Facade impregnation: how it works, benefits, drawbacks and costs

What is facade impregnation?

Facade impregnation involves applying a water-repellent treatment to masonry. The product penetrates the pores of the substrate and reduces the absorption of liquid water, such as wind-driven rain.

A suitable treatment does not simply form a completely closed layer over the facade. The aim is to make it harder for rainwater to enter while still allowing moisture to move out as water vapour.

Impregnation is therefore also called hydrophobic treatment.

It is important not to see it as a solution to every damp problem. Moisture can also result from leaks, rising damp, damaged pointing, condensation or construction defects. The cause must be established first.

What are the benefits of facade impregnation?

When both the facade and the selected product are suitable, impregnation can offer several benefits.

Less rainwater absorption

The main aim is to reduce the amount of rainwater that enters porous masonry from outside. Facades exposed to considerable wind-driven rain may particularly benefit.

Reduced moisture exposure in the masonry

When the outside absorbs less rainwater, the moisture load on bricks and joints can decrease. Under the right circumstances, this can help protect the facade.

Dirt may penetrate less easily

Depending on the product and substrate, a treated facade may absorb less water and certain forms of dirt less readily.

Impregnation does not replace good maintenance, however. Damaged bricks, poor pointing and other construction problems must be repaired first.

What are the drawbacks of facade impregnation?

Impregnation is not automatically the best solution for every exterior wall.

Not every facade is suitable

Performance depends strongly on the substrate. Brick type, porosity, pointing and any previous treatments all matter.

The properties of reclaimed masonry bricks can also vary considerably by batch and building period. A treatment that works well on one facade is not automatically suitable for another historical facade.

The facade must first be in good condition

Cracks, damaged pointing and other defects must be addressed before treatment. Otherwise, the underlying problem remains unresolved.

An incorrect treatment can cause problems

Using the wrong product or inadequately preparing the facade can produce disappointing results. Extra caution is therefore important with historical facades.

The treatment is not permanent

An impregnated facade does not remain water-repellent indefinitely. The effective lifespan varies with the product, substrate, weather exposure and quality of application.

Can an old facade be impregnated?

It can in some circumstances, but assess the construction and materials first.

Historical bricks and old pointing mortars can have different properties from modern masonry. Damp in an old building can also have various causes. Simply making the outside water-repellent is not always the right solution.

Check, among other things:

• The condition and porosity of the bricks.
• The condition of the pointing.
• Cracks and damage.
• Possible sources of moisture.
• Any previous coatings or treatments.
• Which impregnating product is suitable for the substrate.

If in doubt, ask a specialist familiar with historical facades to assess whether impregnation is advisable.

Does the facade need cleaning first?

Before impregnation, a facade must be clean, sufficiently dry and in good condition. Dirt, algae, loose material or other contamination can prevent even absorption of the treatment.

The suitable cleaning method depends on the facade.

Caution is particularly important with old bricks. An overly aggressive method can damage the brick surface or pointing. Pressure washing, sandblasting or other intensive methods should not be used without assessing the material first.

With historical facades, test a small, inconspicuous area to see how the bricks and joints respond.

How is a facade impregnated?

The exact method varies by product and substrate, but broadly follows these steps:

1. Inspect the facade. Check the bricks, pointing, cracks and possible damp problems.
2. Repair where necessary. Deal with damaged bricks, joints and other defects first.
3. Clean. Remove contamination using a method suitable for the particular facade.
4. Allow to dry. The substrate must meet the requirements of the selected product.
5. Apply the impregnating treatment. Apply it evenly according to the manufacturer’s instructions.
6. Allow absorption and drying. Give the facade enough time to absorb the treatment and for it to cure.

Always follow the technical instructions for the product used.

What does facade impregnation cost?

Costs vary considerably by situation. Facade area, accessibility, masonry condition, necessary cleaning and repairs, and the selected treatment all affect the total price.

Impregnation alone is generally considerably cheaper than a complete treatment that first requires cleaning, repointing or local repairs.

Preferably request a price based on the actual facade instead of relying solely on a general price per square metre.

Can you impregnate a facade yourself?

It is technically possible, but good preparation matters. Assessing the substrate is particularly often underestimated.

Anyone doing the work themselves must first check suitability, repair defects and select the right product for the bricks and joints.

Weather conditions matter too. Application during rain, frost or conditions outside the product’s specifications can affect its performance.

For a valuable old or heritage facade, professional advice is sensible. An incorrect cleaning or treatment method can be difficult, or even impossible, to reverse completely.

Reclaimed bricks and facade maintenance

Old masonry bricks can be decades or centuries old and differ substantially in size, hardness, porosity and texture. That is precisely why no treatment is automatically suitable for every historical facade.

Do you want to clean, repair or impregnate an existing old facade? First assess the bricks, pointing and the cause of any problems.

If instead you are looking for authentic reclaimed bricks for restoration, renovation or a new build, Van Dillen Antieke Bouwmaterialen has a large, changing selection of old masonry bricks from demolished and existing buildings.