By John Lam Asset Enhancement • Building Law • Building Technology • • 0 Comments

“Common Staircase” shared by adjoining lot in Hong Kong

The leftover structure coming from rapid Urban redevelopment in Hong Kong

In the urban development , the land was delineated by “Block” and was subsequently craved or partitioned in a different section and eventually further craved into different sub-section. It resulted a lot of common boundary to each piece of lands adjoining to each other.

 

The common boundary bought in the typical implication of “party wall” and “common staircase”. There was a blog written by GBE about “party wall”. The reader is welcome to comment. “Common staircase” is what this article goes deep.

 

The main staircase of the building became as “common” because it was commonly shared between two pieces of land. The common staircase was jointly owned for the enjoyment of the entire building. Since it was common to two adjoining pieces of land, it naturally positioned at the boundary line. It was not a must but naturally came up in the middle between two lots.

Redevelopment and remaining common staircase

With the re-development took place in one piece of land, the adjoining land where the original main building sitting on was necessitated to maintain the common staircase for access. This came up the situation alike to the “Party wall” where the common staircase needs to be retained and still occupy land and space on the land going to be redeveloped.

 

The first and immediate concern is obviously the common staircase is an enclosed space and fall into the definition of GFA. Nevertheless, this common staircase is nothing helpful and undesirable to new development. To cope with this, the above-extracted part plan has illustrated the example of how the PNAP ADM -2 resolves the GFA problem. In short , the entire footprint of the common staircase be deductible from the GFA calculation. According to PNAP ADM-2 from the Buildings Department, the existing common staircase for an old building can be excluded from site coverage and plot ratio calculation.

 

Case Study in two adjoining Urban buildings

Building “A” was redeveloped in 1992. The landlord was obligated to leave the common staircase un-touched and exempted its footprint from accountable GFA. Building “B” was subsequently redeveloped in 2008, but the redevelopment of Building B has demolished partly the “common staircase” sitting on the respective piece of land.

Ground Floor Plan of Building A (showing the Location of Common staircase with Building B)

 

 

GFA Calculation of Building A

 

Ground Floor Plan of Building B (showing the Location of Common staircase with Building A)

 

 

Site Area Calculation in Building B

Another example showing the common staircase issue

Building “C” was redeveloped in 2004, while Building D was redeveloped in 1994. Building “C” and Building “D” retained the common staircase after both redevelopments.

Ground Floor Plan of “Building C”

Ground Floor Plan of “Building D”

Funny interesting maintenance issue

The interesting things come up is that building A which developed earlier than Building B was containing the old “common staircase” . This old left-over common staircase in Building “A” was not GFA counted by the time of redevelopment. The owner of Building A is caught in dilemma. The site where building A sitting on has fully exploited its GFA potential by the time of its redevelopment in 1992. It is now found no surplus GFA be able to assign to this leftover physical ” common staircase” space in the hope to light up again the space utilisation, particularly valuable in highly urbanised city area. The landlord of building A is naturally no incentive to maintain nor convert this common staircase to other proper usage. The only value is the external wall of the left-over common staircase which was being poised for signage in Building “A” (as shown on the photo below. Obviously, the author is wondering the maintenance liability to the grandfather jointly owned structure , i.e Common staircase

 

By John Lam Asset Enhancement • Building Law • Uncategorized • • • • 0 Comments

Misery of Non-accountable GFA in Existing Building. The road from plain drawings to value-added

GFA is the core asset in real estate

GFA – Gross Floor Area is considered as the core valuable asset in real estate. One of the significant governing regulation to GFA stated in Buildings Ordinance is Building (Planning )Reg 23. The Reg 23 (3)(b) have listed in literal form the areas which can be subject to non-accountable GFA whereas the Reg 23(3)(a) has included all areas within the external of buildings as GFA countable.

The Ordinance allows some accountant GFA in 23(3)(a) becomes considered as non-accountable GFA through the power vested to Buildings Authority by section 42 of Buildings Ordinance and explained by the ADV – 02 (PNAP 30 in former version). Some GFA calculation cases are further complicated by the injection of sustainable development requirements stated in APP 151.

Existing Building GFA vs Regulation 23(a) 

In existing Building which was built in decade ago plus , the control to the non-accountable GFA was relied by Reg 23(3)(b) which generally covered the essential plants / duct / carpark etc. When the landlord wants to review/revamp the existing GFA hoping for unlocking the hidden potential, the latest requirements in 23(3)(a) mentioned before will kick in to the backdrop.

Some areas within the building which had been exempted from accountant GFA in the past may have to re-examine under Reg 23(3)(a) and is assessed in the ADV -02. The interesting but painful point is that some typically exempted in the past may now become accountable unless the modification is granted by BA. In some case, the modification is not straight-forward but under complex assessment such as BEAM requirement in APP 151. Obviously, the latest GFA requirements has blocked the unlock of some potential GFA.

