How to Choose and Control a Building Contractor
The safest way to choose a contractor is to reduce the number of things that depend on trust. A clear drawing, scope, price, payment schedule, variation procedure and inspection record protect both the homeowner and the builder because fewer decisions are left to memory and argument.
Contractor scorecard
Get three comparable prices, not three random prices
Three quotations are useful only when all three contractors are pricing the same thing. Give each bidder the same approved drawings, structural information and schedule of finishes. Ask them to return the quotation using the same headings: site, foundation, structure, roof, doors/windows, plumbing, electrical, finishes, external works, exclusions and provisional sums.
A payment plan should follow visible progress
| Weak arrangement | Stronger arrangement |
|---|---|
| Large advance because “materials are expensive” | Advance limited to clearly identified mobilisation/material needs, then payments against completed, checked stages. |
| “Pay when I ask” | Written payment milestones and invoice procedure. |
| Owner changes things verbally on site | Written variation showing cost and extra/reduced time before work changes. |
| Builder chooses substitutes without discussion | Specified products/performance with written approval for substitutions. |
| No one records hidden work | Photographs and inspection before concrete, ceilings or finishes conceal critical work. |
Photograph what you will never see again
- Foundation excavation and reinforcement before concrete.
- Under-slab plumbing, electrical and communications conduits.
- Termite treatment stage and damp-proof membrane.
- Reinforcement in columns, beams, lintels and slabs.
- Roof-to-wall connectors and concealed straps.
- Plumbing pressure tests and drain routes before walls/ceilings close.
- Waterproofing before tiles.
Red flags
No written exclusions
A short quotation with one total can be more dangerous than a higher detailed quotation because you do not know what is missing.
Price changes without paper
If the contract value can change verbally, neither side knows the real cost to complete.
Pressure to cover work quickly
Critical reinforcement, plumbing, waterproofing and connections should be checked before they disappear behind concrete or finishes.