District 5 roof waterproofing, New Cairo
The roofs at District 5, in New Cairo, were closed with a sprayed waterproofing membrane, turned up at the walls so the field and the upstand are one film.
01 · Project overview
What is District 5?
District 5 is one of the large districts of New Cairo, east of the old city, with a mall, streets and long low roofs around the parking. Those roofs are the lid over shops and back-of-house rooms. When they fail, the leak shows up inside a building that is open to the public.
The waterproofing on these roofs is a sprayed membrane. It is taken across the flat and turned up the wall, so the joint between deck and facade is not a separate strip of mastic. Krypton Chemical supplies the resin systems for this kind of roof. The crew sprays them in place.
| Project | District 5 |
|---|---|
| Place | New Cairo, Egypt |
| Scope | Roof waterproofing |
| Membrane | Sprayed, turned up at the walls |
02 · The challenge
What does a New Cairo roof ask?
The sun here is direct from late morning until the light drops. A dark roof becomes a hot plate. The deck grows in the afternoon and shrinks after dark. A rigid cement coat maps that movement into cracks, and the cracks open at the wall first.
The roofs are broken by facades, outlets and plant. Water does not leak through the middle of a sound bay. It gets in where the membrane stops at the cladding and someone has tried to finish the line with a bead. District 5 needs that line to be the same film as the field.
03 · The solution
A sprayed membrane, one film
A sprayed membrane was used because it can follow a flat bay and a vertical turn without a lap to peel. The light colour of the finished roof matters in New Cairo: a pale surface throws more of the sun back than a black one, and the rooms under a mall roof feel that.
The upstand against the facade is part of the same coat. Outlets and the joint at the wall are closed before the field is called finished. That is the whole of the idea on a roof this exposed.
04 · Application
How a sprayed roof is built
The deck is prepared first. Dust, laitance and anything that will not hold a film come off. Cracks are cut out and filled. The concrete, or the existing roof, has to be dry enough for the resin that is going down. A damp deck blisters a membrane the first hot afternoon.
Details lead. The turn at the wall, the outlets and any penetration are done before the open bay is treated as finished. On District 5 that turn is the line under the cladding, where water will sit if the film is thin. The spray is taken up the wall in the same pass as the floor next to it, so there is no joint between them.
Thickness has to be honest at that turn, not only in the middle. A bay can look perfect and still leak at the facade. The cure then has to finish before foot traffic and before the next trade stacks plant on the membrane. A light colour is the face that stays in the sun.
The exact temperature window, the consumption and the return to service are the ones in the data sheet of the resin used on the deck. They are typical product data, not a reading taken on this roof.
05 · Results
What this roof has to stand behind
District 5 stays open. The roofs over it have one job: keep the weather out of the rooms, including at the wall, and stay elastic through a New Cairo day. The sprayed film is there so that line does not depend on a bead of mastic.
06 · FAQ
Frequently asked questions
Why does this roof need an elastic membrane?
New Cairo sun heats the deck all afternoon and the night pulls it back. A rigid coat cracks at the wall. The membrane has to stretch with that movement.
Where does a roof like this leak?
At the turn against the wall, at outlets and at fixings. The open field is the easy part. The upstand has to be the same membrane.
When can people walk on it?
Light foot traffic waits until the film has cured. The exact window is the one in the product data for the resin that was sprayed. It is not a same-day handover.
Does the sun affect the colour?
A light roof stays cooler than a dark one. If the resin is aromatic, an aliphatic topcoat is what holds the colour while the membrane keeps the water out.
What has to be ready before the spray?
A dry, sound deck. Cracks and the joint at the wall are closed first. Dust and laitance come off. Spraying over a dirty upstand is how the film lets go.
07 · Photos
The roofs
