Metrotile’s Fire Safety Rating Explained

Conservatory refurbished with a Metrotile Lightweight Roof System Shingle Charcoal

At Metrotile, much of our 30 per cent growth last year came from expansion in the conservatory market, as the benefits of our lightweight steel roof tiles became more widely appreciated.

Fire safety is not something we talk about that often, but the benefits are vital, literally.

While we are happy to extol the aesthetic, practical and sustainability benefits of our tiles, they also meet the highest fire safety standards. Compared to some of the alternatives, the safety benefits can save lives.

Indeed, safety regulations are focused on the importance of saving life, rather than saving property. Tests are based on how long each element of a structure will stand up to fire but have little to do with what happens once the fire has actually become established.

In our area of specialism, fire safety tests are intended to show how well a roof can resist a fire from a source outside the building itself, firstly regarding the penetration of the roof, and secondly spreading across its surface.

The relevant industry test is the punchily-titled BS 476-3: 2004 – Fire test on building materials and structures – Part 3: Classification and methods of test for external fire exposure to roofs. It’s shortened, generally, to BS 476-3: 2004.

Fabricators and installers who wanting to know which products meet the highest standards of fire safety will come across a degree of fire ratings under this standard.

It’s also important to mention that, as innovative products become more commonplace, that you ensure you are using genuine products, fitted by improved installers. We have recently identified copycat companies which are piggy-backing on our success and offering inferior products under a similar name.

For Metrotile, our products have all achieved the highest possible rating in their category, which is EXT.S.AA.

What does this mean? Well, the EXT means it is for external roofs. The S stands for sloped – the alternative you will come across is an F for flat.

The two As are the ratings for resistance to fire penetration, first, and flame spread, second.

For fire penetration, the A rating means the tested product has not been penetrated within one hour of testing under flame. The lowest rating, rating D, means the product was penetrated almost straight away, which the B and C ratings are given to those which fall either side of the 30 minute mark.

For fire spread, rating A means that there was no spread of flame during testing for 60 minutes. B means a spread of 21 inches or less, C means more than 21 inches and D means the product carries on burning five minutes after the flame is removed, or that there is a 15 inch spread straight away.

So it’s safe to say that an AA rating means that your customer’s conservatory roof is going to be pretty safe from any external fires.

There is also an additional rating, which is the addition of a letter X (for example EXT.S.BCX), which denotes the presence of any flaming droplets from the edge of the product, mechanical failure or any development of holes under testing. Worth remembering so that your customer can be confident that their expensive floors and their flowerbeds are protected, too!

As to European standards, there is ENV 1187 which is the basis for standards which are intended to eventually replace BS 476-3: 2004. As yet, ENV 1187 has yet to be granted full European Standard status but when an amended version of it is sent through, it is likely to take over our national standards.

At Metrotile, our products are tested against these standards as well. We like to excel where we can. The classification is known as BS EN 13501-5 and runs from B at the top end to F at the bottom, followed by “roof (t4)”, with t4 showing that a two-stage test method has been used, incorporating burning brands, wind and supplementary radiant heat.

UK or EU – the measurements are the same. So when the standards are met to the highest classification, you can be sure that a roof will not be penetrated by external fire in an hour, it will carry on burning for less than five minutes and that flame spread will be minimal.

The other issue to consider is distance from boundaries with regards to building regulations. Anything with Broof (t4) or an AA, AB or AC rating can be safely constructed six metres or less from a property boundary.

As the ratings become lower, the distance to the boundary needs to be greater, up to 20 metres or more for a product with a Froof (t4) or a DA, DB, DC or DD rating.

Basically, the best ratings mean the safest roofs – not only for anyone inside the conservatory but also anyone inside the rest of the house. So if a neighbour’s errant firework lands customer’s conservatory roof, you can be pretty sure it’s not going to go on and burn the house down.

It has only been in the past few years that the concept of a conservatory has developed from being a barely-usable room – too hot in summer, too cold in winter – to something more with more potential.

Today, innovative products and more readily available new methods of fabrication are making conservatories much more of an attractive feature to a home, one which can add genuine value and provide enjoyment all year round.

It is important, therefore, that these high quality constructions are protected by products which match the investment and minimise risk of that investment going up in smoke.