GRP Riser Flooring
GRP riser flooring is load-bearing GRP grating fixed across a building's service risers at each floor. At UIS, we design, fabricate and install riser floors and riser grating with our own teams across the UK.
A permanent floor over every open riser.
GRP riser flooring is load-bearing glass-reinforced plastic grating fixed across a building's service risers at each floor level. It closes the fall risk over the void the day it goes in, gives maintenance teams a permanent floor to stand on, and lets the trades cut service openings in place.
Closing out the risers on a multi-storey building? The floor at each level has three jobs at once: carry your maintenance teams for the life of the building, let the fit-out trades work over the void now, and close the fall risk as the access scaffold comes out.
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Designed as one system
We fabricate the support framework, cut the GRP panels to fit and install both together, so the floor is never split across two suppliers when a service penetration moves.
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Sized to your engineer
38 mm grating on a GRP or steel frame is the usual build, sized to the load your engineer sets and graded to the class your fire strategy asks for.
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Non-conductive, and removable
GRP does not conduct beside the live cable in a riser, and panels can be fixed to lift out wherever your maintenance teams need into the void.
Riser floor specification at a glance.
What goes into a GRP riser floor, and what decides each choice. Your engineer sets the loads; your fire strategy sets the fire class.
- Panel depth
- 25 mm, 38 mm (the usual choice) or 50 mm
- Decided by: The clear span between supports and the load your engineer specifies
- Panel type
- Moulded open mesh, mini mesh, or solid top
- Decided by: Whether small items must be stopped from falling, and whether people work below
- Openings
- Must not pass a 35 mm sphere, or a 20 mm sphere where people work below
- Decided by: BS 4592-0, the ball-fall rule
- Surface
- Quartz-gritted or concave anti-slip
- Decided by: The wet slip value: a PTV of 36 or more to BS EN 16165 is low slip potential
- Resin grade
- Standard, fire-retardant or phenolic
- Decided by: The riser's fire strategy, to BS EN 13501-1 or BS 476-7, certified for the grade supplied
- Support frame
- GRP angles and channels, or a steel frame for longer spans
- Decided by: Void size, slab edge, cast-in or post-fixed, and the fire-stopping line
- Fixings
- Clips to the bearers at the manufacturer's centres, with the end bearing the manufacturer specifies
- Decided by: Panel type, and whether panels must lift out for maintenance
- Load
- A uniformly distributed load in kN/m2 plus a point load
- Decided by: Your structural engineer; deflection held within span/200 or 10 mm, whichever is less, with no more than 4 mm difference in level from the next panel (BS 4592-0)
- Service openings
- Cut in place with a diamond blade under dust extraction, no hot works
- Decided by: The M&E sequence on each floor
Buying panels, or a fitted riser floor
Panels from a supplier
- Who measures each void
- Your team, floor by floor
- What arrives
- Panels and clips, cut to your schedule
- Service penetrations
- Cut by whoever is on site
- Who answers for the fit
- The installer you appoint
- Handover
- Product data
Designed, supplied and installed by one contractor
- Who measures each void
- We survey the risers, with a 3D scan on refurbishment work
- What arrives
- A frame and panels detailed to your loads and fixed in place
- Service penetrations
- Pre-cut to drawing in our workshop, trimmed on site as services move
- Who answers for the fit
- One contractor, from survey to handover
- Handover
- An O&M pack with the slip values, the fire class for the grade and the as-built detail
Where it is used
- GRP for Data CentresGRP roof walkways to the cooling plant, step-overs, riser flooring and plant platforms.
- GRP for Housing and Local AuthoritiesGRP anti-slip stair treads, flat-roof walkways and riser flooring for housing blocks and public buildings.
- GRP for Main ContractorsAll the GRP on a project, from riser flooring to roof walkways, detailed, made and installed by one subcontractor.
What decides the price
We do not publish a price list, because a riser floor is priced on the building rather than per panel. The main drivers are:
- the number of risers and floors, and the size and shape of each void
- panel depth and type, and whether a fire-retardant or phenolic grade is needed
- a GRP or steel support frame, and whether it is cast in or post-fixed
- how many service openings are cut, and at what stage of the build
- access, working hours and phasing in an occupied or live building
Further reading
- GRP riser flooring regulationsFire classes, protected shafts, fire stopping and who signs it off
- Fire-resistant GRPReaction-to-fire classes, resin grades and smoke
- GRP grating load tablesReading span, depth, load and deflection for a panel
- Moulded vs pultruded GRP gratingHow each is made, which spans further and which suits corrosive areas
- GRP anti-slip gratingHow slip resistance is measured, and which PTV to ask for
From survey to installed riser floor.
We measure the shaft, fabricate the covers to fit, and install them in live, occupied buildings.
Survey and measure
We survey the shafts and openings and agree the panel layout and support detail with you. On a refurbishment, we 3D-scan the existing riser and overlay the design in CAD, so the panels fit the shaft you actually have rather than the one the original drawings describe.
Design, detailing and quotation
We detail the panels and the support framework, take the loadings from your structural engineer, and return an itemised quotation that includes the framework, the cutting and the installation. Quotations on major commercial packages come back within 1 to 2 weeks, because a proper take-off against your general arrangements deserves more than a guess, and the framework is priced in rather than turning up as a change order on site.