Example showing the effect impact from tightening of GFA assessment

Assuming there is plant room , this plant room is assumed be acceptable by Reg 23(b). The implication of GFA will be manifest because the protected lobby going with the plant room will be exempted. To the contrary, If the said “plant room” is NOT in Reg 23(b), the GFA exemption will be at the stakes. The wall and associated protected lobby solely serving for plant rooms will be subject to the “non-mandatory features”. The area of wall and associated protected lobby will be barred by the overall cap of 10% in paragraph 4 APP 151 for non-mandatory features) . The capping 10% will effect some GFA from non accountable back to accountable.

Case by Case assessment 

Valuable assets in the urban areas are all GFA driven for the best maximization of property value. This is the key driving incentive to closely review and revamp from time to time to unlock the potential hidden GFA in the active asset management.

(Reader is advised to look also other strategies which have been shared in our other blog” of this website)

 

 

 

 

By Mike Mak Asset Enhancement 0 Comments

EV Parking vs Additional FSI

Demand for EV Charger facilities in existing (old) building carpark is definitely rising in the town. Many would focus on reliability of new power consumption, enhancement of infrastructure and how best to house those new facilities. In GBE, fire safety with respect to the additional fire load of EV charger facilities is also our key consideration on design and planning of project. Incorporation of smoke detection system, fire extinguisher, Direct Link connection and Fireman’s emergency switch, etc. are encouraged for the relevant project. Enhancement of client’s assets and upholding of high level of safety are one of our major deliverable to our clients.

By John Lam Asset Enhancement • Building Technology • Design 0 Comments

Part 2 : Coating materials for Aluminium cladding – Misery of “Self-cleaning”

Following with our part 1 discussion, we now share another hot topic about coating applied on the aluminium. “Self-cleaning” is indeed a merchants’ name . The behind sciences are varying from among different manufacturer. We have conducted some comparison among different materials being applied to the cladding surface.

Theory of “Self-cleaning”

Self-cleaning : Hydrophilic approach 

In short, there are a few theories behind the “self-cleaning” . One typical approach is to create the surface which reduce the water surface tension. When the water droplet lands on the surface, the water droplet has formed an wetting angle to the surface of cladding. The stronger the water tension, the more acute the wetting angle is. The below diagram explains the wetting angle and how it carries the dirt / stain / attachment on the surface. Different manufacturer has formulated different chemical materials to reduce the water tension and flatten the wetting angle. The water is to carry and flush away the dirt. The most typical chemical approach is to create the coating surface which offer better hydrophilic (hydrophilic is origin from latin word, the word philic means love).

 

 

Self-cleaning : Photo-catalytic Oxidation 

Another theory is by “Photo-catalytic Oxidation” . We are not Chemist and cannot cite the theory . Nevertheless, we found one extract from “Chemosphere 193( 2018-198-206)” ,  there explains the “photo-catalytic oxidation” with the below graphic. In short, it is the oxidation process to the VOCs by UV and Photon. This is again alleged by many peers as ” self – cleaning” , but obviously the theory is very different from “hydrophilic approach”

Self-cleaning : Hydrophilic approach

To the contrary of “Hydrophilic” , some manufacturer applied the opposite ; hydrophobic approach. The theory behind is to keep the strong water tension of the droplet and let the droplet to “PICK” the dirt away. From our very preliminary scanning , this technique was more relying on the water – repellent nature ,

Product in the market : – 

We have encountered different approaches in the market. All suggest their “self-cleaning” properties. We try to cite some examples to illustrate different theory behind . We are not in the position to comment each performance and indeed it is difficult to do comparison. We hope this articles can offer some ideas for future research

Kansai Paint : 

One of the product is made by Kasiai, we were given the understanding that the materials is silicon-based modified resin materials with their own additive untold to the public. This is to create the “Hydrophilic” by flush and deliver the dirt.

 

 

Hydrotech from TOTO

Hydrotect is the tradename by TOTO. We extract their self-allegation from their official website. In short, they claimed their coating technique is photocatalytic which is to OXIDE the VOCs in the air. Their website further suggests this “Hydrotect” can offer the hydrophilic surface to flush the dirt

XX Sheet film paper 

A manufacturer , named to be untold here, claimed that there film sheeting offer the self-cleaning. We cannot identify their theory online. Nevertheless, we did a quick water spray test on the surface. We noticed that the water droplet kept intact on the surface and did not appear wetting pattern which is for flushing the surface.  From the picture below, the water – droplet keeps visually keeps the sharp and the droplet drip pattern is in the form of line.

 

 

By samsontam@me.com Asset Enhancement 0 Comments

Condensation Issue in Building – Part 1

Unwanted condensation can cause the building damage and also affect human health. In Hong Kong, condensation is a common problem which almost every single owner has to deal with. Temperature difference and high humidity are the main causes lead to condensation occurs.

