Weather Proofer

Weather proofer is a coating put on soft top roofs to help protect them against moisture, oxidation and mould.

This is sometimes called water proofing, however, while the coating repels water, it doesn't make the roof waterproof, it is the membrane and rubbers that keep the water out of the car.

Making the fabric repel water just means that it stays dry. You can tell when the weatherproofing has worn off of your car because after it rains, your hood will be soggy.  A wet hood is an invitation to mould, fungus, algae and lichen to grow.

Most weather proofers will contain a mould inhibitor to help prevent this, and because they coat your fabric, also act as a sacrificial layer which prevents UV light causing oxidation. 

What it means

Weather proofer is a protective product used on fabric convertible roofs to help them shrug off water and dirt. On mohair and similar fabrics it normally soaks into the outer layer and leaves a hydrophobic finish so rain beads and runs off instead of soaking straight in. Some products are more like a penetrating waterproofer, others behave more like a modern coating, but the basic aim is the same – to improve water repellency and keep the roof cleaner for longer.

Why it matters

• Helps keep the roof dry on the surface: A properly proofed roof beads water nicely. This reduces the time the surface stays wet and makes it less inviting for algae, moss and grime.
• Makes cleaning easier: Proofed roofs tend not to hold on to dirt as stubbornly, so regular maintenance washes are more effective and less aggressive.
• Supports the membrane, it does not replace it: On modern multi-layer roofs, the hidden membrane is what actually keeps water out of the cabin. Weather proofer helps the outer fabric shed water, but it is not a cure for split membranes, bad stitching or leaks.
• Extends cosmetic life: By reducing how often the roof is soaked and filthy, good proofing can slow down surface wear, fading and the onset of heavy roof green.

Where you’ll see it

You will see weather proofer mentioned in soft top restoration packages, detailing menus and retail products aimed at cabriolet owners. Typical phrases include roof cleaned and weather proofed, fabric roof requires clean and reproof or do not use polish, use roof proofer. It is mainly used on mohair and other fabric roofs rather than vinyl, which are usually treated with dressings rather than absorbed proofers.

Context

Weather proofer is one part of looking after a soft top, alongside cleaning, occasional dyeing and general leak prevention. The usual sequence is: deep clean to remove grit, algae and contamination; allow the roof to dry fully; then apply weather proofer in thin, even coats so it can bond or soak in correctly. On many cars the underlying membrane and seams are already doing the heavy lifting for waterproofing, so proofing is primarily about surface behaviour and ease of maintenance. It will not cure leaks caused by failed membranes, damaged stitching, blocked drains or perished seals, but it will help a sound roof stay presentable and easier to live with.

Common mistakes

• Applying weather proofer to a dirty or only half-clean roof, which seals in contamination and wastes product.
• Expecting proofing alone to fix leaks caused by failed membranes, seams, drains or seals, when those need proper diagnosis and repair.
• Flooding the roof with very heavy coats, causing runs, patchiness or a stiff feel instead of building up protection in controlled layers.
• Assuming a roof that no longer beads is simply “old”, when in many cases it just needs a thorough clean and fresh proofing to perform properly again.

Written by Danny Argent. Last updated 04/12/2025 03:30