National annexes

Where nationally determined parameters change the answer, how to select the right annex, and what to state in the report.

Design checks 3 min read

A Eurocode is not usable on its own. Each country publishes a National Annex setting the nationally determined parameters: partial factors, ψ values, choices between alternative methods, and limits the base document leaves open. The same model checked under two annexes gives different answers, and both are correct.

Choosing the annex

Set it at project level, before you run any check. It belongs to the project, not to a member, because a mixed set of parameters is never valid.

The right annex is the one for the country where the structure is built, not where you or the client are based.

What an annex typically changes

Parameter	Base recommendation	Commonly varied
Combination equations	6.10, or 6.10a/6.10b	Which pair is permitted or required
$ξ$ (reduction on permanent)	0.85	Yes
$ψ_{0}$ , $ψ_{1}$ , $ψ_{2}$	Table A1.1 values	Yes, by category
$γ_{M 0}$ (steel cross-section)	1.00	Yes — 1.05 in Italy and Norway
$γ_{M 1}$ (steel buckling)	1.00	Yes — 1.10 in Germany
$γ_{M 2}$ (fracture, connections)	1.25	Yes — 1.10 in the UK
Deflection limits	None — EN 1990 A1.4 leaves them to the annex	Always national
Snow and wind maps	Not in the base document at all	Always national

The mixed-jurisdiction problem

Projects designed in one country and built in another are common, and so is a client specification that overrides parts of the annex. Where that happens:

Use the annex of the country of construction as the base.
Apply project-specific overrides explicitly, one by one, as documented decisions.
Never mix parameters from two annexes because one gives a more convenient number. The factors within an annex are calibrated together; cherry-picking breaks the calibration that makes the target reliability meaningful.

Actions are national too

Snow load, wind speed, seismic hazard and thermal actions come from national maps and tables in EN 1991. Elementarium does not generate site actions from a location. You determine the characteristic values and apply them as load cases. The annex governs how those actions are combined, not what they are.

What to state in the report

The Eurocode parts used, with their year.
The National Annex applied.
Any parameter overridden from the annex default, with its value and the reason.
Which combination equations were used: 6.10 or 6.10a/6.10b.

Coverage in this release

Around forty entries ship, grouped by family in the project settings:

Family	What is carried
Eurocode	The base EN recommended values, plus a named annex for every EU and EFTA country and several beyond — ÖNORM, NBN, ČSN, DS/EN, DIN, NF, UNI, NEN, NS, PN, SR, SS, SIST, UNE, TS, BS EN and the rest
United States	IBC / AISC 360, where the method — LRFD or ASD — replaces $γ_{M}$
Brazil	ABNT NBR 8800
Switzerland	SIA 26x, with $γ_{M} = 1.05$
Custom	Nothing prefilled; you set the factors yourself

Most Eurocode entries adopt the EN recommended $γ_{M}$ values, because that is what those annexes do. Where an annex is known to depart (Germany, Italy, Norway, the UK) its own values are carried instead.

The factors an annex sets are the part Elementarium applies. Everything else an annex changes (permitted combination expressions, ψ values, site actions) is yours to enter, and the combination generator's factors are editable fields for exactly that reason. Deflection limits are the exception: the serviceability checks carry them as annex presets.

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