How insulation can help to improve accessibility in schools

7 June 2019 Kingspan Insulation UK

Roof terraces are increasingly being incorporated within school architecture. These areas provide useful outdoor spaces where ground playing areas are otherwise limited and can also provide exciting, alternative places for learning. As many existing school buildings feature flat roofs, they can be retrofitted into older buildings relatively easily and affordably.

When designing in a roof terrace, careful attention needs to be paid to the door threshold and floor heights to ensure accessibility for all students. This can be complicated by the need to incorporate insulation within the roof deck construction to prevent heat loss from the space below.

Accesibility Regulations

Approved Document M to the Building Regulations 2010 (in Wales) and 2015 (in England) clearly states that its “objective is for all to travel vertically and horizontally within buildings conveniently and without discomfort…” and “…to have access to, and the use of, all the facilities provided by the building.”

This guidance is echoed in Section 4 (Safety) to the Building Standards 2017 (Scotland) which states that “safe, unassisted and convenient means of access should be provided throughout the building”.  More specifically, in relation to thresholds, the documents suggests that “To be accessible, a door should not present unnecessary barriers to use, such as a step or raised profile at a threshold, that might present difficulties to a wheelchair user or be an entrapment or trip hazard to an ambulant person, whether or not using a walking aid.”

To ensure compliance with these requirements and provide a safe and welcoming experience for students and staff, it makes sense to specify products which will allow a seamless transition out onto the balcony deck. When selecting insulation materials for these constructions, there are a couple of application options.

Insulation Options for a School Roof Terrace

In many cases, the terrace concrete deck is a continuation of the internal floor deck. Whilst this helps to reduce build costs, it often means that little depth is available for the insulation layer and floor surface for the balcony. This can make it challenging to meet the U-value requirements within Approved Documents L to the Building Regulations 2013 (England), 2014 (Wales), and Section 6 (Energy) to the Building Standards (Scotland).

Figure 1 - Concrete balcony deck 

One way to resolve this with conventional insulation materials is by installing some or all of the insulation below the concrete deck. Whilst this can allow the desired U-value to be met with a level transition, it can result in awkward changes in room height for the space below and can make rooms feel more cramped. Careful condensation risk analysis is also essential for this approach to ensure moisture does not form on the underside of the concrete deck.

Figure 2 - Concrete balcony deck using an above and below insulation approach. 

The alternative is to simply install insulation above the roof deck. However, when using conventional insulation materials, this will often require a step-change to be created between internal and external spaces. For example, to meet our recommended best starting point U-value for new build flat roofs in England (0.14 W/m²·K) above a concrete deck with a plasterboard ceiling, more than 260 mm of XPS insulation (assumed to have a thermal conductivity of 0.036 W/m2K) would be required.

Figure 3 - Concrete balcony deck using an above deck insulation approach with XPS insulation. 

To resolve this issue, designers are increasingly looking to vacuum insulation solutions, such as Kingspan OPTIM-R and Kingspan OPTIM-R E. With thermal conductivities as low as 0.007 W/m.K, these systems can allow the required U-value to be met with a greatly reduced insulation thickness.

Vacuum Insulation Solutions for Roof Terraces 

Vacuum insulation systems typically incorporate both Vacuum Insulation Panels (VIPs) and high performance rigid insulation infill panels of the same thickness which can be cut to size to allow penetrations and to fill areas around the perimeter of the space. A further thickness of high performance rigid insulation is also installed as an overlay across the entire balcony layer.

In Kingspan OPTIM-R Roofing System applications, our technical services teams provide detailed system layouts. These support a fast installation and ensure the best possible ratio of VIPs to infill panels, allowing the desired U-value to be met with a minimal insulation thickness. For example, in an application above a concrete deck with a plasterboard ceiling, a U-value of 0.14 W/m²·K can be met with just a 60 mm thickness of the Kingspan OPTIM-R Roofing System with a 25 mm overlay of Kingspan Thermaroof TR27 LPC/FM.

Figure 4 - Concrete balcony deck using an above deck insulation approach with vacuum insulation

To further streamline installations, we also offer the Kingspan OPTIM-R E Roofing System. In this system, the OPTIM-R VIP is encapsulated within an 80 mm high performance rigid insulation. This can allow the best starting point U-value in England (0.14 W/m²·K) to be met without the need for an insulation overlay in a concrete deck application, further reducing the installation time.

By taking advantage of these vacuum insulation systems, specifiers can now create easily accessible roof terrace spaces for schools without needing to compromise on thermal performance.

Discover more about how to best insulate terrace and balcony areas.