HYDROPHOBIC TREATMENT

Façade waterproofing with a water-repellent treatment

Façade waterproofing, also known as façade impregnation or a water-repellent treatment, reduces the amount of rainwater absorbed by a suitable porous exterior wall. The treatment penetrates the mineral surface instead of covering the façade with a visible layer of paint.

Before treatment, Nu-Isoleren checks the façade, mortar joints, cracks, contamination and possible moisture problems to determine whether the exterior wall is suitable for impregnation.

What is a water-repellent façade treatment?

A water-repellent façade treatment is a penetrating impregnation for suitable exterior walls and masonry. The product penetrates the pores of a mineral surface and reduces the capillary absorption of rainwater.

Unlike a thick waterproof coating or paint, the treatment does not create a visibly sealed layer over the façade. Its main purpose is to reduce the absorption of liquid water caused by wind-driven rain while preserving the existing appearance of the wall.

Which exterior walls can be waterproofed or impregnated?

Façade impregnation is primarily suitable for porous mineral surfaces, including certain brick façades and masonry walls that absorb rainwater.

The wall must be sufficiently absorbent, stable, clean and technically sound. Cracks, damaged mortar joints, frost damage, active leaks or incompatible existing coatings should first be assessed and repaired where necessary.

We therefore inspect the exterior wall before deciding whether a water-repellent treatment is technically appropriate.

Benefits of façade impregnation

A correctly applied treatment can reduce rainwater absorption while maintaining vapour permeability.

A hydrophobically treated façade absorbs less rainwater and can dry more quickly after wet weather. This helps reduce weather exposure and moisture-related soiling. It does not replace repairs to defective pointing, cracks or other building defects.

Reduced rainwater absorption
Vapour-open performance maintained
Lower moisture load
Useful after professional façade cleaning

Protecting an exterior wall against wind-driven rain

When people search for exterior wall waterproofing, the goal is often to prevent the wall from absorbing large amounts of rainwater.

A penetrating water-repellent treatment does not make the wall completely sealed or hermetic. Instead, it penetrates a suitable porous surface and reduces the amount of liquid rainwater absorbed by brickwork, mortar joints and other mineral materials.

This provides additional protection against weather exposure while largely retaining the original appearance of the façade.

Why clean a façade before waterproofing?

The façade should be clean and sufficiently dry before a water-repellent treatment is applied.

Moss, algae, atmospheric deposits, dust and other contamination can prevent the impregnation product from penetrating the surface evenly. Where necessary, we therefore carry out professional façade cleaning first.

Cleaning also makes it easier to identify damaged joints, cracks and other defects that should be repaired before treatment.

Learn about façade cleaning

Does façade waterproofing help with damp walls?

A water-repellent treatment can help when a suitable exterior wall absorbs moisture from wind-driven rain.

It does not treat rising damp, where moisture travels upward from the ground through the wall. Rising damp requires a different treatment.

Condensation, plumbing leaks and structural defects also have different causes. The source of the moisture should therefore be identified before a façade treatment is selected.

How is a façade waterproofing treatment applied?

Correct preparation is essential.

After inspection and any required cleaning, the impregnation is applied evenly until the substrate is sufficiently saturated. Windows, doors and surfaces that must not be treated are protected. Once cured, the appearance of the façade remains largely unchanged.

Inspect the façade

We assess the wall material, mortar joints, cracks, contamination, absorbency and possible moisture problems.

Clean and repair

Where required, the façade is cleaned and defects are repaired before treatment.

Allow the surface to dry

The exterior wall must be sufficiently dry for the impregnation product to penetrate correctly.

Apply the water-repellent treatment

The product is applied evenly to the suitable surface. Windows, doors and other areas that should not be treated are protected.

How much does façade waterproofing cost?

The cost of façade waterproofing depends on the condition and characteristics of the property, so there is no single fixed price per square metre for every façade.

The price depends on factors such as:

total façade area
accessibility
type and absorbency of the surface
level of contamination
condition of the mortar joints
whether façade cleaning is required first
any repairs required before treatment

A clean, accessible façade in good condition requires less preparation than a heavily contaminated or damaged exterior wall.

