FACTA Rating and ABCDEF load classes

Manhole or access cover?

Let’s start with explaining the difference between a manhole cover and an access cover, as this is easy.

A manhole cover is a form of access cover, but not all access covers are manhole covers. A manhole is large enough for a (reasonably fit and slender) man to pass through and enter an underground chamber – generally speaking, part of the storm or foul water drainage system. Because public drains are most commonly laid along roads, this is where you are most likely to see manhole covers, and they therefore need to be strong enough to take the weight of heavy goods traffic. And that’s why they are mostly made from cast iron, ductile iron, galvanised steel, concrete or a combination of these materials.

On the other hand, access covers not for public drains might be quite small and located on pavements, driveways and inside floors. If they are for access to domestic sewers they may look a bit like a manhole cover, but as they only need to take the weight of a car in a drive, they will be of a much lighter-weight construction, such as pressed steel. Smaller access covers such as those used for water meters, are even made in strong plastic.
 

What's A Facta Rating?

For the last twenty years since trade association FACTA (Fabricated Access Trades Association) developed this rating system, it has almost been the industry standard for access covers and frames.

More commonly used for recessed covers. FACTA load test ratings are based on structural engineering calculations for fabricated components.

One big advantage of FACTA is that it allows for a greater variety of materials and design flexibility than are possible with cast iron covers, offering load classes that address the shortcomings of BS EN 124:2015.

Like BS EN 124:2015, FACTA ratings also use an A-F scale although since its introduction, AA and AAA have been added between A and B.

The following classification table produced by FACTA shows what each loading class can withstand, in terms of both gross laden and slow moving, as well as the comparison against the EN124 specification. It also details the typical application for each loading.

*Under the Road Vehicles (Authorised Weight) Regulations 1998, axle weights for the UK are limited to 11.5 tonnes maximum.

  Refer to Acceptance Test column for maximum design load/load-bearing capacity.

**Slow-moving wheel loads are deemed to be speeds no greater than 20mph.

***These comparisons are for guidance only and are not intended to be exact.

What Does BS EN 124 Mean?

The European Standard BS EN 124 was how the strength of a grating, manhole or access cover was originally rated, and this was revised in 2015 to include annexes that cover the various materials used for covers.

BS EN 124 takes into account the dynamic vehicle loading of fast-moving traffic and has six ratings based on the cover’s ability to withstand test loads of different forces: A15, B125, C250, D400, E600 and F900. The number featured in each rating refers to the force a grating or cover will withstand in kilonewtons (kN).

Under BS EN 124:2015, fabricated (not cast iron) access covers are normally restricted to areas where vehicle speeds are limited to 20mph.

Ultimate test loads are therefore substantially higher for BS EN 124:2015 than those for FACTA. For example, BS EN 124:2015 Class D400 has an ultimate test load of 400kN compared with 220kN for a FACTA Class D rating. This means that for fabricated covers to achieve BS EN 124:2015 they require additional reinforcement that given the application is unnecessary.

Which Rating Or Class Should You Use?

If you are using traditional cast iron access covers, BS EN 124:2015 is quite acceptable. However, with many types of access cover now being fabricated from an extensive assortment of materials and to a wide range of designs today, FACTA is a much more versatile system to base your calculations on.