NBS doesn't publish its prices openly, which is itself telling. But reported figures from architects and public procurement records paint a clear enough picture.
A single NBS Chorus licence started at roughly £1,495 plus VAT back in 2020. By 2025, architects were reporting renewal quotes 31% higher year on year, with some told they were still on a "preferential legacy tariff," meaning new customers pay even more. One architect shared publicly that a licence costing £1,385 in 2015 had risen to £7,350 by 2025. That is not inflation. That is a five-fold increase in a decade.
The tier structure adds complexity. NBS Chorus comes in several flavours: the base Chorus product, Chorus Pro with organisation-wide search and collaboration features, and Chorus Premium with master specification management. Each tier costs more, and the features that most mid-size practices actually need tend to sit in the higher tiers.
There is also no small practice discount. A sole practitioner and a 200-person firm pay the same rate per licence. For a five-person studio, that single concurrent licence might represent a significant portion of the entire annual software budget, second only to BIM or CAD.
The licence fee is the most visible cost, but it is rarely the largest. Every practice that adopts NBS Chorus invests significant time in onboarding, and that time has a pound value attached to it.
Training alone typically takes several days per user. NBS offers courses and webinars, but learning to use Chorus effectively takes months of regular use. Knowing which clause libraries to select, understanding how to customise standard clauses for a specific project context, and building confidence that the output is accurate are skills that develop slowly. During that learning period, spec writing is slower, not faster.
Then there is library maintenance. Chorus provides clause libraries that require periodic updating as regulations change, new products enter the market, or project requirements evolve. Someone in the practice has to manage this. In larger firms, that person is a dedicated specification manager. In smaller practices, it is the principal or a senior technologist fitting the work in around billable project hours.
Coordination overhead adds further cost. Chorus produces specifications, but those specifications still need to be manually cross-referenced against drawings, schedules, and other project documents. When a door schedule changes at RIBA Stage 4, someone has to trace that change through the specification to ensure consistency. That manual coordination is where errors creep in and where practices lose the most unbillable hours.
Add it all up and many practices find their true cost of using NBS Chorus sits at three to five times the licence fee once staff time is factored in. A £3,000 annual licence quietly becomes £10,000 to £15,000 in total expenditure when you account for the hours spent inside and around the tool. Most practices never run that calculation, and NBS has no incentive to encourage it.
NBS was originally developed under RIBA, the Royal Institute of British Architects. It was sold to Byggfakta Group, now operating as Hubexo, in a deal worth tens of millions to RIBA. Since that acquisition, pricing has increased at a pace that far outstrips inflation.
Hubexo has said the increases reflect investment in a cloud-based platform. And to be fair, Chorus is a more capable product than the old NBS Create desktop software it replaced. The question is whether the rate of price increase is proportionate to the value architects receive, particularly when practice profits are under pressure. RIBA's own 2024 Business Benchmarking Report showed chartered practice profits fell by 2%.
Former RIBA president Paul Hyett said architects had "every right to be dismayed and disappointed" by the cost hikes. A LinkedIn post by one architect on the subject received more than 400 reactions and nearly 200 comments. The frustration is not theoretical. It is felt across the profession, and it is sharpest among smaller firms where the per-licence cost absorbs a larger share of revenue.
There is also the question of lock-in. Practices that have built years of customised clause libraries inside Chorus face a genuine switching cost. That accumulated knowledge makes the tool more useful over time, but it also makes it harder to leave. NBS knows this. Any vendor that can rely on switching costs rather than satisfaction to retain customers has less pressure to keep prices competitive. It is the same dynamic architects know well from the Autodesk side of their software stack.
Avoice takes a different approach to specification software. Rather than providing a library of static clauses that architects select and edit manually, Avoice uses AI agents that generate specifications from a practice's own project data, classified under Uniclass, CAWS, NATSPEC, and CSI MasterFormat standards.
That distinction matters for cost because it changes what you are paying for. With NBS Chorus, you pay for access to a clause library and a platform to assemble specifications. With Avoice, you pay for an AI workspace that ingests your firm's existing documentation, including sheets, schedules, material libraries, codes, and historical projects, and uses that data to produce specifications that cite the right standards, products, and clauses grounded in your own practice's work.
The practical difference is time. Architects using Avoice report saving roughly 15 hours per week on documentation and coordination tasks. At typical architectural hourly rates of £50 to £90 for a mid-level technologist, those hours represent £2,500 to £4,500 per week in recovered productive capacity. Over a year, that figure exceeds £100,000 for a single user. Even a fraction of that saving changes the economics of specification software entirely.
Avoice's pricing is available on request rather than published as a fixed rate card, so a direct pound-for-pound comparison requires a conversation with their team. But the cost discussion shifts when you measure what each tool produces per hour of architect time, rather than what the annual invoice says.
Licence cost is the wrong metric for this decision. The question a practice manager should actually be asking is: what does it cost us to produce a complete, accurate specification for a typical project?
That cost includes the software licence, divided across the number of projects per year. It includes the hours of staff time spent writing, reviewing, and coordinating each specification. And it includes the cost of errors caught late, or not caught at all, when a specification fails to align with the drawings or schedules.
Consider a practice producing 20 specifications a year on a single NBS Chorus licence at, conservatively, £3,000 per year. The software cost per spec is £150. Reasonable enough. But if each specification takes 40 hours of staff time at £65 an hour, the labour cost per spec is £2,600. The software accounts for less than 6% of the total cost. The hours are where the money goes.
This is where AI-powered specification tools change the equation. If Avoice cuts specification writing time by even half, you save £1,300 per specification in labour costs. Over 20 projects, that is £26,000 per year in recovered time. Even if the licence costs more than NBS Chorus, and that is not necessarily the case, the total cost per specification drops because the labour component shrinks substantially.
Avoice also handles something NBS Chorus does not: automated consistency checking between specifications and other project documents. It flags mismatches before those errors reach the contractor. Each error caught early saves hours of rework later, and for any practice that has dealt with post-tender specification queries or on-site discrepancies, the value of catching those problems at RIBA Stage 4 rather than Stage 5 is not abstract at all.
If your NBS Chorus renewal is approaching, run a few numbers before signing. Calculate your actual cost per specification, including labour, not just the licence. Look at how many hours your team spends on specification-related tasks each week. Consider whether your current tool reduces that time meaningfully or simply structures it differently.
Ask whether the features you pay for in your current Chorus tier are features you actually use. Many practices pay for Pro or Premium tiers but rely on only a fraction of the capability, because the productivity gains they truly need cannot be purchased from a clause library alone.
And look at what has changed in the market since you last evaluated your options. Tools like Avoice that use AI to generate specifications from your own project data did not exist three years ago. The category is new, and the value proposition is different enough from traditional specification software that it deserves serious evaluation rather than a quick dismissal based on how spec writing has always worked.
The same logic applied to hand-drafting before CAD, and to 2D drawing before BIM. The firms that moved first gained an efficiency advantage that compounded over years of project work. Specification writing is following that same trajectory, and the cost of waiting is measured in the hours your team spends every week on work that a machine can now do faster and more consistently. If you want to see how this works on a real project, Avoice offers demos tailored to your practice.
