Action for Children Roof Waterproofing
An Action for Children flat roof, 2,000 square metres, was waterproofed with Impermax after the floating Sarnafil single-ply started to fail at the joints and the fixings.
Overview
An Action for Children flat roof, 2,000 square metres, was waterproofed with Impermax after the floating Sarnafil single-ply started to fail at the joints and the fixings.
| Place | United Kingdom |
|---|---|
| Area | 2,000 square metres |
| Substrate | Floating roof, Sarnafil single-ply |
| Membrane | Impermax |
| Walkway | Pigmented Colodur with anti-slip quartz |
Challenge
The roof is a floating build over a Sarnafil single-ply membrane. The joints were breaking apart, the membrane was wearing thin, and water was coming through, including at the roof fixings. Weak spots and fissures had spread. The roof had become hazardous. A patch along the old joints would have followed the same lines.
The area is 2,000 square metres. That is large enough that a slow method with a torch would have kept the building open to the weather, and to a fire risk, for a long time. A maintenance route was also required, so people could walk the roof without using the field membrane as a path.
Solution
Impermax is Krypton Chemical’s cold-applied liquid polyurethane membrane. It goes on by roller, brush, spreader or airless equipment, in two coats of about 1 kg per square metre each. The coats are different colours, so a missed patch shows while the work is still open. A spiked roller is run while the coat is wet, to break bubbles before they set. A mesh is not required across the field. It is used at edges and corners, the places a liquid film is asked to turn.
Elongation is 450 to 600 percent and tensile strength is 2.5 to 4.3 MPa. Those figures are typical product data, measured on the product under stated conditions. They are not a cut taken from this job. On a surface that moves with heat, that elongation is why the film can stay with the substrate instead of cracking where the plane changes.
The substrate wants to be between 5 and 40 degrees C. Above 45 degrees C the work needs extra measures. Pot life is about 4 to 6 hours for 1 kg at 20 degrees C and 50 percent relative humidity. People can usually walk the film in one or two days. It reaches about 90 percent of its properties in three days. Final hardness takes 10 to 15 days, and standing water should wait for that. The European Technical Assessment is 06/0263, with CE marking for the 10-year and 25-year working-life categories. The system also carries a BBA agrément.
Cold application is the point on a roof that is already leaking. Impermax does not bring a torch onto that build. Fissures, weak spots and upstands were dealt with first, then the two coloured coats. A defined walkway was marked in pigmented Colodur with anti-slip quartz in the top coat. The quartz line is what people walk. The field is the waterproofing. Pigmented Colodur, as a product, has a Shore hardness around 60D and an elongation around 70 percent. That is product data for the wearing coat, not a test of this roof. The walkway is there so the wearing line and the waterproofing are not the same film.
Application
Stir the pail slowly so settled solids come back and bubbles can leave. Do not thin it with a solvent that is not the Rayston PU solvent. The surface is cleaned, cracks and weak spots are dealt with first, then the two coats go down, including upstands and outlets in the same passes. Details are not left for a leftover tin at the end of the day.
On this job the same rule applies at every edge. the old joints were already opening and water was already coming through the fixings, so a missed patch sits on a leak that has a path. A holiday in the second coat is a path. The colour change is how that path is seen before the surface is handed back. Outlets, upstands and fixings take the same two coats as the field, because water does not fail in the middle of a bay. It fails where the plane changes.
Results
The finished roof is an Impermax film over 2,000 square metres, with the fissures, fixings and upstands taken in the same coats, and a quartz walkway in pigmented Colodur where people have to walk. The build sits in the 10-year working-life category of ETA 06/0263, with the BBA agrément behind the same system.
Products
Impermax
Cold-applied liquid polyurethane. Two coats at about 1 kg per square metre each. Elongation 450 to 600 percent. Those figures are typical product data.
Colodur
Pigmented aliphatic top coat on the maintenance walkway, with anti-slip quartz embedded. The wearing line. The waterproofing under it is Impermax.
FAQ
How is Impermax applied?
By roller, brush, spreader or airless equipment, in two coats of about 1 kg per square metre each. The coats are different colours so a holiday shows. On this roof that matters because the old joints were already opening and water was already coming through the fixings, so a missed patch sits on a leak that has a path.
How long before the film can be walked?
Usually one or two days. About 90 percent of the properties are there in three days. Final hardness takes 10 to 15 days, and standing water should wait for that. On this roof a film that is walked or flooded early is still soft.
What temperature does the substrate need?
Between 5 and 40 degrees C. Above 45 degrees C the work needs extra measures. A surface in full sun can pass that even when the air feels moderate, and this roof is no exception.
What do the strength figures mean here?
Elongation is 450 to 600 percent and tensile strength is 2.5 to 4.3 MPa. Those are typical product data, not a test cut from this job. They are why the film can follow movement at upstands and outlets on this roof.
Where do the cure times come from?
From the Impermax technical data sheet, measured on the product under stated conditions. They are not a stopwatch reading from this roof. The ETA for the system is 06/0263.