Concealed Steel Beams in Timber Floors | Ormiston
You can run a structural steel beam through a timber floor without it dropping below the ceiling by concealing it within the depth of the floor joists. On a new two-storey detached house in Ormiston, in Brisbane's bayside area, that is exactly what the design called for. Network Steel supplied steel beam and column assemblies with the beams concealed within the plane of the timber floor joists, so the house got the spans it needed with no steel showing beneath the floor.
How do you hide a steel beam within a timber floor?
You size it to sit inside the joist depth. When a timber floor needs to span further than the timber can manage on its own, a steel beam carries the load, and setting that beam within the plane of the joists keeps it flush and out of sight. The result is an open span above and a clean ceiling below, with the steel doing the work invisibly. It takes accurate detailing to get the beam depth and the connections right, which is why these assemblies are drawn and fabricated to suit the specific floor.
What steel do you use over a garage door opening?
A beam sized for the load above it. On this house, Network Steel installed a steel beam across the garage door to support the upper wall framing, with a shelf plate carrying the upper level brickwork. The span called for a 300 Parallel Flange Channel with a 150 x 10 flat mild steel shelf plate stitch welded to the PFC, supported by a 75 square SHS column at each end. That combination carries both the framing and the brickwork above a wide opening, which is a common requirement in two-storey homes.
When should coastal steel be galvanised instead of primed?
When it is exposed to the elements, in contact with porous materials, or close to salt air. On this build, the perimeter beam over the garage was fully hot dip galvanised for three reasons: it sat on the perimeter of the structure, it supported porous brickwork, and the house is close to a bayside saltwater environment. All the other steel beams inside the timber-framed building were buffed and primed in line with the project specification. Matching the protection to the exposure is the sensible approach. Galvanise what the weather and the salt can reach, prime what stays protected inside.
Project at a glance
| Detail | |
|---|---|
| Project | New two-storey detached house |
| Location | Ormiston, bayside Brisbane, QLD |
| Supply | Steel beam and column assemblies |
| Design feature | Beams concealed within the plane of the timber floor joists |
| Beam over garage opening | 300 PFC |
| Shelf plate | 150 x 10 flat mild steel, stitch welded to the PFC |
| Columns | 75 square SHS at each end |
| Perimeter beam finish | Hot dip galvanised [confirm to AS/NZS 4680] |
| Internal beam finish | Buffed and primed to project spec |
FAQ
Can a steel beam be hidden inside a timber floor?
Yes. A steel beam can be concealed within the depth of the floor joists so it sits flush and out of sight, while still carrying the load that lets the floor span further. Network Steel did this throughout the Ormiston house.
What steel beam goes over a garage door in a two-storey house?
It depends on the load above, but a Parallel Flange Channel is a common choice for a wide opening carrying framing and brickwork. On this project a 300 PFC with a 150 x 10 shelf plate on 75 SHS columns did the job.
Do steel beams near the coast need to be galvanised?
Beams exposed to salt air, sitting on the perimeter, or in contact with porous brickwork should be hot dip galvanised for corrosion protection. Beams that stay protected inside the building can be buffed and primed to spec, as they were here.
Why galvanise some beams and prime others on the same house?
To match the protection to the exposure. Galvanising is used where steel meets the weather, salt air or porous materials. Priming is enough for internal steel that stays dry and protected. This keeps the build sound without over-specifying every member.
Does Network Steel supply steel beam and column assemblies in bayside Brisbane?
Yes. Network Steel delivers assemblies like this to residential builders and renovators across Brisbane and the Gold Coast every day. [Link to Cleveland location page.]
Need steel beam and column assemblies for a new build or renovation? Speak to our team, or get a quote online.
