Much has been written recently about the use of various types of insulation around the building envelope, particularly the façade. However, with so much focus on the facade, the roof seems to have been overlooked, which is concerning considering the significant number of roof fires.
Not taking care of the roof potentially introduces a weak link into the building envelope. Therefore, it is just as important to have non-combustible, thermally efficient insulation on the roof as it is on the façade.
Firstly, let’s look at efficiency.
According to the Carbon Trust as much as a quarter of a building’s heat loss occurs through the roof. Conversely, in warmer summer months, the angle of a flat roof ensures maximum exposure to the sun – which can cause indoor temperatures to rise up to 35ºC higher than ambient.
Properly insulating the roof addresses both these issues by cutting heat loss by up to 90% and reducing unwanted solar gain.
Secondly, it is vital to consider the fire safety impact of insulation in roofing applications. Roof systems are becoming areas where the demand for non-combustible insulation is rapidly increasing and rightly so. Roof fires on high-risk commercial buildings, such as, warehouses, distribution centres and retail units, not only endanger life but also cause damage to the business and the community.
As an example, take the recent fire at the landmark Bank Buildings on Castle Street in Belfast, home to the Primark store. The building was undergoing a major £30m refurbishment at the time but a fire started because of hot torch works taking place on the roof. A charred shell is now all that remains of the building. But the damage does not end there. Since the fire in August, fourteen businesses have been forced to close and Belfast City Centre is losing up to £3 million per month in lost revenues, with footfall at the nearby Castle Court shopping complex down 49%.
The site is still in an extremely dangerous state, which has caused the main thoroughfare in the area to be closed, effectively dividing the city in two, creating further disruption. A fire of this scale has larger implications for people’s lives and livelihoods than the destruction it causes to the building itself. Its economic impact is felt far and wide.
In the same week, twelve fire engines and about 80 firefighters were called to a fire at the Roding Primary School in Dagenham, one of the largest primary schools in the country. The fire destroyed a large part of the single-storey building and the cause has been attributed to hot works being carried out on the roof. The fire took place just before the new school term and meant that the school and the local council had to find places for the 378 pupils who attend the Hewett Road site during the closure.
In June last year, the iconic Glasgow School of Art Mackintosh Building was destroyed by fire for the second. It is believed that the insulation installed on the roof during the refurbishment was an element in causing the fire to spread so rapidly. The fire not only destroyed over 50% of the Mackintosh building but it also spread to several other properties including the O2 ABC Venue. In February, plans were submitted to demolish the building as it was so badly affected by the fire. The building has a 143-year history of holding live events and is actually older than the Mackintosh Building. The Centre for Contemporary Arts (CCA) and the 18 businesses and institutions it holds were affected for months due to the area being sealed off by a safety cordon following the fire.
In September last year, firefighters were called to a fire at a half-built apartment complex in Loughton, Essex. The £10 million project was being carried out on behalf of Epping Forest District Council and due to include 51 affordable units, made up of 17 affordable homes and 34 flats. The fire completely gutted the three-storey building and investigations found a molten tar bucket had sparked insulation on the building’s roof. The fire was a serious setback for the councils plans for affordable housing in the area.
When looking at some of the causes of these fires and the way in which they spread, it is important to understand how a how a non-combustible flat roof insulation could have led to a different outcome. The time has come to re-consider the entire building envelope when it comes to fire protection, and that includes the roof. If you have one weak link, then the whole envelope is weak.
Meeting the challenge
ROCKWOOL has recently launched a new Thermal Roof Board (TRB) insulation product which is purpose-designed to give an enhanced thermal performance across roofs that are subject to maintenance-only foot traffic. This non-combustible dual density flat roof insulation board is ideal for large roof areas such as distribution centres and warehouses.