How Much Does It Cost to Waterproof a Balcony?

Balcony waterproofing cost depends mostly on what is under the surface. Metro Vancouver contractors publish roughly $15 to $35 per square foot installed for a new membrane over a sound existing surface, and $35 to $75 or more for a full tear-off and replacement. Valordek membrane material starts at $3.74 per square foot (CAD).

Those two numbers explain most of the bill. The membrane itself is a modest share of the price. The rest is labour, access, removal of the old surface, detailing at the walls, doors and drains, and above all the condition of the plywood underneath. A balcony that is re-waterproofed while the substrate is still dry costs a fraction of one where water has already reached the framing. This guide breaks down what drives the number, how the main waterproofing methods compare on cost over time, and what a vinyl membrane costs in materials. For how the membrane system works, see our vinyl decking overview and our guide to balcony waterproofing.

How much does it cost to re-waterproof a balcony?

Re-waterproofing a balcony typically costs $15 to $75 or more per square foot installed in Metro Vancouver, and where your balcony lands in that range depends on how much has to come off before the new membrane goes down. Published contractor pricing is still the most useful reference, as long as you read what each range includes.

Two cautions when you compare quotes. First, contractor ranges are installed prices, while a manufacturer's price is for material, so they are not comparable line for line. Second, ranges this wide exist because the hidden condition of the balcony varies so much. A quote that looks high may simply include plywood replacement that a cheaper quote has left out.

What drives balcony waterproofing cost?

The biggest single cost driver is whether water has already reached the substrate, because that turns a surface job into a rebuild. After that, cost follows the details a contractor has to get right.

• Substrate condition. Sound, dry plywood can be prepared and covered. Wet or rotted plywood has to be replaced first, and damaged framing below it adds structural work. Our guide on how to tell if there is rot under your vinyl deck membrane covers the warning signs.
• Removal of the old surface. Taking up tile, a failed coating or an old membrane adds labour and disposal.
• Slope and drainage. Valordek's installation guidance calls for a minimum slope of 1/4" per foot. A flat or back-sloped balcony needs to be re-sloped before any membrane will drain properly.
• Edges and penetrations. The wall, the door threshold and railing posts are where most leaks start, and each one is detail work. See where vinyl deck leaks actually start and balcony leaks at the sliding door.
• Access. A ground-floor sundeck is simple to reach. An upper-floor balcony may need scaffolding or other access equipment, which is priced separately.
• Size and shape. Small balconies cost more per square foot, because setup and detailing are spread over fewer square feet. Corners, steps and cut-outs add time.

What does a vinyl membrane cost?

Valordek vinyl membrane starts at $3.74 per square foot (CAD) for material, so the membrane for a 10 by 10 foot balcony starts at about $374 before adhesive, sealant, flashing, drains and installation. That is the one hard manufacturer number in a field of contractor estimates, and it shows how small a share the membrane is of the installed price.

The rest of a vinyl membrane job is the system around it: contact adhesive, sealant at the walls and penetrations, flashing at the edges, and drains or scuppers where the balcony needs them. If you want to price materials for your own balcony, the Valordek material cost calculator builds a full materials list from your dimensions, including heat-welder rental at $55 per day for welding the seams. Our vinyl decking cost guide covers installed-cost examples in more detail.

What you get for that material cost is a membrane that is the walking surface and the waterproofing in one layer, engineered for -40°C to 80°C and, for Valordek's 68mil balcony membrane, tested by CCMC and exceeding code 37.54.95 for decks over living space. It carries 15 years of waterproofing coverage and 5 years of appearance coverage. The warranty is valid when the membrane is installed by a certified installer using Valordek-approved adhesives and components. Full terms are on the Valordek warranty page.

What is the best way to waterproof a balcony for the money?

The cheapest balcony to waterproof is the one waterproofed before the substrate gets wet, whichever system you choose. After that, the methods differ less in upfront price than in what they cost you over the following years.

We compare these options surface by surface in our guide to waterproof balcony flooring, and coatings against membranes in waterproof deck coatings vs vinyl membrane. For the ten-year view of what different surfaces cost to own, see decking total cost of ownership.

