DIY Composite Deck Build

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My full DIY composite deck build, reasons I did it myself:

  • Cost, the quoted price of a similar sized deck was approximately double the cost of materials
  • The challenge pulled me in, I’ve never built something this large before
  • Did I mention cost? We’re talking over $10k in savings

Would I do it again? Oh boy, ask me in a couple years, the pain is still fresh. I lost a whole summer to this deck. See the “what I would do differently” section at the end, all of these improvements would help, but this was still a lot of work.

Over a year from start to finish.

October of 2017 we took the old deck down, over 1,000 sq ft of rotten decking, joists and posts. We filled a 40 yard dumpster….twice.

Old decking neatly stacked in dumpster
Almost full with the first load

With the old deck out of the way, we had the yard graded, we often had a small pond after a lot of rain. They added over 50 yards of dirt, the pond shouldn’t come back anymore.

Backyard re-graded
The slate wiped clean
Large puddle in the backyard
Before re-grading, the deck occasionally became a dock

With the slate wiped clean, we had some quotes on building a new deck. Unfortunately that gave me the whole winter to figure out I could build it myself for around half. By January I had submitted plans to the city and had an approved building permit in hand.

New deck CAD drawing

Eagerly awaiting the ground to thaw, I shopped materials and formulated my plan of attack. Done by Memorial Day…no problem.

The all clear from Miss Dig
The all clear from Miss Dig – Thank you!

Despite my can do attitude and apparent lust for hard physical labor, I decided against digging the post holes myself. I was referred to a local guy that was very reasonably priced, I called and told him what I needed, he came out a couple days later and got straight to work. He made 20 large holes in my backyard, we found large rocks, lots of broken brick, some bottles….sadly no doubloons.

Robert digging the holes
Digging for buried treasure

As he finished, I covered each hole with plywood to help keep rain, wildlife and the neighborhood kids out (mine were the most likely to end up in there). The plywood worked well for everything except the rain and wildlife DOH! I rescued a handful of frogs and had to re-dig a couple of holes that caved in from the rain just one day prior to my inspection.

Despite the muck and some additional cave in, I managed to pass the hole inspection based on a promise to dig a couple holes back out to the proper depth – which I did, pinky swear.

With my fresh green “passed” sticker in hand, I quickly ordered delivery of 8,000lbs of dry concrete mix. I reserved a mixer from the local tool rental and phoned a friend. I picked up the mixer first thing Saturday morning.

Pro-tip: the REAL pros pick up their tool rentals as soon as the store opens, so if you go first thing expect to wait in line for a while. My time would have been better spent enjoying my coffee and giving them an hour to sort out the pros.

The concrete arrived just before lunch as did the help. We set up the wheel barrow, covered the path with plywood and formulated a plan of attack. We decided to tackle the far ones first and work our way closer…hours of deliberation at the pentagon couldn’t have come up with much more…brilliant.

By the 3rd or 4th load we really got a rhythm going, one would hoist and dump the bags while the other sprayed water into the mixer. We’d complain about being sore or tired while it mixed, then dumped the contents of the mixer into the wheel barrow and took turns running it into the backyard. We managed to mix and place all 100 bags worth of concrete in the one afternoon. It was satisfying but exhausting work, the neighbors we thoroughly impressed.

I ordered the first load of lumber to be delivered the following Friday. This load had the posts, beams and hardware. As soon as I got home from the day job and wanting to get straight to work, I attempted to haul the lumber piece by piece from the driveway into the back.

My plans called for 6×6 posts, and code in my area requires post holes within 6 feet of the house to be set at the same depth as the foundation. This meant I had more than 10 holes over 8 foot deep. Most of my posts were 10 foot 6×6. These were halved for the posts at the bottom of the steps. I didn’t put one on a scale but I’d guess they’re in the 300 to 1,000,000lbs range.

After nearly dropping one on my foot, I strapped one end to my small furniture dolly and dragged them one at a time into the back. The 2x12s for the beams were heavy as well, but I was able to get these up to my waist and uncomfortably carry them.

Once the pile was moved, I took a break for the evening. A light rain started and continued the whole weekend. I remember working to backfill the first post in the rain and looking up to see my daughter and two of her friends watching me through the window. They wanted to know why I was working in the rain like an idiot instead of driving them to a trampoline place.

First three posts set and leveled
The first 3 posts in place

Once I had the first row of posts set and aligned, this gave me a good reference point to measure from. It did take a while to get the rest in place and back filled. Due to all the rain we had that spring I ended up having to order a couple yards of dirt to finish back filling my post holes.

