The Invisible Shield: How Waterproofing Membranes Protect Structures from Within

What Is a Waterproofing Membrane?

A waterproofing membrane is essentially a thin layer of material that is laid or applied over a surface that needs protection from water leakage or seepage. This waterproof membrane is continuous and stops water to pass through it.

To give you an example, a flat roof will usually have a waterproof membrane laid or applied above the concrete or structural slab and below the flooring. This is to ensure that water is stopped to pass through into the base of the roofing.

The tiles as well as the membrane are usually laid over a filler matter. This material is angled to ensure that water flows towards the drains. Any water that is stagnant as puddles may likely to seep through the slab, so puddles are risky and are to be taken care of at all costs.

Normally, any waterproofing membrane has to be strong while being flexible, should be tear-resistant as well as elastic in nature. Elasticity allows it to cover any cracks as well as allows it to move and size as per the building structure.

In case the membrane has to be exposed to the sunlight, you should choose a waterproof membrane that is UV resistant. The idea is to choose a membrane that can be stretched and shaped to lay over any type of construction structure.

There are two types of membranes that are widely available, let us understand them at length

1. Sheet based:

This sheet goes by its name, these membranes are rolled in form, when they are ready to be laid down, these are unfurled on a solid surface. The most widely available form of this waterproof membrane is bituminous.

This membrane is fixed to the subsurface using hot tar heated using a blowtorch, this hot tar acts as a form of adhesive.

If in case the membrane falls short, additional membranes are added using the same process of hot adhesive. These sheets are normally overlapped by 100 millimeters that form a watertight joint. There is another way of joining these membranes that is by using hot air.

These membrane joints must be sealed perfectly to avoid problems in the future.

The other sheet based membranes include PVC as well as composite membranes. The latter has a fabric base that ensures durability and tear-resistance; a special chemical is used to provide water resistance.

These membranes are mass-produced in factories and hence the quality of these products is usually consistent.

2. Liquid Applied:

This type of waterproof membrane comes to the construction site in form of liquid; this is normally sprayed or applied using a brush or roller. The liquid absorbs air and cools down to become a uniform, joint-free waterproof membrane.

The amount of thickness you want for this type of membrane is ascertained by the number of layers of this chemical per square foot. Since the process to apply this membrane is quite fast, you should finish the area you want waterproofing for, in a day.

This will ensure there are no gaps or “cold joints”. If the area is large and cannot be completed in a single day, it is ok to complete it the next day, cold membranes can be taken care of by overlapping a new layer over it.

In today’s construction landscape, where durability, safety, and sustainability are non-negotiable, waterproofing membranes are no longer optional — they are essential. These invisible barriers work tirelessly behind the scenes, protecting your investment from the constant threat of water intrusion and structural decay.

CONCLUSION

At Costarchem, we don’t just provide waterproofing solutions — we engineer them with precision, innovation, and performance in mind. Whether you’re safeguarding a basement, roofing a high-rise, or sealing a swimming pool, our range of advanced waterproofing membranes delivers lasting protection and peace of mind.

Because when it comes to building, it’s not just about what you see — it’s about what you protect.