Limestone cleaning & sealing tips

Limestone, with its timeless elegance, graces many exteriors, offering both beauty and durability. However, its porous nature makes it susceptible to staining and weathering over time. Proper cleaning and sealing techniques are paramount to preserving its allure. This Limestone cleaning and sealing tips guide delves into essential tips for effectively cleaning limestone surfaces and explores the best sealers tailored for exterior walling, ensuring lasting protection and maintaining the splendor of your limestone installations.

What is the best sealer for Limestone exterior walling?

When applying a penetrating sealer to Limestone exterior walling, you are first and foremost requiring water repellency. There are good options for this in both water and solvent-based options. The 4 best products for this application are:

1. Defender CSD 50 – Provides water repellency and surface consolidation (strengthening)
2. Defender Gold WB – Provides premium water repellency as well as a high degree of oil repellency
3. Defender SV – Water repellent and rising damp cure (solvent-based)
4. Defender WB – Water repellent. (water-based)

What coverage would I expect to get from a penetrating sealer on a Limestone exterior wall?

Limestone is typically very porous. However vertical surfaces tend to accept less sealer. Probably around 1Lt per 4m2 / application. To assess coverage, if the area to be treated is large, complete a trial of few square metres.

How many applications should I do of the sealer?

The standard amount of applications is two. However, please note that three applications may be required if the surface is highly porous.

How do I clean the surface of the stone before applying the sealer?

Best results will be achieved using Tile & Grout Power (dilute 1:60). Use Chlorosan for any mould or discoloured areas which remain. Rinse the surface very well after cleaning. Leave walls approximately 24 – 48 hours between cleaning and sealing.