Setting posts
Setting deck posts in the mud, could be a nice title for my autobiography

Once they were finally all back filled, I borrowed a super fancy, self-leveling Bosch laser thingy. I used this to mark my cut-off line on each post. There were a few that only had a doubled 2×12 beam, so these were notched instead of cut flat.

And yes, I realize this deck will likely outlast the house…

The laser level was magical, it took me less than an hour to set up, figure out my post height and mark every post. I cut the posts with my trusty circular saw. On a 6×6 post this left a 1 inch square in the center of the post that the saw blade couldn’t reach. I finished these off with a hand saw and stacked the scrap out of the way. These made a nice makeshift workbench for sawing, drilling or just keeping tools out of the mud.

All winter I had built the deck dozens of times in my head. Every time, once the posts were in place and cut to the correct height, that’s when things started going quick. My plan was to sister up the 2x12s to make my beams, set them into the brackets on top of the posts, nail them in place and move on to the next one.

Not once in the many times I thought this through did it occur to me how heavy one of those 2×12’s is, let alone 3 of them nailed together.

So when it came time to do this in the real world, I re-measured along the posts to get the real world beam length. Cut each 2×12 to length and set them, one at a time, into the brackets. Adding the 3rd one made things a little snug in the bracket, but I was still able to adjust them to get them flush at the ends and level on the top. I used clamps to pull them together when necessary before driving in the nails.

I opted to buy a decent framing hammer for this project. An old school, manual hammer. While it worked far better than my small general purpose hammer, my arm was getting wobbly by the time I was done driving all the box nails through the post top brackets. I believe 32 nails are required per bracket.

Memorial Day…

Before I knew it, Memorial Day came and went…Father’s day, that’ll be my new finish date…easy. Now that the beams are in place the rest just sits on top, right?

The second load of lumber was delivered, this bundle was all the joists. These are all 2x10s the “short” ones are 12 footers and the rest are 16 foot.

Wood delivery
Wanna come whittle wood with me?

My stack of lumber came with a helper, she really only helped me scare my wife and kids though. Not great at physical labor.

The far section of the deck (relative to where the pile of lumber was dropped) is just a large rectangle. Seemed the obvious place to get my feet wet with throwing down some joists. I laid a dozen or so joists on the beams and marked a rim joist with my correct spacing, for me this was 12″ on center as required by the composite being laid on an angle.

I decided that I’d end nail all 16 joists to the rim joist and then slide the whole thing towards the house. This wasn’t the best idea I’ve ever had. After lots of pushing, shoving, a few flying drop kicks and lots of swearing, the section was nearly in place. Unfortunately all the jostling back and forth wiggled the rim joist loose from the end nailing. So I took it apart and started over. This time I only attached the rim to two joists, one at each end. This held the rim in place while I slid it up to the house, I added diagonal driven nails “toe nailed” in order to better secure it.

I adjusted the rim joist to get the correct gap between the house and the rim. I then attached the rest of the joists, again toe nailing them. With all the nailing, I had to correct the rim joist position several times. Overall this was a better plan than my original.

Other options, that I thought of afterwards are:

  • Blocking instead of rim joist – because I’m not allowed to anchor to the brick facade, my deck is essentially a floating deck. This means the only purpose of the rim joist near the house is keeping the joists correctly spaced and standing upright. This could have been accomplished with blocking. Chopping several dozen pieces to 10 1/4″ would have given me the 12″ on center spacing I was after and allowed me to nail each piece in much easier.
  • Joist hangers – these would have added a lot of cost given the number of joists and are really overkill as the rim joist is not structural. But it would have allowed for stronger nailing and easy alignment. I used these in other areas as required by code, and one place that earned me a puzzled look from the inspector.
Joists installed
Joists, joists and more joists

Father’s Day…

Beyond the simple rectangle I started with was a section that would really test me. In the area near this bump out of the house I had to frame around the chimney and deal with a large cantilever. I set my posts and beam as close to the chimney as I could, but this still left me with more overhang near the house than is “allowed” using single joist framing. To deal with that, I was asked to use doubled joists. You can see that both sides of the chimney get this doubled up treatment. The only exception was directly on each side of the chimney where these are tripled. This is so I could hang the cross piece directly in front of the chimney. In my drawing, this did not rest on the beam. In real life it did, and probably wasn’t necessary.

Joists around chimney
Slightly stronger than the deck of an aircraft carrier…

Once the joists were done, there appeared to be little to no progress for quite a while. I was still making lots of noise, but no visible change. This is because it took me a while to toe nail each joist to the beam, install all the blocking as required for structure and to support the decking at the edges. There were additional horizontal blocks added for anchoring the posts for my railing.

