Bay extensions
Extra bays added to the end or side of an existing building, matching its grid and roof.
Project types · Extensions & re-roofing frames
Grow or renew your building while it keeps working
Bay extensions to existing factories and warehouses, new roof frames over leaking or asbestos roofs, raised roofs for taller racking and renovation steelwork. Surveyed and designed to fit what is already there, fabricated in our own factory.
2018delivering steel structures to Thailand
Surveyexisting building measured before design
EXC3EN 1090 execution class for welded steel
2,500 Tfabrication capacity every month
Building on what you already have
An extension has to fit the building, not the drawing
Many Thai plants built in the 1990s and 2000s now need more space, a taller roof or a new roof altogether. Old drawings are often missing or wrong, the frame has moved over the years, and the business cannot stop while the work is done.
We start from a survey of the existing building, check what the old frame can carry with your engineer, and design the extension or new roof to connect cleanly to it. Every piece is fabricated in our factory to the surveyed dimensions and arrives as a bolted kit, so site work is short and planned around production. We have delivered expansion and renovation steelwork for factory and resort projects; non-Thai projects are shown as references.
- Bay and span extensions to factories and warehouses
- New roof frames over old or asbestos roofs
- Raised roofs and added cranes
- Renovation and strengthening steelwork
Structural solutions
Work we design and fabricate
Each option is engineered member by member in our design office, then built on our own fabrication lines.
Side lean-tos
Lean-to extensions for storage, loading and utilities along an existing wall.
Over-roof frames
New roof frames built over a leaking or asbestos roof, often while the plant keeps running.
Raised roofs
Higher roofs for taller racking, cranes or new process lines.
Crane additions
New crane runways and strengthened columns for overhead cranes.
Strengthening and renovation
Steel to strengthen, repair or convert existing buildings.
Your challenges, our answers
What owners ask us, and how we solve it
The questions we hear most often from Thai owners, designers and contractors.
Challenge 01
No reliable drawings
Our answer
We survey the existing frame and design from measured dimensions.
Challenge 02
Can the old frame take it?
Our answer
Existing columns, footings and connections checked with your engineer before design.
Challenge 03
Production must continue
Our answer
Bolted kits and phased installation planned around your shifts.
Challenge 04
Old roof leaks or contains asbestos
Our answer
Over-roof frames add a new roof above, so the old one can be removed safely later or left in place.
Challenge 05
Joint between old and new leaks
Our answer
Flashings, gutters and expansion joints detailed at the interface.
Challenge 06
Must match the existing look
Our answer
Roof slope, cladding profile and colour matched to the old building.
Inside the structure
Typical design ranges for extensions and re-roofing
Every project is engineered to its own brief and site. These are the ranges we work in most often.
| Design item | Typical range we engineer |
|---|---|
| Extension | One or more bays, matching or new spans |
| Connection | Tied to the existing frame or free-standing beside it |
| Over-roof frame | Supported on existing columns or new independent columns |
| Roof | Metal sheet with insulation, skylights and ventilation as needed |
| Cranes | Runways added where columns and footings allow |
| Survey | Site measurement of grid, levels and existing members |
| Installation | Phased, zone by zone, around operations |
Design highlights
- 01
Measured, not guessed
Fabrication follows the site survey.
- 02
Clean interface
Old-to-new joints detailed for water and movement.
- 03
Low disruption
Bolted kits shorten time on site.
- 04
One package
Frame, roof, cladding and crane steel from one factory.
Designed and made by World Steel
From our design office to your Thai port, in one company
Your structure is not bought from a trader or subcontracted: it is engineered by our team and fabricated, inspected, painted and packed in the World Steel factory.
World Steel factory · Tay Ninh, Vietnam20,000 m² · 2,500 T/monthISO 9001 · ISO 3834-2 · EN 1090 EXC3 · AS/NZS 5131 CC3 · IAS AC472
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01Designed by our own engineers
World Steel structural engineers calculate to Thai and international codes and produce the Tekla 3D model, approval drawings and every shop drawing. Nothing is outsourced.
