Terrace Waterproofing Solutions for Energy-Efficient Buildings

Terrace waterproofing is particularly important and is considered a priority as the roof is always exposed to harsh climatic conditions and weather changes.
Rajeev Gupta, Business Head, ECMAS Construction Chemicals Pvt. Ltd.

An effective waterproofing solution ensures the durability of the structure by controlling water seepages. Eco-friendly and high-performance proofing solutions are essential for multi-level applications in a building. Waterproofing of flat terraces is extremely challenging as the water cannot run off the structure quickly, and will move slowly or pool above the surface, leading to leakages.

In India, traditional materials and techniques like brickbat Coba, Lime terracing, or the “Mud Fuska” are still very much in use, offering a limited degree of waterproofing along with some insulation against heat. But these systems have some major limitations as outlined below:

• Heavy loading on the slab
• Cracks on the surface, especially in the case of brickbat-coba
• Very labor intensive
• Application expertise required for lime terracing/mud fuska and not as good as in the olden days
• Rely more on the slope than a leakproof or a water-tight system
• Breaking and re-doing the same system is risky for the slab; cracks caused in the slab increase the problem of leakage

Nowadays, a wide range of products is available in the market - from the basic to premium and advanced, each of which cater to a specific requirement.

Key selection criteria for an effective waterproofing system for terraces & green roofs:

• Complete water tightness
• Capability to accommodate the structural movements & thermal stresses
• Ability to carry heavy intense built-ups such as landscaping, gardens, pavers etc.
• Robustness to take pedestrian/vehicular traffic
• Capability to sustain climatic conditions and UV exposure.
• Resistance to root penetration, chemicals, pesticides, etc.
• Long-life expectancy along with minimal maintenance

Alongside waterproofing, managing the thermal comfort of the occupants is to be considered keeping in mind the well-being of the people and also cutting down on energy requirements. Constructing energy-efficient buildings will reduce power bills and contribute to the saving of fossil fuels. High levels of comfort are obtained through utilization of sunlight, ventilation, and other modern methods of construction. Thermal comfort can be provided to the occupants at diminished levels of power usage through strategic planning and design of building, and effective use of heat insulation materials in the construction.


Why is Thermal Insulation important for buildings?
In countries with extreme climatic conditions, more than 65% of the energy consumption goes into the air conditioning to maintain comfortable indoor temperatures. This poses a great challenge to architects and designers; they must conduct analytical studies to make maximum use of natural lighting, ventilation, along with performance-oriented thermal insulation materials, limiting the U-value for roofs and external walls in the building.

Use of high-quality premium insulation materials help in controlling the heat transfer through the walls and reduce the heat transfer rate from outside to the inside during the hot summer months and the reverse during the winters.

The quantum of heat transfer through roofs and walls ranges between 60-70%. This heat shall be removed by air-conditioning. Therefore, the use of insulation materials for roofs and walls is very essential for energy conservation as it helps in the following:

• Reducing the energy consumption required for cooling and heating.
• Reducing the capacity of air-conditioning equipment and hence reducing capital cost.
• Reducing thermal stresses (thermal expansion & contraction with temperature changes).
• Maintaining a comfortable indoor thermal environment.

With the increasing emphasis on sustainability and sturdiness and the introduction of recent ECBC codes, the concept of terrace waterproofing and thermal insulation is becoming a replacement trend, especially in commercial and high-end residential buildings. Although it may require higher initial costs, overall life cycle costs are much lower because the payback is achieved within 5-7 years.

Key Selection Criteria for good thermal insulation material for roofs:

• Low thermal conductivity
• Dimensional stability
• Higher Compressive Strength
• Negligible water absorption & low vapor permeability
• Good fire resistance

Recent Trends in Roof Waterproofing
Roof waterproofing along with thermal insulation: A high-performance roofing system is achieved by combining waterproofing alongside thermal insulation. It includes a highly impermeable and sturdy waterproofing membrane that guards against extreme climatic conditions, irregular temperature variations, rain, and suitable thermal insulation material. Generally, insulating materials like Spray applied PUF insulation, XPS, or EPS insulation boards are applied in a controlled thickness (as recommended by the consultants) on the well-prepared, clean substrate followed by liquid applied waterproofing membrane like spray-applied Polyurethane or Polyurea membrane or sheet membrane-like TPO or vice-versa and with or without protection screed. A typical system that is being employed at a prestigious project site, is shown above.