Joists complete
Joists completed
Starting on stairs
Where’s the grill you ask?

4th of July…

And those steps, those %$*&#*&% steps…

Getting the rise and run math right wasn’t too big a deal. But that corner was a nightmare. Hours of searching google for a video, blog or even just some pictures describing how someone, preferably a pro, framed out these style of stairs.

Some pictures I found looked like forms for pouring concrete steps, one that looked like increasingly smaller boxes set on top of each other. There were plenty of outside corner style stairs, but nothing like mine. With sufficient time wasted in contemplation, I decided just to start cutting and nailing.

Getting a piece near that corner with the right rise and run and keeping the necessary thickness to the stair stringer was tricky. This is the piece that appears to be missing the corners in the photo below. I’ll summarize by saying that took more than one try. For that piece, each rise is cut on a compound angle to match the rest of the stringers.

The true corner of the steps was floating in nothingness, so I blocked in that section. With all the stringers in place, this was well within my skill set to put together though all the cuts and measuring took a lot of time. From the neighbor’s house, I’m sure there was, again, a lot of noise throughout the afternoon without much visible change/progress.

Steps complete
I should have paid more attention during stair stringer class
Blocking for border and railing
A beautiful shot of my blocking for the picture framed decking and for anchoring the railing posts.

When I FINALLY finished framing everything I called to schedule my structural inspection. A few days later the inspector arrived. I said I’d grab my shoes and meet him out back. When I got out there he was standing on the framing shaking his head – oh crap.

He turned to me and asked “are you in construction?”


“Well, you could teach a lot of the pros how to do this. This looks great.”


We talked through the plans, why I framed things the way I did. Discussed decking material and layout, railing etc. In the end he confessed he was really excited to see a home owner taking on such a big, complex deck project. He said would really love to run home and grab his tool belt to come back and help. He didn’t. Not only did I pass the inspection, when I later called him to modify my plans slightly to add a second, much smaller set of stairs, he said just to send him the modified drawings and a couple pictures once it was done. From everything he’d seen he had no doubt I would do things correctly. That felt good.


With my second green sticker in hand, I was able to start laying down the decking. I waited a little over a week for the special order to come in. Many places keep Trex in stock, but the place with best price I found at the time didn’t.

Decking test fit
The neighbors were happy to see some grass in the back again

I threw a bunch of the deck boards down to start test fitting. It was designed to have a picture frame pattern. We picked a hickory/mahogany color decking throughout the middle (the field) and a darker border. With the deck being fairly large, I found that angling the field boards just a bit more than 45deg allowed me to almost entirely avoid butt-end joints. I ended up with only two butt-end joints in the field of the entire deck.

I snapped a chalk line and installed the hidden clips along the first plank. It was fairly easy to bow these planks, especially when working with 20 footers in the August heat. Once the first few were installed and tightened down I was able to move a little faster. This went really quick because I wasn’t cutting anything to length. I just had to make sure I had enough overhanging a chalk line I snapped all the way around defining the border location. Once I had the field of the larger half of the deck installed I made a new jig for my circular saw.

Many people have far better descriptions of this jig along with great instructions. One such site is The Handyman’s Daughter. I put some sticky stuff on the bottom of mine in order to help it hold it’s place. I simply snapped a new chalk line where I wanted to cut the decking off, laid the jig down with the edge against the chalk line and started cutting. Very, very carefully cutting.

My First BIG issue

It wasn’t until I installed the second border planks that I ran into my first “big” issue.

Joist bowed out
Looks good, until you notice the nearly half inch of wood showing

The end joist here was bowed out in the middle. It could have been like this originally, or I may have caused it by making my blocking a little too snug. I decided to take the border off and see if I could remove the joist to fix the bow.

Correcting joist bow
Minor cosmetic surgery

With the border out of the way I measured and snapped a new chalk line. After a lot of cursing, prying and hitting stuff with a hammer, the end joist eventually came free. I removed the blocking and cut them to the mark on the chop saw. The railing anchor points stayed in place and I cut them down with the circular saw. Once shortened, I reinstalled the blocking and joist. The border came out much better with a consistent gap. Hopefully I wouldn’t have to deal with that again.

Is he really foreshadowing in a blog about deck building?

The only other place I took a while to get going was at the center of the deck. This is where the border divides the pattern into a mirrored angle. I tried hard to get the ends to meet at the same point of the border to truly look mirrored. I was off by a very small amount, I notice it, nobody else does.

Once I locked in the location of the first mirrored plank, I was off and running. I had to re-snap my chalk border after some rain washed it off.

