Inspect first, then choose
The key question is not which product should be applied, but whether the existing roof build-up is suitable to retain. A professional inspection should consider adhesion, moisture, blisters, cracks, detailing, falls and the condition of the existing waterproofing.
If the existing construction is sufficiently stable, a renovation system may be a strong option. If the roof build-up is structurally poor, heavily saturated or technically unreliable, full replacement may still be necessary.
Why renovation can be attractive
- Less material to remove and dispose of.
- Less disruption on sites that need to remain operational.
- Faster treatment of complex details with a liquid-applied system.
- Possibility to combine waterproofing with a reflective finish.
- Extension of the useful life of a technically sound existing roof build-up.
Bituminous roofs as a renovation base
Many professional flat roofs use bituminous membranes. ONE®, 2.0 and various Wingum Plus H₂O systems can, according to Winkler, be applied to existing bituminous membranes under the correct conditions.
The phrase ‘under the correct conditions’ is important: age, surface condition, contamination, oxidation, adhesion and moisture issues must be assessed. The manufacturer defines the required preparation, primers, reinforcement and waiting times for each system.
Complex details are often the real challenge
Risk on flat roofs is often concentrated around upstands, drains, rooflights, installations, joints and interfaces between different materials. Liquid systems can be especially practical here because they conform to the geometry.
That does not eliminate the need for reinforcement and detail products. Winkler uses accessories such as ONE® MAT, sealing bands and pads in several system build-ups.
Renovation does not automatically mean cheaper
A renovation system can save material and labour, but it must first be technically correct. Additional preparation, moisture problems, local repairs or complex detailing can influence total cost.
The relevant comparison is therefore not only price per square metre, but also expected service life, project duration, disruption and technical risk.
Practical project approach
- Visual and technical roof inspection.
- Determine which existing layers can remain.
- Substrate testing and, where useful, a test area.
- Select membrane, reinforcement, primer and detail products.
- Define coverage and layer build-up.
- Apply under suitable weather conditions.
- Inspect details and final layer.
Sources
Assess a project?
Send WLS Group the project situation or request a sample for a test area.
