Sandblasting an old facade: is it a good idea?

Can you sandblast an old facade?

An old facade can be blasted in certain situations, but historical masonry requires caution. The force used, abrasive medium, distance from the facade and, above all, brick type determine how much the treatment affects the surface.

The aim should not be to make an old facade look completely new as quickly as possible. An overly aggressive treatment can damage the original fired surface, colour nuances and texture that give the brickwork its character.

What happens when a facade is blasted?

Blasting propels an abrasive medium against the masonry with air to remove dirt or surface layers. Depending on the technique, the treatment can be relatively gentle or very intensive.

The term ‘sandblasting’ alone therefore says little about how heavily the facade will be treated. With old bricks, the combination of abrasive, pressure, working distance, technique and experience is what matters.

Why are old facades blasted?

Over decades, a facade can acquire atmospheric deposits, soot, paint, lime or cement traces and other contamination. Sometimes these are removed to reveal the original masonry more clearly.

Newly built facades using reclaimed bricks may also deliberately retain lime and cement traces or other signs of use. Many people value that weathered appearance. Where a cleaner look is wanted, a suitable cleaning method can be considered.

The risk: damaging the fired surface

The outside of a brick can have a different structure from the material beneath it. Removing too much of this outer layer changes not only the appearance but can also leave the surface rougher and more open.

This can become visible more quickly with some reclaimed handmade bricks than with harder batches. However, moulded bricks also vary considerably by production period and batch. The production method alone is not enough to determine how much treatment a brick can withstand.

A test area in an inconspicuous place is therefore one of the most important steps before treating an entire facade.

Sandblasting, fine abrasive blasting or another cleaning method?

Not all contamination requires intensive blasting. Sometimes a gentler treatment is enough. The suitable method depends on the material and what actually needs to be removed.

Fine abrasive blasting, known in Dutch as luchtgommen, can be applied relatively gently and with greater control, but correct settings still matter. Stubborn layers may require a more intensive treatment.

Our comparison of cleaning old bricks: fine abrasive blasting or sandblasting explores the differences in more detail.

Can an old facade be cleaned with a pressure washer?

Excessive pressure can also cause damage when cleaning with water. Old joints may come loose and vulnerable brick surfaces can be harmed. Pressure washing is therefore not automatically a safe preliminary step before blasting.

Water cleaning can be part of the solution for light dirt, but pressure, temperature, distance and masonry condition all need consideration. Always start as gently as possible with historical material.

Must a facade be impregnated after sandblasting?

Not as a standard rule. In some situations, impregnation after cleaning may be appropriate, but it is not automatically necessary for every blasted facade.

First assess the condition and porosity of the brick, the pointing, moisture exposure and how much cleaning has changed the surface. Existing damp problems must also be addressed at their source.

For this assessment, read our detailed explanation of facade impregnation.

Cleaning old facing bricks for reuse

Loose reclaimed bricks are different from an existing masonry facade. For reuse, bricks usually do not need to be made completely uniform or spotless. Lime traces, colour differences and signs of use may be part of the desired appearance.

The main requirement is to remove old mortar from the relevant faces where necessary so the bricks can be laid again. This is often done by carefully chipping away the mortar. Read more about having reclaimed bricks cleaned of mortar.

Intensively blasting the visible surface is therefore often unnecessary. The more original surface retained, the more historical character remains visible in the batch.

What does sandblasting an old facade cost?

Costs vary by project. Area, accessibility, contamination type, cleaning method, pointing condition and required labour all play a role.

A price per square metre means little without first assessing the facade. With historical masonry especially, a cheap, highly aggressive treatment is not a saving if it damages bricks or joints.

Sandblasting an old facade yourself?

We advise considerable caution about blasting a complete old facade yourself without experience of historical masonry. The difference between sufficient cleaning and permanent damage can be small.

Blasting also involves dust, flying abrasive and other safety risks. Necessary protective measures and any rules concerning abrasives and dust control depend on the technique and situation.

Anyone considering treatment should first have a sample area prepared and assess the result before the entire facade is treated.

Common mistakes when sandblasting old facades

Trying to remove too much material

An old facade does not need to be completely uniform in colour. Lime traces, subtle variations and light signs of use can be part of its historical appearance.

Treating the whole facade immediately

Without a test area, you do not know how the bricks and joints will respond. Test a small section first and assess it again once the surface is fully dry.

Treating every old brick in the same way

Hardness and surface vary between batches. Even bricks that look very similar in colour and size can react differently to the same treatment.

Automatically following with impregnation

Impregnation can be useful, but it should be a considered choice based on the facade construction and its condition after cleaning.

What counts as a successful result for an old facade?

Successful cleaning of historical masonry does not necessarily mean every brick has exactly the same colour. The aim is to reduce contamination sufficiently without unnecessarily removing original material.

With reclaimed facing bricks, differences in colour, lime traces and texture can create the desired character. Browse our projects using reclaimed building materials to see how this natural variation works across complete facades.

Advice on reclaimed facing bricks

Whether working on an existing old facade or building one with reclaimed bricks, decide on the desired appearance before cleaning or laying. Sometimes very little cleaning is needed; in other situations, a controlled treatment is more appropriate.

Van Dillen Antieke Bouwmaterialen offers a large, changing range of reclaimed masonry bricks for restoration, renovation and new builds. Considering both the batch and the intended facade beforehand helps avoid unnecessarily removing valuable historical features.