A professionally engineered composite deck. Built by you.

12×20 Composite Deck

Build your own 12×20 composite deck with A-DIY. Our professionally engineered deck kit gives you 240 square feet of outdoor living space, with every component prepared to fit together. No measuring or cutting required for standard assembly.

Regular price

$8,600.00

or $8,100.00 with code

Starting at $338/mo at 0% APR over 24 months if approved, with code FALL500

*Financing payment based on the $8,100 sale price (code FALL500) over 24 months at 0% APR; about $358/mo at the regular $8,600 price. Subject to eligibility check and approval; terms and conditions apply. Estimated payment excludes taxes and shipping.

Show more sizes
12x20 composite deck kit from A-DIY, in Amazon Gray, built by a customer

12×20 composite deck at a glance

  • 240 sq ft Finished deck area
  • 8–16 hrs Typical build, one weekend
  • 15,000 lbs Engineered load capacity
  • 25 years Composite board warranty

Space planning

What Can You Fit on a 12×20 Deck?

A 12×20 deck provides 240 square feet of outdoor living space, with room for separate lounge and dining zones. The right layout depends on your furniture, available walking space, and how you want to enjoy your backyard. Is a 12×20 deck big enough? For a lounge area and a dining table with room to walk between them, usually yes; if you also want a hot tub or an outdoor kitchen, a larger deck may suit you better.

Forest Wood A-DIY composite deck along a wood fence

12×20 Deck along the Fence Line

A low Forest Wood deck tucked along a wood privacy fence.

Gray A-DIY composite deck with rocking chairs on a mulch bed

12×20 Deck with Rocking Chairs

Rocking chairs on a gray deck, set level on a mulch bed.

Newly built gray A-DIY composite deck on a cleared yard

12×20 Deck Freshly Built

A newly built gray deck, set level on a cleared yard.

“I love my composite deck. The Amazon grey color is beautiful. The assembly of the kit is very easy. Just purchase another one for my parents house.”
Roy · Google review · A-DIY deck kit

Every backyard has a fit

Explore Other Composite Deck Sizes

Looking for something bigger or smaller than a 12×20 deck? Explore additional composite deck sizes to find the right amount of space for your backyard.

See all Composite deck kits

Don’t see your size? We build many more.

Plenty of sizes aren’t listed here. Chat with a deck specialist to find out what we can build for your yard.

Chat now
Forest Wood A-DIY composite deck kit built with a dining set

Kit inclusions

What’s Included in Your 12×20 Composite Deck Kit?

A-DIY's 12×20 composite deck is supplied as an engineered system with composite deck boards, prepared pressure-treated frame components, structural connections, and guided assembly instructions. What materials do you need for a 12×20 deck? A traditional build needs decking boards, joists, beams, structural connectors, fasteners and a foundation. This package supplies all of them, so you add a drill and prepare the site.

Shop the 12×20 composite deck

In the crate

  • Composite Deck Boards

    Fade, stain and moisture resistant boards in Amazon Gray or Forest Wood, with a 25-year warranty.

  • Engineered Frame Lumber

    Premium Grade 1, kiln-dried and pressure-treated substructure beneath the boards.

  • Structural Hardware

    Galvanized metal brackets, connectors and screws that join the frame and fasten the boards.

  • Deck Foundation

    Tuff Block foundation blocks carry the beams on prepared, level ground, subject to your site.

  • Assembly Instructions

    Step-by-step instructions and a 3D instructional app guide each stage of the build.

12×20 composite deck specifications

Deck size
12 ft × 20 ft (nominal)
Deck area
240 sq ft
Product type
DIY composite deck, supplied as an engineered deck system
Decking
Composite deck boards, Amazon Gray or Forest Wood, fade and stain resistant, with a picture-frame border
Frame
Grade 1 Southern Yellow Pine, pressure-treated, kiln-dried
Joists
2×8, set 13–14 in. on center
Beams
6×6
Foundation
Tuff Block foundation blocks (included)
Hardware
Galvanized screws and metal brackets
Standard height
15–17 in. off the ground
Load rating
Engineered for 15,000 lbs
Typical assembly
8–16 hours with a drill; varies with experience and site
Warranty
25-year warranty on the composite boards; 5-year structural warranty
Not included
Power drill, site preparation, and optional steps, railings or taller post kits
Add-ons
Railings, steps and different-height post kits are available. Chat with a design specialist to add them to your 12x20.

