Do water-repellent sealers help control biological growths?

January 12, 2024

Do water-repellent sealers help control biological growths?

Water repellent external sealers are sometimes used on stone, brick, roof tiles, and render in an attempt to increase the life of building materials. Brickwork and clay tiles for example, become porous after a few years, leading to the surface breaking up through the action of winter frost.

In our experience we've found no evidence that water repellent sealers inhibit the return of biological growths. In fact our experience of the products we've used is that they have no effect whatever.

Can sealers damage buildings?

Reducing the external porosity of a surface may lead to adverse effects on the inside of a building, including increasing damp. This advice particularly applies to older buildings, especially those built with lime wash and lime mortar, which are purposely designed to flex and "breathe".

Regardless of the construction or age of a building, our experience suggests the wisdom of never using a non-breathable sealant, i.e. one that does not allow the building to breathe.

Sealants of this quality are not cheap but the potential long-term damage to a building by using an inferior, non-breathable product could be considerably more expensive.

Quick tip: Our experience suggests that even the best sealants will benefit from a supplementary pre-treatment with Benz Bio Cleanze softwash biocide.

Without a biocide treatment, even if the surface is cleaned before sealing by pressure washing, it will return to its “dirty” – i.e. biologically colonised – state shockingly quickly.

Whereas a property treated with Bio Cleanze – after giving a first treatment of Benz Lightning Cleanze biocide to rapidly kill the surface growths and clean the surface – and then sealed can remain clean for several years.

We hope this information is helpful and sincerely wish you great success in your soft washing business,

Benz Team

Click here to get more practical soft washing how-to tips

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Click here to download our Product Documentation Pack (includes Application & Dilution guides, SDS, PDS, RAMS, PPE & Mask info, COSSH, sample Contract and more)

Order Benz Softwash chemicals & equipment online or by phone:

GB (England, Scotland, Wales)

Phone: 0800 70 74 222 


Ireland and other countries

Phone: 00353 214 622 978


Lines open Monday - Friday, 9am – 5pm

Please note: The above numbers are for orders only (click here for tech support)

PS: Click here to set up your "Clean & Maintain" programme
. After completing an initial soft wash treatment, put your customer on a "Clean & Maintain" ongoing maintenance programme. Your customers will enjoy a permanently clean property and you will enjoy a steady stream of repeat business.

This is clearly a win-win arrangement for you and your customers.


Click here to explore the extensive range of Benz softwash cleaning chemicals & equipment

Benz Softwash Bio Cleanze DDAC biocide & Benz Softwash Lightning Cleanze SH sodium hypochlorite biocide

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