Find the cause and the responsibility before buying a coating
A damp ceiling below a terrace can involve a pipe, drain, junction, damaged waterproofing or several defects. Ask a qualified professional to inspect the accessible construction and identify the next investigation. A photograph of a stain cannot select a membrane, prove the defect’s location or establish who must pay.
Check whether the laje, roof, drain or finish is private or common, and what building records and agreements apply. The condominium duties in the Civil Code and professional reform-plan guidance are relevant to the building interfaces. Do not authorise removal of a common waterproofing system as if it were merely your private floor finish.
Ask for a coordinated system and measurable boundaries
The IBI’s project guidance supports specifying the solution before execution. Ask the designer to define substrate condition, falls, drainage, junctions, movement, upstands, penetrations, exposure and the expected traffic. An exposed non-traffic roof and a terrace used for furniture and people do not necessarily use the same build-up.
- State what is removed and how the exposed base will be inspected.
- Identify repairs and slope correction included in the price.
- Draw drain connections, thresholds, wall junctions and terminations.
- Name the specified system, its application requirements and protection.
- Allocate reinstated paving, access protection, transport and waste.
The IBI technical guide addresses coordinated design, surface supervision, protection and testing. Its historical performance references should not be converted into an automatic lifetime or warranty for every renovation. Request the project-specific obligations, maintenance and written warranty terms.
Measure the actual treatment area
In a separate invented 5 × 6 m terrace, horizontal area is 30 m² and perimeter is 22 m. If the designer’s example detail includes a 0.3 m upstand around that perimeter, the vertical area is 6.6 m² and the treatment area is 36.6 m². The 0.3 m is an example design assumption, not a universal required height.
Agree whether details are measured separately or included in a rate. Sheet overlaps, product consumption and packs affect procurement and cannot simply be added to the contractor’s measured area without checking the pricing rule. The horizontal paving reinstatement can remain 30 m² even when waterproofing measures 36.6 m².
Compare a complete project budget
| Item | Amount |
|---|---|
| Inspection and defined design | 1 600 |
| Removal of existing finish | 1 800 |
| Base repairs and slope preparation | 2 400 |
| Defined drain and junction work | 900 |
| Specified treatment: 36.6 m² at 100 | 3 660 |
| Agreed checks and records | 600 |
| Protection layer and replacement finish | 3 000 |
| External waste transport | 800 |
| Defined project subtotal | 14 760 |
| Unresolved hidden-damage allowance | 1 500 |
| Chosen reserve: 10% of defined subtotal | 1 476 |
| Total funding | 17 736 |
A coating-only price is not comparable with this whole project. Ask a bidder who excludes removal, new falls or paving to price them explicitly. The Procon guidance on estimates supports itemising the total. Keep unpriced damage visible rather than attaching a false fixed total to an incomplete proposal.
Agree checks before protection hides the work
Ask the designer and installer which checks apply, who witnesses them and what constitutes release for covering. The method must consider the construction, system instructions, curing and safe loading. Do not improvise ponding, block a drain or use a roof edge as a work platform based on an online checklist.
Keep dated records of substrate, details, specified application and results. Agree how a failed check is investigated, corrected and checked again before reinstatement. A successful check at one stage does not authorise later drilling through the system or use contrary to its instructions.
Close the allowance, account and maintenance plan
If investigation replaces the R$1,500 hidden-damage allowance with an accepted R$1,200 repair, funding becomes R$17,436 with reserve unchanged. Remove the allowance before adding the repair. The reserve is not automatic permission to carry out every discovered extra; agree the scope and its technical consequences first.
- Receive the final system description, invoices and relevant professional records.
- Identify any outstanding repairs or reinstatement.
- Obtain maintenance, cleaning and access instructions.
- Record limitations on later fixings and who to contact after a leak.
- Reconcile approved changes, payments and the remaining balance.
Keep the project stages and recorded costs in Reno Pro alongside the responsible parties’ documents. A useful waterproofing quote describes a maintainable completed system and the surrounding work needed to deliver it.
Sources, date and scope
- Instituto Brasileiro de Impermeabilização — Selo de Qualidade IBI — Projetista
- Instituto Brasileiro de Impermeabilização — Guia de aplicação da norma de desempenho para impermeabilização
- Crea-RJ — Síndicos — orientações para reformas e manutenções
- Presidência da República — Código Civil — condomínio, art. 1.336
- Procon SC — Orçamento para serviços — custos discriminados
Sources checked on 19 October 2026. Unless stated otherwise, the local example is São Paulo city; check municipal and condominium rules for the actual address and work. Teaching figures are invented final amounts in Brazilian reais, not surveyed prices, offers or official fees. Projects in different articles are independent. Technical assessment, professional records and authorisations remain with the competent people.