How to protect steel from fire: a comparison of fire-protection methods
When a structure needs to be brought up to the required fire-resistance limit, the designer and the client face a choice between several fundamentally different methods. They all «work», but they cost differently, look differently and suit different conditions. Let us review the main methods honestly — with their pros and cons.
Fireproof plaster (thick-layer coating)
A classic proven over decades. A thick layer of a special cement-mineral compound — from 10 to 40 mm — is applied to the metal. The layer holds high fire-resistance limits, up to R150–R180, and is not afraid of moisture.
The downsides are significant. First, weight: several centimetres of plaster noticeably load the structure. Second, appearance — open beams and columns in an office or showroom cannot be finished nicely this way. Third, labour intensity and requirements to the substrate (reinforcing mesh, adhesion). Plaster is good where aesthetics do not matter but the maximum limit is needed: technical floors, tunnels, industrial areas.
Fireproof boards and mats
The structure is clad with non-combustible boards (basalt, silicate, gypsum-fibre) or wrapped with mats. The method is «dry», gives high limits and is convenient for boxes around columns and for protecting air ducts.
But boards «eat up» space, create extra volume around the element, and require careful installation of joints and a frame. For complex joints, trusses with braces and gussets this is expensive and inconvenient: cladding a straight column is easy, a lattice truss almost impossible.
Thin-film intumescent paints
This is the modern and most versatile approach, which is our primary focus (the TERM range — see the fireproof paints page and the TERM-001, TERM-007, TERM-009 cards). The paint is applied in a layer from a fraction of a millimetre to a few millimetres — like an ordinary coating. In its calm state it is a thin, almost invisible film. In a fire it swells dozens of times, forming a heat-insulating char that protects the metal.
Why it is chosen more and more often:
- Minimal weight and thickness. It does not load the structure and does not «steal» space.
- It preserves geometry. Ideal for open steel structures visible in the interior: the paint can be tinted, the structure stays «readable».
- It is applied to any shape. Truss, lattice, gusset, shaped profile — the paint does not care, it goes on by brush, roller or spray.
- It really provides R30–R90, and with the required thickness in the system — even higher.
The downsides honestly: thin-film compositions are sensitive to service conditions (humidity, aggressive environment) and require a proper thickness selection and a compatible primer. But this is solved by the right coating system and, if necessary, a finishing varnish.
How to choose
There is no universal answer — it all depends on the facility:
- Maximum limit on hidden structures, aesthetics not important — plaster.
- Boxes, air ducts, straight columns in technical rooms — boards.
- Open steel structures, complex shapes, appearance and weight matter, limit R30–R90 — thin-film paint. In most civil and commercial facilities it is exactly the one that wins.
STATERM helps choose the method for the specific facility rather than «selling what is in stock». We will select the fire-protection system, calculate the thickness for the required limit and carry out the application with quality control.
Call: +998 90 918 81 88.