How to Make a Deck Bench Seat - Built-in Seating to Make Your Deck Bigger

We may earn a commission on purchases made after clicking links on this page.

Intro by Robin
Steps by Ed
adding bench to existing deck

Many of us inherit old decks when we buy new properties. Some are really nice - others are poorly made or designed.  That was the case with our weekend place - our good ol' Mobile Home Makeover project.

We love that it came with a deck - with a covered porch roof, no less.  What we didn't love was that it was not structurally sound, kinda ugly and not completely safe.  We've been working one project at a time to make our old deck better.

This old deck was crying out for a deck bench seat! (It was also begging for a deck extension - you can read about that here.)  

There were a few reasons we decided that adding a deck bench to this existing deck was a good idea - and we're so very glad we did! After building it we realized benefits we hadn't predicted.

First the obvious reasons:

This deck is a pretty good depth - it's as deep as it could be without removing trees.

It should be plenty deep for entertaining, but it just isn't. 

There isn't a railing - so no one could feel comfortable unless sitting a few feet away from the edge.  So we'd end up pushing chairs up against the home and pretty much sit in a line.  Weird for conversation and such a waste of space.  I knew we needed an edge of some sort to max out the usefulness of the deck.

I also wanted to add table seating here to have outdoor meals under the porch roof - for shade and cover from the rain. But there wasn't room for the table and enough chairs to be useful and safe.

The deck bench seat we built solved these problems and more!  If you'd like your deck to be bigger, safer, more useful and more attractive - adding a bench to your existing deck might just be the DIY project for you.

We love how it turned out!  It looks great and makes the porch area perfect for comfortable dining.

The total cost - with railing and skirting - was less than $180.  I think it adds many times that in value to the home. 

deck bench seat
An unplanned benefit: this is now Ed's favourite spot to lean with his feet up and read a book with a cold drink.

deck bench seat diy

How to Make a Deck Bench Seat

Tutorial by Ed

Deck Bench Seat Materials:

10 - 8' x 5/4" PT Deck Boards
1 -  8' x 4"x4" PT Fence Post
2 - 36" Fence Post anchor spikes
5 - 8' x 2" x 6" PT lumber
2 - 8' x 2"x4" PT lumber
6 - 8'x1"x6" fence boards (for skirting)
Deck Screws

1. Make a Mock-up of your Deck Bench

A mock-up of your specific project will save you time in the end.  You can get the size and angles just right - without wasting good material.

The mock-up was super-helpful to decide the seat height and angle for the backrest. Since the whole unit was being grafted onto the existing deck, we also used our mockup to check for structural strength and appearance. Worth the extra effort!

2. Build the Base of the Bench

This is basically a small deck that you are going to build out of 2"x6" and then anchor to the joists on the main deck.  Ours is 70" x 24" - part of that 24" will be overlapped by the existing deck boards.

(Please avert your eyes from the mess underneath.  Broken cinder blocks are what the previous owners used to "support" deck. We've since added actual structural support and just left their mess underneath to hide it.)

3. Anchor the Deck Box Frame to the Deck and Ground

Anchor your new baby deck in place by sistering it up to the old joist with screws/nails. Level it and attach a temporary board (the middle one above) as a support post to level everything. 

Position your Fence Post anchors and push them down by hand as deep as they will go - be careful to keep them straight.

Cut sections of 4"x4" fence post, secure into the post anchor spikes and drive the spikes the rest of the way in using a mallet or sledgehammer.  

The heights of these posts will vary with your ground - ours were between 24"-30" tall. We cut them to the height of the base of our seat - your measurement will be specific to your deck.

4. Add Sloped Back for Bench

plans for a deck bench
So far, most of the work has been structural - which means it needs to be strong and secure, but it will also be hidden, so it doesn't need to be pretty. 

We are now going to start on the parts that people will see, so take your time and get all of your angles correct. I can't tell you the specific exact angle we did for this, because we didn't measure. We simply adjusted the mockup until we found a comfortable angle, then scribed it onto the boards.

This is made with 2"x6" boards, cut to about 4.5' long and anchored to the frame with screws.

5. Build Deck Seat and Railing

how to build a deck bench
This was a test seat, to make sure we were still happy with the height (16") and the backrest angle. We were indeed still happy.  

We attached a temporary top rail to stabilize things while working and to verify the back was level too. 

6. Build Seat Base Uprights

Time to frame the seat. This was done with 2"x4" and was 16" high, but about 22" deep. Remember, about 6" of the back depth will be overlapped by the backrest, so the depth is more like 16" too. 

Anchor securely and add some scab pieces of off-cuts to stabilize until the rest of the boards are in place.

7. Add the Seat Boards

plans for deck bench
Now we are getting some structure. Add deck boards on the seat. Face the bench with deck boards as well.

8. Build Railing Top

bench deck plans
Now for some fancy mitre cuts. Use a circular saw (unless you have one of those gigantic sliding mitre saws). Trace a line and cut the mitre freehand - you're amazing! You've just tied your deck railing seamlessly (almost) into a new bench seat!

deck bench plans
Now do it again! You're still awesome at freehand cutting a mitre. Well done. Attach everything with screws.

You'll amaze yourself at how you can clean up less than perfect mitres with a good sanding.

9.  Finish the Deck Seat Back

Add more deck boards as backrest/ wraparound railing. Use a level and measure thrice! There are lots of stupid angles to keep an eye out for.

10. Build Skirting Around Base of Deck Bench Overhang

building deck bench
We use fence boards for skirting - cut them to size and attached with screws. A big improvement from the wonky lattice.

11. Finish Skirting around the front of Desk Bench Seat

deck bench plan
Mentioned above, but this shot shows the deck boards we attached to cover in the bench better than the previous photo. You're done! Grab a cold drink and a book - this bench seat needs proper testing.

If you're interested in adding onto a deck - here's how we built the deck extension you see above. What a difference these projects have made to how the home looks and feels!

Keep reading for more of our budget DIY ideas!

© Frugal Family Times. Design by FCD.