

5.2 Recommendations

Selected buildings will be discussed for investment below:

Gatehouse of Nga Tsin Wai Village

It is the significant building for the village with functional background in security. It

situated at the urban area of San Po Kong leads to easy accessible from public.

However the usable area of it limited the reuse and redevelopment of this property. It

seems use as exhibition centre may be the only way for further consideration. The

profitability is low and potential maintenance cost for significant structural crack is

high. Therefore, it is not recommended for investment.

St. Joseph’s Chapel

The Italian Romanesque style church and maintain degree of religious function till

now although most local villagers moved out. It is large usable area and it is very

suitable for exhibition, a convention and variety possible proposes. And it has the

potential to be redeveloped to incorporate to the surrounding open space. However, it

situated at Yim Tin Tsai Island of Sai Kung makes tourist, public, occupants difficult

to reach and high maintenance cost. Which limit the revenue to be made and

profitability is impeded. One thing important that, when approaching to




redevelopment, change of use should be formal applied for consent from various

government departments. It may also be opposed when in open counselling by local

power and lead to abortive project. Therefore, it is not recommended for investment.

Stone Houses

It is the traditional tenant houses after War II. By the condition surveyed, it is no

renovation work carried out for several decades. It used to spend much to recondition

the building due to the large usable area. The property abutted centre zone of

Kowloon City and served by various traffic service to most places of Kowloon

peninsular. The property provides the largest usable floor area by comparing to the

others, it is vital and fulfilling the desire when to be developed into commercial

purpose without catering the time-consuming Gloss Floor Area (GFA) application.

Prompt development will lead to early return for the investor. The property also be

possible to be converted into highly profitable columbarium as it is very close to the

Hau Wong Temple and cemetery nearby to meet the rising demand of it in Hong

Kong in recent decade. Local power’s obstruction will be less since its superior

strategic location. Field study, educational, visitor center, etc. are always to be

permitted to be redeveloped which are also beneficial for development varieties.

Therefore, it is recommended for investment.




6.0 PERSONAL REFLECTION

It is very interesting assignment for me to act as a property redevelopment investor

point of view to handle a building surveying project. It is not be experienced for me

along as I was in building surveying field for several years.

I thought it is not very difficult for me at the beginning of the assignment because I

always familiarize to conduct building surveying to the buildings until I have fallen

into dilemma when conducting survey to historical buildings. In the historical

building, they are so much difference to what I saw in building maintenance point of

view no matter the background information retrieving, building structure, material use,

roofing system, etc. aspects. Especially for timber structure, I could not conduct any

inspection and propose maintenance work while it is really my first touch on these

issues. I was confused in writing on such. Therefore I spent much time to study the

topics relating biodegrading research.

The other difficulty at this assignment is to conduct the visit to those buildings

especially the St. Joseph’s Chapel is located at the off-shore island. I can only reach it

by joining local tour since timetable of ferry is not convenient for me. Fortunately, by

the local tour, I captured much valuable historical story of the island which leading

the chapel to be exclusive from all another in Hong Kong or even in China. It is the

extra benefit of this assignment and made me more and more interesting on the

research.

For proposing the maintenance scheme, it is so quite difference from those work to be




conducted to typical modern buildings which always be reinforced concrete structure

in absence of conservative background. Extra-care and more detail should be

corporate during judgement to avoid the downgraded from original building and

historical characteristics. On the other hand, I needed to take cost into the account

during proposing repairing intervention when to fulfilling the investor’s characters. It

required me to incorporate value management technique to cater the problem.

Finally, for investment issue, it is not as simply as expenditure and profit analysis that

I thought it before. Revitalization of historical building is the key element when to

make the property be unique and operational in Hong Kong. I didn’t direct the

investment into eating place, place of entertainment, etc. but think more in-depth

demand from current society. I started to retrieve the records and study from several

revitalization projects in Hong Kong such as Mallory Street Revitalization, Lui Sang

Chun Revitalization, etc. to endeavor the elements of difference apart from them. So

that it may make the project more famous and profitable in Hong Kong. Investor may

feel comfortable and easier to accept my idea and recommendations.

In this interesting and challengeable assignment, it help me wider vision to the

building surveying technology and sophisticate equipment to help the diagnosis. And

that provides a great lesson to learn for me. It also leads me to think deeper on value

and return behind the building maintenance or revitalization project. I did grateful for

all challenges brought me in this assignment.

< 20 pages excluding cover, content pages and reference page>




7.0 REFERENCE

1. Centre for Architectural Heritage Research of the Chinese University of Hong

Kong, (2009), Historical cum Social Study on Kowloon City district in connection

with Kai Tak Area P.166-175, P.212-215;

2. Centre for Architectural Heritage Research of the Chinese University of Hong

Kong, (2011), Heritage Impact Assessment for Revitalization of the Stone Houses

at Junction Road Kowloon City into Stone Houses Family Garden P.31-35;

3. Revitalising Historic Buildings Through Partnership Scheme Secretariat, (2009),

Revitalising Historic Buildings Through Partnership Scheme – Stone Houses –

Resource Tookit P.8-13;

4. The HKU Scholars Hub, (2004), From salt pan to resort plan : heritage

conservation for the Island of Yim Tin Tsai, Sai Kung

http://hdl.handle.net/10722/40003 accessed 26 April 2012;

5. Antiquities and Monuments Office, Historic Building Appraisal – No. 31-35 Hau

Wong Temple New Village, Kowloon City, items 949;

6. Courtesy of Survey and Mapping Office, Lands Department, Hong Kong SAR

Government, survey sheet no.: CXXXVII-NE-6;

7. Chu Wai Tak 朱維德, Xhianjiang jiumao <香江舊貌> [The Old Scenery of

Hong Kong], Hong Kong, Cosmos Books Ltd., 1993;

8. Sai Kung District Board (ed.), <西貢風貌> [Scenes of Sai Kung], Hong Kong:

Sai Kung District Board, 1996;

9. Yoshihisa Fujii et. al., (2010), Characteristics and diagnosing technology of

biodegradation in wooden historical buildings A case study on Amida-do in

Higashi Hongan-ji Temple in Kyoto.

Documents

BUILDING SURVEY REPORT for 18th 19th and 20th century building in Hong Kong