Waterproofing is a feasible, economical, and environment-friendly solution than recovering existing roofs and basements from water damages repeatedly. Not only do they provide protection from water damages in harsh weather conditions, but also improve the tensile strength and impact resistance of the structure.
The global waterproofing membrane market is driven at a robust rate by its growing trend in infrastructural construction and mining activities.
Waterproofing membranes is a thin-layer of water-tight sheath that is laid upon a surface (generally over flat roofs) to prevent water leaks or damage. It helps to stop water infiltration into a foundation and protect the structure from water damage. Waterproofing membrane is added to the concrete that helps water impenetrable as well as making it easy to maintain.
Categories of Waterproofing Membranes
Waterproofing membranes are broadly of the two forms – sheet based membrane (pre-formed sheets that can be laid on firm surface), and liquid applied membrane (that can be sprayed or brushed onto the surface).
- Sheet based membrane
As the name suggests, these membranes come in form of sheet rolls, that are unfurled and laid on a firm surface. They are reliable and durable thermoplastic sheets that fulfil the requirements of even the most demanding below-ground structures, including those exposed to highly intense ground conditions and stress, and dynamic forces due to earthquakes. These membranes are stuck to the substrate with hot tar based adhesives using a blowtorch. The joints between the adjacent membranes are also made of the same hot adhesive. Some membranes are can even be joined by melting them with hot air gun and then overlapping them on the previously laid sheet. The joints between the sheets are critical and should be done carefully in order to avoid leakage.
- Liquid applied membrane
These membranes come in liquid form that are either sprayed or brush-applied on to the surface. The thickness of the membrane can be controlled by applied more, or less liquid coating which cures in the air to form a seamless, joint-free membrane. The membrane can however tear or break if it is too thin, so care must be taken in the application in order to provide the right thickness. To avoid cold joints, the application procedure of this type of waterproofing membrane should be finished in a single day. However, cold joints can still be done by overlapping the new membrane over the old and the chemical will stick to itself readily. These membranes are usually preferred more than sheet based membranes as they are joint-free.
Based on these two broad categories, waterproofing membranes are of the following types –
- Bituminous Membrane: These are made from asphalt with a mixture of sticky organic liquid which is a great choice for a low-sloped concrete roof.
- Polyurethane Membrane: These come with a fiber-enhanced liquid-based component that has been designed for a large range of applications, where it can be covered over tiles, concrete, screeds, etc.
- Thermoplastic Membrane: These membranes are a blend of polypropylene and ethylene-propylene, and often reinforced with polyester. These sheets can contain UV absorbers, colorants, flame retardants or other additives to achieve required physical properties.
- Polymer-modified Bitumen Membrane: These are polymer-bitumen roll-fed sheet membranes which could be used as an underlay for pitched roofs, or as a vapor barrier. These can withstand temperature fluctuations, providing flow resistance that helps in a very hot climate, and high mechanical loads.
Factors to Consider While Choose a Waterproofing Membrane
Some important properties to consider while choosing a waterproofing membrane are as follows –
- Surface: The type of membrane should be compatible with the surface that it is to be applied to in order to avoid damage. For example, urethane can cause re-emulsification over acrylic elastomeric.
- Resistance to heat and sunlight: The membrane material should be UV resistant or UV stable if applied over roof or open surface that is exposed to the sun in order to preserve its strength.
- Elongation: The material should have the ability to stretch to accommodate movements. It is a must for high-rise building, or buildings made with steel.
- Breathability: In order to prevent water from penetrating into the structure, waterproofing membranes may trap water into its surface. Hence, some membranes are designed to be breathable, allowing trapped water to evaporate.
- Resistance to tear and abrasion: This is an important property. It should be able to withstand wear and tear as it has the ability to elongate and gets exposed to extreme climatic conditions. A membrane with low abrasion resistance may get damaged in such conditions, which can cause water to leak through.
- Chemical stability: The membrane needs to be chemically inert with respect to the environment of the structure it is been laid upon. If it isn’t inert, it can break down.
- Geometry: The membrane needs to have the flexibility to fit overall shapes. Upon complicated shapes such as the junction of a column and beam, it is preferable to use liquid applied membrane as a sheet based membrane could wrinkle or crease and leave gaps.
Today, waterproofing structures has been a necessary requirement. It also brings a significant environmental cleanliness solution for not having to throw tons of scrapped roofing materials every year into the landfills.
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