Quick Answer

A deeper, stronger deck profile can span further between supports.

Spanning further lets you widen secondary beam centres, or remove some beams altogether.

Fewer beams means less steel to fabricate, deliver and erect, and often less or no temporary propping.

The trade-off is a deeper slab and a little more self weight, so it is a balance, not a free win.

The span a profile can reach comes from its load and span tables for your loading and slab depth. Ask us to check before you specify.

Why are deeper deck profiles becoming more popular?

Deeper deck profiles are turning up on more and more steel frame floors, and it usually comes down to one thing: steelwork. If you have ever looked at a floor plate and wondered whether every one of those secondary beams is really needed, this is where the answer often starts. The profile you choose does not just decide the slab. It quietly shapes how much steel sits underneath it.

The slab density and depth is really based on fire, acoustic, thermal and head height limitations.

This guide explains what a deeper profile actually gives you, how spanning further takes steel out of the frame, what it costs you in return, and why the decision is best made early against the steel drawings rather than late in value engineering.

What is a deeper deck profile?

Composite floor decking comes in a range of profile depths. The MetFloor range we sell goes up to MetFloor 80 and our ComFlor range goes up to the ComFlor 100. The depth is the height of the steel rib, and as a rule a deeper rib gives the profile more strength and stiffness across a given span. In plain terms, a deeper deck can generally carry its loads over a longer distance between supports than a shallower one of the same gauge.

That single characteristic, the ability to span further, is what makes the profile depth such a useful lever on a steel frame job.

How spanning further reduces steelwork

Secondary beams are there for one main reason on a composite floor: to break the floor plate into spans the deck can handle. The deck spans between the secondary beams, the secondary beams span between the primary beams, and the primaries carry it all back to the columns.

So if a deeper profile can span further, you have two options. You can open the secondary beam centres out wider, or you can remove some of those beams altogether. Either way you end up with fewer lines of secondary steel across the floor. Less steel to design, less to fabricate, less to deliver, and less to lift and connect on site.

A worked example

Take a floor plate that is 12m wide, framed with a primary beam down each side. The secondary beams break that width into spans the deck can cope with.

Say a shallower profile suits secondary beams at 3m centres. Across the 12m width that gives you internal secondary beams at 3m, 6m and 9m, so three lines of secondary steel.

Now say a deeper profile lets you open those centres out to 4m. The same 12m width then needs beams at 4m and 8m only, so two lines. That is one full line of secondary beams removed along the length of the floor. Multiply that across every bay and the steel tonnage starts to come down noticeably.

The centres a given profile can reach are not a guess, though. They come straight from that profile’s load and span tables for your loading, slab depth and fire period. The arithmetic above shows the principle. The design check gives you the real numbers.

The knock-on benefits

• Fewer secondary beams does more than trim tonnage. It ripples through the whole job:
• Fewer beams to fabricate and fewer connections to detail and bolt up.
• Fewer lifts during steel erection, and a quicker route to a safe working platform for everyone following on.
• Lower delivery and handling on site, with fewer members to move around.
• Often less temporary propping, because a deeper profile that spans further may reach the same span without props that a shallower one would need. That takes a step out of the programme and frees up the space below the slab.
• On tight sites and tight programmes, those practical savings can matter as much as the tonnage.

What a deeper profile costs you

A deeper deck is not a free win, and it is only fair to be straight about the trade-offs. A deeper profile usually means a deeper overall slab, which adds to the structural zone and can affect floor to floor heights and levels. It also adds a little self weight, which feeds back into the design. And the deck itself may cost more per square metre than a shallower one.

The point is that the saving in steel has to be weighed against the deeper slab and any level implications. On most steel frame floors the steel saving wins comfortably, but not always, and that is exactly why it is a design decision rather than a default.

When a deeper profile is the right call, and when it is not

A deeper profile tends to pay off where the floor is steel heavy, where secondary beams are closely spaced, and where opening those centres out removes real tonnage. It is less clear cut where the structural zone is already tight, where levels are fixed, or where a shallower propped solution suits the build better. There is no single right answer. There is only the right answer for your loading, your levels and your programme.

How the decision actually gets made

The profile and span decision is driven by the load and span tables published for each deck, worked against your imposed and dead loads, slab depth and fire period. The design sits within the recognised framework for composite floors, including BS EN 1994-1-1 (Eurocode 4) and the older BS 5950-4, with wider best practice guidance such as SCI P300 and the manufacturer technical datasheets from Tata Steel for ComFlor and CMF for MetFloor.

None of that needs to be daunting. It simply means the profile is chosen to suit the numbers, not the other way round.

Where RMD Profiles fits in

We supply the full ComFlor and MetFloor ranges, so we are not tied to one profile or one manufacturer. That means when we look at your floor, the advice is about what balances span, slab depth and steelwork for your project, not about pushing a particular deck.

Send us your floor layout and loads and our drawing office will help you weigh up whether a deeper profile takes steel out of your frame, and whether the deeper slab is a fair trade. For the related detail on how those deck ends need to land on the steel, see our guide on metal deck bearing and the 50mm rule. For more on props, see our FAQ on whether composite slabs need temporary propping.

Frequently asked questions

Do deeper deck profiles really reduce steelwork?

Often, yes. A deeper profile can generally span further, which lets you widen secondary beam centres or remove beams. Fewer secondary beams means less steel to fabricate, deliver and erect. How much you save depends on the floor, and the achievable spans come from the profile’s load and span tables.

Does a deeper deck mean a deeper slab?

Usually, yes. A deeper profile normally increases the overall slab depth and the structural zone, which can affect floor to floor heights and levels. That deeper slab is the main trade-off to weigh against the steel saving.

Can a deeper profile remove temporary propping?

Sometimes. Because a deeper profile can span further, it may reach a span unpropped that a shallower profile would need props to achieve. Whether propping is needed still comes down to the profile, span and construction stage loads, so it should be confirmed by design.

Is a deeper deck cheaper overall?

Not on the deck alone, since a deeper profile can cost more per square metre. The saving comes from the steel it takes out of the frame and the site time it can save. On most steel frame floors the overall picture favours the deeper profile, but it should be checked case by case.

Which standards cover composite deck design?

Composite floor design sits under BS EN 1994-1-1 (Eurocode 4) and the older BS 5950-4, supported by SCI P300 guidance and the manufacturer datasheets for the specific profile such as MetFloor and ComFlor. Span and load capacities are taken from those published tables.

How do I know which profile suits my floor?

Start from the span, the loads, the slab depth you can allow and the fire period, then check the tables for a profile that fits. If you send us those details, we will do that check and tell you which profile balances span and steelwork for your job.

Design it in from the start

The easiest way to get the steel saving is to choose the profile early, against the steel drawings, before the frame is fixed. Send us the following and our drawing office will help you weigh up profile depth against slab depth and steelwork before anything is committed:

• the steelwork general arrangement (GA) drawing
• the architect’s floor plans
• finished floor levels or allowable slab depth, if known
• the imposed and dead loadings, if known
• the fire resistance period required

Summary

Whether you need a bespoke high-performance roof or a quick, reliable solution, RMD Profiles has the products, experience, and support to keep your project on track. – we stock a full range of MetFloor and ComFlor products. Call us today , or visit rmdp.co.uk. or email us here.