Fabrication and pre-cutting
We fabricate the support framework and pre-cut the GRP panels to the approved drawings at our Rotherham workshop, so the bulk of the cutting is finished before anything is delivered to your site.
Installation
Our own team installs floor by floor under an SSSTS supervisor, working to full method statements and around the other trades. Where a panel needs trimming for a service that has moved, we cut it on site with a diamond blade under dust extraction, with no hot works and no sparks near live cabling, and we work in occupied buildings and out of hours where your programme needs it.
Handover, documentation and aftercare
At handover you receive the O&M pack with the BS EN 16165 pendulum slip values, the fire classification for the grade specified, and the BS 4592 flooring compliance. A defect liability period of 12 months runs from practical completion in line with standard JCT terms (unless your contract sets different terms), and if anything is not right in that first year we come back and put it right.
Why the floor over live cable should not conduct.
A service riser is full of live cable, so the floor that sits over it should not conduct, and GRP does not. It also weighs roughly a fifth of the steel equivalent, so one person can safely lift a removable panel to reach the services below in a confined shaft.
Tour our workshop
Riser floor panels and frames.
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Why one team should own the riser floor.
Light enough to lift by hand in a confined shaft, cut to fit on site with no hot works.
About UIS-
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One accountable team for the whole riser floor
We design the panels, detail and fabricate the support framework, cut the GRP to fit around your cabling and pipework, and install the lot with our own teams. When a wet riser or an HVAC duct shifts during the build, there is one number to call, not a procurement argument between the firm that supplied the panels and the firm that was meant to fit them. We have kept design, fabrication and installation under one roof since 1994, which is how the coordination, programme and compliance risk of a multi-supplier package is removed in a single decision.
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Light enough to lift by hand in a confined shaft
We supply GRP riser panels that weigh roughly a fifth of the steel equivalent, so one person can safely lift a removable section to reach the services below without a second pair of hands or a lifting aid in a tight shaft. That matters every time the building is maintained, not just on the day it goes in, because the panel a technician has to move in five years is the same panel we install now.
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Non-conductive, and cut to fit on site without hot works
A service riser is full of live cable, so the floor that sits over it should not conduct, and GRP does not. It can also be trimmed on site around a penetration that has moved, using a diamond blade under dust extraction, which means no sparks, no fire watch and no hot-works permit next to a busbar. We pre-cut the panels to your drawing at Rotherham, so most of the cutting is finished before anything reaches your floor.
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Our own carded teams, proven in live and occupied buildings
We install your riser flooring with our own teams, not a labour-only chain subcontracted down until nobody on site holds the right ticket. Every project runs under an SSSTS-qualified supervisor, every operative carries a CSCS card, and the site teams are PASMA and IPAF certified, working to full method statements. We have installed steelwork on night shifts inside a live supermarket at Oban, so an occupied building is a programme to plan around, not a reason to decline the work.
"I've worked with UIS for several years on some high profile and very complex projects. Their attitude and work ethic are second to none - providing high quality services and products which are delivered safely and on time every time. Overall they are a pleasure to do business with and wouldn't hesitate recommending UIS for any steelwork or metalwork packages."
Riser floor questions.
Yes. We pre-cut the panels to your approved drawing at Rotherham, and where a service penetration shifts on site the GRP can be trimmed with a diamond blade under dust extraction. Cutting GRP does not spark, so there are no hot works and no fire-watch permit needed next to live cabling.
On a support framework that suits the shaft: GRP perimeter angles or a steel framework, cast in on a new build or post-fixed into an existing shaft on a refurbishment. We detail and fabricate that framework and install it with the panels as one package, so the support is never a separate supplier's responsibility.
The loadings come from your structural engineer, and we design and fabricate the flooring and its framework to meet them, which is why we do not publish generic capacity figures. The flooring itself is made to BS 4592-0:2006+A1:2012, the UK standard for industrial-type flooring and walkways.
Yes. Our own installation teams are CSCS-carded, SSSTS-supervised and PASMA and IPAF certified, and they work to full method statements around the other trades. We have installed steelwork on night shifts inside a live supermarket at Oban, so occupied and out-of-hours programmes are routine.
You receive an O&M pack containing the BS EN 16165 pendulum slip-resistance values, the fire classification for the GRP grade specified on your project, and confirmation of BS 4592 flooring compliance, so the specification is auditable from day one.
Most riser floors use 38 mm deep grating, with 25 mm for small voids and short spans and 50 mm where spans are longer or loads are heavier. The depth comes from the manufacturer's load table, so the panel carries your engineer's load within the deflection limit at the real clear span between supports.
GRP is classified on its reaction to fire, and the class depends on the resin system: standard, fire-retardant and phenolic grades all perform differently, with phenolic usually chosen where low smoke matters. Your riser's fire strategy sets the class needed, to BS EN 13501-1 or BS 476-7, and we issue the certificate for the grade supplied rather than quoting one blanket rating. Our fire-resistant GRP guide explains the classes.
Temporary boarding over a riser has to be lifted, cut and replaced every time a service goes in, and the void is open while it is. A permanent GRP floor closes the fall risk at each level the day it is fixed, lets trades cut openings in place with a diamond blade under dust extraction, and stays in for the life of the building as the maintenance floor.