Having water ingress, leaks an mould can quickly escalate into a disaster. Major cost implications can arise if water is not managed and mitigated effectively.
The problem however is that building membranes can be a confusing area of building construction, especially as the names are often abbreviated and can be easily mixed up if you are not careful.
However, they are such a crucial part of a design that can prevent very costly damages to the building from within the walls, floors and ceilings. So, it’s important we get this right.
Waterproofing, air tightness and breathability are important factors that control the amount of moisture vapour within the building fabric. Temperatures vary quite considerably between outside and inside of the building, causing condensation leading to mould and other costly issues.
In this blog we will outline the various types of waterproofing membranes to help keep you informed, so that your buildings can stand the test of time.
Waterproof Sheet Membranes
When it comes to keeping water out of a building, waterproof sheet membranes are one of the most trusted solutions. These membranes come in large rolls and are applied as continuous sheets, forming a tough barrier that blocks moisture before it can seep in. Since they’re pre-made in controlled conditions, you can count on consistent quality and reliable performance every time.
Popular options include HDPE, EPDM, TPO, and PVC—each offering unique benefits like flexibility, durability, or resistance to chemicals and UV rays. You’ll often see sheet membranes protecting foundations, basements, and roofs—places where long-lasting waterproofing matters most.
While professional installation is usually recommended to avoid problems at seams, their proven track record makes them a top choice for builders and developers who want dependable, long-term moisture protection.
Damp Proof Membranes (DPM)
What is it: Typically, DMPs are made from high-density polyethylene (HDPE) due to its strength and full water repellent qualities. DPMs can also be made from Bitumen and Aluminium, however for the purposes of keeping things simple we will look deeper into HDPE.
When to use it: Because HDPE damp proof membranes are so flexible and reliable as a material, they are often used to protect the structure from water ingress. They are typically found at foundation level, substructure, above lintels, and even DPC trays, so they are used in many different situations throughout the build.
- High effective resistance to moisture.
- Long lasting, 50+ years.
- Resistant to many chemicals and also can be used as a RADON barrier.
- Cost effective.
- UV sensitive.
- Flammable if not properly managed.
- Susceptible to stress cracks.
- Sensitive to extreme temperature ranges.
EPDM Membranes (Single Ply)
Ethylene propylene diene monomer (EPDM) is a type of rubber that is adhered to the substrate of the roof. It is highly resistant to UV radiation, and extreme temperature which makes it any ideal choice for flat roofs.
- Durability and longevity with a 25-50 year lifespan.
- Minimal upkeep and low maintenance.
- Affordable. Between £45-110 per square meter in 2024.
- Quick and easy installation.
- Sustainability and made from recycled materials.
- Excellent waterproofing with fewer seams on larger sheets.
- Easily repairable.
- Industrial plain look.
- Vulnerable to punctures if debris or foot traffic is a risk.
- Old EPDM is vulnerable to shrinkage and leaks.
- Improper installation of seams can cause leakages.
- Not compatible with petroleum products which can damage EPDM.
- Some are fire resistant but not fire-proof.
TPO - Thermoplastic Membrane (Single Ply)
Thermoplastic polyolefin (TPO) is a type of thermoplastic elastomer (TPE), which is a blend of polypropylene (PP) or polyethylene with rubber that often includes fillers such as talc or fibreglass. It is an especially durable and flexible material that can withstand harsh weather conditions and even chemical exposure.
TPO is usually applied by either manual full-adhering or self-adhering with easy installation using a release liner to the substrate, or by using mechanical fixings such as screws and plates.
- Very cost effective. £3-10 per square metre in 2024.
- UV resistant, and resistant to punctures and tears making this a highly robust material.
- Highly recyclable and generally free from harmful chemicals.
- Lightweight and easy to install leading to faster installations.
- White colour reflects UV rays making it more energy efficient.
- Improper installation of seams can cause potential weak points, especially when exposed to extreme weather fluctuations.
- Sensitive to high temperature fluctuations.
- Slippery when wet, poses a hazard during installation.
- Ponding can be an issue and is often excluded from warranties.
- Product quality can vary from supplier to supplier.
PVC - Thermoplastic Membrane (Single Ply)
Polyvinyl chloride (PVC) is another type of durable thermoplastic membrane that has been used for over 60 years as a roofing material, mainly due to effectiveness against water penetration and its resistance against UV radiation.