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02CNC cutting and drilling
Plates and sections cut by plasma, laser and CNC drilling lines straight from the model, with first-piece inspection before the batch runs.
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03Built-up members welded in-house
Submerged-arc welding lines and qualified welders make columns and rafters to ISO 3834-2 and EN 1090 EXC3.
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04Inspected before it leaves
Dimensional checks, UT and MT weld testing and paint thickness readings, recorded piece by piece in the QC dossier you receive.
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05Blasted and painted in the factory
Shot blasting and an ISO 12944 paint system chosen for inland, coastal or port sites, or intumescent fire protection up to R120.
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06Packed by erection zone, shipped CIF
Every piece marked, bundled by erection zone and loaded so the first members your erector needs reach site first.
Scope of supply
What you receive, and what stays local
A clear split of work keeps your budget and schedule predictable.
World Steel designs, makes and ships
- Structural design and calculations to Thai and international codes
- Approval drawings for your Thai engineer (กว.) to review and sign
- Main steel frame, C/Z purlins, bracing and all connection bolts
- Shop painting or fire-protection paint, packing and CIF shipping
- QC dossier, erection drawings and remote technical support
Your Thai team on site
- Site survey, soil investigation and foundations
- Building permit with the local authority or IEAT
- Unloading at site and erection by your contractor or our partners
- Roof and wall sheeting, doors and MEP (or sourced in Thailand)
Thai codes and standards
Designed to pass Thai permitting
Building Control Act B.E. 2522
Construction permit from the local authority, or IEAT inside an industrial estate; we prepare the structural drawings and calculations.
DPT 1311-50 · DPT 1301/1302-61
Thai wind and seismic standards applied for the province of your site.
Engineering Profession Act B.E. 2542
Your licensed Thai engineer reviews and signs; we answer every comment.
Building Control Act (alterations)
Extensions and structural changes usually need a permit for alterations; your Thai engineer prepares the submission with our drawings and calculations.
Work we have delivered
Expansion and renovation references
Factory expansion and renovation steelwork we designed, fabricated and delivered. These are outside Thailand and are shown as references.
2020
Vietnam
Tien Giang Tongwei Animal Feed Factory (Expansion)
Factory
4Vietnam
Binh Chau Hot Spring Renovation Project
Commercial & retail building
4Projects outside Thailand are shown as references with the same type of structure.
Why World Steel
One partner from first sketch to Thai port
Exporting to Thailand since 2018
Steel buildings for manufacturers, developers and retailers across Thailand.
Our own certified factory
20,000 m² in Tay Ninh, 2,500 T a month, ISO 3834-2 and EN 1090 EXC3 welding quality.
Engineers, not traders
The team that designs your structure is the team that answers your Thai engineer and supervises fabrication.
CIF or DDP to your site
Shipped to Laem Chabang, Bangkok, Map Ta Phut or Songkhla, with documents for your customs broker.
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FAQ
Questions Thai clients ask us
We have no drawings of our old building. Can you still help?
Yes. We survey the existing frame on site and design the extension or new roof from the measured dimensions.
Can we keep working during the work?
In most cases. Over-roof frames and bolted extensions are installed in phases around production.
Can you build a new roof over an asbestos roof?
Yes. An over-roof frame adds a new roof above the old one. Removal of asbestos, if planned, is done by a licensed Thai contractor.
Will the existing columns carry the extension?
Your engineer checks them with our loads. If needed we add new columns so the extension stands independently.
Do you supply roofing and cladding too?
Yes. We can supply the steel frame with roofing, cladding and accessories matched to the existing building.
Other project types
Steel structures for every type of building
Steel warehouses & distribution centresFactories & manufacturing plantsCold storage & food processingRetail stores & supermarketsCar parks & multi-storey buildingsAircraft hangars & wide-span buildingsMarkets & community buildingsSports halls & leisureAgriculture & agro-industryShowrooms, offices & residentialEnergy & industrial plantsMezzanines & equipment platformsMulti-storey steel buildingsCanopies, carports & walkwaysSteel & pedestrian bridges
Need to extend or re-roof your building?
Send photos, approximate sizes and any old drawings you have. We reply within one working day with next steps and a budget range.