GRP C-Channel and Deep Channel Sections

There is no separate lipped-channel family in our pultrusion programme. The section a drawing calls a C is supplied from the GRP channel range, and this page shows which of those sections suit a side-bolted fixing in hanger, rail and bracket systems. Pultruded by NA-ME Composite.

Send your C channel dimensions

↳ include the hanger spacing and we will pick the section to match

If your drawing says C-section, read this first

We do not run a separate lipped C-channel family. That is a straight answer rather than a stock problem, and in nearly every case the section you actually need is already in our programme under a different letter.

"C" gets used for two different things on drawings, and separating them settles most enquiries in a sentence.

The first is simply a plain channel drawn with its opening facing sideways: a web with two flanges, bolted back against a wall, a column or a main beam so that the open face looks out. That is a channel section. Which way up it is drawn is an installation decision, not a different product, and the profile that arrives on the lorry is the same one either way. Most of the enquiries that reach us asking for a C-channel are asking for exactly this, and they are answered from the standard channel range.

The second is a lipped cee, the shape inherited from cold-formed steel purlins, where each flange turns back on itself in a short return lip. That lip is there for a steel reason: a thin cold-formed flange needs its free edge stiffened, or it buckles locally long before the material itself is anywhere near its limit. Pultrusion does not face the same constraint in the same way — wall thickness is set by the die, and stiffness is bought with thickness rather than with a fold. So the lipped geometry is not part of our standard programme, and we are not going to invent a code for it and hope.

What we supply instead: the deep, narrow channels

The useful property of a C-section, for most of the jobs it appears in, is its proportion rather than its lip: a tall back and a short flange, so that the profile sits flat against a surface, bolts through the web from the side, and still has real bending stiffness in the plane that matters.

Our channel family carries those proportions. What follows is the deep-and-narrow subset — a working shortlist of the deeper, narrower channels, the ones that behave the way a C-section is expected to behave in a hanger, a rail or a bracket. Look at the codes when you get there: every one of them begins CPU. That is not a typo, and it is the entire point of this page. These are channel sections, gathered here because this is what people are looking for when they type "C".

Nothing is renamed, no code is invented for the occasion, and no dimension on this page exists anywhere except on our production programme. If a section is not listed, it is not made.

Deep channel sections

Deep, narrow channel sections for side bolting
Code	Height A (mm)	Width B (mm)	Wall t (mm)	Weight (kg/m)
CPU-O-103	56	24	2	0.85
CPU-O-105	60	26	3	0.78
CPU-O-108	82	28	3	0.72
CPU-O-109	87	30	5	1.50
CPU-O-113	140	50	7	2.39
CPU-O-114	150	38	6	2.40
CPU-O-115	150	43	9	3.70
CPU-O-116	200	55	9	4.70

↳ a shortlist, not the whole family — the full channel range runs from 30 × 20 × 3 up to 300 × 75 × 12

The table above is deliberately a shortlist, chosen for one shape of problem. For the complete range of channel sections, including the wider and shallower proportions, see the GRP channel profile page. If none of the proportions there suit your detail, the honest answer is a custom die rather than a substitute section that is nearly right.

Choosing between them

Three things decide which row you want.

The back is the fixing face. Its height sets how much room there is for a bolt pattern, and whether you can get two fixings in depth rather than one. If the section is carrying an eccentric load hung off its flanges, that second fixing is usually the thing you are really buying.
Depth drives stiffness. Bending stiffness rises sharply with the depth of the section, so going from an 82 mm back to a 150 mm back does far more for deflection than adding wall thickness ever will. Deep and thin beats shallow and thick more often than people expect.
Deflection usually governs, not strength. GRP has high tensile strength along its length but a low to moderate modulus of elasticity. In practice the section is almost always chosen by how much it is allowed to sag rather than by how much it could carry before failing. Design to a deflection limit and the strength question tends to look after itself; the mechanical properties page sets out why that is, and what the direction-dependent behaviour of the material means for a side-loaded section.

One more point, which belongs to the material rather than to the section: GRP is roughly a quarter of the density of steel. A hanger run that needed two people and a lift in steel channel is often a one-person job in composite, and the anchors spend far less of their capacity carrying the support itself before they carry anything useful.

Where these sections are used

The deep, narrow channels turn up wherever something has to be held off a wall or a ceiling in a place that punishes metal:

Cable support and tray runs. The material is electrically insulating, so the support builds no conductive path of its own and there is nothing to bond.
Pipe hangers and brackets in wet, chlorinated or chemically loaded rooms, where a galvanised bracket starts bleeding rust at the fixing holes long before it loses strength.
Panel, hatch and frame edges, where the flat back seats fully against the structure and the open side takes an edge, a gasket or a cover.
Rails and sub-frames on outdoor structures, where the metal alternative commits somebody to painting at height on a repeating cycle for the life of the building.

The thread running through all of them is corrosion at the interface. On a side-bolted section the trouble almost never starts in the middle of the span; it starts along the contact line and around the holes, which is exactly where a composite section has nothing to give up. See installation and fastening for how holes are drilled and cut faces sealed, and the structural shapes overview if an angle, beam or box suits the detail better than a channel.

Resin, and what to do if you genuinely need a lip

Every section in the table is available in all six of our resin systems — orthophthalic, isophthalic and vinyl ester, each in a standard and a flame-retardant grade — and the letter in the middle of the code is where you specify it. CPU-O-113 and CPU-V-113 are the same 140 × 50 × 7 mm channel at the same weight per metre; one is the general purpose grade, the other is built for a chemical environment. GRP resin systems covers how to place your environment against the three, and what a flame-retardant grade does and does not do.

If your design genuinely depends on a return lip — because a panel clips into it, a seal seats in it, or you are matching an existing steel detail that is not open to change — then say so at the enquiry. NA-ME cuts its own dies, so a lipped section can be made; it is a tooling decision with a cost and a lead time attached rather than an impossibility. What we will not do is send you a section that is close enough and let you discover the difference on site.

Send the section your drawing asks for

Send the back height, the flange width and the wall thickness, or simply a photograph of the drawing. Add the span, the support or hanger spacing and what the section has to carry, and we will come back with the channel that meets it — or tell you plainly that a custom die is the right answer. Either way you get a real code, a real weight per metre and a price against the job.

Send your C-section dimensions, get a quote