It seems common in some commercial construction to use corrugated steel plates to form a 'deck' surface which concrete is later poured onto. The combined steel/concrete then forms a very strong floor surface.

I am interested if there are any guidelines for doing a similar process on a residential or DIY level. For example, an elevated shed floor could conceivably be constructed out of metal roofing over wooden joists, with concrete poured on top. Perhaps even a freestanding deck.

Ideally I'd like to find out if there are standards or guidelines for the wooden deck framing, metal gauge and other dimensions, if rebar or mesh is to be used, concrete thickness, etc. And/or what building codes might have to say about this.

Here's a commercial example just to make the general idea clear:

enter image description here

I don't know if such a guide is published but if this is ever something done by contractors on a small scale then... maybe.

Also though I'm in the US where wood framing is common in many countries masonry seems to be more typical, so any global examples/information would be welcome also.


  • 1
    FYI, to address one issue, The corrugated metal used in these applications is NOT "metal roofing"
    – Alaska Man
    Commented Jun 30, 2018 at 16:19

3 Answers 3


This is not a complete answer to the question but it is at least a residential example of this kind of construction. It shows how a front porch is put together.

So it can be done although the backgound of whether this was a custom engineered project or how else the design was arrived at is not clear.

Steel C-channel is used as "joists" (the C-shape is facing down):

enter image description here

Steel deck pans are installed. These do look generally similar to roofing but seem like a purpose-made product:

enter image description here

The pans are cut to fit and overlap to some extent: enter image description here

Concrete is poured over the deck pans:

enter image description here

  • Will concrete not corrode the corrugated sheets? Commented Nov 18, 2018 at 22:02
  • 1
    @DaviddCeFreitas that's an important consideration. Concrete itself will not damage steel (steel reinforcing bar is used regularly embedded within concrete) but a high degree of moisture within the concrete (ie from rain) could. Concrete is a "reservoir" material and actually can absorb & hold liquid water, even once cured & hardened. Concrete could be reactive with other materials as well, such as aluminum. Commented Nov 19, 2018 at 1:06
  • 1
    The major concern is with rust/oxidation. Rebar also comes coated to prevent this, and I would assume any steel decking would be coated as well. Another concern would be the difference in thermal expansion which could put stresses on the concrete itself and crack it. A counting layer between them would also mitigate this. And as a side note, concrete has far greater compression strength than tension strength, so any cantilever or suspension should be handled with wood or steel.
    – Digcoal
    Commented Jun 3, 2021 at 10:36

Here is another method - this is almost a counterexample to the other answer. Non-structural concrete over standard wooden structural framing.

In the metal-pan approach, if the metal is not providing any structure itself then it is really just a form for the concrete until it cures and then the concrete supports its own weight; but in THIS example it is the opposite - a wooden structure already exists and it is topped with concrete. The concrete is basically just flooring material and does not support its own weight.

This has all the advantages of concrete as a surface - durability, hardness, you could bond tile to it, etc. But it does not rely on the concrete for actual structural strength of the building, as a metal-pan would in a commercial setting.

Important considerations for this method:

  • The wood under the concrete has to be protected from moisture in an exterior installation.

    Concrete is not waterproof and will actually absorb water and rot out any wood touching it. In Figure 2 you can see that waterproofing has been carefully applied to the plywood subfloor & up the walls.

    Also the wall flashing appears to be correctly designed to lap over the floor waterproofing.

  • The dead load of the concrete has to be accounted for in the design of the wooden structure.

    This is not as bad as you might imagine - 4" (10 cm) of concrete would weigh about 50 PSF (lbs / sqft) which while not insignificant can be designed into your floor loads. E.g., a normal residential deck might be designed for approx. a 50 PSF total load.

    In Figure 1 below you can see that 2x10 or 2x12 framing, 16" centers has been used - fairly standard.

  • Deflection of the substrucure has to be accounted for, to prevent the concrete from cracking.

    Probably you'd need to design this like you would for a tiled floor, such as L/360 or better. Although even if it did crack, this might only be unsightly and not a serious issue.

    And/or some rebar could be added although that was not done in the example here.

Figure 1: Framing of timber substructure enter image description here

Figure 2: Placing concrete over the waterproofed subfloor enter image description here

Figure 3: Finishing the concrete surface to desired smoothness enter image description here

Image source


I don’t have any pictures but all of my house is steel and cement new house built on water in ma about 21,000 gsf 14,000 living 7,000 per level the basement is 10ft High with the foundation on re enforced cinder block. Basement has larger steel I beams supporting lighter steel framing. The first floor, floor is 6 inch steel decking with 2inch of concrete with finished floor on top the exterior walls are mostly light gauge steel framing the wall facing ocean is re enforced cinder block to withstand storms. The same system is used for the second floor. The only part of wood structure in the house is the roof plywood for nailing purposes. The interior load bearing walls use steel studs and interior patroons are light weight steel studs. You may say this is over the top but after loosing a house to a storm and another to a fire you would understand. The biggest plus is that there is not many interior load bearing walls so you can have what ever flow you want.

  • Hello, and welcome to Home Improvement. Thanks for the answer; keep 'em coming. And, you should probably take our tour so you'll know how best to contribute here. Commented Dec 7, 2019 at 11:11

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