Concrete Waterproofing for Decks, Balconies, Planters and Walls

Water rarely appears where it enters. It runs along surfaces, through cracks and across the underside of slabs before it shows. Tracing means looking at the whole surface above the leak: slope, drains, joints, penetrations, wall to deck transitions and the condition of any coating.

We walk the area, test where we can and tell you what we think is happening and how confident we are. Sometimes a water test, such as flooding a small area, helps.

Decks and balconies need slope, drainage, a sound surface and sealed joints and edges. Many leaks come from a failed coating or a poorly detailed edge, where the deck meets a wall or a railing post. A coating system can protect the surface, and sealants and flashings protect the details.

Waterproofing a deck is not just painting it. We look at the structure, the slope and the existing coating, and we recommend the layers that make sense.

Waterproofing coatings range from thin protective coatings to thick membranes. Thin coatings protect the surface from weather and staining. Thicker, flexible membranes bridge small cracks and resist water penetration more reliably. Some are traffic bearing, and some are not.

The right choice depends on movement, traffic and exposure. We name the system in the scope and explain what it is designed to do.

Planters hold water against concrete, so they are demanding. They need a membrane that stands up to constant moisture, drainage that moves water away and protection for the membrane from soil and roots. Failure shows up as stains and efflorescence on faces below the planter.

If you have planters over occupied space, tell us. These details are worth getting right the first time.

Walls leak through cracks, joints, windows and penetrations, and through porous masonry that absorbs rain. Sealing cracks and joints, repairing damaged surfaces and applying a coating or a sealer can protect a wall. Our page on elastomeric wall coatings covers flexible wall coatings.

Do not seal a wall that is wet from the inside, since trapping moisture can cause damage.

Most waterproofing failures happen at details: where a deck meets a wall, around posts and pipes, at drains and along edges. Flashings, sealants and careful transitions protect these points. A scope that talks only about the flat surface misses where leaks usually start.

We list details separately so you can see what is included.

A waterproof surface that holds water is a problem. Standing water finds weak points, shortens coating life and can add weight. We look at slope and drains and tell you if correction is needed before coating, and we price that separately.

Waterproofing often touches roofing, windows, stucco, railings and landscaping. A change in one can affect another, and a waterproofing warranty from another contractor may be affected by work nearby. Tell us who else is involved, and we will coordinate and note anything that could affect existing coverage.

Some water problems are beyond a coating or a sealant: below grade leaks, hydrostatic pressure, structural cracks or failing drainage systems. These may call for an engineer, a waterproofing specialist or a different trade. We tell you plainly when a problem is outside what we do, and we describe what we see so you can speak with the right professional.

An honest referral is better than a repair that cannot work.

After waterproofing, confirm that it worked. A water test, such as ponding or a controlled spray, can show whether a detail is sealed. Watch the area during the next heavy rain, and check the leak location inside. If a leak continues, tell us immediately, because early information helps us trace the cause.

We describe the verification we recommend in the scope.

White powder on concrete or masonry, called efflorescence, shows that water has moved through the material and carried salts to the surface. Dark stains, rust marks and peeling paint also point to moisture. These signs help locate the path of water and judge how long it has been active.

Photograph stains and note dates, and share them with us. A record of how a stain changed over time helps us trace a leak and recommend a fix.

Keep records of what was installed, where, when and with what product, plus photos of the area before and after. When ownership or management changes, pass the records along. If another trade holds a warranty on the area, tell us before work begins, so the work does not affect it.

Ask what is being waterproofed and why. Ask how the leak was traced. Ask which layers are included and how details are handled. Ask what is excluded and what happens if the leak continues. Put the answers in writing. A scope that is clear about all of this is worth more than a low price.

Inspect waterproofed areas each year. Keep drains clear and look for cracks, blisters, worn coating and failed sealant. Small repairs prevent big ones. Your written estimate explains the terms that apply to the products used.

Our caulking cost guide explains what moves the price. Send photos and rough dimensions through the free estimate form and we respond within 24 hours. Site walks are available the next day or later, depending on availability, and you receive a written scope after the visit.

A good scope lists the area, the diagnosis, the layers, the details and the exclusions, and it describes how the work will be checked. Ask each contractor to put those items in writing. Ask for photos of existing conditions, and ask what happens if the leak continues. A scope that is specific lets you compare bids fairly, and it protects you if something goes wrong later.