• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Home
  • DIY Home Projects
  • Home Tour
  • Recipes
  • About

Craving Some Creativity logo

menu icon
go to homepage
search icon
Homepage link
  • DIY Home Projects
  • Home Tour
  • Recipes
  • About
  • Free Email Series
    • Facebook
    • Instagram
    • Pinterest
  • ×

    Home » Home Decorating » Outdoors

    Published: Aug 30, 2021 · Modified: Nov 20, 2022 by Rachel

    How To Create a Waterproof Ceiling Under Your Deck (Step by Step)

    This post may contain affiliate links. Read my disclosure.
    9409 shares
    • Share
    • Tweet
    Jump to Tutorial Print Tutorial

    Free up some extra space in the garage or expand your outdoor living space with this inexpensive project to make a waterproof ceiling under a deck. We added a shed under the deck this way. Includes step by step instructions, variations, and expert tips to make it last.

    Collage of waterproof deck ceiling drainage system showing the inside and outside of the deck area.
    Contents show
    1 Tools and Materials
    2 Choose Your Waterproof Ceiling Design
    2.1 1. The Cheapest Method
    2.2 2. Designed to look like a Ceiling
    3 Designs for Different Types of Decks
    3.1 1. Simple Deck Design
    3.2 2. Decks with Cantilevers
    3.3 3. Decks with Beams and Braces
    4 Step by Step Instructions
    4.1 Step 1: Add the sloping structure
    4.2 Step 2: Screw the panels to the spacers
    4.3 Step 3: Add gutters
    5 How We Enclosed Our Deck for a Shed
    6 Tips for An Expert Installation
    7 FAQs
    8 How to Add a Waterproof Ceiling Under A Deck
    8.1 Tools
    8.2 Supplies
    8.3 Instructions
    8.4 Notes

    If there is one thing every house never seems to have enough of, it’s storage. Even if there is sufficient storage, it’s not where you need it. For example, the garage in our home is a DIY and carpentry workshop, motorcycle storage, and outdoor supplies including the lawnmower.

    To say it was a bit tight would be an understatement. One of those categories had to go somewhere else. And we had just the idea of where that would be.

    Our raised deck is 7 feet tall in front but only 5 feet in the back, rendering it useless for an outdoor living space. And we didn’t need another outdoor living space. However, we needed to provide a dry space underneath to store the lawnmower, outdoor tools, and supplies.

    That brings us to this project – creating a waterproof ceiling under a deck. After extensive research (and living with the project for a few years), I am happy to share a step-by-step guide of not only how we did it, but how you can add a waterproof ceiling to a variety of deck styles.

    Tools and Materials

    • Circular saw or Compound Miter Saw
    • Cordless drill
    • Drill bit set
    • Safety glasses
    • Stepladder
    • Under Deck Ceiling System (see Choosing Ceiling Design Below)
    • Gutter and downspout
    • Pressure treated 2x4s
    • Metal Roofing screws (you can use non-rusting decking screws with rubber washers)
    • Waterproof sealant (flex seal tape, outdoor caulk)

    Choose Your Waterproof Ceiling Design

    Every deck is different, as is what you are designing the space for. Tool storage? A place to put the lawnmower? To entertain or an outdoor dining area? There are a few different options for designing a waterproof ceiling to look into.

    1. The Cheapest Method

    We used these Plastic Corrugated Roofing Panels and they are pretty inexpensive. A 2’X12′ panel was about $30 per sheet. When measuring, keep in mind that the sheets need to slightly overlap so there are no gaps.

    2. Designed to look like a Ceiling

    There are a few designs depending on what type of deck you have and where in the process of building it you are. Some, like

    This style by Trex uses sheeting to create a trough between joists for water to flow. It’s made to be put with a trex deck and I probably wouldn’t recommend unless you already plan on replacing the top decking boards or haven’t laid them down. However, you can have a beautifully flat ceiling with this style.

    Man hammering in a rubber trough for an under deck ceiling.

    There is one other design options that I am familiar with that may work for simple deck designs and have a flat ceiling look to them. Zip-Up Under Deck Ceiling (view their installation guide here on youtube)

    Designs for Different Types of Decks

    1. Simple Deck Design

    If you have a simple deck design (attached to the house, no additional posts, etc. The ceiling will look something like this:

    Cross section of a deck with an attached ceiling design shown.

