Outdoor Deck Waterproofing · CSLB #1060736
Commercial Outdoor Deck Waterproofing in California
We protect elevated and ground-level decks on apartment communities, condominiums and HOA properties across the Bay Area, Central Valley, and Sacramento. There is more than one way to protect a deck from water, and they do not do the same job. The right one depends on what is under the deck and whether its surface can be sloped, so every project starts with those two questions.
- CSLB #1060736 Licensed California contractor
- 9+ yrs Waterproofing decks on occupied buildings
- Chosen by what is below The option depends on the space under the deck
- Commercial & HOA Apartments, condominiums & HOA communities
01 Why it matters
Water resistant or waterproof: what is under the deck decides
A deck with open boards and a penetrating sealer is water resistant. The sealer slows down how much water the wood takes in, but rain still runs through the gaps between the boards onto the joists and whatever is below. For a low deck over gravel, that is usually fine. For a deck over a patio, a carport, a storage room or another unit, it is not, because the space below gets wet every time it rains.
A waterproof outdoor deck keeps that water out of the space below. To do that it needs a continuous surface that sheds water, and a slope that sends the water to an edge or a drain. Coating manufacturers build that into their requirements: the ICC-ES evaluation report for one widely used walking deck system, ESR-1714, does not allow it on less than 1/4 inch of fall per foot. A level surface holds water in puddles, and a waterproof layer under standing water is working at its limit.
Many older decks were built level, with open boards, because nobody expected them to keep the space below dry. When the use of that space changes, or water damage shows up under the deck, the frame has to be given a slope before any waterproof layer goes on. That step, more than the choice of product, decides whether the deck stays watertight.
A sealer makes a deck water resistant. Keeping the space below dry takes a continuous surface and a slope that sends the water somewhere.
02 The D&B difference
How we choose the waterproofing for a deck
The space below is the first question
Gravel, a patio, a carport or a room: what sits under the deck sets whether water resistant is enough or the deck has to be waterproof.
Slope comes before the product
Where the deck has to be waterproof, we give the surface a slope toward an edge or a drain, by shimming the joists or reframing, before the waterproof layer is installed.
The surface people want stays possible
A coated surface, boards over a membrane or pavers on pedestals can all keep the space below dry. We match the option to the use, the height and the framing, not only to the look.
03 · Service Areas
Where We Work in California
Every city links to a dedicated local page — crews, recent projects and compliance details for that area.
Sacramento Metro
20 cities
East Bay
28 cities
North Bay
14 cities
Central Valley
13 cities
South Bay & Peninsula
27 cities
Don’t see your city? We likely still cover it — call (916) 848-2728.
04 How a project runs
How the work runs, from assessment to drainage
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01
Assessment
A free property assessment, scheduled within a week. We look at what is under each deck, the slope of the surface, stains below and the condition of the framing.
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02
Options
The approaches that fit the deck, with what each one needs in framing and slope.
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03
Quote
An itemized quote within five business days, per deck and per square foot.
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04
Framing and slope
Damaged wood replaced, joists shimmed or reframed so the surface slopes to an edge or a drain, new sheathing where the system needs it.
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05
Waterproofing
Coating, membrane or membrane with pavers installed, with flashing at the wall, door and edges.
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06
Drainage
Drip edges, scuppers and downspouts so the water leaves the deck and does not run down the building.
05 Scope
What our exterior deck waterproofing covers
Waterproof deck surfaces Framing and slope Edges and drainage
- Walking deck coating over sloped plywood, with a textured finish
- Outdoor deck waterproof membrane under deck boards set on sleepers
- Membrane under concrete pavers on adjustable pedestals
- Penetrating sealers for open-board decks where water resistant is enough
- Joists shimmed or reframed so the surface slopes to an edge or a drain
- Sheathing of the type and thickness the waterproofing system requires
- Damaged joists, ledger and posts repaired before anything is covered
- Waterproofing turned up the wall and flashed at each door
- Drip edges, scuppers and downspouts
- Railing post bases sealed into the waterproof layer
Built to current code: ICC-ES evaluation report of the installed walking deck system · CBC 1604.8.3 deck attachment where the ledger is repaired · SB 721 (Health & Safety Code 17973) and SB 326 (Civil Code 5551) requirements for waterproofing of exterior elevated elements
06 Investment
What deck waterproofing costs
Typical range: $25–$60 per square foot, usually 1–4 days per deck.
What sets the number
- Square footage of each deck and how many decks there are
- The option chosen: coating, boards over a membrane or pavers on pedestals
- Whether the frame has to be shimmed or reframed for slope
- Wood repairs found once the surface is open
- Length of wall line, number of doors and post bases
- Scuppers, drains and downspouts
- Access to elevated decks
Why slope changes the number: a deck that already slopes to an edge can go straight to the waterproofing. A level deck needs its frame reworked first, and that work, not the coating, is often the larger part of the price.
