How to Build a Playground: Step 1 – Towers and Bridges
Step-by-step instructions for building playground towers and bridges.
If you’ve read my Design Concepts post, you know that towers and bridges make up the structural components of a playground. So, these are the first parts of a playground that need to be built. In this post, I’ll provide a detailed guide for constructing playground towers and bridges.
By the end of this post, we will have two towers connected by a bridge. The playground will look like this (and for you, hopefully without the snow!):
Or in CAD, at the end of this post the playground will look like this:
This is the 1st post of my step-by-step How to Build a Playground series. You can read the other posts in this series through these links: Step 2 – Deck Boards, Step 3 – Bracing and Blocking, Step 4 – Swings and Monkey Bars, Step 5 – Railing, Step 6 – Rock Climbing Wall and Step Ladder, Step 7 – Step Ramp, and Step 8 – Staining Wood. This series will show you how to build a playground that looks like this:
There are additional posts and a separate six-part series covering the fundamentals of building a playground; you can explore those on my Playground page.
Notching Posts: Overview
I have mentioned this previously: building a playground is essentially the same process as building a free-standing deck. When building a deck, you commonly use notched 6×6 posts, with double 2x support beams running through the notches. That’s exactly what I did for my playground, and what I’ll show you how to do. It’s an incredibly strong and sturdy method of construction as it utilizes the 6×6 posts for load-bearing, and the fasteners used to connect posts and support beams simply secure the two together (the fasteners keep the support beams in the notch, but are not handling the load). Notched 6x6s with double 2x support beams look like this:
You could (and is unfortunately common for DIY backyard playsets) use 4x4s as posts and fasten them together with 2x’s and through bolts. You don’t notch 4x4s, so in this method of construction the load-bearing is placed entirely on the through bolts. In most cases, this is probably ok as a backyard playset probably isn’t handing as large of a load as a deck (think about deck furniture, BBQ grills, and adults on a deck – that adds up to a lot of weight – vs. the comparatively little weight of a few kids on a playset). However, it’s not as solid or safe as using notched 6×6 posts, so I didn’t go down this route. Just for comparison, if you were to use 4x4s connected with 2x’s, it would look like this:
Step 1: Notch the 6×6 Tower Posts
The first thing you’ll want to do, and the most time-consuming due to the woodworking involved, is to notch the 6×6 tower posts. It is very helpful to sketch out and number the posts for notching so you know exactly how each post needs to get notched and where it will go in the tower.
In my playground design I have two towers. Each tower has four posts, numbered 1-4, so you essentially have to duplicate the exact same notching for the second tower. The only difference is the tower on the left, which has an additional post (number 5) for the monkey bars. The following diagram shows the numbered 6×6 tower posts:
When notching the 6×6 tower posts, you will actually notch each post twice. Once at the bottom of the post, and once toward the top of the post. The bottoms of the posts will get connected and rest on the ground – this is an easier alternative to digging the posts in the ground and setting them in concrete. The notches at the top of the posts will similarly get connected, and will be where the joists and deck boards will go.
Below I show all three dimensional views for notching post 1 (this view is of the notch at the ground/bottom of the post). As a reminder, I am using 6×6 posts and 2x10s for everything else. The 5.5″ x 5.5″ measurement is the 6×6 post. A 2×10 is 1.5″ x 9.25″. The 1.5 inch measurement is for a 2×10 rim board and the 3 inch measurement is for double 2×10 support beams.
You will perform the same notching for tower post 1 toward the top of the post. But be a little careful with where you make this notch! Using my playground as an example, I wanted a deck/platform height of 7 ft., which is 84 inches. However, I was using 2x6s for the deck boards (which are 1.5 inches thick). Since the deck boards will rest on top of where the notches are, I needed to subtract the thickness of the deck boards (1.5″) from the desired deck/platform height (84″). So, 84″ – 1.5″ = 82.5 inches. That’s why you see the number 82.5″ in the image below. You will similarly need to take into account deck board thickness when making the notches toward the top of the posts.