After inspecting the façade, we can provide an accurate quotation for the complete treatment.

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Façade waterproofing in practice

Explore façade projects completed by Nu-Isoleren and see how we clean, repair and, where technically suitable, protect exterior walls with a penetrating water-repellent treatment.

Frequently asked questions

Answers about hydrofuge, façade impregnation, moisture, preparation and pricing.

What does a water-repellent treatment do to my facade?

A penetrating water-repellent treatment makes a suitable porous facade less absorbent to rainwater. The impregnation product penetrates the mineral surface and reduces the amount of wind-driven rain absorbed by the masonry.

Unlike a thick waterproof coating or paint, facade impregnation does not cover the wall with a visible sealed layer.

Nu-Isoleren.be uses facade waterproofing to protect suitable exterior walls against moisture coming from outside. It does not repair cracks, damaged mortar joints, leaks or rising damp.

When should an exterior wall be waterproofed or impregnated?

Facade impregnation can be useful when a porous exterior wall absorbs significant amounts of wind-driven rain while the masonry itself remains technically sound.

A wall that stays wet for a long time after rainfall or visibly absorbs water may benefit from a penetrating water-repellent treatment.

Nu-Isoleren.be first checks whether the moisture is actually caused by rainwater rather than damaged joints, cracks, leaks or rising damp. The treatment should always match the actual cause of the moisture problem.

How is a facade waterproofing treatment applied?

Nu-Isoleren.be first inspects the facade material, mortar joints, cracks, contamination, moisture problems and surface absorbency.

Where necessary, the exterior wall is cleaned and repaired first. The surface must then be sufficiently dry.

The penetrating facade waterproofing treatment is applied evenly so that the product can enter the porous mineral surface. Windows, doors and other areas that should not be treated are protected during application.

How often does a facade need to be re-impregnated?

There is no single fixed interval for every facade. The service life of a water-repellent treatment depends on the product, the porosity of the masonry, exposure to wind and rain and the general condition of the exterior wall.

A facade therefore does not automatically need another treatment after a specific number of years.

If the wall begins absorbing noticeably more rainwater again, Nu-Isoleren.be can assess the facade and determine whether a new treatment is appropriate.

Does facade waterproofing help with damp walls?

Facade waterproofing can help when dampness is caused by wind-driven rain being absorbed through a suitable porous exterior wall.

It does not treat rising damp, where ground moisture moves upward through the masonry by capillary action.

Condensation and leaks also require different solutions. Nu-Isoleren.be therefore identifies the likely source of the moisture before recommending facade impregnation or another treatment.

How much does facade waterproofing cost?

The cost of facade waterproofing depends on the surface area, accessibility, wall material and condition of the facade. There is therefore no single fixed price per square metre that applies to every property.

The price can be influenced by:

total facade area;
accessibility;
surface type and absorbency;
level of contamination;
condition of mortar joints;
facade cleaning requirements;
repairs required before treatment;
scaffolding where necessary.

After inspecting the exterior wall, Nu-Isoleren.be can provide a quotation based on the work actually required.

What are the disadvantages of facade waterproofing?

Problems mainly arise when a water-repellent treatment is applied to an unsuitable wall or without proper preparation.

Facade waterproofing does not repair cracks, damaged mortar joints, leaks or rising damp. Certain wall materials and existing coatings may also be unsuitable for penetrating impregnation.

Nu-Isoleren.be therefore assesses the exterior wall first. If cleaning, repointing or other repairs are required, these should be completed before the water-repellent treatment is applied.

Can a brick facade be waterproofed or impregnated?

Yes. Many porous brick facades can be treated with a penetrating water repellent, provided that the bricks and mortar joints are technically suitable and sufficiently absorbent.

The exterior wall should also be clean, stable and sufficiently dry. Cracks and damaged mortar joints should be repaired beforehand.

Because different bricks and finishes absorb water differently, Nu-Isoleren.be assesses the surface before carrying out brick facade impregnation.

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