Posted by Vanja Landeck - 13 August, 2021
A sustainable solution that provides effective protection and waterproofing plays a key role in the long-term structural integrity of a facility and its cost-effectiveness during use. So how can you ensure that car park surfaces are permanently and reliably protected? Here’s what to consider when choosing a protective waterproofing system:
1. Car parks take a lot of stress
Although a solid concrete slab may seem extremely durable – even indestructible – this isn’t actually the case. Structurally speaking, car park concrete has to withstand considerable loads. Mechanical impact is the first point to consider: most modern cars weigh around one tonne, and SUVs are heavier still. At any given time, the structure has to cope with dozens or even hundreds of these vehicles, some stationary and some moving (mechanical loads). The car park’s surface also takes a hit from exhaust fumes, grease, brake fluid and de-icing salts. On top of that, the roof level car park is exposed to the elements.
2. Left unprotected, concrete erodes
Concrete erodes. Weathering causes it to become increasingly porous and leads to cracks. Over time, water and de-icing salts penetrate the reinforcement, triggering and speeding up the corrosion process. Add mechanical loads into the mix, and the situation becomes dangerous. The integrity, safety and durability of the structure are significantly compromised by these factors acting simultaneously. The only lasting solution to avoid or address this scenario is to apply an effective finishing that waterproofs and protects the surface.
3. A high-performance system is essential
When specifying a protective and sustainable system, excellent resilience and crack-bridging properties are crucial. The protective coating must be strong enough to withstand typical car park loads. In addition, the upper deck – normally exposed to the elements – is particularly prone to cracking over time. The protective coating must bridge these cracks to prevent the ingress of water and harmful substances that can cause significant damage to the floors below roof level. Other critical technical requirements are slip resistance and visual variation to define parking spaces or indicate directions on the floor. In practice, it’s often challenging to find a system that ticks every box.
The upper floors of multi-storey car parks are usually uncovered and open all year round, constantly exposed to changing weather conditions. In addition to chemicals and mechanical loads, car parks located on the roofs of buildings are exposed to UV radiation, rain, snow and ice, as well as extreme temperature fluctuations. In this harsh environment, the reinforced concrete structure requires specialised treatment to:
- Protect against corrosion, which can be caused by ingress of chlorides from de-icing salts, petroleum-based substances leaking from cars or battery fluid
- Prevent humidity penetration in the concrete matrix, avoiding majority of degradation causes linked to water
- Protect lower floors from water penetration
- Meet the required safety level by providing adequate slip resistance
- Facilitate traffic flow and communication through demarcation of traffic zones
- Achieve pleasant design aesthetics
- Support cleanliness and avoid high cleaning costs
The range of MasterSeal car park deck coatings from Master Builders Solutions has been developed to meet all of these criteria.
4. Preserving the integrity of car park decks is challenging
Cracks in a car park’s concrete deck of a car park can occur for many reasons, from temperature differences, imposed loads and the sudden acceleration and deceleration of cars to shrinkage cracks during service. Secondary cracks also occur in areas subject to localised stress concentrations. And do not forget that during hardening and due to shrinkage, concrete can crack (read more about concrete cracking in our series “Why does concrete crack?”). Therefore, the choice of resin membrane should be based on the highest possible material elasticity and crack-bridging ability – both from static and dynamic loads.
5. Top-deck design details can cause leaks
Unfortunately, surface damage and cracks are not the only causes of water leakage to lower decks. Waterproofing a multi-storey car park’s external top deck involves sealing many small details, including plinths, inlets and drains. To ensure that elements adjacent to the floor plane can be fully waterproofed, they must be made of a strong but flexible material that will compensate for building deformations thanks to their flexibility and extensibility.
Gullies can be particularly problematic and generate many leaks due to cracking at their edges, which can allow water ingress and leaks in the lower decks. Careful application of the waterproofing membrane, connecting the concrete substrate with the inserted elements, is necessary to avoid related damages.
6. A protective system must be fit for purpose
There is no one-size-fits-all specification or method that will suit all surfaces. Each project must be considered as unique, and the choice of system depends on what you are dealing with. In a new-build project, the concrete has not had a chance to sustain damage or reinforcement degradation, but shrinkage is a problem. With a repair and refurbishment project, the structure is likely to be in a different condition, often with significant damage. Experience is key in this matter. Our experts at Master Builders Solutions will advise you to choose the right solution for your individual challenge.
7. Protective waterproofing systems for car parks are a specialist area
When opting for a waterproofing system, either spray or hand applied, pay attention to the contractor's experience and the system manufacturer's recommendations and warranty. This minimises the risk of project failure and provides a high guarantee of project completion within the planned timeframe. As you consider the specification, don’t forget to factor in whole-life costs, which manufacturers should be able to advise on.
8. Using a built-up system is essential
For a system to be effective, car park coatings must have two to four separate layers, each with different properties for the different tasks they have to perform. How these layers are combined ultimately determines the performance and durability of the coating, as well as the time needed for application. The details can vary considerably from project to project, so it’s important to clarify the requirements at a very early stage.
A typical system build-up comprises:
- Primer coating: the basis of all systems, this ensures adhesion of the protective system to the substrate.
- Waterproof membrane: the waterproof, elastic and flexible layer that gives its properties to the final system. The other layers must ensure good adhesion of the membrane to the substrate and protect the membrane from mechanical and chemical attack.
- Wear coating: this protects the membrane from traffic damage and gives a rough surface finish. Combined with the top coat, it provides slip resistance.
- Topcoat: the thinnest layer in the system, it plays a key role and must provide full protection against: sunlight, de-icing salts and rim abrasion, while also being easy to clean and allowing the facility to return to operation quickly.
For non crack-bridging systems, often applied to intermediate floors, the wearcoat and the membrane can sometimes be combined into a single layer. In crack-bridging systems, applied on top decks, the topcoat and the separate wearcoat provide adequate protection of the waterproofing membrane.
9. Different decks have different requirements
The conditions are the most demanding on the external top deck, where systems with a separate membrane and wearcoat will be required to maintain the high elasticity of the membrane and offer adequate protection against abrasion and impact at the same time. Including a primer and topcoat makes the top deck systems the most complete build-up, normally involving four layers.
Intermediate decks are usually enclosed and not directly exposed to weather conditions such as sunlight or rain. Nonetheless, they must have good crack-bridging properties to increase the safety and durability of the entire structure. Here, the system usually consists of two or three layers.
At the lowest level, or where crack bridging capacities are not required, the condition of the substrate under the concrete is a very important factor to consider. The lower level may require additional waterproofing to protect against groundwater or soil moisture. Again, the whole protective system often involves two or three layers.
Remember that ramps are very demanding areas (especially spiral ramps) – as potential hot spots for accidents, they need greater slip resistance. On straight and serpentine ramps, the energy is mass times speed equation comes into play. This energy has a direct effect on the ramp’s surface, meaning it must be particularly well protected against mechanical loads as well as providing a non-slip surface with high wear resistance. In these zones, the most robust systems, are needed.
To find out more about Master Builders Solutions’ MasterSeal protective waterproofing solutions for car park protection, click here!
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