Green roof solutions: Garden roof systems are specialized roofing solutions designed to support roof gardening. Green roofs provide a variety of benefits in an urban context starting with giving an aesthetic appeal to the unused roof. The plans and soil protect the roofing membrane from being exposed to harmful ultraviolet rays, extreme climatic conditions, and physical damage, thereby increasing the durability and life span of the roof and roofing material. Green roofs contribute to lowering greenhouse gas emissions, using direct shading of the roof, evapotranspiration, and improved insulation values.


A typical Green Roof System includes the following:

• Durable Waterproof Membrane (ECMACOAT FLEX PU 60 or ECMACOAT FLEX PUR 10)
• Root Barrier
• Drainage Layer
• Filtration Media (Geotextile Mat)
• Growing Media or Soil (50-100 mm in depth)
• Vegetation layer: low-growing, stress-tolerant alpine and herb species

The components act together to provide a suitable environment that supports plant growth while not compromising the waterproofing function of the roofing membrane.

Cool roof solutions: Dark-colored roofs absorb the Sun’s energy and get hotter as the day progresses. The roof surface can become superheated up to 80°C on a 35°C normal day, and therefore, the temperature of rooms below becomes unbearable leading to an increase in air-conditioning costs. Hot buildings also increase the Urban Heat Island effect.

The best method is to stop the roof space from heating up in the first place by reflecting heat away from the roof surface. A cool roof has been designed to reflect more sunlight and absorb less solar energy than a typical roof. Cool roofs are often made from a highly reflective sort of paint or a sheet membrane.


ECMAGUARD THERMOCOAT is a cool roof coating with high SRI (roof’s ability to reject solar heat) and low thermal conductivity, is capable of reflecting a large portion of ultraviolet, infrared and visible light, and offers a list of benefits to the building occupants as mentioned below:

• Reduces indoor temperature by 3-10oC (improved thermal comfort)
• Reduces roof surface temperature by 10 to 30oC
• Reduces air-conditioning costs
• Helps reduce heat islands
• Can be applied over a variety of roof surfaces

High-performance waterproofing: Although, multiple choices are available to the building owners and designers fitting into their technical requirements, and budgets. Some common solutions are Cementitious coatings, liquid applied acrylic coatings, polyurethane and polyurea membranes, bituminous sheet membranes, TPO membranes, etc. But liquid applied pure Polyurethane and Polyurea membranes from ECMAS have become increasingly popular thanks to their long-term heavy-duty performance and optimal costs. ECMAS offers a multiple choice of high-performance PU and Polyurea membranes which are ideal for waterproofing huge terraces, green roofs, and podiums.

Non-exposure grade pure Polyurethane membrane (ECMACOAT FLEX PU 40); Exposure and trafficable grade pure Polyurethane membrane (ECMACOAT FLEX PU 60 2K); Hybrid Polyurea membranes (ECMACOAT FLEX PUR 10 & PUR 20) are popular high-performance, liquid-applied waterproofing solutions offered by ECMAS.


Insulation materials: Roofs are often insulated either over the deck or under the deck. Generally, over-deck insulation is preferred, to avoid the absorption and retention of warmth by the concrete surfaces. Commonly used roof insulation materials include Expanded Polystyrene boards, Extruded Polystyrene boards, Spray applied PUF Insulation, Foam Concrete, Exposure grade liquid membranes with high SRI; etc. ECMAS is a leading player offering high-performance thermal insulation products like ECMAFLEX PUF 40 which is a two-component, polyurethane resin (PUR) based, seamless, fully bonded, closed-cell rigid foam to be applied with a specially designed spraying machine. It provides high-performance thermal insulation for terraces, green roofs, walls, etc.

ECMASHIELD TPO: The eco-friendly sheet membrane system is a perfect solution for both heat shielding and waterproofing roofs. Thanks to its high SRI values with high emissivity — it reflects over 90% of the sun’s heat, thus insulating the roof below. This exceptionally durable and versatile membrane does not allow water to percolate below, thereby waterproofing at the same time. ECMASHIELD TPO membrane is efficient, eco-friendly, and straightforward to put in solution for many projects (old or new construction, terraces of residential, commercial, or industrial buildings)

Conclusion
The advancements in construction technology have led to a growing trend for high-rise constructions. These constructions look out for modern methods for increasing sustainability and energy-saving options. Demand for high-performance waterproofing and insulation systems has grown exponentially. The green roof and cool roof solutions are the talks of the town today providing quantitative benefits to the building owners and better comfort levels to the occupants. This is accelerating the demand for better insulation products such as spray-applied PUF insulation, XPS boards, high albedo solar reflective coatings, and high-performance waterproofing solutions to support the latest trends.