Page 18 - Surveyor 50.2 2015

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The Malaysian Surveyor

is the presence of deposited dirt around the RWDP area, reaching a height of 35 mm.
Cleaning the dirt in these areas ensures the smooth flow of rainwater into the drainage
system. However, routine inspection of flat roofs is difficult to implement, especially
for the purpose of detecting the presence of water ponding at any real point of time.
Theoretically, this paper suggests the use of automatic sensor technology as one of the
best approaches to achieve real-time detection of water ponding on a flat roof.

Keywords: roof, condition assessment, water ponding, rainwater downpipe, criticality index.

1.0 Introduction As a main building component, the roof case, the drainage system (Wijte, 2006).
is vulnerable to defects and must be Although the National Roofing Contractor
The roof is the main maintained along with the other building Association (NCRA) believes that the short
protection component of components. Therefore, it is important to duration of water ponding (less than 48
a building. There are two ensure that every roof functions properly hours) is acceptable (Wilen, 2012), it is
types of roofs, namely, through an effective monitoring process. still considered a defect because short-
pitch roof and flat roof. term water ponding can ultimately lead to
Compared with the pitch Hakim and Min (1991) reported that building disaster in the long term (Snijder,
roof, the flat roof has a slope that is less the use of flat roofs in Malaysia has 2006; Blaauwendraad, 2006; Lawson,
than 10 degrees; thus, many activities increased in recent years. There are 2012).
can be performed on top of it. However, many advantages of using a flat roof;
such advantage comes with one common however, there is one main problem For a flat roof made of concrete slab,
problem: water ponding. Water ponding is often associated to a flat roof: water water ponding usually does not have
a serious problem that can lead to other ponding. Water ponding is the presence immediate effects that can lead to a
defects on a building. For example, water of stagnant water on flat roof surfaces building disaster if the structure is strong
ponding on lightweight flat roof can cause during or after rainfall. The failure of a enough to accommodate the load.
collapse if the applied load is excessive. building’s rainwater drainage system is However, Eldridge (1976) stated that its
Moreover, water ponding is the main the main cause of water ponding. Wijte moisture effect will slowly weaken the
source of moisture on a flat roof made of (2006) reported that the failure of the building’s material strength. Recurrent
concrete slab. regular rainwater drainage system can water ponding can worsen the moisture
be on the roof itself or within the drainage effect and eventually weaken the
To address this issue, we conducted a system. building’s structure. Thus, it is important
study on the condition of the flat roof in to identify possible locations of water
one of the academic buildings in Penang, “For a given return period, the maximum ponding on a flat roof surface so as to
Malaysia. The aims of the study are to rate of runoff will result from a storm overcome other related problems that can
identify the potential location of water event in which the duration of the endanger the building and its occupants.
ponding and its possible causes. The peak intensity is equal to the time of
selected building has a concrete slab flat concentration, which is the minimum time 3.0 Research Method
roof, which is considered a heavyweight for the whole area of the roof contribute
roof. flow to the point of discharge. A time of The condition survey was carried out
concentration of 2 minutes is considered on the selected flat roof of an academic
2.0 Literature Review typical for many roofs” - British Standard building in UiTM, Pulau Pinang, on 19
(2000) September 2014. The objectives of
The roof is the main protection this survey were to identify the flat roof
component of the building and protects Based on the statement above, water condition and to detect the possibility or
the internal space from natural factors, trapped on roof surfaces for more than likelihood of a water ponding problem.
especially rainwater and sunlight (Zuraida, 2 minutes is considered water ponding. The survey was done to carry out a visual
2010). The roof also acts as indoor Water ponding is a building defect inspection and produce a pictorial and
environment controller (Nurfatiha, 2008). because its existence is caused by a written report. The survey area involved
failure of a building component, in this

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