A building's frame (foundations, columns, beams and slabs) is one of the largest items in construction cost, and the structural design is what sets its quantities of concrete and steel. So good structural design is not an extra cost to buy at the lowest price, but a real saving tool: the difference between a considered design and a rushed one can show in tonnes of steel and metres of concrete, or in problems that appear years later. This guide explains where design affects cost, where you can safely save, where you must never compromise, and why the cheapest design can cost more.
Where Does Design Affect Cost?
- Foundations: their type and size depend on the soil report and loads. Read: The soil investigation report.
- Column layout: a regular grid reduces beam sizes and steel quantities.
- Slab type: each system has its own cost and suitability for spans.
- Spans: unnecessarily long spans increase quantities.
- Coordination with the architect: an architectural design that considers the structure saves a lot.
- The structural system: concrete, steel or hybrid. Read: Concrete or steel structure.
Common Slab Systems
| System | Suits | Note |
|---|---|---|
| Solid slabs with beams | Small and medium spans | Common in villas |
| Hollow-block (hordi) slabs | Medium spans | Lighter, with relatively better insulation |
| Flat slabs | Commercial buildings and car parks | Level soffits and easy services |
| Ribbed or waffle slabs | Long spans | Reduce weight over wide spans |
Where You Can Safely Save
- A regular plan with columns aligned between floors.
- A slab system suited to the actual spans.
- Avoiding unnecessary complexity in the massing.
- Accurate design instead of exaggerated safety factors due to missing information.
- Standardising element sizes to ease formwork and reduce waste.
Where You Must Never Compromise
- The Saudi Building Code requirements, including the loads code (SBC 301) and the concrete code (SBC 304).
- The soil report and its recommendations.
- Quality of materials, workmanship and supervision of reinforcement before pouring. See our supervision service, and read: Stages of concrete pouring supervision.
- Waterproofing of foundations.
Why the Cheapest Design Can Cost More
A rushed design without study may put in extra quantities "to be safe", or too little, so problems appear later. Both are losses. And clashes between drawings cause demolition and rework. Read: Clashes between drawings.
| Design | Design cost | Construction cost and risks |
|---|---|---|
| Rushed, without study | Lower | Excess or insufficient quantities, clashes, comments that delay the permit |
| Considered and coordinated | Slightly higher | Accurate quantities, smoother construction, lower risk |
How to Check Design Quality
- Ask for estimated quantity schedules for concrete and steel.
- Ask for a third-party review on large projects. Read: Third-party structural review.
- Make sure it is coordinated with the architectural and MEP drawings.
Frequently Asked Questions
Can steel be reduced to save money?
Only through more accurate design to the code, not by cutting quantities arbitrarily.
What is the best system for a villa?
The designer decides based on spans and the architecture. Read: Concrete or steel structure.
Does a basement raise cost a lot?
Usually yes, because of excavation, shoring, waterproofing and retaining walls. Read: Excavation shoring.
Does the design affect construction time?
Yes, a regular, standardised design speeds up formwork and pouring.
Does cost differ between cities?
Material and labour prices differ, but the principles of economical design are the same.
How Abak Engineering Consultancy Helps
Abak is an accredited engineering office in Riyadh that designs structures accurately to the code, coordinating with the architect to reduce quantities without compromising safety, with supervision of construction. Learn about our structural design services, or Learn more about our Structural Drawing Design (Concrete & Steel) service. contact us.
Regulatory information is based on the Balady platform and the Ministry of Municipalities and Housing, and procedures may be updated by the competent authority. Last reviewed: October 2026.