Clear Water Repellent (Silane & Siloxane)
For Brick, Concrete and Facades: What It Does and Does Not Do (2026)

What a penetrating water repellent is

Most waterproofing products form a film or a membrane on top of the surface. A penetrating water repellent works differently: the liquid soaks into the pores of the material and lines them with a water-repelling layer. The surface looks almost the same, the pores stay open so water vapour can escape, but rain that lands on the wall beads up and runs off instead of soaking in.

Our DIY waterproofing guide describes the "nano waterproofing" sprays sold in shops as exactly this: penetrating water repellents, silane or siloxane-class chemistry that changes the surface so water beads instead of absorbing.

Silane, siloxane and blends

Water-based and solvent-based versions of each exist. The right product depends on the material, how porous it is and how the wall is exposed; the maker's data sheet should say which substrates it is for.

Where it works well

• Fair-faced brick walls and fences that you want to keep looking like brick.
• Exposed concrete on facades, columns, parapets and boundary walls.
• Natural stone and cultured stone cladding outdoors.
• Unpainted render or cement finishes that take driving rain.
• Walls with rain-splash staining near the ground, once any rising damp is dealt with.

The DIY guide lists repelling rain off a porous facade wall with a silane-class treatment as one of the jobs where DIY products genuinely work. Our exposed brick guide explains why bare brick is sealed with a clear, breathable sealer.

What it cannot do

The DIY guide is plain about the limits: these products do not form a film, bridge visible gaps or resist water under pressure, so they cannot fix slab seepage. In practice that means a repellent will not stop:

• Water running through a crack, a failed joint, or a gap around a window or aircon hole.
• Ponding on a flat roof, balcony or planter, where water sits instead of running off.
• A leak from a roof, a gutter, a bathroom above or a burst pipe.
• Rising damp from the ground, or water pushing through a basement or retaining wall.
• Rain getting in through a painted wall whose paint has failed; the paint is the problem there.

If water is coming through the wall, find where it enters first. ClickBina leak detection is a separate paid visit at RM300 – RM800.

What to fix before treating a wall

1. Repair cracks and failed mortar joints; a repellent does not fill them.
2. Re-seal gaps around windows, pipes and aircon holes with a proper sealant.
3. Fix gutters, downpipes and parapet flashings that dump water onto the wall.
4. Deal with rising damp and salts; white powder on a wall means water is moving through it.
5. Clean off moss, algae, dirt and loose material, and let the wall dry thoroughly.

White salts are a sign to slow down: our efflorescence guide explains why salts appear and why sealing over an active source traps the problem.

How it is applied

The application itself is simple; the conditions around it are what matter.

• Apply to a clean, dry wall in a dry spell, not straight after rain or before a storm.
• Flood-coat from the bottom up so the surface is saturated evenly, usually wet-on-wet if a second coat is needed.
• Follow the maker's coverage rate; too little leaves patches that still soak up water.
• Protect glass, window frames, plants and paintwork; some products mark glass.
• Test a small patch first to check the product does not darken or leave a sheen on your material.

How to tell if it is working

A treated wall should make water bead and run off. Spray a little water on it: if it darkens and soaks in, the treatment has worn off or missed that area. A simple check a few weeks after treatment, and again after each rainy season, tells you when to re-treat. Pay attention to the most exposed faces and the bottom of the wall, which wear first.

How long it lasts

Life depends on the product, how deep it penetrates and how exposed the wall is. The DIY guide gives a realistic lifespan for shop sprays of months, up to about 2 years on a sheltered surface. Professional products applied at the right rate on prepared walls usually last longer, but the maker's data sheet and a periodic water test are the honest guide, not the label on the can.

Repellent, coating or paint?

Painted and rendered walls are usually better served by a proper exterior repaint; our exterior repainting guide covers the system. Tall buildings with leaks into several units need a facade programme rather than a repellent alone.

What it costs

These are the related published figures on ClickBina guides (indicative 2026, Klang Valley). A professional repellent application is priced by area, access and preparation, so it is quoted.

Access often costs more than the product: ladders for a fence, scaffold or rope access for an upper storey. Ask for the product name, the coverage rate and the preparation to be written into the quote.

How ClickBina can help

Wall treatments are quoted case by case. WhatsApp us your job details for a quote: what the wall is made of, whether it is painted, roughly how big it is and how high, whether water is actually coming through, and whether there are cracks or white salts. We reply within the hour, the price we agree is a flat price with no hidden charges, and a site visit is RM150, waived if you go ahead.

Sources & methodology

• ClickBina DIY waterproofing guide — what silane/siloxane sprays do and cannot do, spray price and realistic lifespan.
• ClickBina building facade waterproofing guide — rooftop comparison price; facades priced per project.
• ClickBina exposed brick and efflorescence guides — breathable sealers and salts.
• ClickBina porch seepage guide — leak detection price; convenience store fit-out guide — site visit wording.

How we estimated prices: every RM figure and year figure on this page is quoted unchanged from the ClickBina guides named above. They are indicative Klang Valley market ranges for 2026, not fixed rates. Product chemistry is described generically; follow the maker's data sheet for any product.