What’s under a deck matters more than what’s on top

How Is a 12×20 Composite Deck Built?

A composite deck relies on a properly designed foundation and structural framing system. How does a 12×20 deck frame work? The composite deck boards sit on 2×8 pressure-treated joists, the joists rest on 6×6 beams, and the beams carry the load down to the Tuff Block foundation. Spacing and connections follow A-DIY's engineered design; check local building requirements for your site.

Exploded diagram of an A-DIY composite deck showing deck boards, frame, joists, beams and Tuff Block footings
  1. 01

    Decking

    Composite boards in Amazon Gray or Forest Wood, fade and stain resistant

  2. 02

    Frame

    Rim and galvanized brackets that keep it square

  3. 03

    Joists

    2×8, set 13–14" apart, carry the boards

  4. 04

    Beams

    6×6, notched; carry the joists down

  5. 05

    Footings

    Tuff Block foundation spreads the load to the ground. In-ground footings, sono tubes or helical piles can also be used.

  • Elevated pressure-treated wood deck with railing and wide stairs behind a gray house

    Deck Height

    Standard Height:
    Each kit comes ready to assemble at 15–17 inches off the ground.

    Increase Height:
    Use longer posts to raise the deck. We also offer longer post kits with bracing. Chat with our design specialists for details.

    Decrease Height:
    Dig a few inches where the footings sit to lower the deck.

    We offer different height post kits:
    Each kit includes the posts and bracing. Contact our design team for more details.

  • Homeowner standing on a large composite deck built on a wooded slope

    Uneven Ground

    Even if your yard isn’t perfectly flat, your deck can be. Just cut the posts to level things out, or use our longer post when you need more height.

    Pro Tip:
    On slightly uneven ground, use gravel or cement tiles under the posts to even out the height.

    We offer different height post kits:
    Each kit includes the posts and bracing. Contact our design team for more details.

Real A-DIY Deck Reviews

4.8
Based on 1,821 reviews
5 stars
91%
4 stars
9%
3 stars
0%
2 stars
0%
1 stars
0%
★★★★★
Wood Deck 12x20

Went together real easy. Plans were easy to follow.

★★★★★
I would highly recommend this company

I would highly recommend this company. I ordered the 12x12 deck and with the easy instructions I was able to build the deck by myself in a day. I’m already looking into another deck.

★★★★★
Wood Deck - 12x12

I’m a 62yr old nurse. I put this together by myself . The instructions are wonderful. I feel blessed to have this space for rest and relaxation.

★★★★★

A great product well put together will definitely refer you to other people and I might buy an extension for another 12 x 12 platform to go off the one I have. Thank you so much for a great product.

★★★★★
Composite Deck - 12x12

We are so proud of our deck! We saved a ton of money by building it ourselves, giving us a sense of accomplishment. Thanks to A-DIY, the directions were easy to follow and materials well packed and arranged. We have been able to enjoy sitting out with a drink and have had a family gathering all ready.

Family relaxing on a gray composite deck outside a sliding door
★★★★★
Wood Deck 12x12

The deck itself seems to be good quality and once I got the footings in place went together pretty easily.  Yes, all and all I would definitely recommend this kit. Happy building peeps!!!

Pressure-treated wood deck with railing and patio umbrella on a lawn
★★★★★
Easy build 12x12 pressure treated deck

I bought a 12x12 pressure treated deck. Great company communication throughout. All materials come packaged in a crate. The material is packaged in order of use as you take from the top, allowing us to time our build over several evenings without having lumber scattered across the yard and remaining protected in the crate. Instructions are clear and there’s also an online step by step video guide. I’m not a construction oriented individual, but my wife and I put it all together (including site prep) in four evenings. About 16 hours, including beer breaks - and it still came out level and great looking. We put a sauna on it and now it’s our favorite place in the yard. Easy, painless, cost effective. I am planning on a second deck and will use A-Diy again.

