Car Park Waterproofing and Bridge Deck Membranes with Hot-Spray Polyurea

Multi-storey car parks, exposed parking roofs, underground garages and bridges share the same problem: a concrete slab that moves and vibrates, carries repeated loads, and takes water from above or from the sides. When water reaches the reinforcement, corrosion starts and the structure deteriorates from within. Good car park waterproofing is therefore about protecting the structure’s life, not just stopping drips onto the level below. Krypton’s car park roof waterproofing systems page sets out the approved build-ups.

Why car parks and bridges need a specialised membrane

• Movement and vibration. Slabs move with load and temperature, so the membrane must bridge cracks even in the cold.
• Mechanical load. Traffic, braking and turning demand high abrasion, impact and puncture resistance.
• Rebar corrosion. Water that enters through cracks eventually reaches the steel. In fact, as one real project below shows, the end result can be demolition.
• Downtime. Every day that a commercial car park or bridge stays closed costs money.

Impermax Polyurea H Flex: a bridge deck waterproofing membrane for moving slabs

Impermax Polyurea H Flex is a hot-spray hybrid polyurea. It holds European Technical Assessment ETA 21/0740 (EAD 030675-00-0107) as well as CE marking for bridge deck waterproofing. According to its TDS, it offers:

• 400% elongation, 15 MPa tensile strength, Shore 90A/40D and 43 N/mm tear resistance;
• crack bridging A5 at 23 and -10 °C, and B4.2 at -20 °C;
• 22 mg abrasion loss and 24.5 N·m impact resistance (Class III);
• watertightness at 60 kPa (EN 1928);
• Broof(t2) external fire rating, together with hail resistance;
• rain resistance after 15 minutes, then light traffic after about 1 hour.

In addition, Krypton’s magazine reports an ETE 16/0149 to ETAG 033 for bridge deck waterproofing with a 25-year service life. The note on ETAG 033 bridge deck waterproofing covers it in detail. For the ETAG/EAD framework itself, see the EOTA ETAG archive.

Note that these approvals belong to H Flex only. Therefore, they do not transfer to pure Polyurea Rayston or to one-component roof coatings.

Real projects, real numbers

Jorge Newbery Airport car park, Buenos Aires

An 11,000 m² underground car park at Jorge Newbery Airport sits on land reclaimed from the Río de la Plata. As a result, it is a demanding groundwater setting. The build-up was Primer Epoxy 100 on the concrete, then H Flex, as the Newbery airport underground car park case describes. These conditions are comparable to basement car parks in Egyptian cities near the Nile or the coast.

Colmenar M-40 bridge, Spain

On a new 6,000 m² bridge, the contractor used a complete kit of primer, H Flex membrane and protective coat. The previous deck had to come down because deficient waterproofing had let corrosion set in. It is a clear lesson in the cost of getting this wrong.

Other references

• The Guadalmez–Córdoba railway section in Spain, 30,000 m².
• Faw Port in Iraq, 25,000 m², using Rayston Proof Bridge (Primer Epoxy 100 with H Flex). It is also a reference from the Arab region.

Read more in Krypton Chemical’s guide to long-lasting bridge waterproofing.

Application steps

1. Prepare. Shot-blast or scarify to sound concrete. For reference, the comparable H Flex Alum guidance gives a pull-off of at least 1.4 N/mm².
2. Prime. Apply Primer Epoxy 100 to the concrete. Even if the membrane cures fast, never skip the primer.
3. Spray. Then hot-spray H Flex with components at 70 °C and the hose at 65 °C.
4. Protect or wear layer. This depends on the car park. Exposed roof decks need a UV-resistant finish, while underground decks see no sun. Finally, the vehicle wearing course is a separate system that the spec must define.

Tips for hot-climate sites

• On exposed parking roofs, work in cooler hours, because substrate temperature must not exceed 40 °C.
• Watch the wind, since anything above 25 km/h affects spray quality.
• Write the product name and ETA number into the specification rather than just “polyurea”.

For advice and supply in Egypt, see Krypton Egypt polyurea waterproofing or contact our team.

FAQ

What is the best waterproofing for a car park deck?

Use a continuous, elastic membrane that bridges cracks and withstands traffic, such as Impermax Polyurea H Flex (ETA 21/0740). Then combine it with a protective or wearing layer that suits the car park.

Is underground car park waterproofing the same as roof deck waterproofing?

No. Underground decks see no UV but face groundwater and pressure from below, so the build-up differs.

How soon can a car park reopen?

The H Flex membrane takes light traffic after about 1 hour. However, reopening to vehicles depends on the wearing course and final protection.

Does polyurea prevent rebar corrosion?

It stops water from reaching the concrete and steel. As the old Colmenar deck showed, that water is in fact the main cause of deck corrosion.