Expert: Arshad Khan - 9/28/2009

Question
QUESTION: I was told that due to extreme variations in temperature in a day (night time and day time in 1 day), the expansion joints in Saudi Arabia are much closer than the normal practice in other parts of the world.

Is it true and what is the normal range or is it governs by the building code or building by laws?

Thanks

ANSWER: Hi Hong,

The daily range is around 15-20 deg C, and the maximum recommended spacing of joints is around 50m. However, with detailed thermal analysis, and rebar designed for the additional stresses, you can increase the spacing to 75m or even 100m, especially in buried/covered structures. The roofs (exposed to direct sunlight) usually are detailed with closer spaced joints, though.

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QUESTION: Salam Arshad

Are building expansion joints spacing in Middle East particularly Saudi Arabia governs by building codes or regulations? Someone told me due to very hot days and freezing nights, the authorities a regulation to ensure safe buildings.

BTW, what happens if the superstructure of a building is cladded with precast non load bearing walls bolted to the frames? On the roof, it is thermally insulated with foam insulation and roof tiles with expansion joint. In this case, the thermal stresses are on the outside and will not affect the superstructure. In this case, in theory, the building length can be very long - somewhere close to a buried structure?

Thanks for providing me with the information and knowledge.


Answer
Hi Hong,

As far as I know, there are only guidelines, not strict requirements. However, some local authorities interpret the guidelines as legally binding, while others will accept properly engineered solutions, as I mentioned earlier.

The scenario you have quoted is true for the long-term, but many of the thermal movements/problems occur during construction before the external insulation (or internal HVAC) is in place. So you need to engineer the structure to suit temporary conditions too (sometimes by incorporating a narrow shrinkage/expansion strip, to be filled in later).