★★★★★
Composite Deck 12 x 12

I loved the pre-cut and pre-measured pieces to this deck. I feel it's very good quality. The color coating of the parts was very helpful.

★★★★★
Wood Deck 12 x 12

Easy

★★★★★
Wood Deck - 12x12

As easy to assemble as advertised. Nice fitment. Friends have complimented on it.

★★★★★
Wood Deck Kit - 12x12

We love the finished product and will be using it for years to come.

Wood deck with railing and steps at the door of a manufactured home
Customer comments praising the quality of an A-DIY deck kit
Customer comment about assembling an A-DIY deck in a weekend, with photo
★★★★★
Backyard went from blah to WOW!!!

My wife and I wanted to make better use of a portion of our backyard and transform it into something both practical and enjoyable. To create more usable space facing our swimming pool, we decided to remove a built-in grill island that I had constructed in the early 2000s. This opened up the area and gave us the opportunity to create a true outdoor living and entertainment space rather than simply maintaining a patch of grass. After many discussions about our vision for the space, we decided on a wood deck topped with a pergola. Our goal was to create a dedicated entertainment and relaxation area overlooking the shallow end of the pool, where family and friends could gather and enjoy the outdoors. As with any project I take on, I devoted a significant amount of time to research. I reviewed hundreds of photos, studied landscaping concepts, compared deck designs, and explored numerous options before making a decision. After extensive evaluation, I chose A-DIY as the deck provider for several key reasons: competitive pricing, the kit-based assembly system, the warranty, and the fact that the product was engineered by professionals. I was particularly impressed by the thoughtful design. Everything arrived pre-measured, pre-cut, pre-drilled, and complete with all the necessary hardware, making the process incredibly efficient. The ordering process was straightforward and user-friendly. I reviewed the available layouts and dimensions, selected the design that best suited our space, and was pleasantly surprised to receive a discount as well. A few weeks after placing the order, three pallets of materials arrived. I reviewed the plans and overall design concept with my handyman so he could fully understand the intended look and layout. He was immediately impressed by the quality of the materials and confidently stated that the deck could be assembled in days rather than weeks. He was absolutely right. The entire project took approximately eight days to complete. Along the way, we incorporated a few custom touches, including a built-in step and wrap-around skirting to prevent animals from nesting beneath the deck. Since completing the deck and pergola, we've hosted several gatherings with family and friends. The feedback has been overwhelmingly positive: “Oh my God, that's beautiful!” “That came from a kit?” “It took less than 10 days to build?” “This looks like something you'd see at a resort!” My wife and I couldn't agree more. We are absolutely thrilled with our decision to choose an A-DIY deck. From the initial consultation and material selection process to delivery and assembly, every aspect of the experience exceeded our expectations. As an engineer myself, I have a deep appreciation for good design and thoughtful execution. The engineering, material quality, packaging, instructions, logistics, and overall assembly process reflect a tremendous amount of planning and attention to detail. Kudos to the entire A-DIY team, from the designers and manufacturing staff to the shipping and customer service teams, for creating such an exceptional product. The finished deck has completely transformed our backyard. Not only does it look incredible, but with the durability of the Trex materials, we're confident it will provide years of enjoyment and stand the test of time. Thank you, A-DIY, for delivering an outstanding product, a seamless ordering experience, and excellent customer service. We couldn't be happier with the result.

Composite deck with black pergola and sun loungers beside a backyard pool
Customer comment thread about an A-DIY deck order
Customer review recommending A-DIY with a photo of their finished deck
Customer review describing a great A-DIY deck buying experience, with photo
Customer comment thread asking about an A-DIY deck
Customer comment thanking A-DIY, with a photo of their gray composite deck
★★★★★

Every board is clearly marked for quick assembly. The fitment was good, impressed with the strength of the deck.Overall appearance was excellent.

