What a Mid-Project Change Really Costs: A Worked Example

Moving a wall after first fix looks like a small change. Here is how the cost assembles once rework, sequence and delay are counted.

Owners usually price a change by imagining the new work in isolation. Contractors price it by counting what must be undone, redone and delayed. The gap between those two views is where most variation disputes live, and the example below makes it visible.

The situation

A villa has reached mechanical and electrical first fix. The owner decides to move a partition wall by two metres to enlarge a living area. The wall is not structural, so the change appears straightforward.

Assumptions (illustrative)

• New blockwork required: 14 square metres.
• Assumed blockwork rate including plaster: SAR 220 per square metre.
• Existing wall to be demolished and removed: 12 square metres.
• Assumed demolition and disposal rate: SAR 90 per square metre.
• Electrical points and conduits to relocate: 6 points, assumed SAR 180 each.
• Two air conditioning duct branches requiring rerouting, assumed SAR 2,400 in total.
• Assumed programme impact: 5 working days.
• Assumed site overhead: SAR 1,100 per working day.

Step 1: The visible new work

14 square metres multiplied by SAR 220 equals SAR 3,080.

This is the figure the owner has in mind when calling the change small, and it is the only part of the cost that produces something visible.

Step 2: Undoing what exists

12 square metres multiplied by SAR 90 equals SAR 1,080.

Demolition produces nothing. It is pure cost, and it exists only because the decision arrived after the work did.

Step 3: Services rework

6 points multiplied by SAR 180 equals SAR 1,080, plus SAR 2,400 for duct rerouting, giving SAR 3,480.

Services are the reason mid-project changes escalate. Once conduits and ducts are installed, moving a wall means moving everything that runs through and near it.

Step 4: Time cost

5 days multiplied by SAR 1,100 equals SAR 5,500.

Site overheads continue while the change is executed, and following trades wait. This is the component owners most often refuse to accept, and the one contractors most reliably include.

Step 5: Total change cost

SAR 3,080 plus SAR 1,080 plus SAR 3,480 plus SAR 5,500 equals SAR 13,140.

The new wall accounts for less than a quarter of the total. The rest is the cost of changing your mind at this point in the sequence rather than earlier.

Step 6: The same change made during design

Had the wall been moved on the drawings before construction, the cost would have been the difference in blockwork area alone, a few hundred riyals at most.

The change did not become expensive because it was large. It became expensive because of when it was requested.

What changes the answer

• If the wall had been structural, the change would require redesign, approval and possibly strengthening, multiplying the cost.
• If finishes had already been applied, tiling, plaster and paint rework would add substantially.
• If the change delayed a following trade with limited availability, the programme impact could exceed five days considerably.
• If the same review produced several changes at once, the shared programme impact would be counted once rather than repeatedly.

What the numbers tell you

• Price changes by what must be undone and delayed, not only by what will be built.
• Group changes into a single review rather than issuing them one at a time, so time impacts are shared.
• Walk the building at first fix, when conduits are visible and changes are still comparatively cheap.
• Require written cost and time impact before any change is executed, so this arithmetic happens before the decision rather than after.

Limits of this example

Every figure above is an illustrative assumption used to show the method, not a quote, valuation or market rate. Costs, rates, fees and regulations change and must be confirmed with the relevant authority, lender or supplier before you commit.

If you are preparing to build, Domira can review your drawings, scope and contractor offers before you commit, and supervise delivery against the programme and specification you agreed.