Condensation is created when warm moist air begins to cool down and the moisture is released. This moisture then settles on cold surfaces making them damp. This can happen quickly when warm moisture in the air connects with cold air or surfaces, such as having a shower and the steam from the shower hits the cold window or mirror making it wet to touch, this is condensation.

Source: https://www.falkirk.gov.uk/services/homes-property/council-housing/repairs-maintenance/docs/condensation/Condensation%20in%20your%20home.pdf?v=201910291603#:~:text=Condensation%20is%20created%20when%20warm,and%20the%20moisture%20is%20released.&text=This%20can%20happen%20quickly%20when,to%20touch%2C%20this%20is%20condensation.

Information from Hong Kong Observatory

March and April are milder although there are occasional spells of high humidity. Fog and drizzle can be particularly troublesome on high ground which is exposed to the southeast, and air traffic and ferry services are occasionally disrupted because of reduced visibility. May to August are hot and humid with occasional showers and thunderstorms, particularly during the mornings. Afternoon temperatures often exceed 31 Degree C whereas at night, temperatures generally remain around 26 Degree C with high humidity. There is usually a fine dry spell in July which may possibly last for one to two weeks, or for even longer in some years.

Source: https://www.hko.gov.hk/en/cis/climahk.htm

 

On average, May is the most humid.

On average, December is the least humid month.

The average annual percentage of humidity is: 77.0%

Source: https://weather-and-climate.com/average-monthly-Humidity-perc,Hong-Kong,Hong-Kong

Due to such high temperature and high humidity environment in Hong Kong, condensation will be easily occurs if lack of consideration in daily operation and usage of room. GBE has deal with many condensation cases caused by lack of communication in design stage and also in wrong material selection. With an detailed study and planning before design stage which can help in material selection and insulation. Also, the heat source from outside the unit or building will be needed to consider through out the design process.

Negative pressure in building which may cause a big effect of condensation as the hot air from outside collide with the cold air within the building. Many people deal with condensation problem with balancing the temperature and humidity difference between indoor air with outdoor air by ventilation. However, such measure is not practical when outside air is in high humidity which the ventilation system is not sufficient for get away the moisture within the area as the high humidity air will get through the window to indoor by negative pressure.

Source: https://basc.pnnl.gov/sites/default/files/images/HVAC515_whlbldgvent4_DS_1-10-13.jpg

The above image show that the exhaust-only ventilation only system may cause negative pressure which can easily made the outdoor air to the building or unit. In below example, a cold storage with 24 hours A/C control store room which was found with condensation problem with hot air getting through from outdoor air by negative pressure. The owner has installed a few dehumidifiers which were not sufficient to get rid of the moisture as the hot air from outdoor is non-stoppable. In such case, the high cost in electricity usage and also high maintenance cost may affect the owner in daily operation. GBE has studied and apply the insulation to stop the hot air to get in from the electrical cable duct and also can save the cost for running the dehumidifiers and prevent the rusting effect at the electrical cable duct. 

By John Lam Asset Enhancement • Building Technology • Uncategorized • • 0 Comments

Part 1 : Coating materials for Aluminium cladding – Non-Combustibility

From natural anodisation technique to PVF2 coating technique , the aluminium finishing coating has undergone a lot of revolutionary advancement. In recent years, there came with the discussion about “Self-cleaning” of the aluminium coating surface. This is about the coating materials which gives effect to flush its’ surface every time in raining. “Self-cleaning” is indeed a merchants’ name . The behind sciences are varying from among different manufacturer.I have conducted some comparison among some cladding’s surfaces being applied to different “treatment” allegedly claim the self-cleaning properties.  In my small research , some coatings are sheet- applied on the surface of anodised aluminium cladding. Unfortunately, my research (limited online data searching) cannot conclude sheeting-applied one was made up compilable to the Section E clause 10.1 of FS code or as per the BS476 -part 4. Well, many peers have messed up the concept of BS476 – PART 6 / PART 7 which is about spread of fire to BS476 – part 4 which is non-combustibility .

 

There are some testing to confirm “non-combustibility”. The FS code of Hong Kong does a job to cite a reference table E1 to facilitate the conversion between BS and European standard . There are many building in Hong Kong are cladded with aluminium-panel externally , but the lack of attention is paid to its “non-combustibility” requirement. Example like “self-cleaning” sheet lining or coating or spray-paint applied materials and even the fire – ratardard which are applied on external architectural features. The add-on materials on top of the aluminium are sometimes commercially attractive in term of ease of application and its price but to the sacrifice of fire safety.