★★★★★
Pressure treated - 12 x 18

Absolutely love it! The experience has been exceptional, and I’ve already recommended it to several friends. It’s always a pleasure to support a service that truly delivers quality and excellence.

★★★★★
I did it myself

I recently built my own deck kit from A-DIY, and the experience was beyond my expectations! I’m not a DIY expert by any means, but the instructions were incredibly user-friendly, and all the materials arrived securely packaged and ready for assembly. The most impressive part? I didn’t have to hire a contractor! The assembly process was smooth, ...

Wood deck with navy gazebo and potted plants on a lawn
★★★★★
Wood Deck 16x32

Deck was perfect. My landscapers installed it and one of them happens to be a framer by trade. He was impressed by how it went together rather quickly. It took them about 2 hours to put together. Whereas if they would have built it from scratch would have taken a full day. He said he would recommend this deck if anyone was looking to have one built. That speaks volumes! I am glad I found your company and I will recommend that people purchase this item from you if they are looking for a deck. And just as advertised with all the bits and pieces that went to put it together. Everything was there and everything went smoothly. I couldn't be more pleased!

★★★★★
Everything was as Promised

Everything was as promised with the quality and ease of putting pieces together. The delivery personnel were very courteous and professional.

★★★★★

They worked to create my custom size.

★★★★★

Quality, PROFESSIONAL service, Quality materials...I even had extra pieces 👏 👌...PROFESSIONAL and timely delivery

★★★★★
Very Impressive Deck

I’m just the person to prove this product is foolproof. Very easy to follow and build. I highly recommend using A-DIY. They are easy to work with and they use a great carrier in Estes.

★★★★★
Great Product

Great product and the customer support is the best . Went out of there way to make sure everything was right .

Freestanding pressure-treated wood deck on the lawn behind a modern home
★★★★★
I'm going to be totally honest

I'm going to be totally honest. The end result makes me so happy. My deck is beautiful and sturdy but the installation was frustrating.A shout out and big appreciation to Jay. Once she escalated my problems to upper management, they were resolved and I was a very happy customer. When a business explodes like A-DIY did, some manufacturing oversight gets lost. They promised they were going to do better. Their product is fabulous. My husband and I did not kill each other during installation so that is a big plus. I gave 4 stars because of the initial frustration. The finished deck is perfect.

★★★★★

Directions were good with the addition of the app. Everything lined up and it looks great. The quality is good.

★★★★★
Very easy

Very easy, quality wood. Very, very good customer service.

★★★★★
Very nice deck. 16x16 I put together myself. Great product.

It was a lot cheaper and of the best quality. THANK YOU!

★★★★★

professional, quality 👌 👏 materials

★★★★★
Customer support is great!

They customer support it's great, I had a little issue and they helped me to get it done right away! Thank you!

Pressure-treated wood deck with patio furniture beside a gravel garden
★★★★★

The deck materials were delivered and there was no damage. Nice looking boards and easy to assemble. A little disappointed that 6 divider boards were missing and had to wait 2 weeks to get them to finish assembly, but pleased nonetheless.

★★★★★
Just finished building our 16x20 deck…

Just finished building our 16x20 deck and I couldn’t be happier with the experience from start to finish. Everything we needed came in the kit, even the bit for the impact driver. The only thing we had to supply was the screw gun or impact driver itself. The deck turned out solid and all of the wood arrived in excellent condition.

Stained wood deck beside a travel trailer on a gravel campsite
★★★★★

Overall the project came together but I did a lot of research on building decks before building this deck and I was looking for areas where it said to level the foundation or make sure the whole project was square before moving from one step to another but I felt the directions lacked those caveats. I built the deck for about 2 hours a day after work in the hot sun and between heat exhaustion, heavy beams, and just being a little sick it took about 10 hours or would have if not taking the occasional day off

★★★★★

I got a great quality deck kit at a great price. Assembly and directions were easy to follow.

