Polyurethane (PU) Waterproofing
Waterproofing with polyurethane (PU) — tough, highly flexible, and very elastic, forming a seamless waterproof film that withstands foot traffic and loads. Ideal for rooftops, balconies, bathrooms, and areas in constant contact with water.
- Highly flexible and very elastic
- Seamless waterproof film
- Withstands loads and foot traffic
- Resists chemicals and UV
What is PU waterproofing?
Polyurethane Waterproofing means waterproofing with a tough, highly flexible polyurethane material. Once applied, it forms a continuous, seamless waterproof film that stretches with structural movement, so it resists cracking.
PU outperforms acrylic waterproofing in toughness, load-bearing, and resistance to constant water contact, making it ideal for areas with foot traffic or standing water — such as walkable rooftops, balconies, bathrooms, and water tanks.
Key properties
Highly flexible
Highly elastic — accommodates structural movement and reduces cracking and leaks
Seamless
Forms one continuous film with no seams for water to penetrate
Load-bearing
Tough enough for foot traffic and movement — ideal for walkable rooftops
Chemical / UV resistant
Withstands weather, UV, and chemicals well, for a long service life
How a PU waterproofing system is built up, layer by layer
Waterproofing that lasts does not come from a single coat of liquid. It comes from laying the full system, layer by layer — skipping any one step is usually what brings the leak back.
Primer
A primer seals the pores in the concrete and improves adhesion. This layer decides how long the waterproofing film stays bonded.
Reinforcing the vulnerable points
Tape or synthetic fabric is added at corners, joints and around pipes — the points that leak most often in waterproofing work.
PU waterproofing layer (base coat)
Polyurethane is applied to the number of coats and the thickness set in the specification, forming one continuous, seamless film across the whole area.
Top coat
Adds UV resistance and durability underfoot; a non-slip formulation can be chosen for areas that are walked on often.
How the DMH team works
Our crews follow this order on every job, because waterproofing that lasts starts with finding the cause and dealing with the details, not with coating over what is already there.
01 Survey and locate the leak
We check cracks, ponding spots, pipe surrounds and wall edges to find the real cause of the leak before any work begins.
02 Prepare the surface and repair cracks
Cleaning, grinding, filling cracks and voids, and correcting the fall so all water drains away.
03 Apply the primer
A primer coat improves adhesion and seals the concrete before the waterproofing system goes on.
04 Apply the PU waterproofing system
Polyurethane is applied to the number of coats and the thickness set in the specification.
05 Detail the corners, pipe surrounds and edges
Tape or reinforcing fabric is added at the vulnerable points, where leaks most often start.
06 Flood test and hand over
A 24–48 hour flood test confirms there is no seepage, then the job is handed over with care instructions.
Read more: Roof waterproofing systems: what the options are and how to match them to the job
Suitable applications
- Rooftops / walkable concrete roofs
- Balconies and outdoor floors
- Bathrooms and wet areas
- Ponds, water tanks, and submerged areas
What to know and how to maintain it
PU waterproofing outperforms acrylic in several respects, but there are conditions worth knowing before you decide — and maintenance that can add years to the system.
It needs a dry surface
Too much moisture in the concrete makes the film blister and peel; the slab has to dry and be moisture-tested before the system goes on.
The fall matters more than people think
Standing water is the real enemy of waterproofing; a roof without enough fall ages the system faster than it should.
It costs more than acrylic
In exchange you get toughness, load capacity and a longer service life, which pays off on areas that are actually used.
Inspect once a year
Look for cracks and blisters and keep the drains clear, so problems are caught while they are still easy to repair.
Clean it as you normally would
Water and ordinary cleaning products are fine; avoid scraping with sharp objects.
It can be spot-repaired
If a crack or damaged film appears, that spot can be repaired straight away without stripping the whole area.
Frequently asked questions
How does PU waterproofing differ from acrylic?
Can you walk on a PU-waterproofed surface?
Is there a warranty?
Have a leak problem? Interested in PU waterproofing?
Free on-site survey and quote nationwide — by the professional team at DMH Groups