Repair or replace: the cost decision

A small, recent problem on a sound balcony is a repair; widespread wear or a wet substrate is a replacement. The difference in cost is large enough that it is worth getting the diagnosis right before accepting either quote.

On a vinyl membrane, a puncture, a tear or a lifted seam on an otherwise sound deck can be fixed with a heat-welded patch, a contained job. Replacement makes sense when the membrane is worn across the surface, when leaks have recurred in several places, or when the plywood underneath is soft. Our vinyl deck repair guide walks through that decision in detail. Whatever the surface, the expensive mistake is patching over a wet substrate: the patch holds, the rot underneath keeps spreading, and the eventual repair costs far more.

What should a balcony waterproofing quote include?

A useful quote tells you what the contractor will find, fix and warranty, not just a price per square foot. Two quotes that look far apart often describe different jobs, so compare them line by line.

1. A substrate inspection and a plywood allowance. The quote should say how the plywood will be checked and what replacing damaged sheets would cost, per sheet or per square foot. A quote with no allowance either assumes the substrate is sound or leaves the surprise for later.
2. Removal and disposal of the existing surface, if any.
3. Slope correction, if the balcony does not drain at the minimum slope.
4. Every termination. Wall flashing, the door threshold and sill pan, railing post penetrations and drains or scuppers should each appear in the scope.
5. The system by name, including the membrane or coating, its thickness and the adhesive or primer it will be installed with.
6. Two warranties. The manufacturer's material warranty, and the contractor's terms for workmanship, which is the installing contractor's responsibility rather than the manufacturer's. Our guide to vinyl decking warranty coverage explains how they differ.
7. Access and cleanup, including any scaffolding or equipment an upper-floor balcony needs.

How to keep balcony waterproofing costs down

The most effective way to keep balcony waterproofing cheap is to act while the job is still a surface job. Most of the escalation on the cost ladder comes from time.

• Keep up the annual check. Valordek's care instructions call for an annual inspection of the sealant joints where the membrane meets the building, posts and drains, and of the seams. Resealing a joint costs little; a leak through a failed joint can cost a substrate.
• Keep drains clear. Standing water from a blocked drain stresses every joint on the balcony.
• Fix punctures promptly. A small hole in a vinyl membrane is a patch today and a plywood repair after a wet season.
• Get stains below investigated. A ceiling stain under a balcony means water is already past the waterproofing, and every month adds to the repair.

Strata balconies: who pays and when

On most BC strata balconies, the membrane is part of the building envelope, and its repair or replacement is generally the strata corporation's responsibility under its bylaws. That makes cost a council decision, usually planned years ahead.

Membrane replacement often appears as a line item in a depreciation report, with an estimated cost and year. Deferring it tends to move the job up the cost ladder above, because water damage below a failing membrane grows while the vote is postponed. Our guides to strata balcony waterproofing in BC and to a depreciation report that flags the balcony membranes explain who decides and who pays. This is general information, not legal advice; your strata's bylaws govern.

Frequently Asked Questions

How much does it cost to waterproof a balcony?

Metro Vancouver contractors publish roughly $15 to $35 per square foot installed for a new membrane over a sound surface, and $35 to $75 or more for a full tear-off. The biggest variable is the substrate. Valordek membrane material starts at $3.74 per square foot (CAD), before adhesive, flashing, drains and installation.

How much does it cost to repair a balcony?

It depends on how far the damage goes. A patch on a sound vinyl membrane is a contained repair, while replacing wet plywood, flashing or framing multiplies the cost. Diagnose the substrate before accepting a quote, because patching over wet plywood leaves the expensive problem in place.

Is a leaking balcony covered by insurance?

It depends on the policy and the cause. Many policies treat sudden, accidental water damage differently from damage caused by gradual leaks or wear, which is often excluded. On a strata balcony, the strata's policy and bylaws also decide who claims. Check your policy wording before assuming either way. Valordek's own warranty covers manufacturing defects that cause leaks.

Does a balcony need waterproofing?

Yes, if there is living space, a garage or another unit below. The structure beneath must stay dry, so the balcony needs a continuous waterproofing layer, not just a finish.