Snow and wind loads for a steel building in Belgium

What the Eurocodes say

Snow is covered by EN 1991-1-3 and wind by EN 1991-1-4. Each country adds a national annex: the ANB in Belgium, the NB in the Netherlands, the AN-LU in Luxembourg ^[1][2][4][6]. The standards are paid for. The values below come from public BBRI/Buildwise fact sheets, course material and third-party tools.

These values are for scoping a project. They must be confirmed in the national annexes before any structural calculation, which is the engineer's job. Every value not confirmed is flagged "to be verified" below.

Belgium: the snow load

The characteristic ground snow load sk is 0.5 kN/m² for an altitude A of 100 m or less. Above that, the fact sheet gives sk = 0.5 + 0.007 (A - 100) / 6, with A in metres ^[1]. Ce and Ct are always 1 in Belgium, and the shape coefficient mu1 is 0.8 for a roof pitch of 0 to 30 degrees ^[1].

To be verified: the formula is the one extracted from a 2008 fact sheet and must be confirmed in the ANB, which may have been revised ^[1]. Do not size any structure from this table.

Belgium: the basic wind speed

The basic wind speed vb,0 takes four values: 26, 25, 24 or 23 m/s. It is assigned by postcode, with no gradual transition between zones ^[3]. In a KU Leuven course, Arlon is at 26 m/s and Bruges at 23 m/s. The reference pressure goes from 331 N/m² to 423 N/m², a 28 per cent difference ^[3]. So 26 m/s is a Belgian maximum, not a uniform value.

In the BBRI fact sheet the direction factor is 1.00 for north, 0.85 for east and 1.00 for west. The orography factor is 1 where the general slope is below 5 per cent, and the structural factor may be taken as 1 for a building under 15 m high ^[2].

To be verified: the full postcode map must be obtained from NBN or BBRI. No complete list was consulted.

The Netherlands and Luxembourg

In Luxembourg the exact scope of the 2011 formula is not established, so we derive no value from it until it is checked in the national annex ^[6][7]. The exact wind assignment by Dutch area is to be verified in NEN-EN 1991-1-4/NB.

Second generation Eurocodes: timeline

These are deadlines: Member States may publish earlier ^[8]. The engineering office determines which editions and national annexes apply to each project, taking the transition rules into account ^[8].

To be verified: the second generation national annexes, snow and wind values included, may differ from the values above for Belgium, the Netherlands and Luxembourg.

Why a kit sold without a site-specific calculation is risky

• Loads change from site to site: in Belgium the reference wind pressure varies by 28 per cent between Arlon and Bruges ^[3], and snow rises with altitude ^[1].
• A published price rests on assumptions. A German price brochure states its conditions: snow zone 2, wind zone 2, altitude up to 500 m ^[9].
• A German hall seller adds 12 to 25 per cent for a crane runway or snow zone 3 ^[10]. These are German figures, to be validated in Belgium.
• In the Hallfort configurator, the load class changes the steel weight used in the price.

Hallfort's binding price therefore follows a stability study of the actual site, with the fabricator's calculation notes for the permit file. Prices on the site stay indicative until the quote.

What the configurator's "standard" and "high" load classes mean

These classes serve to estimate the price. The final check is always the stability study. Try the configurator, then request a quote. For the requirements on the structure itself, see EN 1090 and CE marking.