Kingspan Insulation - Kingspan Insulation Knowledge Base

Mineral fibre and walkability

Kingspan Group Kingspan Insulation

The walkability of mineral fibre flat roof insulation


In warm deck flat roof construction the flat roof insulation layer plays a key part in the integrity of the roof, as any compressive load applied onto the roof will be distributed through the insulation layer.

Flat roofs are often exposed to dynamic compressive loads, e.g. pedestrian traffic. These loads occur during construction of the building and during regular maintenance of plant installations on the roof post-construction.
Industry experience shows that, despite good static compressive strength, certain flat roof insulation materials can be susceptible to damage from repeated pedestrian traffic. Some materials can lose their compressive strength after a few load cycles. This can result in the deeper imprint of a pedestrian’s feet into the top surface of a flat roof. The stress that this causes on the waterproofing membrane may lead to penetration of a mechanical fixing through the waterproofing membrane if the foot fall is close by. This could result in liquid water penetration into the flat roof construction.

If the insulation material is unsuitable for common dynamic compressive loads, such as repeated pedestrian traffic, then this may have an adverse impact on its lifetime performance.

There are no normalised test methods for the assessment of the effect of dynamic compressive loads on the long term performance of flat roof constructions. Often the static compressive strength and/or point load resistance of an insulation material is used as an indication, but this method only applies a load once, and thus can not test deterioration due to repetitive loads at the same point on a flat roof.

Download the Walkability of Rock Mineral Fibre Flat Roof Insulation White Paper.