11 The Roof - Part 2

The roof, by far, has been the most complex structure to design, build and implement.  Though it looks like any ordinary roof, it isn't.  The specifications were according to industrial standards and suited for a factory rather than a residential building.  Comprising 7 layers and covering an area of approximately 5,300 square feet, the roof took more than a month to construct.  Why all the fuss?  Simple.  It's main purpose was to keep the internal temperature of the house between 26-30 degrees Celsius, 24 hours a day, seven days a week, without the use of active energy!

Pic 1: Week 1 - Calculating pitching and leveling of the concrete roof beams.

Pic 2: Week 2 - Fastening of steel trusses and brackets on the concrete roof beams.

Pic 3: Week 3 - Securing insulation foil and 100mm thick rock wool across the entire roof.

Pic 4: Week 4 - Installation of facia board and final adjustments prior to mounting roof tiles.

Pic 5: Week 5 - Hoisting and laying of roof tiles and dry fixing.

Pic 6: Close-up of C-channel purlins, each measuring 152mm X 66mm X 1.6mm thick, covering an area of approximately 5,300 square feet.

Pic 7: Close-up of 100mm thick rock wool from CSR Australia.

Pic 8: View from underneath showing the steel mesh holding up the insulation foil which in turn, supports the rock wool.

Pic 9: Top view of steel rafters and GCI clay roof tiles prior to laying. Note the reflective foil which adds an additional layer of insulation.

Pic 10: View of the south wing's roof under construction.

10 An Unexpected Discovery

While constructing the roof beams, I discovered something rather unexpected.  While standing on the roof, it was possible to see the KL Tower, Petronas Twin Towers and Menara Maybank in the North East direction from the house!  It was also  possible to see some of the other familiar landmarks in Petaling Jaya such as Menara TM, Menara MBPJ, Amcorp Mall and Jaya 33.

Pic 1: Roof top view looking North East. Clearly visible is Menara TM on the right.  Note the KL Tower and Petronas Twin Towers in the distance on the left.

Pic 2: Close-up view of KL Tower and the Petronas Twin Towers as seen from the roof of the house.

Pic 3: Close-up view of KL Tower and the Petronas Twin Towers with Menara Maybank clearly visible on the right.

Due to this discovery, it was decided that the roof should incorporate a roof top balcony that would offer an unobstructed view of the surrounding PJ landmarks as well as the impressive view of the KL Tower and Petronas Twin Towers.

09 The Roof

The roof, being the biggest and most important construction element in the overall house design, needed to be carefully planned and constructed.  Simplicity was the guiding principle.  A symmetrical dual pitch roof with a gentle gradient of 20 to 25 degrees on each side was chosen as the basic form.  This eliminated unnecessary ridges and gullies that could become a potential point of leakage.  Spanning the entire width of the house, the roof would stretch over 120 feet from the North wing to the South wing with a single ridge dividing the roof in the middle.

With such a wide area being exposed to the sun and heat throughout the day, it was critical that the roof design effectively overcome the issue of solar gain.  Interestingly, the design drew its inspiration from Land Rover with its safari roof.

The safari roof was a device designed for the Series Type Land Rovers operating in the hot tropics.  A simple sheet of aluminium mounted on top of the vehicle with metal feet, sandwiched a layer of air for insulation, which, when heated sufficiently, dissipated the air along with the heat while drawing in cool air through a repetitive cycle.  More about this later.

In order to support the large expanse of roof, it was decided that large horizontal concrete beams would be constructed at regular intervals. The height of each was staggered to accommodate the pitch of the roof. I called this the "hurdle" design after the track and field sport.  This design was not new but borrowed the design method of the 1960s thereby adhering to the architectural style of the period.

Pic 1: The staggered "hurdle" beams that would eventually support the roof.

Pic 2: South wing extension viewed from the front.

Pic 3: A big challenge was to construct the concrete beam on top of the three main columns two storeys high.

Pic 4: Close-up of the concrete beam as it cures.  Note the circular cap that carries the columns' form all the way to the top.

Pic 5: Top view of the staggered "hurdle" beams and cross support beams.

