Renovation Waterproofing Cape Town

Renovation waterproofing Cape Town deals with the hardest detail in the trade: the junction where new construction meets an existing building.

On a clean site everything can be sequenced properly. In a renovation the existing structure decides what is possible. New construction is under new build waterproofing, and systems under Waterproofing Cape Town.

Send the area involved and photos of the surface as it stands. That is usually enough to price it.

Get a Quote

The Junction Problem

New and old structures move independently. Whatever bridges them absorbs that movement, and if it is rigid it splits. Most extension leaks are at this junction rather than anywhere in the new roof.

It needs a proper flashing or a movement-tolerant detail, chased into the existing wall rather than sealed against its surface. Sealant smeared along the joint is a temporary measure, not a detail.

Common Renovation Situations

Situation	What needs attention
Flat-roofed extension to a pitched house	Abutment flashing at the wall junction, and falls on the new roof.
Enclosed patio or stoep	Frequently built to a lower standard than the house, then leaks at the junction.
Converted garage	No damp-proof membrane under the slab and no course in the walls, because it was a garage.
New bathroom in an old house	Under-tile membrane over a substrate that may move or hold moisture.
Second storey added	New loads on old walls, and a new roof meeting an existing one.
Opened-up wall or new opening	The damp-proof course interrupted, and rarely reinstated.

Renovation Waterproofing Cape Town Prices

Job	Indicative range	What moves it
Flashing replacement	R250 – R600 per linear metre	Material and detailing.
Torch-on membrane, single layer	R300 – R400 per m²	Flat and low-slope roofs.
Liquid-applied system	R140 – R400 per m²	Coat count and reinforcement.
Screed to correct falls	R250 – R600 per m²	Where water is ponding.
Wet area waterproofing	R4,500 – R12,000	Per bathroom or shower.
Crack repair	R150 – R450 per linear metre	Width, depth and reinforcement.
Tanking, negative side	R400 – R1,500 per m²	System and preparation.
Leak trace and inspection	R750 – R2,500	Area, access and testing time.
Surface preparation	R20 – R100 per m²	Cleaning, crack filling, priming.

These are indicative market ranges, not a quotation. They are compiled from published South African waterproofing and roofing pricing to give you a starting point for budgeting. They are not the rate card of any company on this platform.

Compare quotes on the system specified, the number of coats, what preparation is included and what the guarantee covers. A rate per square metre means nothing until you know what the rate covers.

Compare quotes on what is included, not on the total alone.

Request Quotes

Sequencing With Other Trades

Waterproof before finishes. Not after tiling, screeding or plastering.
Flood test before covering. One day now against lifting a floor later.
Agree penetrations upfront. So services are not drilled through a finished membrane.
Protect completed work. Boarding over membranes that other trades will walk on.
Fix existing defects first. Renovating around a live leak simply hides it behind new finishes.

Related Services

Waterproofing Cape TownSystems, methods and full service list.New Build Waterproofing Cape TownNew construction.Roof Flashing Repair Cape TownThe junction detail.Bathroom Waterproofing Cape TownNew wet areas.Damp Proofing Experts Cape TownExisting damp before work.

Frequently Asked Questions

Why does my extension leak where it joins the house?

The two structures move independently and whatever bridges them takes that movement. A rigid seal splits. It needs a proper flashing chased into the existing wall rather than sealant run along the surface.

Should existing damp be fixed before renovating?

Yes. Renovating around a live leak or a damp wall hides it behind new finishes, and the repair afterwards costs the renovation as well as the waterproofing.

How long does the work take?

A domestic-scale job is often two to four days including preparation and curing. Larger or multi-section work runs one to three weeks. Rain stops work entirely.

How long does waterproofing last?

A correctly installed torch-on system generally gives 10 to 15 years. Liquid acrylic runs shorter, often 5 to 8. Both assume outlets are kept clear and the surface is checked once a year.

When should waterproofing be booked in Cape Town?

Late summer or autumn. Membranes and coatings need a dry substrate and a dry curing window, and contractors fill up as soon as the first winter fronts arrive.

Can waterproofing be applied over the existing coating?

Only where the existing layer is sound, dry and compatible. Coating over a blistered or delaminating membrane traps moisture underneath and the new work fails early.