One final consideration with the notches toward the top of the posts: measure from the ground/bottom of the post up. A 6″ x 6″ x 8′ is supposed to be 8 ft., but you might find the actual height of the post to be off from 8 ft. by 1/4 inch or so. If you measure where you need to make both the notch for the bottom of the post and the notch for the top of the post from the bottom-up/ground-up, any error in post height won’t affect you. That’s why the arrow in the below picture is pointing from the bottom-up/ground-up.
Here is a complete list of notches required for the tower posts:
To make the notches, you will need a circular saw, chisel set, hammer, and hand saw (refer to my Materials & Tools post for the exact tools I used). Mark all measurements with a pencil and make your initial cuts into the post with the circular saw (be careful of kickback from the circular saw when doing this). Use the chisel and hammer or hand saw as needed to refine the cuts and remove the notches. Depending on how clean the notch cut was, you can use the chisel (and even some sandpaper) to smooth the notched surface.
There are a lot of resources on how to notch 6×6 posts on the internet, such as this how to or this YouTube video.
Once you’ve notched the posts, use a router with a 45 degree Chamfer bit to blunt the edges of the 6×6 posts. Use some sandpaper to further smooth the routed edge.
Step 2: Fasten the Double 2x Support Beams
With the 6×6 tower posts notched, the majority of the hard woodworking for the towers and bridge is done. The last thing you need to do before you can assemble the frames of the towers is fasten the double 2x support beams (I used double 2x10s for the support beams). You will need four double 2x support beams per tower (two at the bottom of the post and two at the top of the post), for a total of eight double 2x support beams for the two towers. As a reminder, these are the double 2x support beams for one of the playground towers:
To fasten the double 2x support beams, take two 2x’s and place one (as perfectly as possible) on top of the other. From my Connectors & Fasteners post, I used six total 3 inch Simpson Strong-Tie timber screws to fasten the the two 2x boards together. I secured the two boards together using two screws at one end (about a foot in from the edge of the boards), two screws at the other end (again, about a foot in from the edge of the boards), and two screws toward the middle of the boards. This image illustrates how to fasten the double 2x support beams together:
You will notice that in my playground, I used double 2″ x 10″ x 12′ support beams on the ground and double 2″ x 10″ x 8′ support beams toward the tops of the 6×6 posts. I used the 12 ft. beams on the ground to add more bracing to the playground frame, as the direction of these beams is also the direction that swinging occurs on the playground. It’s not necessary – I just liked the idea of adding a little more bracing here. You can certainly use 8 ft. beams for both the bottoms and tops of the posts.
Once you’ve fastened the double 2x support beams, use a router with a 45 degree Chamfer bit to blunt the edges of the beams that will face up (you don’t need to worry about the edges that face down toward the ground – they’ll never come in contact with anyone). Use some sandpaper to further smooth the routed edge. While used in the next step, you can also rout the single 2x rim boards in a similar manner at this time too.
Step 3: Assembling the Tower Frame
With the notched 6×6 posts and the double 2x support beams, we can now assemble the tower frame. From my Connectors & Fasteners post, you will need the 7 inch FastenMaster ThruLOK Screw Bolts, the ML26Z and/or the ML24Z Simpson Strong-Tie ML Angle Connectors, and the Strong-Drive SDS Heavy-Duty Connector Screws (1/4 x 1-1/2 Inch). From my Materials & Tools post, you will need both sets of clamps (bar clamps and C-clamps) and the level for posts.
Start assembling the base of the tower first. Place the double 2x support beams on the ground, then square off the base by placing the single 2x rim boards on the ground. Do not screw anything together yet. The tower base should look like this:
Now place a tower post on one of the corners. I will be using tower post 1 as an example. While you can build the vast majority of this playground by yourself, this is one of the rare times that you’ll need an extra set of hands. I had my awesome wife keep the 6×6 post level (using the post level) while I fastened the beams to the post.