★★★★★
Great product!

The ease of ordering my new deck, the cost was in line with my budget. The staff was professional and answered all my questions.

★★★★★

The customer service from day one was great. I had not seen the specific size deck I wanted so reached out and the team was very responsive and said it wasn't a problem at all accommodating the size I needed. Absolutely everything needed came with the kit. I didn't need to get anything extra. The build process could not have been simpler.

★★★★★

The deck expert answered all my questions. I was able to track my order easily. When it arrived there was one cracked board. I took a picture and responded to the email they sent asking if the order had arrived in good condition. I received my new board within a week. The quality of the wood was outstanding! The instructions are clear and all the pieces are clearly marked. We have already highly recommended ADIY to our friends. We will be putting it together next week and are beyond excited!

★★★★★
Very easy to assemble.

Very easy to assemble! Greta consumer service!! The price was great! Highly recommend!

Backyard wood deck with outdoor sofa and shade sail under trees
★★★★★
16 x 28 grey composite deck

I ordered the 16 x 28 composite deck in grey, with 39 inch risers, for my front porch. It went together very well. I love it. I am so happy with it that I ordered another 16 x 28 for my back porch. The front is finished except the gazebo and rod iron railings ( which will be later). The back porch is almost finished, and I ordered another smaller deck for my sliding glass door. 5 star.

★★★★★
Composite Deck 16x20 

Great service with a real effort towards the customer. Can’t complain a bit. I loved the approach of “here is what we understand and how we are proceeding, if this doesn’t work for you please let us know, no need to get back with us if everything is ok”. I missed a call or two along the way and this was the approach taken. Information provided in the messages was detailed so I was well informed, I had the opportunity to make a correction if necessary and if all was good then there was no need to follow up. I hate when companies just say to call them back with no info and it was something completely trivial and wasting my time. The A-DIY approach was PERFECT for me as it progressed the order and I was fully informed even if I missed the call.

Homeowner assembling a gray composite deck with dining set behind a new house
★★★★★

Precut and color coded pieces were extremely easy to work with. Good quality material.

★★★★★
I absolutely love my deck

I absolutely love my deck. From the start, the A DIY team was super helpful. They gave me great advice on what size would work best for my space and made the whole process really smooth. The kit arrived in about 10 days, packaged securely in a solid case. One of the parts looked a little damaged, so I reached out and they sent me a replacement t...

Wood deck with chaise lounges on artificial turf under tall trees
★★★★★
Coming along great!

I am almost done assembling the deck kit. I had to stop in between and give a review and share my progress, as I was so surprised by how easy the process has been so far. My wife cant believe that I am able to build a deck myself :). Thank you A-DIY.

Brown composite deck with matching railing beside a white house
★★★★★

Good communication. Easy construction with clear instructions. Looks good, functions great.

★★★★★
I am glad I found your product

I am a single mom to a 12 year old autistic son. I work full time and am always strapped for time and resources. I got this deck up myself! I am glad I found your product.

Person lying on a freestanding A-DIY wood deck on a wooded lot
★★★★★
Great company, great quality

The customer service from the start was useful and very thorough. I needed to see if my space would be a good match for the kit and was guided through the process. And, yes it works and it looks great. The instructions were clear and straightforward.

★★★★★
It went together so easily and nothing…

It went together so easily and nothing was missing. Great quality and satisfying experience.Looks perfect in its place.

★★★★★
It's done

Cant wait for the grandkids to enjoy it now!

Stained wood deck platform in a fenced backyard
★★★★★
Can be built by one person

As a 61-year-old retiree, I was able to assemble my 12 x 24 composite deck completely by myself (on a compound slope, no less). This is a credit to their design team's ability to make the build process nearly "Lincoln Log" esque. The fit was spot on for the most part, and only minor adjustments were needed. Typical of any large construction project. I came up short of a few composite screws and plugs, but their customer service quickly sent me the missing parts. They even reimbursed me for one board I had to replace due to warpage. I saved enough money by doing it myself, it was like getting the hot tub I put on it for free.