    2. Decks with Cantilevers

    A cantilevered deck means that there is one end of the deck that hangs unsupported beyond the posts. Usually, a cantilever on a deck isn’t more than 2 feet so you could choose to exclude this area. The other option is to double the gutter system and go through any posts if want to take it to the end.

    Cross section of a deck with cantilevers and an attached ceiling design shown.

    3. Decks with Beams and Braces

    Despite appearing connected to a supporting wall such as a home, a deck may actually be built as a free-standing structure. Over a certain depth, these freestanding builds require additional support and bracing. If you have cross braces or knee braces (stiffeners that run between a post and a joist to increase rigidity). There are a few options for this type of build:

    1. I would highly recommend consulting a professional about ways to remove the braces while maintaining proper structural support.
    2. Ours is only a storage area, so we elected to work around the braces (which are near the outside edges). We added boards that sloped to the bottom of the large beams that run crosswise for the deck.
    Ceiling under deck with knee braces to keep rain out.

    Step by Step Instructions

    This is the deck area we started with. It is a 20×10 freestanding deck with cantilevers, 2 beams, and knee braces.

    Raised deck with gravel lined storage space underneath

    Step 1: Add the sloping structure

    First, to the underside, spacer blocks should be screwed into the joists every 2 feet and on every joist or every other joist depending on your spacing. Each block is ½ thicker than the last as it runs down the joist. This creates enough slope to direct the water down to the edge and into a gutter.

    Boards added underneath raised deck for draining water away from storage area built underneath.

    I recommend a slope of about 1 inch over 4 feet, or more if possible. I have seen recommendations for a slope as little as ¼ inch over 4 feet. However, it is my experience that small dirt, warping over time, dog hair and debris find their way into the troughs. A higher slope will help the carry the water away better.

    Step 2: Screw the panels to the spacers

    Next, we added corrugated plastic panels like these or polycarbonate panels. Starting at one end, attach the panels to the spacers with non-rusting roofing screws or deck screws and rubber washers. Line up and screw into the high points, not the water channels. Overlap edges of panels and seal with caulk or flex tape, if desired.

    Screw placement in hills of pvc corrugated board.

    Step 3: Add gutters

    Adding gutters does make an under-deck ceiling more aesthetically pleasing as well as functional. Plan ahead and attach the panels so that there is space for the water to properly flow into them and for you to be able to clean them out if necessary.

    Because ours is a simple storage area for the tractor, we didn’t add gutters. It drains into the gravel below which has the appropriate slope away from the house.

    How We Enclosed Our Deck for a Shed

    We wanted to enclose our deck to make it more attractive, and provide more protection for our outdoor tools and equiptment.

    Progression of framing a deck to create a storage enclosure underneath.
    You may notice the ceiling designs are different than this photo. This way didn’t work and we redid it.

    We added 4×4 posts underneath the deck, back far enough back to give space for the boards. This was definitely the hardest part, because we dug the holes by hand with a post hole digger and breaker bar. For anyone keeping count (we were!), that’s 15 posts.

    One of the hardest things we had to deal with was the giant support beams that ran end to end. On the larger platform (photo above), we decided to just frame it out and leave the support beam intact.

    After framing, we wrapped all sides, including the stairs, with 6 inch wide decking boards.

    Enclosed deck and around stairs completed with mulch.

    Tips for An Expert Installation

    • Screw through the highest point of the corrugation, rather than through the channels the water will flow.
    • We pressure wash our deck every 1-2 years and use this time to also wash out the panels and clean the gutters. Even small debris can build over time like algae, dog hair, caked dust, and pieces of grass. We use a plant safe house wash like this one.
    • Panels can be cut to length with a circular saw and carbide blade or cutting shears.
    • For a plain corrugated panel, I recommend a slope of 1 inch over 4 feet, or more if possible. I have seen recommendations for a slope as little as ¼ inch over 4 feet. However, it is my experience that small dirt, warping over time, dog hair and debris find their way into the troughs. A higher slope will carry the water and debris away better.
    • You can direct the corrugated drainage system either across the joists or along the joists. The first time we did this, we directed long ways, but realized it wouldn’t work for our situation because of the knee braces and debris, so we redid it.

    And here it finished and stained in a solid color:

    Completed raised deck storage area with surrounding mulched flower garden

    Check Out Our Many Other Ideas for Outdoor Improvements:

    • How to Restore An Old Deck
    • 7 Ways to Refresh Your Front Porch
    • Building An Outdoor Table
    • How To Spray Paint Outdoor Furniture

    FAQs

    How do you clean under deck ceiling?

