Which measurements and questions should I take to a bathroom installer?

A four-step working method

1. Map entry, wet area, fixtures and door movement with actual measurements.
2. Record the user’s task and preferences rather than copying a generic room plan.
3. Ask qualified installers to confirm substrate, waterproofing, load and electrical constraints.
4. Separate quoted work, exclusions and professional sign-off before comparing bids.

Common errors to avoid

• Using an allowance percentage as a real contractor quotation.
• Treating an empty worksheet field as a confirmed zero or a verified fact. Mark missing information explicitly.
• Sharing a working brief as a professional conclusion. Keep assumptions and unanswered questions attached.