Lock in extra-work agreements for UK solo trades
Voice-note the variation, customer signs on their phone, the invoice can't be challenged
Executive Summary
In a nutshell
A purpose-built UK SaaS that solves one specific dispute pattern for solo plumbers, electricians, builders and heating engineers: the customer who said "go ahead" on the extras and then refused to pay. The tradesperson voice-notes the change on-site, AI extracts the new scope, new price and new completion date, drafts a one-page variation order, and the customer signs it on their phone via SMS link with timestamp, GPS and photo evidence baked in. The signed variation locks in the new scope and price under the Consumer Rights Act 2015. Existing job-management suites (Tradify, Powered Now, Joblogic, Commusoft) bundle quoting and invoicing but treat mid-job variations as an afterthought. Procore and Planyard own enterprise variation management but are wildly overbuilt for a two-person plumbing outfit. The wedge is solo-trade specific, the price point sits below the all-in-one suites, and the timing is good: voice-to-structured-data hit production quality in 2024-2025 and quantum meruit disputes are still the most common small-claims story on UK trade forums.
The Story
Meet the user
Marcus has been a self-employed plumber in Reigate for eleven years. Yesterday's job in Dorking was a straightforward bathroom refit, three days budgeted at £2,400. On day two the customer opened a cupboard and asked if Marcus could also re-pipe the airing cupboard while he had the floorboards up. Marcus said "yeah, that's another £380 and probably an extra day", the customer said "great, do it", and Marcus cracked on. Yesterday afternoon, when he handed over the invoice for £2,780, the customer paused and said "I don't remember agreeing £380, I thought you said you could squeeze it in." Marcus has no signed quote for the extra work. He has a verbal agreement, no witness, and an invoice the customer is now disputing.
He's sat in his van at six in the evening trying to remember if he texted her the figure. He didn't. Then his mate Aaron, an electrician in Crawley, mentions a new app he's been using. Marcus voice-notes the change to the app on-site, it spits out a one-page variation, it gets texted to the customer's phone, she taps to sign with her finger, and a signed PDF is in both their inboxes before the cordless drill comes out of the bag. No more "I don't remember agreeing".
Scores
How does this idea stack up?
7.0/10
748,000 self-employed UK construction workers plus 118,600 plumbing/HVAC and 198,300 electrical workers. The all-in-one segment is crowded but the variation-order wedge is wide open.
Quantum meruit disputes are the most-cited story on UK trade forums. £10,000 small-claims limit covers the typical disputed job. Citizens Advice and JustAnswer threads document the pattern weekly.
Whisper or Deepgram for voice, GPT-4o or Claude for scope extraction, Twilio for SMS, Dropbox Sign or DIY canvas for e-sign. MVP in three to five weeks for a competent solo dev.
Voice-to-structured-data hit production quality in 2024-2025, and the all-in-one suites are still treating variations as a checkbox feature. The product wedge exists right now.
Disputes about extra work are a permanent feature of the trades. The Consumer Rights Act 2015 is not going anywhere. Evergreen demand.
Tech is easy. Distribution into solo trades is famously hard (no LinkedIn, fragmented forums, word-of-mouth dominant). Real cost is acquisition, not build.
Strongest
Pain, 8/10
The evidence is unambiguous across legal advice sites, trade forums and small-claims patterns. People are losing money on this every week.
Watch out
Effort to Build, 5/10
Reaching solo plumbers and electricians is the hardest part. Plan for paid Facebook group placements, trade-show stands and direct merchant-counter partnerships, not Google Ads.
Pain Point
The problem
“Verbal contracts are enforceable but you need evidence: text messages, WhatsApp, emails, bank transfers, witness statements. The more documentation, the stronger your case. Without it, you're at quantum meruit, and a small-claims judge will pay you only what they think the work was reasonably worth.”
— paraphrased from multiple UK legal Q&A threads on JustAnswer and JustClaim, recurring pattern
The acute pain is structural, not occasional. Consumer Rights Act 2015 s.51 says the consumer must pay a reasonable price for the services when no price has been agreed. s.52 says the service must be performed within a reasonable time. The phrase "no price has been agreed" is exactly where the dispute lives: the customer says nothing was agreed, the tradesperson says it was. Without a signed variation, courts default to quantum meruit, which means an independent assessment of "fair value" that almost never matches what the tradesperson actually charged.
Citizens Advice is explicit: a tradesperson can charge more for extras only if they let the customer know in advance and the customer agreed to pay more. The implicit standard the small-claims court applies is "in writing, signed, before the work started". Most solo trades operate on verbal agreements made while standing over a hole in the floor.
The forum evidence is consistent across r/Tradesmen, MoneySavingExpert, Screwfix's forum, the JustAnswer UK Law queue and HomeForce. Every week there is a fresh post from a tradesperson chasing payment for extras the customer "agreed to" and a fresh post from a homeowner being charged for extras they don't remember agreeing to. The product solves both sides of the same problem.
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