Insulation for roof parking decks

Offices, retail developments and hospitals often include parking areas on the uppermost roof deck to optimise available space. The challenge is to construct a durable, trafficable surface that protects the waterproofing system and ensures the building roof is adequately insulated.  

Fit for purpose 

The design of an optimum solution involves multiple structural and product aspects – from anticipated loading of the roof deck, waterproofing, drainage, insulation and the choice of trafficable surface. 

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. The product must be light in mass yet possess the compressive strength to match design performance criteria for a system lifetime of minimum 50 years, and it must maintain thermal performance over this period. 


When thermally insulating above the waterproofing system with IsoBoard XPS, the membrane is protected by the bulk of the insulation and requires no maintenance. The membrane is protected from aging due to weathering, ultraviolet (UV) exposure and thermal shocks, as well as against mechanical damage resulting from vehicle traffic and damage caused by interstitial condensation. 

An important benefit is that the thermal mass of the concrete roof deck is maintained at the internal temperature, assisting hugely in providing temperature control to the environment below. 

Insulation for roof parking decks

Design of an optimum solution considers the anticipated loading of the roof deck, waterproofing, drainage, insulation and the choice of trafficable surface.

Case study: Steve Biko Academic Hospital, Pretoria 

More than 20 years ago, IsoBoard was installed beneath the paved roof parking areas. It continues to perform as designed, providing thermal insulation to the building below, protecting the waterproofing system and accommodating vehicle traffic, with no collapse of the paved surface. Waterproof maintenance has been limited to exposed upstands. 

Issue: Thermal insulation solutions for roof parking decks. 

Solution: IsoBoard XPS delivers proven design performance criteria over the long term. 

 For more information, contact IsoBoard: 

Tel: +27 21 347 0186 

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