Accepting flat roof waterproofing: what to check before the work is completed
Date Published
An even surface does not, by itself, confirm the quality of the entire roof. These questions help clients check the result and obtain records of the completed work.
Acceptance starts before the final layer is installed
Once the roof is covered, the condition of the substrate and lower layers cannot be assessed by appearance alone. Agree inspection stages with the contractor in advance: which areas must be shown, which photographs must be taken, and what must be recorded before subsequent layers conceal the work.
This guide will help you prepare for a discussion with your contractor. The scope of inspection and acceptance criteria are determined by the design and the documentation for the materials used.
1. Check the materials against the agreed specification
Check product names, grades and intended uses against labels and delivery documents. Keep batch information and technical data sheets. If the contractor proposes a substitution, check its compatibility with the other layers and agree the change before installation.
Descriptions such as “equivalent” or “the same thickness” do not, on their own, establish suitability. What matters is where the material is used and the system it forms part of.
2. Ask for evidence of substrate preparation
You need more than photographs of the finished waterproofing: you also need information about what lies beneath it. How were defects repaired? Were the substrate’s condition and moisture level checked? Which primer was used, if priming was required by the installation method?
Substrate requirements and application conditions come from the design and the specific product’s instructions. A visibly clean surface does not, by itself, confirm that all requirements have been met.
3. Inspect the surface and joints
In accessible areas, look for tears, punctures, folds, blisters and open seam edges. Record suspicious locations on the plan and in photographs without damaging the covering yourself.
Ask the contractor to show the joint inspection results. The checking method depends on the material and installation technology. The same criterion cannot automatically be applied to both torch-applied bituminous sheets and welded polymer membranes.
4. Set aside time for details
Abutments at parapets, pipes, roof drains, roof access points and equipment locations should be inspected separately from the main roof area. Compare the work with the design details: how are edges secured and protected, and how are transitions and joints formed?
Record details that will later become inaccessible before they are covered. If the work differs from the design, ask for an explanation and an agreed solution, rather than just a promise that “it will not leak here.”
5. Check the drainage arrangement
Make sure roof drains and drainage routes are not blocked by construction debris. If persistent ponding remains after rainfall, mark the locations and ask the contractor to check the falls and drainage against the design.
Do not carry out a roof flood test yourself. Specialists must determine whether testing is needed, how it should be performed and under what conditions, taking the building structure and design requirements into account. The absence of a leak after one rainfall does not replace acceptance of the work as a whole.
6. Collect the handover records
Request the final specification of installed materials; records of completed and concealed work required by the design and contract; test results, where tests were performed; photographs of details; and maintenance recommendations.
Record any outstanding issues, including their location, description, the person responsible for correction and the reinspection deadline. Clarify warranty terms and the procedure for making a claim separately. The material warranty and installation obligations may be the responsibility of different organisations.
Сохраните контрольный список
Перед завершением приёмки проверьте: материалы сверены; скрытые этапы подтверждены; поверхность и швы осмотрены; узлы проверены; водоотвод свободен; замечания оформлены; документы переданы.
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Phone: +998 77 057 57 53
E-mail: info@marja.uz
MARJA — a manufacturer of waterproofing materials in Uzbekistan since 2004.
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