    Different systems have different recommendations. If your boards have some gaps between them, you can use a pressure washer (1000-2500 PSI) flushing the gutters and system. Use a house cleaning agent for algae. I recommend removing the panels every few years or annually to clean thoroughly.

    How do I cover under my deck?

    A few popular choices to enclose a deck space include lattice panels, fence boards, decking boards, vinyl siding, faux stone or brick, and feathered cement over concrete blocks.

    How much is an under deck roof?

    With labor cost, expect to pay $1200-4,000 depending on style and which specific system. The lowest cost option is using corrugated panels and gutters which is about $20 per linear foot. For example, a 10×10 foot deck would cost about $250 for parts and supplies.

    What is the best material to put under a deck?

    If under your deck is exposed, do not put a vapor barrier underneath as this can cause moisture to build up. The cheapest option is gravel and good drainage system or slope away from the house. Clean up leaves and debris that retain or trap moisture annually. If weeds are a concern, you can use landscaping fabric.

    Weekend DIY project. A pegboard organizer in the craft room above the desk workspace.

    Grab our free series "Weekend Home Projects that will Transform Your Life"

    Sign up below to receive updates including free printables, organization tips, home improvement projects, recipes and more!

    More DIY outdoor Projects

    Gravel walkway path with stones on each side.
    Make A Budget Friendly Landscape Path
    Blue front door on red brick house with planters on either side.
    Refresh your Front Entry!
    collage of before and after refinishing an old deck
    Restoring A Deck
    Wood farmhouse table in X cross pattern with black legs.
    Building An Outdoor Table

    PS I love seeing your creations! Be sure to take a photo and tag #cravingcreative on Instagram! You can also stay in touch with me through following me on Instagram, Pinterest, and subscribing to the newsletter!

    Solid color stained raised deck with shed area underneath.

    How to Add a Waterproof Ceiling Under A Deck

    Free up some extra space in the garage or expand your outdoor living space with this inexpensive project to make a waterproof ceiling under a deck. We added a shed under the deck this way.
    5 from 6 votes
    Print Pin Rate
    Project Time: 1 day
    Total Time: 1 day 2 hours
    Author: Rachel
    Cost: $200

    Tools

    • compound miter saw
    • Cordless drill
    • Drill bit set
    • Safety glasses
    • Stepladder

    Supplies

    • Gutter and downspout
    • Pressure treated 2x4s
    • Metal Roofing screws
    • Waterproof sealant
    • Corrugated Fiberglass or PVC panels

    Instructions

    • First, to the underside, add spacer blocks to every joist if spaced 12 or more inches apart. Blocks or shims are cut from a treated 2×4 and spaced every 2 feet on a joist. Each block is ½ thicker than the last as it runs down the joist. This creates enough slope to direct the water down to the edge and into a gutter.
      Where to add a waterproof ceiling from under a deck looking at the joists.
    • Starting at one end, attach the fiberglass panels to the spacers with non-rusting roofing screws or deck screws and rubber washers. Screw into the valleys, not the water channels. Overlap edges of panels and seal with caulk or flex seal, if desired.
      Screw placement in hills of pvc corrugated board.
    • Adding gutters does make an under deck ceiling more aesthetically pleasing as well as functional. Plan ahead and attach the panels so that there is space for the water to properly flow into them and for you to be able to clean them out if necessary.
      Cross section of a deck with an attached ceiling design shown.

    Notes

  • Screw through the highest point of the corrugation, rather than through the channels the water will flow.
  • We pressure wash our deck every 1-2 years and use this time to also wash out the panels and clean the gutters. Even small debris can build over time like algae, dog hair, caked dust, and pieces of grass. We use a plant safe house wash like this one.
  • Panels can be cut to length with a circular saw, carbide blade, or shears.
  • Tried this Project? Tag me Today!Mention @CravingCreative or tag #CravingSomeCreativity!
    « 20 Creative Craft Room Storage Ideas
    Tangy Corn and Black Bean Salad »

    Reader Interactions

    Comments

      Leave a Reply Cancel reply

      Your email address will not be published. Required fields are marked *

      Recipe Rating




    1. Whitney says

      March 19, 2022 at 2:08 pm

      5 stars
      Hello! The 2x4s being parallel to the house, should they be the length of the deck? Ours is 20 feet so do I HAVE to use 2x4x20s? Or is there an alternative method? Thanks!

