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Key points

  • Walls are built by a printer depositing special concrete layer upon layer from a digital model.
  • ICC-ES AC509 sets guidelines for evaluating the material and durability properties of printed concrete, and the structural performance and fire resistance of printed walls.
  • The technology is still young; roofs, services and finishes are usually done by other methods.
  • Ask about approval, structural and fire evaluation, and the thermal insulation of the printed wall.
Written for:OwnerContractorSupplier

3D printing in construction means a robotic arm or gantry deposits a specially designed mortar or concrete in layers, forming the wall without conventional formwork.

1) How is it evaluated?

Because printed concrete and printing methods are usually proprietary, evaluation criteria have emerged. The International Code Council Evaluation Service issued ICC-ES AC509, which sets guidelines for evaluating the material and durability properties of proprietary 3D concrete, and the structural performance and fire resistance of 3D concrete walls1.

2) Where things stand

General observations on the state of the technology.

  • Printing speeds up wall construction, but roofs, windows, services and finishes are usually done conventionally or prefabricated.
  • A printed wall usually needs a thermal insulation solution (insulated cavities or external insulation), which is very important in our climate.
  • Cost and feasibility depend on project size, repetition and equipment availability.

3) Questions before contracting for a printed building

  1. Does the system have an evaluation or approval (such as AC509), and is it accepted by the local authorities?
  2. Who is the structural designer, and how is the wall reinforced and tied to the roof and foundations?
  3. What is the U-value of the printed wall? See thermal insulation.
  4. How are electrical and plumbing services run inside the wall?
  5. What warranties cover cracking and leaks?

4) Pros and cons

Pros

  • Fast wall construction and freedom of form.
  • Less formwork waste.

Cons

  • A young technology with evolving criteria.
  • Needs specialised equipment and expertise.
  • Insulation and services need extra solutions.

Sources

The number next to a statement points to its source in this list. Sources back the general information; anything marked “practical advice” is editorial experience, not a quoted source. Anything that affects safety, structural design or electrical installations needs a licensed professional, and in Saudi Arabia the binding reference is the Saudi Building Code.

  1. 13D Printing — AC509 Acceptance Criteria for 3D Automated Construction Technology for 3D Concrete Walls — ICC Evaluation Service (ICC-ES)
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This guide is for general information and planning, based on standards and technical guides. Standards are revised periodically; in Saudi Arabia the binding reference is the Saudi Building Code and the instructions of the competent authorities. For design and execution, use a licensed engineer or technician. Found an error? Tell us.