PVC membranes are typically installed in sheets and can be welded, adhered or mechanically fixed down to the substrate, making it a highly effective waterproofing membrane for flat roofs especially.
There are two types of PVC membranes, the standard PVC which is often reinforced with a polyester mesh, or there’s the Fleece-backed PVC membrane which has an additional layer of fleece material on the underside to feature better insulated properties and better adhesion to the substrate.
- Durability and longevity with a 20–30-year lifespan.
- Highly resistant to chemicals.
- Fire resistant, some have a Class A rating.
- Energy efficient, with a thermal conductivity of 0.14-0.17W/mK.
- Recyclable at the end of their lifespan.
- Mould and bacteria resistant.
- Watertight when properly sealed to prevent any leaks.
- More expensive than TPO or EPDM. £25-50 per square metre in 2024.
- Requires a clean flat surface to install and some contractors may find it more challenging to install.
- More difficult to repair, particularly if the type made by manufacture is no longer available.
- Can become brittle in colder climates, which may cause more repairs.
- When aged, PVC can shrink due to separation of plasticizers, which can lead to leaks.
- Higher carbon footprint than some other roofing materials.
Modified Bitumen (Permanent VCL)
Bitumen otherwise known as Asphalt is a naturally occurring by product of crude oil refining that has been used in man-made shelters for centuries, even ancient civilizations of Mesopotamia and Egypt were found to have used it for its inherent waterproofing qualities. It is waterproof, malleable and relatively cheap and is often used in road construction, roofing and other applications such as sealants, insulation and adhesives.
In the early 20th century, a French building materials trader invented a waterproofing sheet membrane named MAMMOUTH, which was produced by dripping bitumen onto a canvas. It wasn’t until the mid-1960s when modified bitumen was in use for built-up roofing in Europe.
Modified bitumen on the other hand has been enhanced by polymers such as SBS (styrene-butadiene-styrene: a rubber-like substance) or APP (atactic polypropylene: a plastic-like substance) to improve the qualities of the raw natural material.
Modified bitumen is usually torched down using a propane torch, this then melts the sheet so that it self-adheres to the base sheet underneath. The base sheet is usually mechanically fixed prior to torching.
- Waterproof and reliable permanent vapour barrier (VCL).
- Durability and longevity with a 15–20-year lifespan.
- Reinforcement layers of fibreglass or polyester create tear-resistance.
- Flexible and can adapt minor differential movements of the building structure.
- Very cost effective. Between £30-70 per square metre in the UK in 2024.
- Black colour absorbs a lot of heat which can increase cooling costs.
- Requires trained professionals and specialist equipment to install.
- Is susceptible to ponding if not installed correctly at the appropriate fall.
- Requires proper maintenance, especially in extreme temperature fluctuations can cause cracking and delamination of the membrane.
- Limited UV resistance, which makes this product less effective in hot climates.
Liquid-applied Waterproofing Membranes
Waterproofing membranes can also be applied in liquid form, which create a seamless application that can work itself into any crevices to provide a watertight seal. This is a very versatile solution that can adhere to various substrates and eliminates weak points of having seals and seams to worry about.
As previously mentioned, bitumen had been used for centuries, however the invention and application of more modern types of liquid membranes such as acrylic or emulsion systems date back to the late 20th century.
Acrylic Polymer Waterproofing Membranes
This cold applied liquid membrane is especially useful for areas of the building that have complex geometries, as it can form around various shapes whilst curing and hardening into solid membrane. As mentioned, before you will not have any seams or joints to worry about with acrylic membranes.
With the addition of some polymers, acrylic membranes can be improved to enhance weatherproof and UV protection, not to mention the good adhesion to various substrates.
- Easy application as it can be applied by anyone with basic training.
- Adheres well to various substrates.
- Highly reflective, contributing to a potential 15% energy saving per year for homeowners.
- Great UV resistance.
- Also, a breathable membrane which allows moisture to escape, 5,000 – 10,000g/m².
- Cost effective, at around £20-30 per square metre.
- Ponding is an issue; proper drainage falls are needed.
- Extreme weather fluctuation causes the lifespan to be reduced.
- Overtime coatings can become brittle.
- May need more frequent recoating.
- Can be damaged by certain solvents.
- Certain substrates it’s not ideal, like timber, GRP (glass reinforced plastic) or other rubber/plastics.
Epoxy Waterproofing Membranes
A coating of epoxy resin and a hardener can create a tough waterproof roof finish on concrete substrates. Concrete absorbs water, so this product is ideal for providing weather protection to prevent structural damage.