Final pricing follows an on-site assessment. Request a free estimate — no obligation.
In the field
Decks over carports, podiums, patios and gravel
A deck over a carport, pavers on pedestals, a sealed board deck, a frame opened for waterproofing and a finished deck and stair.
07 Project example
A recent deck kept as boards, made waterproof underneath
The property wanted to keep a board surface on the deck, but the patio underneath was getting wet every time it rained. We removed the old boards, added sheathing with a slope toward the outer edge and covered it with a waterproof membrane turned up at the wall. Pressure-treated sleepers on top of the membrane carry new composite boards, so water that passes between the boards runs off the membrane to the edge instead of onto the patio.
We did not want a coated surface on that deck. They kept the boards and put the waterproofing underneath, and the patio below stays dry. Property Manager · California apartment community
08 Case studies
Recent Projects, Documented
Real commercial properties — what the building needed, what we did, and what it delivered.
Deck RepairElevated Deck Reconstruction & Waterproofing — 24 Balconies, SacramentoOpen board decks sitting directly over enclosed garages. Every gap between the boards was a route for water…View case study 
WaterproofingBalcony & Walkway Waterproofing — Sunset Park Apartments, SacramentoThe concrete had never been coated. Water sat on it, worked through the cracks and ran to the…View case study 
WaterproofingElevated Walkway & Balcony Waterproofing — 40-Unit Apartment Community, Rio LindaDry rot had opened holes straight through the walkway decks. We shored the spans, rebuilt the framing underneath,…View case study 09 Client feedback
What property managers say
We did not want a coated surface on that deck. They kept the boards and put the waterproofing underneath, and the patio below stays dry.
We had been resealing the boards every couple of years and the carport still got wet. They explained why, and changed the deck instead of the sealer.
The quote separated the framing work from the coating, so the board could see that most of the cost was giving the deck a slope.
10 FAQ
Questions about keeping a deck dry
What waterproof deck options are there?
Four main ones: a coating over sloped plywood, a waterproof membrane under deck boards set on sleepers, a membrane under pavers on pedestals, and a penetrating sealer on open boards. The first three can keep the space below dry. A sealer makes the boards water resistant, but water still passes between them.
Is water resistant the same as waterproof?
No. A water resistant deck sheds some water and slows down how much the wood absorbs, but rain still reaches the joists and the ground below. A waterproof deck has a continuous layer and a slope that carry the water off the deck, so the space underneath stays dry.
What is a waterproof deck coating system?
Coatings for walking decks are applied in several layers, typically a reinforced base, a membrane and a textured wearing surface, over plywood or concrete. The manufacturer’s ICC-ES evaluation report lists which substrate, slope and layer sequence the coating was approved for, and we build the deck to match it.
Can a deck keep its boards and still be waterproof?
Yes, with a waterproof membrane underneath them. The membrane goes on sloped sheathing and turns up at the wall, sleepers sit on top of it, and the boards are fastened to the sleepers. Water passes through the board gaps and runs off on the membrane, so the boards keep their look and the space below stays dry.
Why does slope matter in waterproofing a deck floor?
Without slope, water stays on the surface in puddles and sits on every joint and seam until it evaporates. Evaluation reports for deck coatings set a minimum fall; ESR-1714 is one example, at 1/4 inch per foot. That is why a level deck is shimmed or reframed first.
How much does it cost to waterproof a deck?
Typically $25–$60 per square foot, and 1–4 days per deck. The low end is a deck that already slopes and has sound sheathing; the high end is a level deck that needs reframing, new sheathing and drainage. The itemized quote follows a free assessment.
Does SB 721 or SB 326 apply to deck waterproofing?
Both laws inspect elevated decks, balconies and walkways whose walking surface is over six feet up and whose structure relies mainly on wood. The inspection covers the waterproofing that protects that structure: flashings, membranes, coatings and sealants. SB 721 applies to rental buildings of three or more units; SB 326 applies to condominium associations.
How do you choose among deck coating companies?
Ask what the contractor will do about slope, flashing at the wall and doors, and damaged wood under the surface, and which evaluation report covers the system they propose. A quote that only prices the coating leaves those questions open.
Are you deck waterproofing contractors near me?
We work across the Bay Area, Central Valley and Sacramento, including waterproof deck work for apartment and HOA properties in Sacramento, with free property assessments scheduled within a week. Framing, slope, waterproofing and drainage come from one CSLB-licensed contractor (#1060736). Call (916) 848-2728 and tell us the city and what is under the deck.
11 Start here
Book a free outdoor deck waterproofing assessment in California
Send us photos of the deck surface and of the space underneath, especially any stains or drips. We schedule the assessment within a week and send an itemized quote within five business days.
CSLB #1060736 · 9+ years · Insured & Bonded · Commercial, multifamily & HOA properties across the Bay Area, Central Valley & Sacramento