Choosing a steel structure supplier is one of the most critical decisions affecting the quality, budget, and timeline of an entire project. Whether you are planning an industrial building, warehouse, bridge, or shopping center — the supplier must meet specific criteria. This article helps you understand what to check and when to walk away.

1. Certifications and standards compliance

This is the most important criterion. Every steel structure manufacturer in the EU must hold an EN 1090-2 certificate (CE marking for steel structures). Also check:

• EN 1090-2 Execution Class (EXC) — does the supplier hold EXC 2, EXC 3, or higher? Your project requires a specific class (see our separate article on EXC classes)
• ISO 9001 — quality management system (shows business processes are documented)
• ISO 3834-2 — welding quality requirements
• Notified Body — verify the certificate was issued by a recognized body (e.g., TÜV NORD, TÜV Eesti, DNV)

Red flag: if the supplier doesn’t have an EN 1090 certificate, they cannot legally sell structures in the European Union.

2. Production capacity

Ask the supplier:

• How many tonnes of steel structures do you produce per month?
• What is the largest single project you have completed?
• Are both small (from 1 t) and large (over 500 t) projects welcome?

Production capacity determines whether the supplier can meet your deadlines. For a large project, choose a manufacturer whose capacity is at least 3× your scope.

3. Production base: what is done in-house and what is subcontracted

Ask directly which part of the work the supplier does itself and which it passes on:

• Cutting, welding and painting — in the supplier’s own plant or at subcontractors? Every subcontractor means extra transport, extra time and blurred responsibility.
• An in-house blasting and paint booth, and its size — if an element does not fit, it gets cut into parts or sent elsewhere for painting.
• Crane capacity and maximum element weight — determines whether a large beam can be fabricated in one piece.
• Surface preparation grade and corrosion categories — which grade (Sa 2.5 or Sa 3) and which categories (C3–C5) the supplier actually delivers.
• Non-destructive testing (NDT) — how it is organised; the scope depends on the execution class and is considerably larger for EXC 3.

The age of the machines says little. What matters far more is whether the whole chain sits under one responsibility.

4. Team and qualifications

A qualified team is at least as important as equipment. Look at:

• Welding engineer — qualification EWS, EWT, or IWE (International Welding Engineer — highest level, required for EXC 3)
• Certified welders — EN 287 or EN ISO 9606 certificates for the material groups used in your project
• Designer experience — does the supplier have an in-house engineering office or use subcontractors?
• Installer experience — do they have on-site experience and required certifications (e.g., safety training)

5. References and previous projects

Ask the supplier for a list of previous projects, especially in your sector (industry, logistics, energy, etc.). Look for:

• Are projects of comparable scope and complexity?
• Can you contact previous clients for feedback?
• Does the company website have a portfolio or list of clients?

Red flag: if the supplier cannot show comparable previous projects or refuses to share contacts.

6. Quote accuracy and transparency

A good quote includes:

• Clear price structure — steel material, processing, installation as separate items
• Steel grade and standard used (e.g., S355JR per EN 10025-2)
• Surface treatment type and corrosion category (C3, C4, or C5)
• Clear timelines — design, manufacturing, installation
• Warranty duration and coverage
• Payment terms

Red flag: a too-short, vague quote (“steel structure — XYZ €”). It indicates the supplier hasn’t reviewed the project.

7. Price, payment and warranty terms

Price matters, but not as the only criterion:

• The cheapest offer is often problematic — it may indicate inferior material, shorter certifications, or missing approvals
• Payment schedule — typically 30% advance, 50% after manufacturing, 20% after installation and acceptance
• Warranty — since the Estonian Building Code took effect on 1 July 2015, a construction warranty no longer arises automatically — only by agreement between the parties. Set out the warranty period, its start date and terms in writing in the contract

Client checklist

Before signing the contract, verify the supplier has:

• ☑ EN 1090-2 certificate with the correct execution class (EXC 2, EXC 3, or as required)
• ☑ ISO 9001 and ISO 3834-2 certificates
• ☑ Certified welding engineer (at least EWS, IWE for EXC 3)
• ☑ Cutting, welding and painting in-house, not subcontracted
• ☑ At least 3 comparable previous projects
• ☑ Detailed quote with all price components
• ☑ Clear timelines and payment schedule
• ☑ Warranty terms set out in writing in the contract

Steel Element and your project

Steel Element OÜ meets all the above criteria:

• EN 1090-2:2018+A1:2024 EXC 3 certificate (TÜV Eesti)
• ISO 9001:2015 (TÜV NORD), ISO 3834-2:2021 (TÜV Eesti)
• IWE-qualified welding engineer Pavel Kopanev
• Production capacity 300 t/month
• Own blasting and paint booth 5 × 15 × 4 m, coatings up to C5
• Overhead cranes 10 t, element weight up to 20 t
• 35 people — designers, certified welders, installers
• See our certificates and PDFs

Planning a steel project? Send an inquiry

Send us a brief description of your project — initial offer in 1–3 business days. The first consultation is free — recommendations on materials, corrosion protection, and timelines. Contact us »