Epoxy resins became popular in the 1950s for industrial and commercial properties for their durability and versatility. They are chemical-resistant and can withstand heavy foot traffic, making it an appealing product for developments such as these.
- Extremely water resistant.
- Long lifespan of 10-20 years depending on application and maintenance.
- High chemical resistance.
- Seamless finish
- Versatility, as it can be applied to concrete, wood, metal and various other materials.
- Higher cost, potentially £25-35 per square meter in 2024.
- Not flexible, susceptible to cracks if there is differential movement.
- UV sensitive and can discolour overtime.
- Requires professional installation as it is difficult to mix and apply the correct technique for a good finish.
- Potential for trapped moisture which can lead to blistering or issues with adhesion.
Polyurethane Waterproofing Membranes
Polyurethane is a type of plastic polymer that is very versatile due to its flexibility and chemical compositional properties. It can be formulated into a rigid solid, or soft-flexible material, and even can be made into foams or adhesives.
Using polyurethane as a waterproofing membrane liquid-applied system was first developed in the 1960s, and they quickly gained popularity due to its ability to be adapted to challenging environments. They are particularly useful for large floor areas due to their quick and efficient application using spray machines.
Polyurethane liquid systems are durable, weather resistant and resistant to both chemical and UV radiation. They create a seamless waterproof protective layer that is free from any seams, a common characteristic of liquid applied systems.
- Flexible and durable, meaning they are a choice for areas with differential movement. Also great for high traffic areas as they resist tearing and cracking.
- Seamless application.
- Strong adhesion to various substrates such as concrete, metal, wood and others.
- Long lifespan, 10-20 years and more with correct maintenance.
- Resistant to chemicals and UV radiation.
- Extremely versatile material.
- Expensive, £40-50 per square metre in UK, including both materials and labour. 2024.
- Requires dry conditions for proper curing, as this membrane is sensitive to moisture.
- Required skilled professionals and specialized knowledge to install correctly.
- Toxic material, which may release volatile organic compounds (VOCs) during application, needs ventilation.
- May take 8-24 hours to fully cure, depending on temperature fluctuations.
- Not an eco-friendly option.
Cementitious Waterproofing Membranes
What is it: As the name suggests Cementitious Membranes are usually a Portland cement-based liquid-applied membrane that have been mixed like concrete with sand aggregates but have been enriched with polymers and additives to create a waterproof barrier in the form of a slurry. The polymers often used are in the form of a dispersible polymer powder (RPP) that enhances the adhesion, flexibility and waterproofing abilities of the mixture. The additives mentioned are usually a form of hydrophobic agents to repel water and also thickness to give the correct consistency.
A brief history: Ancient civilizations such as the Romans would use lime-based mortars enriched with volcanic ash to create durable and waterproof joints. Although the invention of Portland cement was in the 19th century, the development of cementitious waterproofing membranes came into application during the mid-20th century, in the form of hydrophobic concrete.
When to use: Cementitious membranes are often used in basement or foundation application to ensure the structural integrity of the concrete structures. This material is also used in reservoirs, water tanks and any cement based structure that has the potential for water damage.
- Relatively cheap, £15-45 per metre square supply only.
- Durable and can withstand significant wear and tear, including impact.
- Excellent adhesion to concrete and masonry.
- Easy application compared to other liquid applied systems.
- Chemically resistant.
- Versatile in types of applications, such as basements, swimming pools and swimming pools.
- Prone to cracking when differential movement occurs.
- Long curing time, 24-72 hours depending on temperature.
- Not very visually appealing.
- Improper mix can cause the membrane to be compromised.
- Is affected by prolonged UV exposure.
- Not suitable for all surfaces.
To Conclude...
Waterproofing membranes are far more than just a construction afterthought—they are an essential component of a building’s long-term durability and performance. From sheet membranes like HDPE, EPDM, TPO, and PVC, to liquid-applied systems such as acrylic, epoxy, polyurethane, and cementitious membranes, each option carries its own strengths and trade-offs. The right choice ultimately depends on factors like budget, climate, building design, and expected lifespan.
By carefully selecting and properly installing the appropriate membrane, developers can safeguard their projects against water ingress, mould, structural decay, and costly remedial work in the future. In short, investing in the right waterproofing solution at the design stage is not only a matter of best practice—it’s a vital step in ensuring that your building stands the test of time.
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