C24 structural timber: why the strength class matters
On the sauna market, "structural timber" is often a loose term. At TIKKA every load-bearing element is made of C24-grade timber to EN 338 – here is what that symbol means in practice and what you are paying for.
What the C24 designation stands for
C24 is a strength class for softwood defined in EN 338: bending strength 24 MPa, modulus of elasticity 11,000 MPa and characteristic density 350 kg/m³. Every batch is strength-graded – by machine or visually by a certified grader – and CE-marked.
By comparison, ungraded "joinery" timber from a DIY store guarantees no mechanical properties at all. For a structure carrying a snow-loaded roof and two tonnes of self-weight during a crane lift, that difference is fundamental.
Kiln drying and frame stability
The C24 timber in our saunas is kiln-dried to 15–18% moisture content and planed on four sides. The frame does not "work" after assembly – no gaps open in the insulation and no stresses crack the cladding, a common problem with structures built from wet-sawn timber.
It is precisely this stable, insulated frame that separates our saunas from solid-spruce huts – the insulation in a TIKKA wall retains heat that a 45 mm log wall simply cannot hold.
Certification as part of transport safety
A TIKKA sauna is lifted by crane in one piece – the structure must safely carry its own weight on four slings. We calculate the load-bearing frame using C24 values; with ungraded timber such a lift would be a lottery.
If you are planning a sauna in non-standard dimensions, for example for a hotel, our structural engineer recalculates the load scheme as part of a custom design. A declaration of performance for the timber accompanies every delivery.
TIKKA recommendation
When buying a sauna, ask the seller for the strength class of the structural timber and the CE declaration. If neither exists, you are comparing products from different categories. The specification of every TIKKA model, including the timber class, is in the technical table on the product page – for example the Maata model.