Roof Waterproofing and Torch-On

Water finds every weak spot, and good waterproofing stops leaks before they damage ceilings, walls and finishes. Flat concrete roofs, parapets, balconies, showers and damp walls all need the right system, properly applied. BuildingContractors.co.za doesn't do waterproofing. Tell us where the water is coming in and what the surface is, and we pass your request to independent waterproofing contractors in your area, who inspect and quote you directly. The request is free and you are under no obligation to accept a quote.

Roof waterproofing

Roof waterproofing is the most common job, especially on flat concrete roofs, parapet walls, box gutters and older sheeted roofs. Flat roofs need a continuous membrane with proper falls to outlets, so water never ponds. On sheeted roofs, contractors seal laps, screws and flashings, and sometimes coat the whole roof. Before any new layer goes on, the surface should be cleaned, loose material removed and cracks repaired. Highveld summer storms and Cape winter rain both test weak waterproofing quickly.

Torch-on waterproofing and other membranes

Torch on waterproofing: bitumen-based membrane rolls heated with a gas torch and bonded to the surface, ideal for flat concrete roofs and gutters. It is usually finished with a reflective coating to protect it from the sun.
Liquid membranes: acrylic or similar coatings brushed on in layers with a reinforcing fabric, useful on complex shapes and sheeted roofs.
Cementitious systems: for showers, basements, planters and water tanks.
Damp proofing: treating rising damp where the damp-proof course has failed.

A good contractor matches the waterproofing membrane to the surface, the traffic it will carry and the falls available.

Showers, balconies and damp walls

Wet areas inside need waterproofing under the tiles, especially walk-in showers and balconies over living space. This is easiest during building or renovations, before tiling. Damp walls have several possible causes: rising damp, leaking pipes, poor gutters or penetrating rain. Plumbing leaks need a registered plumber, so ask the contractor to identify the cause before quoting a fix. Painting over damp with a sealer seldom solves it, and the stains usually return within a season.

Guarantees and comparing quotes

Ask what system each contractor proposes, the area in m², how many layers, and how upstands, outlets and joints are treated. A written quote should state the guarantee period and what it covers, which often depends on regular maintenance. Check that preparation, crack repairs and rubble removal are included, and that the work will be done in dry weather. Book roof waterproofing well before the rainy season in your area, when contractors are less busy.

Comparing quotes for waterproofing

The lowest price is not always the best value. When your quotes arrive, check:

Scope: what is included item by item, and which materials the contractor supplies.
Payment: a deposit and payments in stages as work is completed, never most of it upfront.
Time: the start date, how long the work will take and what happens if it runs late.
Compliance and guarantee: approvals and certificates needed for the job, and the guarantee on workmanship.

What to include in your request

Where the leak or damp is, with photos inside and out
Surface type: flat concrete roof, sheeting, tiles, balcony or shower
Approximate area in m², and any previous waterproofing
Whether the area is walked on or used as a deck
Address, roof access and how urgent the work is

Frequently asked questions

Do you do waterproofing yourselves?

No. BuildingContractors.co.za is a free quote-request service. We pass your request to independent waterproofing contractors near you, who inspect the problem and quote you directly. There is no charge for the request and no obligation to accept any quote you receive.

How long does torch-on waterproofing last?

Properly installed torch-on on a well-prepared roof with good falls typically lasts many years, especially if the reflective coating is renewed every few years. Ponding water, foot traffic and poor detailing at parapets and outlets shorten its life. Ask each contractor what guarantee they offer.

Can I waterproof over old waterproofing?

Sometimes. If the old layer is well bonded and sound, a contractor may apply a compatible system over it. Blistered, loose or cracked membranes usually need to be removed first. The contractor should inspect and test the existing layer before recommending either option.

What causes damp on inside walls?

Common causes are rising damp from a failed or missing damp-proof course, leaking pipes, blocked gutters and downpipes, cracked plaster letting in driving rain, and condensation. Each needs a different fix, so ask a contractor to find the cause before quoting treatment or new paint.

Waterproofing for Roofs, Balconies, Walls and Wet Areas