Co-Founder, CTO, Construction Operations in London

About Marble

Marble is a climate tech venture studio. We partner with scientists, engineers, and operators to create companies solving hard climate problems in the world's largest industries. Our first 14 companies are building transformative products across energy, industry, agriculture, and climate resilience. 100% have been successful in raising follow‑on to date. We are looking to partner with exceptional individuals to create our next venture.

Empowering the Trades

The UK’s 885,000 construction micro‑businesses deliver £49bn of small construction projects each year. Most run on WhatsApp, spreadsheets, and memory. The unstructured approach costs roughly 20% of each job in scope drift, rework, untracked changes, and delayed compliance. The industry is also highly wasteful, with 13% of materials never being used, and construction accounting for 61% of the UK’s landfill. We are reliant on this highly fragmented industry to refurbish our buildings to meet performance needs and the targets of the Climate Change Act. However, at current rates, it will take 100+ years to decarbonise the UK’s built environment. We are building an AI‑native operating system for independent installers to ease administrative burden, reduce project costs, and accelerate business growth. Our technology empowers tradespeople to grow their business, gain professional independence and administrative efficiency. By de‑risking installations for both the contractor and the customer, we will enable cost‑effective delivery across millions of buildings.

About the Role

As CTO and Co‑Founder, you will be the technical half of a two‑person founding team. You are a peer to the CEO, a partner, sharing leadership and responsibility. You own the technical vision, the architecture, the hire‑and‑build plan for the engineering team, and the technical narrative we take to investors and partners. This is not a "manage the engineers" role. At Pre‑Seed, you are writing the production code, making the call on what we build, what we buy, and what we defer. You will inherit working scaffolding (Ionic Angular mobile app, FastAPI services, agent gateway with LLM SDKs, Supabase data layer, a live React lead‑gen site on Cloudflare) and a product roadmap shaped by over 100 installer interviews. You will own the technical strategy that turns that scaffolding into a defensible, AI‑native operating system for the trades.

Core Responsibilities

• Technical vision and architecture: Own the end‑to‑end stack and the multi‑year technical strategy, data modelling, and infrastructure.
• Shipping software: Write, review, and deploy code.
• AI strategy: Own the agentic architecture (RAG, structured output, human‑in‑the‑loop gates). Train, evaluate, and deploy models.
• Engineering hiring and team building: Build the engineering function. Define the hiring bar, write the JDs, run technical interviews, and set the engineering culture.
• Technical fundraising and storytelling: Own the technical narrative in investor conversations, due diligence calls, and partner meetings.
• Defensibility: Identify what is protectable, what stays a trade secret, and what is published.

As CTO and Co‑Founder, you will partner directly with the current Founder in Residence, who has been developing this project as CEO over the last 12 months. The founder has 20+ years of product development experience in the construction industry, ML, and Computer Vision. Most recently, he was responsible for an AI‑powered quality assurance system used by automotive OEMs, and before that, built and scaled a robotic tool and installer operating system that delivered over 5,000 installs with zero compliance failures.

Requirements

You are a strong fit if you recognise yourself in most of the following:

• Skills
• Software engineering across the stack: You have shipped multi‑tenant SaaS and production systems end to end. Solid CS foundations, including data structures, systems design, distributed systems, testing, and architecture that scales.
• Python backend: Comfortable building APIs, data pipelines, and service integrations in Python. Familiarity with FastAPI, Django, or Flask is useful but not essential; what matters is that you can design clean, testable services. Familiarity with Supabase, Postgres, and pgvector is useful.
• Production AI: You have built agent‑first workflows, RAG, structured output parsing, and evaluation harnesses. You know the difference between a demo and a production system.
• Cloud infrastructure: You can deploy, monitor, and maintain apps end‑to‑end on modern cloud platforms (Supabase, Cloudflare, AWS, or similar). You think about latency, cost, and observability from day one.
• Technical hiring and team design: You have hired engineers before. You know what a good technical interview looks like, what a bad one looks like, and how to set an early engineering culture that scales without rewrites.
• Communication: You can hold both a technical conversation with an investor and a product conversation with a sole trader.
• Behaviours
• Outcome‑driven: You take ownership of outcomes, not tickets. You think in years, not sprints. You see fundraising, hiring, and product as one connected system.
• Builder who scales: Ship imperfect on Thursday over perfect next month, track the debt, and know which debt is dangerous.
• Product over features: You measure output in customer outcomes and revenue, not story points or lines of code written.
• Comfort with ambiguity: You make the call, you write down why, and you move. You revise without ego when reality contradicts the call.
• Transparency: Your actions build trust and strong partnerships.

Bonus Point

• You have been in a founding position before (Co‑Founder, Founding Engineer, first hire, etc.).
• You have built or contributed to developer platforms, internal tooling, or infrastructure automation that another team relied on.
• You have worked with CNN’s and Computer Vision.
• You have a strong appreciation for design and UX.
• You understand UK construction compliance (MCS, RECC, Part P, Building Regulations) or you can pick it up fast.

What we offer

We offer (among other things)

• A €3,000 monthly allowance during your participation in the programme as a Co‑Founder in Residence before spin‑out.
• €250,000 inception funding at incorporation, if you are successful. You and your team will own 80% of the company at incorporation.
• Full‑stack support in our venture creation programme.
• Mentorship and guidance at every step of the way.
• Hands‑on support across technology and market research, landing interviews with experts and customers, techno‑economic modelling, roadmap and scale‑up strategy, sourcing your future co‑founders and advisors, and more.
• Access to an unparalleled network across science, industry, talent, investors, mentors, and other climate deeptech founders.
• Access to our research insights, knowledge base, and curated resources.
• Weekly check‑ins, work sessions in our Paris HQ (or remote) and continuous peer learning with other programme participants.
• Seed fundraising support after the programme. Introductions to the best seed investors and help with term sheet negotiation.
• Founder visa sponsorship if you wish to relocate to France. Remote participation would be a challenge, but we’re open to finding different partnership formats.

We believe that a diverse group of minds is key to solving the climate crisis. We encourage women and people of colour to apply. Studies have shown that under‑represented candidates are less likely to apply for an opportunity unless they feel they meet every single qualification. We are committed to building a diverse, inclusive and mission‑driven cohort. If you’re excited about the programme but your past experience doesn’t align perfectly with what you read on our website, we encourage you to apply anyways!