Installing decking on the second half
Nearly there!!

The Rainy Season

By the end of August we started getting more frequent rain. There were a few weekends lost to sporadic rain that kept the expensive tools in the garage. Between downpours I was able to start on the railing.

Starting the railing
First sections of railing installed

With heavy rain I also spent some time in the basement building a wiring harness for my LED strip lights for the steps.

Wiring up the LED lights for the steps
Wiring up lights for the steps

Once the rain held off for a while, I was able to get a handful more deck boards to finish out the field of the deck. I again snapped my chalk line and very carefully cut the ends off for my border.

Big Problem #2

While I was very careful with my cuts, apparently I wasn’t careful enough with my measurements. On the longest straight cut I was off by one inch at one end.


After contemplating how to address this I ended up, once again, pulling the frame apart to make some adjustments.

Correcting for a bad measurement and cut
More cosmetic surgery

It went a lot faster the second time. Adjustments made, I put the deck back together and finished off the decking and railing.

Completed deck
Nearly finished

Labor Day is gone, into October

Finally, out the summer heat and moving into a cold rainy October. I installed the step lighting and finished the railing on the steps.

Finished deck from the yard

With lighting, railing and even some landscaping installed I called for my final inspection. For the first time, I did not pass on the first try. The inspector pointed out the small area under the railing between steps

Railing issue
Railing issue

On each step, the spacing pointed out in red in the picture above exceeds the allowable space under the railing. I eventually solved this by cutting sections of railing pieces (I believe they’re called the railing styles) and installing them in the bottom of the railing with a sheet metal screw to hold them in place.

Railing issue corrected
Railing disaster averted

The inspector came back, had a quick look and signed off on my completed deck!

What I would do differently.

  • Plan better. I did A LOT of planning over the winter and during the course of the project. Where I failed was finding a good way to integrate help. A couple good Saturdays with a handful of friends could have shortened the time line significantly.
  • Measure the joist lumber. I required 2x10s, which most people realize isn’t actually 2inch by 10inch. But I didn’t realize there was significant variation from board to board. Measuring and marking these would have allowed me to keep consistent sizes together and avoid any waviness in the decking. Because I didn’t check this, I ended up shimming a few places and even shaving down a couple joists.
  • Blocking. I did blocking last, building this again I would pre-cut the blocking and set it in when adding each joist. By doing the blocking last, each one had to be cut just a little different to fit in it’s place. As a counter point, it was a lot easier to toe nail the joist to the beam without the blocking installed.
  • Overhang the border. The picture framed decking looks great, but I used the grooved composite deck boards right up to the edge. The groove is covered by the fascia board. This looks fine, but I’m finding plenty of seeds, leaves, twigs etc like to get caught in between and the winter weather already pushed the fascia away from the deck in several places. The screws holding the fascia in place have a small head to help hide them, this doesn’t provide the holding power of a larger headed screw. I’ll be cleaning out the seeds etc and adding more screws soon.

Some tricks I learned

  • Composite. This stuff cuts smoothly, but it is mostly plastic so the saw dust will never degrade. If the guy at the Home Depot Pro Desk hadn’t mentioned it I would have never thought to use my shop vac and clean up after every cut. A large pile of this stuff blowing around in the yard would be a pain to clean up after.
  • Screw holes. When screwing through the face of the boards, you can hide the hole by sinking the screw below the surface and using a heat gun to warm up the plastic that was pushed out by the screw. Tapping this with a smooth faced hammer filled the hole in and made it blend really nicely. Once I got the hang of this I could make most of the holes almost completely disappear.
  • Hidden fasteners. These make spacing and fastening a breeze, but they were fairly easy to snap if over-tightened. I used the torque setting on my drill to reduce the number of snapped spacers.
  • Installing composite. After setting the first board and snugging the fasteners on one side, leave the other side loose enough to accept the next board. Set the new board in place. Using your foot to apply pressure to the new board, give it a couple smacks with a rubber mallet to fully seat it at one end. Keeping pressure with your foot the whole time, start the new row of fasteners remembering to leave them loose enough to accept the next board. After installing a couple, switch to the far end, again maintaining pressure with your foot and seating with the mallet. The fasteners between the new board and the previous can be snugged up as you go.
  • Installing composite part two. Summer heat can be enough to make these boards easy to bend. Install the starter board when it’s cooler outside if at all possible. This will help avoid bending the board off of straight.

Check this monstrosity of the list….I might need a break before starting the next project.

About Post Author


Husband, Dad, Engineer and Saw Dust Aficionado
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