★★★★★

I had a fantastic experience from start to finish and can highly recommend this company. The whole process was smooth, professional and stress free. Customer service was excellent, always available, even after the initial purchase and delivery. That level of support really made a difference. The delivery was also great. Everything arrived exactly as expected and in perfect condition. Most importantly, the deck looks amazing. It was fairly easy to install, being this my first ever big DIY project (never used a drill and never worked with wood before). I am extremely happy with the final results and would definitely recommend them to anyone looking for quality products and outstanding service.

★★★★★
Great service all around!

From start to finish the service was great. I was constantly updated on the status of my order and it was delivered on time. All parts were there and no damage.

★★★★★
10/10 recommend

It’s amazing. So easy and quick to put together, super efficient, amazing quality. 10/10

★★★★★
14x14 deck

The deck came beautifully packaged and all in great shape. I printed the instructions and read them a couple times and then we started the process of putting everything together. The instructions were spot on and every piece fit perfectly. It was so easy to build…just like a Lego set. I highly recommend A-DIY! I wish I could add photos but it won’t let me

★★★★★

It saves me a lot of time putting it together.

★★★★★
I love my deck

I love my deck, thanks A-DIY.

Stained wood deck under a timber gazebo with patio seating
★★★★★
It will take two people, but so worth it.

The communication was great during the order and shipping process. The boards were cut perfectly and once we found the video instructions it was fairly easy to assemble. You will need 2 people to assemble the base, but one person can easily finish the top and skirt boards. I also used a sealant because I live in Florida and summers are wicked. It took quite a while to receive my kit, but they updated me quickly when I made inquiries. I have a gravel driveway. The driver chose to wait until the end of the day, to unload my crate so that he could back down my driveway and not leave it sitting on the curb. I really appreciated that. He was gracious and did the best he could to get it as close to the site as possible. The deck is amazing. I love using it. I put a protective pad under my firepit and plan on using it until it gets too hot. 12' X 12' is large enough for 4 Adirondack chairs, 2 footstools, 2 small tables and a small square firepit.

★★★★★
I am far from a handyman

I am far from a handyman but the wife wanted a deck in the backyard and I couldn’t see myself dishing out $20,000 for someone to come build it for us. I ended up seeing an ad for this company and was blown away by the price and ease of install. 2 of our neighbours ended up ordering as well!

Low pressure-treated wood deck on a backyard lawn next to a shed
★★★★★
It comes together

The quality of the material was not compromised and customer service stepped up for a few pcs. that were damaged.

★★★★★
A good project that I did myself.

What made it a project that I could do myself is that everything and the box beams were pre-cut and partially assembled. The step by step instructions left very little guesswork. I think almost anyone could build from one of these kits. The only part that took experience or knowledge beforehand was leveling the locations of the footing pads

★★★★★
Easy peasy

Easy to follow the steps to install. The customer service team was great as well.

★★★★★

We built a full 16x20 deck in one weekend with the A DIY kit. Just me, my wife, and a drill. No contractors, no measuring, no guessing. Every single piece was labeled, organized, and easy to follow. The best part? It goes together like legos for adults. We saved thousands doing it ourselves and actually enjoyed the process. Well… most of it. These kinds of projects definitely test your marriage 🤣🤣 The instructions were clear, the kit was complete, and the results look like something we waited months for… but we built it ourselves. I’ve never seen a DIY product this well thought out and user-friendly. If you want a deck fast and don’t want to deal with contractors, this is it. We are blown away. Thank you for giving us our favorite space in our new home.

★★★★★
Deck went together easy and looks great

The deck went together easily and looks great. Had one little issue and A-DIY made it right fast.

★★★★★

Precut lumber is amazing and makes for fast assembly.

★★★★★
Love mine, Getting another for my parents!

I love my composite deck. The Amazon grey color is beautiful. The assembly of the kit is very easy. Just purchase another one for my parents house.