      Reply
      • Rachel says

        March 20, 2022 at 7:14 am

        The spacer blocks don’t need to be full boards, and it’s probably best if they aren’t for maximum air flow. I can see where that could be confusing. The blocks are made from 2x4s, but they don’t measure 2×4 if that makes sense. I cut the 2×4 into blocks to create the slope, but the blocks are only big enough to attach the panels to the boards. For example, the first block row closest to the house might be 2 inches wide x 4 inches long x 2 inch height, and the next block row placed 2 feet down the same joist would be 2x4x2.5 or 3 inches tall. So you cut the 2×4 into blocks that are a little longer each time and then hang them to create the slope.

        Reply
        • Whitney says

          March 20, 2022 at 10:25 pm

          Oh! So the panels are only attached to the spacer blocks. Got it. Thanks for responding!

    2. Lisa says

      August 24, 2021 at 4:27 pm

      What size boards did you use to wrap

      Reply
      • Rachel says

        August 30, 2021 at 8:25 am

        I used 6 inch wide decking boards that match the top of our deck.

        Reply
    3. Barbara Williams says

      October 05, 2020 at 6:27 pm

      5 stars
      How is the water draining under your deck? I don’t see the pvc ceiling leading to a gutter.

      Reply
      • Rachel says

        October 14, 2020 at 8:43 am

        You are correct. That was installed after I took most of these photos, but isn’t super necessary depending on how the deck is installed. We have a gutter at the edge that empties into the rain spout at the edge.

        Reply
    4. Christina says

      August 13, 2020 at 3:55 pm

      5 stars
      Hi Rachel!

      How much gravel did you put down originally? Did you build a floor or just the enclosure around it?

      Thanks!
      Christina

      Reply
      • Rachel says

        August 19, 2020 at 7:52 am

        Great questions! It’s been a few years, but I want to say we originally put 4 cubic feet It’s much cheaper to get in bulk at our landscaping center and they used a wheel loader. We did not build a floor originally since we were just trying to cover the bare dirt. Grass and weeds weren’t growing in it and the dogs would go under the deck to get muddy.

        Reply
    5. Tami says

      August 12, 2020 at 8:28 am

      5 stars
      We want to do this as well. What do you do to the top door deck to prevent water from seeping in from the top? Tami

      Reply
      • Rachel says

        August 19, 2020 at 7:55 am

        I wrote a post on how we added a corrugated roof here.

        Reply
    6. Steve says

      July 03, 2020 at 11:48 pm

      5 stars
      I’ve tried to do something similar. I bought corrugated plastic panels for the roof, but they ended up being incredibly flimsy and even fairly light handling they’d lose their shape. Do you know exactly what product your corrugated panels are?

      looks great btw

      Reply
      • Rachel says

        July 13, 2020 at 4:29 pm

        Thank you! We used these pvc plastic panels.

        Reply

    Primary Sidebar

    Headshot of Rachel Beach, the author of Craving Some Creativity.

    Hi, I'm Rachel!

    Creativity makes me energized and fearless. My husband and I have been renovating homes for over a decade and love to share our passion for all things home. Follow along for remodeling tutorials, recipes, and entertaining ideas sure to inspire!

    More about me →


    Popular Posts

    • How to Paint a Bathroom Cabinet the Easy Way
    • How To Caulk Baseboards like a Pro
    • How To Beautifully Organize Your Linen Closet
    • How To Paint Cabinets with a Sprayer

    Featured On

    Collection of Expert Features including Better Homes and Gardens Magazine, Apartment Therapy, Angie's List, This Old House Magazine, The Huffington Post, Delish, Wayfair, and Real Simple Magazine.

    Comforting Family Recipes

    • Chicken Kale Soup
    • Mediterranean Salmon Avocado Salad
    • Oven Roasted Butternut Squash
    • Ultimate Lemon Blueberry Muffins
    Pinterest Widget including a snapshot of what Craving Some Creativity has pinned recently.

    Footer

    ↑ back to top

    About

    • Privacy Policy
    • Disclaimer
    • Terms & Conditions
    • Accessibility Policy

    Favorites

    • Blog
    • Shop
    • Our Home

    Contact

    • Contact

    Copyright © 2022 Craving Some Creativity