Pic 6: A panoramic view of the roof beams from the south back corner of the house showing the systematic construction process from south to north.

Pic 7: The same view but from the opposite end of the house.

08 Bio-Climatic Based Design Principles

The house was designed along bio-climatic principles.  This meant that particular emphasis was paid to the impact of energy, material and water on the building's function and an overall responsiveness to the local climate. Design solutions had to be passive i.e. low energy / non-dependent on fossil fuels / renewable, and as much as possible integrate with the surrounding vegetation.

Working closely with sustainable experts and using advanced computer software, it was possible to virtually model the facade design, orientation and solar impact on the house.

Pic 1: Basic 3D virtual model.

Pic 2: Front facade option incorporating the use of potential green / plant walls and other solar shading devices.

Pic 3: Front and side facade option viewed from a different angle.

07 Building Upwards

Once the foundation was in place, it was time to build upwards starting with the main structural columns and beams.

Pic 1: Up go the columns and support structure for the south wing.

Pic 2: The original concrete roof slab needed to be hacked to lay the beams for the first floor extension.

Pic 3: Propping up the concrete roof above the porch before it is reinforced.

Pic 4: Intentional overlapping beams and columns were designed to accentuate the original architectural features of line, edge and shade.

Pic 5: Meticulous form and steelwork for the first floor extension in preparation for the concrete pouring.

Pic 6a and 6b: Good weather helped the concrete cure beautifully.

Pic 7: Ground floor concrete structural frame in place.  Note how the house has been "rotated" 10 degrees from its original axis.

Pic 8: Close-up of the axis point showing the re-alignment of the house by 10 degrees.

Pic 9: Specially commissioned pre-cast concrete pillars were secured in place.  These will eventually support the concrete roof beams.

06 Preparing the Foundation 2

Similar to the way a heat sink in a computer's CPU dissipates heat away and cools it, layers of recycled tyres beneath the building's concrete floor absorb heat and keeps the interior of the building cool. See the following simplified diagram:


(Source: The Star, 7 April 2009)

Practice makes perfect.

After the initial experience using tyres to construct the foundation, the team was able to cut the work efforts by half. From constructing the perimeter formworks to the laying of concrete, the team was able to reduce the time taken from 10 to 5 days.


Pic 1: Day 2 - Tyres arranged, strapped and covered with reinforced iron mesh


Pic 2: Day 3 - Corrugated plastic sheets enveloping the tyres; rebars in place for ground beams and concrete slab.


Pic 3: Day 5 - Concrete hardened and perimeter formworks removed

Pic 4: Same process applied to the kitchen area i.e. laying and strapping the tyres.

Pic 5: Enveloping the tyres with corrugated plastic sheets, reinforced steel and rebars

Pic 6: After the initial hardening, the bare concrete floor was kept wet to ensure no hairline cracks developed as a result of over drying. (The daily afternoon thunderstorms were very helpful!)

05 Waste & Water Management

Considering the house was 50 years old, the septic tank was in surprisingly good condition - another testement to the quality of materials and workmanship of the past. Even the clay underground pipes were intact. However, due to the expanded footprint of the new house design, the underground sewage pipes had to be re-routed and replaced.

Pic 1: Two of the four septic tank covers.


Pic 2: Rusted manhole cover and frame.


Pic 3: New GBH clay and Bina Plastic PE sewage pipes.


Pic 4: Newly dug out trenches for the sewage pipes.


Pic 5: Sewage pipes connected and buried.


Pic 6: New service manhole being constructed.

Pic 7: South wing bathroom piping being connected to the new service manhole.

Pic 8: Close-up of sewage outlet pipes from Bina Plastic Industries Sdn. Bhd.

Pic 9: Close-up of sewage outlet pipes leading into the service manhole (partially complete.)

Pic 10: The pipe at the corner manhole was laid at a 45 degree angle instead of 90 degrees in order to ensure a smoother flow.

The conditions of the water tanks, however, were very bad.  Both tanks showed advanced stages of rust and considerable amount of sedimentation.

Pic 11-13: This is what happens to the water tank after 50 years!

Pic 14: Some of the sedimentation that was found at the bottom of the tanks.