Fire accident in Grefell Tower, London

Photo : Wing On building in Sheung Wan was reported to have cladded with non-combustible cladding. Source from ejinsight on the pulse ( http://www.ejinsight.com)

In my next blog , I shall explain in details the “self-cleaning” being applied in aluminium cladding.

 

By John Lam Asset Enhancement • Building Technology • Uncategorized • 0 Comments

“Loose of Neutral” in Electrical Circuit in traditional expensive residential apartment

The night scene of Hong Kong is always representing the prosperity and the stunning pictorial attraction for many people . The backdrop of the night scenery is the densely packed high-rise buildings being lit up.

With the air-conditioning became introduced in Hong Kong , some traditional luxury residential development was designed with 3 phases supply to cope with the loading consumption

Effect of Neutral Loss and Over-heat

The 3-phased live wiring is pairing with the neutral wire. The power runs into your apartment through “live” and return through “neutral . There is a defect called “nentral loose” which means the neutral wire loose contact or in bad connection. If there is “neutral loose” , that may be caused by various reasons, there will be abnormal arcing around the point of connection, a flash phenomena or spake fire will be occurred from time to time to heat up the already loose connection point and adversely causing unpredictable loading of electric current passing through the entire circuit. This circuit connects the load side appliance such as air-conditioners, the electronic parts or protection fuses of these electrical appliances may be damaged.

Inspection by Infra-red scanning and WR 2 checking

Unfortunately, it was not always detectable the abnormal heat up around the connection point . I prefer to adopt the infrared thermography scanning technique in my project or my inspection. However, the electrician today prefer to do by visual inspection which in my view may be subjective in some occasion. Our in-house infra-red is E4 model from FLIR. This is not the latest model, but still fit to our general routine checking.

 

 

 

By John Lam Asset Enhancement • Building Technology • Uncategorized 0 Comments

Acoustic performance in Curtain Wall

Curtain wall system is such a complex external envelope of the building . It is more than an enclosure but also to serve to reduce heat gain and sound proof. The evaluation of  heat gain is commonly considered by the amount thermal transfer in the energy unit. Nevertheless , lesser attention is given to the acoustic consideration . Thank to my friend Dr Man and our peers Lixil who shares me one table. The airborne acoustic reduction is considered by STC value which varies as per the glass panes composition and thickness of glass. STC is to measure the degree of decibel reduction. The reduction is further related to the hertz of sound transmission. For easy communication , each composition of glass panes will be assigned the STC value. The interesting observation is that the “laminated glass” is achieving similar STC value compared to similar glass panes thickness of “insulating glass unit”. Furthermore , A 12mm thick single panes can achieve similar STC value to 6+12+6 insulating glass unit. Indeed, there are more consideration to the curtain wall acoustic including the impact-borne sound transmission caused by impact to the mullion or transom . Sometimes, the provision of the noise barrier or the provision of the balcony projecting out from the external facade can help to reflect the unwanted sound such as traffic away.

 

By John Lam Asset Enhancement • Building Technology • • • 0 Comments

Protect your roofing membrane

When I was a boy, I saw the construction worker at roof heating up the Asphalt block with very bad odour smell. Bituminous asphalt were usually applied in liquid form in row by row with some over-lapping at even interval spacing. Although this materials are proven to be very weather resistance and durable once after curing and set, it is not encouraged to use in new works as per the General Specification (ASD) Clause 12.50. With the advancement of technology , there are now coming with various type of ready-applied roofing felt and some type are even in spraying form.

Nevertheless, the typical defects like blistering of membrane, sagging of membrane, incorrect surface water fall , poor outlet details , lack of backing rod for sealant in expansion, add-on structure impairing the roofing are still prevailing. These are attributed to the poor workmanship, lack of inspection and inadequate design details consideration. Indeed, even though the defects exists , it does not mean we have to end the life of roofing by complete re-roofing. A more sensible way is to carry regular inspection and maintenance than to leave the roof undue long time unattended.

 

By John Lam Asset Enhancement • Building Law • Building Technology • Uncategorized • • 0 Comments

Coring the rock stratum engineering our pile foundation

Site investigation is a term to cover a lot of aspect about the site. For the Engineer in construction site, it means the process to find out the soil and rock condition. From the project management perspective, we see the most essence is whether the quality control system is working well in place . This control system involves sampling , inspection, recording and counter-check. Although the PNAP has imposed a lot of restrains in the site investigation, the entire controlling mechanism still heavily rely on the professional site staff. The sample taken will be inspected the the engineer. This inspection is to be fed back to the Designer to confirm the design assumption of piling coincide well to what happens on site. This is the feedback loop essentially important in the entire QA process.

I witness the coring process and I can say the coring of soil / rock is not a pleasant job. Sometimes, the sample was damaged in the process, sometimes, the sample was dropped in pieces. Thus , a good sampling and coring process did demand patience by labour, right machine set up, on-site engineer inspection and recording.