Can builder refuse a variation?

Under JCT they must comply unless variation is technically impossible or unsafe. They can dispute the price.

What's a fair variation margin?

10–20% management margin is reasonable. Over 25% suggests profit-padding.

Should I get variations in writing?

Always — verbal variations are unenforceable and a major source of disputes.

Does Builderr issue variations in writing?

Yes — every variation is a signed schedule with cost and time impact before work proceeds. Variations dashboard runs live across the project.

Quick Answer

How Do Variation Orders Work on London Construction Projects?

Variation orders (changes from agreed scope) on London projects are typically priced on materials at actual cost plus labour at agreed day-work rates plus builder margin (10–20%). On JCT contracts a written variation must be issued before work proceeds. Common London variations: client material upgrades, scope additions, ground-condition discoveries (extra foundations). Expect 8–15% of total project value in variations on a typical Victorian renovation.

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Common variation triggers

Client-initiated: scope additions (extra bathroom, fitted joinery, upgraded windows), material upgrades (quartz instead of granite, oak instead of pine), aesthetic changes after seeing first fix. Discovery-initiated: rotten joists found in strip-out, unsuitable foundations, asbestos discovered (Part L pre-2000), Thames Water sewer found running through extension footprint. Regulation-initiated: building control inspector requires additional spec (extra fire-safety, structural calcs, Part E sound).

Pricing structure

Materials: at builder's actual cost (trade-discounted) + supply margin (10–15%). Labour: at agreed day-work rates (£250–£420/day for joiner, £280–£450/day for electrician, £380–£550/day for ground-worker in London 2026). Builder management margin: 10–20% on top. Variation cost = materials × 1.10–1.15 + labour days × day rate + 10–20% margin. Get all variations in writing with cost agreed before work proceeds.

Avoiding variation surprises

Front-load decisions: specify all materials at tender (worktop, tiles, kitchen, sanitaryware, doors, ironmongery) so they price into the lump sum. Use PC sums (Prime Cost) for items not yet selected — agreed allowance with variation balance up/down on actual selection. Disclose hidden risks at tender (older property, missing surveys) so builder can price conservatively. Variation pots: agree 5–10% client-side contingency outside contract for genuine extras.

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