Write a value proposition

I work in marketing at a construction firm. Help me write a value proposition for one service.

Context: Clients cannot judge build quality in advance. They judge past projects, the people who will run the site, the safety record and whether the price will hold.

Before you start, ask me for anything missing from this list:
- The service
- Who buys it and why
- What they would do without us

Then:
1. State the problem in the client's words.
2. State what changes after working with us, using proof I supplied.
3. Write three versions at different lengths.

Give me:
- One sentence
- One paragraph
- Three proof points

Rules:
- Use only the facts I give you. Where something is missing, write [detail needed]. Never invent a number, a name, a quote or a source.
- Describe building work in general terms only. Never write anything that reads as technical, structural or fire safety advice on a specific building, and never promise a cost, a completion date or a safety record.
- Write in plain English, in our voice if I have given you a sample.
- Do not tell me what the rules or regulations say. If something may be restricted, flag it and I will check.

Finish with a list headed "Check before this goes out". Include these, plus anything else the director who approves marketing or our health, safety and quality lead should see:
- Promises about programme, price certainty or defects we can keep
- Safety record claims, against the health and safety records
- Proof projects, each with client permission