Some jobs come to you as a finished set of drawings and a fixed scope. Others come to you as a brief and a budget, with the drawings still to be pinned down as the job runs. That second kind puts more on your plate, and more on your risk register, so it's worth being honest about what it actually demands from a contractor.
Pricing design and build contracts is a different exercise from pricing a traditional tender. On a traditional job you price what somebody else drew. On design and build, you're pricing what you're about to draw, and carrying whatever it turns out to need.
You own the gaps now
When you are responsible for turning a brief into buildable drawings as well as the construction itself, there is nowhere to point when something does not work on site. If a detail was never resolved, that is on you, not on someone down the corridor. Build in time to properly coordinate structural, services and finishes information before trades start cutting into materials, not after.
The client's brief (on a JCT design and build job, usually set out as the Employer's Requirements) rarely answers every question. Your response to it, the Contractor's Proposals, is where you commit to how those questions get answered. Anything you left vague there tends to get resolved later in the client's favour, at your cost.
Stage the work and sort approvals early
Break the job into clear stages: brief and scope, developing the drawings to a buildable standard, then delivery. Rushing the middle stage to get on site early is one of the most common ways these jobs go wrong. Time spent resolving details properly before handover to the site team saves a lot more time in variation and rework later.
That staging should show up in the price too. A figure produced from a brief is a cost plan, not a tender. It needs to be revisited as the drawings develop, and each version should say clearly what information it was built on.
Whatever the procurement route, building regulations approval and CDM 2015 duties still apply in full, and they land on your desk earlier than on a traditional job because you are the one producing the information, not just building from it. If you or your design team prepare or change the design, the designer duties under CDM apply to that work as well. Get approvals and duty holder responsibilities sorted before committing labour to site.
On design and build, anything the drawings don't resolve is still in your price. You just haven't found it yet.
Pricing design and build contracts: price the risk, not just the work
This kind of contract carries more uncertainty than one built from a complete, fixed set of drawings, and the price has to reflect that. Build in proper contingency for coordination issues and late client decisions, and be upfront with the client about why the number looks the way it does. Vague pricing here is how contractors end up carrying costs that were never really theirs to carry.
A practical way to break it down before you commit to a figure:
- Measure what's drawn. Whatever exists, measure it properly. Even an early scheme drawing gives you quantities for the main elements.
- List what isn't drawn yet. Foundations awaiting a site investigation, services routes not yet designed, finishes not yet chosen. Write them down one by one.
- Put a number on each gap. An allowance per item, based on what you know, rather than one blanket percentage across the whole job.
- Price the design itself. Your designers' fees, your own time coordinating them, and any surveys or investigations the design depends on.
- Qualify the rest. Anything you can't reasonably price, state as an exclusion or assumption so it's visible to the client.
That approach doesn't remove the risk, but it turns an unknown into a list. A list can be discussed, reduced and priced. A feeling that "it might go over" can't.
Communicate early, communicate often
Clients often do not fully grasp how much is still being resolved once the contract is signed. Keep them close through every stage, flag decisions that need making before they hold up the programme, and put the reasoning behind cost changes in writing as you go.
Say the client hasn't chosen between two kitchen layouts when the price goes in. Carry an allowance, name it, and give them a date by which the choice has to be made. If the decision comes late, the cost of the delay is already on paper and the conversation is about facts, not blame.
Handled properly, taking on both the drawings and the build gives you more control over programme and quality than a traditional split ever will. Handled loosely, it's the fastest way to eat your own margin. For more on the tender side of this, see our guide to what's in a tender submission.
Getting a number on drawings that are still moving
Send your drawings, or whatever you have of them so far, and our cost planning services will put a number on the parts that are defined and set out clearly what's still an allowance. Everything is measured to NRM2 and priced on current UK rates, local to the job, for a fixed fee agreed up front. As the drawings develop, the same structure carries forward, so each update shows what's changed rather than starting from scratch.
A test before you sign
Before committing to a design and build price, take your list of undrawn items and ask one question of each: if this turns out worse than I've allowed, who pays? If the answer on every line is "me", make sure the allowance reflects that, or qualify it out. That single pass is the difference between pricing design and build contracts with your eyes open and signing up for costs you never saw coming.