A waterproofing proposal should explain how the chosen approach fits the basement, its intended use and the construction around it.
A product name or warranty headline leaves important questions unanswered. Ask for the design information, responsibility and handover arrangements behind the proposal.
Use these questions when discussing a new basement, a conversion or remedial work. They help identify what needs clarification before you accept a scope of work.
1. What is the basement expected to provide?
Tell the team how the space will be used. Storage, a plant room and occupied accommodation may place different demands on the finished environment.
Ask the appointed waterproofing designer to define the required performance and explain how the proposal addresses it.
Water ingress, condensation and ventilation are connected project concerns but are not interchangeable explanations. Ask which problem each part of the proposal is intended to address.
For an existing basement, provide dated photographs, the location of symptoms and any records of previous repairs. Separate observations from assumptions about the cause.
2. What information supports the design?
BSI lists BS 8102:2022 as the current code of practice for protection of below-ground structures against water ingress.
Ask the designer to identify the applicable design basis and explain the site information used. A reference to a standard alone does not explain a project's design.
The Property Care Association's guidance describes early specialist design input and consideration of site and ground conditions. Ask which investigations and existing-building records are available.
Identify gaps in the information and who will resolve them. Ask whether any part of the scope or price depends on those gaps being closed.
These questions do not establish compliance with BS 8102. That requires project-specific work by the appointed specialists.
3. What approach is proposed, and why?
The Property Care Association describes three broad forms of protection: Type A barrier protection, Type B structurally integral protection and Type C drained protection.
Type A uses a barrier. Type B relies on a water-resistant structure. Type C collects water within a drained system for controlled removal.
These descriptions help you read a proposal; they are not a method for choosing a system. Ask the designer why the proposed approach suits the site and intended use.
If combined protection is proposed, ask how the parts work together. Identify the drawings, details and responsibilities covering their connections.
Ask what options were considered and what assumptions the recommendation depends on. Keep the answers with the design record.
4. Do the details connect across the whole basement?
Ask to see how walls, floors, joints, penetrations, openings and changes in level are addressed. Include lightwells, stairs and adjoining existing construction where relevant.
Check whether structural and waterproofing drawings describe compatible details. Ask who resolves a conflict and issues the coordinated information.
Ask who controls later penetrations or alterations, including services installed after the main waterproofing work. Record the required checks before finishes conceal the work.
For remedial proposals, ask which areas will be opened up and what remains inaccessible. Make the limits of investigation and treatment explicit.
5. How will installation and inspection be coordinated?
Ask how the waterproofing work fits the construction sequence and the condition of the surfaces or structure it relies on.
Identify who installs the system, who checks the work and what records will be kept. Ask which stages must remain accessible for inspection.
Ask how completed work will be protected from damage by later trades. Clarify who investigates damage and authorises a repair detail.
Request a plan for recording any departures from the design. The person installing a detail and the person responsible for approving it may hold different roles.
6. What needs access, servicing or a response?
If the proposal includes drainage channels, sumps or pumps, ask how water is collected and discharged. Ask who confirms the discharge arrangement is appropriate.
Request the designer's explanation of access, servicing, monitoring and any response required if a component fails.
Ask whether finishes, furniture or later alterations could obstruct access. Check how these requirements will be communicated to the occupier.
Get the maintenance schedule, operating instructions and relevant contact details in writing. Do not assume a warranty removes the need to maintain the system.
Where pumps or alarms are proposed, ask the designer to explain the power arrangements and any contingency measures appropriate to the project.
7. What does the appointment actually include?
Separate the designer's scope, the installer's scope and any inspection, insurance or warranty arrangements. Ask who is responsible for each.
Read the proposed warranty alongside its exclusions, conditions and maintenance obligations. Check who issues it and how a claim would be handled.
Ask what the proposal does not cover: unresolved diagnosis, inaccessible areas, finishes, service alterations or work by other trades may need separate attention.
Before agreeing the work, record the outstanding questions and obtain a revised proposal where the answers change the scope.
When an independent review may help
Darren can review the construction assumptions, interfaces and gaps in a basement waterproofing or remedial proposal.
He does not replace the appointed waterproofing designer, structural engineer, installer or other specialists. They retain their design, installation and approval responsibilities.
Bring the proposal, relevant drawings, inspection reports and photographs, together with the question you need answered. An enquiry starts a discussion about the appropriate scope.
Sources and scope
The Basement Consultant
Sources checked 3 September 2026.
BSI: BS 8102:2022 public standard overview
Property Care Association: Structural waterproofing guidance
The public BSI overview confirms the standard's title and status. This article does not reproduce or claim to replace the full standard.
This is general guidance for discussing a proposal. It does not diagnose water ingress or specify a waterproofing system.