What decides the cost of building a house, and how to budget for it
Two families building the same size of house can end up with very different bills. The difference is rarely the builder’s margin. It is a handful of decisions made early. Here they are, in the order they usually matter.
1. Built-up area, not plot area
Construction is priced on the built-up area: the total covered area of every floor, including balconies and staircases. A 1,200 sq ft plot with three floors is roughly 3,000 sq ft of construction. Always start your budget from built-up area, and be clear with anyone quoting you which figure they are using.
2. The level of specification
Flooring, sanitary fittings, electrical fittings, doors, windows, paint and kitchen choices can move the cost per square foot more than anything else you control. A useful habit is to decide the standard for each of these rooms before you ask for a price, so that every quote you compare is for the same thing.
3. Where you are building
Labour, transport of materials, and approval costs differ between cities and even between neighbourhoods. A rate quoted for one city should not be applied blindly to another. Our estimate calculator adjusts for location for this reason.
4. Structure and height
More floors mean a heavier structure, deeper foundations and often a lift. A basement or stilt parking adds excavation, retaining walls and waterproofing. If you are unsure, ask for the structure to be costed separately so you can see what each choice adds.
5. The extras people forget
- Boundary wall, gate and the entrance area
- Water storage, borewell or sump, and rainwater harvesting
- Solar, inverter and electrical load planning
- Modular kitchen, wardrobes and other loose or built-in furniture
- Landscaping, paving and outdoor lighting
- Design, approval and connection fees, and taxes
None of these are unusual, but they are often missing from a first budget. List them early, even if some will wait.
6. Keep a contingency
Set aside a margin for things that cannot be known until the ground is opened or a decision is changed. Many people plan for somewhere between five and ten percent. If you never use it, that is a good outcome.
7. Turn it into a budget you can hold to
- Fix the built-up area and the number of floors.
- Choose a specification level for each part of the house.
- List the extras above and decide which are in or out.
- Ask for an itemised BOQ (bill of quantities), so that each line has a quantity and a rate.
- Add a contingency and agree how changes will be priced before work starts.
The figures produced by online tools, including ours, are indicative. They are a good way to test whether a plan is realistic. The number that counts is the one in your signed BOQ.