Gray composite deck with white railing, steps and patio umbrella
★★★★★
Lego!

All the pieces fit together like lego. At first I was sceptical, but once I started assembling the deck, everything came together so seamlessly. I was able to add railings and a step to the deck myself. This is a great product and absolutely love the customer support team.

Pressure-treated wood deck with railing and steps behind a white house
★★★★★

The price was great and the delivery time was great. Will look great once I get it installed.

★★★★★
Love my Deck!

Easy to assemble and love my deck.

Small pressure-treated wood deck in a fenced yard beside a dark house
★★★★★
Customer support is great

My spouse & I built this A-DIY 12 x 16 deck for our Airstream. It took as about 8 hours, that includes level the ground. Customer support is great.

Wood deck with striped sun loungers, outdoor rug and planters
★★★★★
Was a fun project

It was a fun project! I'm no carpenter by any means! I've always wanted a deck for my small backyard but 10s of thousands of dollars will never be in my budget. My 93 year old grandmother stays with me and now she can walk comfortably out the back door and enjoy the outside gathering. My friend and I put it up in a day and a half. We raised it from its designed height and built steps. Everything was in the neatly organized crate!! I didn't see a single board! My friend and I had fun and my Grandma was over the moon. Just need Deck railing and possibly a pergola. The price was right!!

★★★★★
Composite Deck 16x16

This is the only way to go if you're considering replacing your old deck. High quality materials delivered to your home. Comes with everything you need and is pretty easy to construct. I love mine!

★★★★★
Composite Deck Kit 12x16

Super easy and awesome quality

★★★★★
Wood Deck 12x18

Great product. Awesome quality.

Wood deck with black railing and steps beside a white shed
★★★★★
Wood Deck 12x18

Beautiful, easy, one weekend job!

Customer review with four photos of their finished A-DIY deck
★★★★★
Wood Deck - 6x20

Ordering was easy, shipping took a little longer than originally expected, but wasn't an issue. The materials were well packed and protected, assembly was easy. I was able to assemble a 6' x 20' deck myself in a day. Highly recommended.

Stained wood deck with rocking chairs and pink flowers along a white house
★★★★★
Wood Deck 12x18

The deck turned out great. I built it on my own and added a few small custom touches, like stairs and supports for a future pergola. The overall process was pretty straightforward, and I didn’t have to worry about the engineering side of things. All in all, it took about five days, including staining and building the pergola.

Stained wood deck with red-curtained gazebo, lounge seating and hammock chair
★★★★★
Composite Deck - 16x20

Great product. Looks beautiful!

★★★★★
Composite Deck - 12x18

I have been very satisfied with the quality and structure of this deck. I would definitely recommend it to anyone looking to upgrade their backyard!

Gray composite deck with black gazebo and patio furniture in a fenced yard

Order today. Build it the weekend it arrives.

How to Build Your 12×20 Deck with A-DIY

Building a 12x20 composite deck traditionally involves material planning, measuring, cutting, framing, and installation. A-DIY simplifies the process with an engineered DIY deck kit and step-by-step assembly guidance.

  1. Step 1

    Choose your deck

    Select the 12×20 deck and any steps, railings or post kits. Pay in full, reserve for $250 or pick a payment plan.

  2. Step 2

    Receive your deck

    Ships in one crate by LTL ground freight, typically in 10–14 business days. The carrier schedules curbside delivery.

  3. Step 3

    Prepare and assemble

    Level the site and check local permit rules, then assemble with a drill, the included bit and the 3D app. No measuring or cutting for standard assembly.

  4. Step 4

    Covered for 25 years

    Composite boards carry a 25-year warranty and the structure 5 years, with A-DIY specialists a call or chat away.

12×20 composite deck FAQ

Frequently Asked Questions About 12×20 Composite Decks

Still have a question?

Talk to an A-DIY deck specialist

Send a photo of your yard and we will tell you if a 12x20 fits, how high it should sit and what it will cost delivered.