By Candy Yip Design • Real Estate • • • • 0 Comments

Click here to know more about building defects!

There is always an indispensable relationship between buildings defects, structural stability, and public health. In general, non-structural cracks, structural cracks, concrete spalling, defective external wall finishes and water seepage, etc can be the common types of building defects, which can be easily found in buildings in which do not receive proper maintenance and repair.

Photo showing concrete spalling from the ceiling

Photo showing cracks inside staircase

Photo showing concrete spalling

Photo showing external wall tiles was found missing

Today, as a surveyor graduate trainee, I want to share some causes for the development of building defects. There can be a combination of factors in causing the above-mentioned defects. All property will face some sort of defects during its life span. As a surveyor graduate trainee, we shouldn’t solely focus on the physical look of building defects, we need to observe the surrounding environment and the actual usage in concluding the cause of the particular building defects.

Design, material, construction, usage, and maintenance are the common angles in diagnosis the causes of defects. Taking concrete spalling as one of the examples, given the design stage, when the building is located near the sea, the chloride attack raised from the sea may corrode the steel bar. With the corrosion of the rebar, the volume of rebar inside the concrete will expand 8 times. Crack and concrete spalling may be found.   At the same time, concerning the construction stage, the high water-cement ratio may bring void for the concrete surface due to the increase in permeability, which has the potential possibility to enhance the corrosion of rebar (you can refer to the blog from GBE dated on 28 June 2020). From the above reasons, we understand that the building defects may not be caused by a single reason only. It is the responsibility of the professional to conduct a detailed building inspection before jumping to a conclusion.

Photo showing the stage of rebar corrosion (retrieved from structural engineering blog)

Water Seepage is also a common building defect in aged buildings. The sources of water may come from rain, groundwater, element, condensation, plumbing, drainage, and user activities. When we observe some symptoms like water stains, water dripping, rusty stains, peeling of paint during the inspection, suspected water seepage maybe happened. Before diagnosing the source of water seepage, a preliminary desk study is required (if you wanna know about the details of desk study in how to tackle the annoying issue comes from water dripping in the living area, you mustn’t miss the blog from GBE dated on 4 Jan 2021). We may need to collect some background information like the location of dampness, the frequency of occurrence, the extent of the dampness, repair record, any complaints on the water seepage in identifying the source of such dampness. Visual Inspection and some testing tools like moisture mete can be applied in determining the source of seepage. In some cases, where we suspected the water seepage was caused by the defective waterproofing membrane from the upper unit or roof, a water ponding test may be adopted. At the same time, when we suspected the water dampness was raised by the leakage of the plumbing pipe, a meter test can be adopted in deterring the actual source of such seepage.

Photo showing a suspected case of water seepage

In order to maintain a safe and healthy environment for occupants, routine inspection, repair works, and maintenance works are suggested to carry out in every building.

By Candy Yip Building Law • Building Technology • Design • Real Estate • 0 Comments

Fire Safety in Commercial Premises

Fire safety can be regarded as one of the primary considerations in building designs. The terms of fire safety cover a wide range of building concepts, ordinances, and regulations under the law. When we consider the fire safety works in banks, the concept of Fire Safety (Commercial Premises) Ordinance should not be omitted. The introduction of FS(CP)O is one of the ordinances which aims to provide better protection to the occupants and visitors on certain kinds of commercial premises.

Prescribed commercial premises and specified commercial buildings are under the scope of the ordinance.  For the captioned the premise, they are required to update that fire safety construction including means of escape, means of access, fire-resisting construction under the Code of Practice for the Provision of Means of Escape in Case of Fire 1996, Code of Practice for Fire Resisting Construction 1996, Code of Practice for the Provision of Means of Access for Firefighting and Rescue 1995 respectively. Also, the premises required to update fire services installation following Codes of Practice for Minimum Fire Service Installations and Equipment and Inspection, Testing, and Maintenance of Installations and Equipment 1994 when the total floor area exceeds 230 square meters.

As a building professional to cope with the above issue, a desktop study needs to be conducted first. It is essential to calculate the number/width of the exit door and exit route following the purposed usage of the premises. The comparison of the recorded plan and Fire Safety (Commercial Premises) Ordinance may draw attention to the fire safety deficiencies. The site visit is followed to identify the deficiencies. fire services system always associates with water supplies and electricity. For the aged building, some non-emergency services like electricity will be located in the exit route. However, those non-emergency services did not enclose by FRR materials. It may post a potential fire hazard. Insufficient width of the MOE route, insufficient number of exit routes to the required staircase, presence of the fire shutter in the exit route, absence of exit sign, absence of the exit door, etc are the common scenario for the aged commercial premises to deal with the ordinance. The reasons for the above deficiency can be caused by certain reasons including the change in use, the absence of the fire safety ordinance during the construction period, and unauthorized building works by the owners.

By Candy Yip Building Law • Design • • • • 0 Comments

Structural Appraisal to the Loading Case in Yuen Long Premise

When I was an undergraduate in Building Surveying, I learned from many textbooks that the structural design process usually starting with the loading assumption. This assumption is presented by outlining different loading cases. In simplicity terms, some loading cases are what we called UDL while some are point load.

Example of UDL

Example of point Load 

When we deepen the idea of loading further, there are generally three types of load including dead loads, live loads, and wind loads. Dead loads are due to the self-weight of the structure. Live loads consist of all the loads which are designated to be placed on the structure, For example, loads of people and furniture. This live load is strongly correlated to the usage and obviously the heavy-load machine will demand strong live load capacity.  Wind loads generally come from the pressure of wind acting on the structure.

Example of live load, dead load and wind load

In order to ensure safety and health for the built environment, Buildings Authority has enforced the Building (Construction) Regulations under HK CAP 123. There emphasizes the minimum imposed load or live load in our term for different usage. For instance, the distributed load for the domestic floor is designed as 2 kPa while the general restaurants are designed as 4 kPa. The structural design should follow this stipulated requirement to attain compliance.

 

Drifting down the river, the user of the structure, i.e. the occupier in the premises, may mis-sue or alternate the usage without carefully considering the designated live load. In our many Structural assessments.We noticed the occupier might have over-loaded the structure unintentionally or might have alternated the usage which exceeds the permissible live load.

 

In the situation like aforesaid said, the structural element itself may exhibit some undue behavior like the development of a huge crack on beam component or deformation. Adversely speaking, it is a very unfavorable observation because the structural damage may cause immutable damage to the elements. Sometimes, immediate propping or secondary support may be required to stop the damaging.