And why they're one of the biggest sources of hidden costs in builder quotes
Upload your quoteA Prime Cost (PC) item is an allowance your builder includes for items that haven't been fully selected yet.
This usually covers things like:
Instead of locking in an exact product, the builder includes a dollar allowance — and you choose the final item later.
On the surface, this seems flexible. In reality, it shifts cost risk onto you.
Prime Cost items are one of the most common ways building costs increase after you sign.
The allowance included in your quote is often lower than what most people actually choose.
That means:
What looks like a fixed-price contract can quickly become thousands more in variations. Combined with provisional sums, these allowances are one of the biggest sources of hidden costs when building.
We see the same issues in builder quotes all the time:
This is part of a broader pattern where important items are either vague or missing entirely from builder quotes.
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Before signing, go through each Prime Cost item and check:
If these aren't clear, you don't really know what you're paying for.
Your quote includes:
Toilet allowance: $250
In reality:
Most homeowners choose toilets in the $800–$1,200 range
Result:
That's over $1,000 difference — for a single item.
Multiply that across your entire build, and costs can escalate quickly.
You don't need to eliminate Prime Cost items — but you do need to control them.
Before signing:
The more detail you lock in now, the less you'll pay later.
BuildWhiz scans your builder quote and identifies:
You'll get a clear breakdown of what to question before signing — so you're not caught out later.
No. They are allowances only. If your final selection costs more, you pay the difference plus builder margin.
The allowance itself doesn't change, but your final cost does if you choose items above the allowance.
Not necessarily. They provide flexibility, but they also introduce cost uncertainty if not properly managed.
There's no fixed number, but the fewer the better. Too many PC items usually means more cost risk.