Specifying inverted roof insulation for parking decks

by Tania Wannenburg
Specifying inverted roof insulation ISOBOARD

When constructing roof parking areas, it is important to select fit-for-purpose thermal insulation that can withstand the load and protect the waterproofing, while doing its job of insulating the building underneath.

To make the most of the available space in buildings such as office blocks, retail developments and hospitals, the uppermost roof decks of these buildings are often adapted to be utilised as parking lots.

The challenge with this maximising solution is to construct a durable, trafficable surface while protecting the integrity of the waterproofing and ensuring that the building’s roof is adequately insulated. The general expectation is that such a solution must meet designed performance criteria for a minimum of 50 years.

Meeting this expectation and constructing an optimum solution involves multiple product and design aspects. These include determining the anticipated loading of the roof deck, selecting suitable waterproofing, drainage and insulation solutions as well as the appropriate choice of trafficable surface.

Inverted roof system
The benefit of thermally insulating above the waterproofing layer is that the membrane is covered and protected by the bulk of the insulation, thus requiring no maintenance. Not only is the membrane safeguarded from aging due to weather exposure and thermal shocks, it is also shielded against mechanical damage resulting from vehicle traffic.

Fit-for-purpose insulation
Choosing a thermal insulator appropriate for this application means specifying a product with the highest resistance to water and moisture absorption, to prevent any performance or compression failure, according to Mark Russell from IsoBoard.

The product must be light in mass, yet possess the compressive strength to support vehicle traffic over 50 years, and maintain designed thermal performance over this period. “This is where IsoBoard XPS comes into its own,” Russell states.

Application of IsoBoard thermal insulation
Twenty years ago, IsoBoard was installed as thermal insulation beneath the roof parking areas at the Steve Biko Academic Hospital in Pretoria. “This product is still performing as designed, providing thermal insulation to the building below, protecting the waterproofing layer and allowing vehicle traffic with no collapse of the paved surface,” Russell highlights.

In 2016, IsoBoard XPS will be installed in the roof parking area of the Military Hospital in Wynberg. “We expect the same positive outcome on this project too, which we look forward to confirming and reporting on in 50 years’ time,” he says.

“When looking to specify thermal insulation that is durable and fit for purpose for the long term, IsoBoard is one to rely on,” Russell states.

Isofoam SA (Pty) Ltd
Tel: 021 983 1140
Website: www.isoboard.com

Criteria for inverted thermal insulation:
1.    High resistance to water and moisture absorption.
2.    Lightweight.
3.    Excellent compressive strength.
4.    Ability to retain thermal performance for decades.

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