The FastenMaster ThruLOKs are equivalent to though bolts – they are the main fasteners that will be keeping the tower frame structurally secure. The 7 inch length is specifically made for notched 6×6 posts. I fastened the double 2x support beams to the notched 6×6 post using four ThruLOKs in a staggered pattern (if possible, leaving room for a ML26Z or ML24Z angle connector). I then fastened the single 2x rim board to the notched 6×6 post using two ThruLOKs (at the top and bottom of the notch), leaving room for a ML26Z angle connector. The angle connectors are really optional, but are a nice way to add extra strength and rigidity to this very important structural connection. This diagram highlights the fastening for tower post 1:
And here is what the fastening of tower post 1 looks like on my actual playground (at the ground/bottom of the post). Note that on one of my towers I was able to fit in a ML24Z angle connector on the single 2x rim board, but on the other tower I was not.
Repeat this same procedure for the other three corner tower posts. The tower frame should look like this now:
With the base of the tower completed, it’s time to do the same thing with the notches at the tops of the posts. You fasten double 2x support beams and single 2x rim boards to posts in the exact same manner as with the notches at the ground. The bar clamps and C-clamps will be your best friends during this part. Slide the double 2x support beams and single 2x rim boards in place, then keep them secured using clamps until you can fasten them to the posts using ThruLOKs.
The tower frame should look like this now:
If your playground design only calls for one tower, then you can move on to Step 4 below. Otherwise, you’ll need to repeat this whole process for the other tower(s). Just be extra careful to make sure you get the spacing in between the towers (where the bridge joists will go in Step 5) correct according to your playground design. Additionally, the tower on the left of my playground had a 5th post for monkey bars – I made the connection between the double 2x support beam and this notched post using four ThruLOKs and two ML26Z angle connectors.
The tower frames should look like this now:
Joists: Overview
Joists hold up deck boards (deck boards are the surface that you’re actually walking on when you’re on a deck). Deck boards run perpendicular to joists, and get screwed or nailed down to each joist.
Joists get fastened to double 2x support beams. There are two ways you can connect joists to double 2x support beams: in-line with support beams or on top of support beams. These diagrams visually show the differences between the two:
I used joists in-line with support beams for my playground. In this method of construction, load-bearing for the joists is placed entirely on the joist fasteners and connectors. It is not as strong as using joists on top of support beams; however, the combination of 8 inch timber screws and joist hangers that I used meant that each joist can easily hold a few thousand pounds of weight.
The reason I used joists in-line with support beams are the numerous birds that inhabit the forest behind our house/backyard. These birds love to make nests under the deck that’s attached to our house, which (like most decks) is constructed with joists on top of support beams. Joists that rest on top of support beams leave a lot of space in between the support beams (that are below the joists) and the deck boards (that are above the joists). Space that birds can use for nests, like this:
Wanting to avoid even more temptation for birds to build nests in my backyard, I opted for joists in-line with support beams for my playground.
Another consideration with joists is how you fasten them to support beams. Since my playground design called for joists to be in-line with support beams, I had three options: I could screw the joists into the support beams, use joist hangers, or use both screws and joist hangers. Since in-line joists place load-bearing on the connectors and fasteners, I opted to use both screws and joist hangers for added redundancy and increased strength.
One final consideration with joists is the spacing in between joists. Joist spacing is actually dependent on the material you are using for your deck boards and the load you want your deck boards to handle. Composite deck boards require narrower joist spacing – usually every 12 inches. Wood deck boards can have joists spaced farther apart – typically 18-24 inches. However, if you are using wood deck boards and want a stronger, sturdier deck/platform, you can use 12 inch joist spacing. I used wood 2x6s for deck boards, but opted for 12 inch joist spacing for the added strength and sturdiness.
Step 4: Add Joists to the Tower
With the double 2x support beams in place on the tower, you’ll want to make markings on these support beams for the joists according to your desired joist spacing. I used joists spaced 12 inches apart, so my markings looked like this:
To actually add the joists to the tower, there’s a nice trick you can use so that you don’t need someone to hold the joists in place while you fasten them to the support beams. Simply screw or nail in two small pieces of scrap wood to the top ends of the joist (one on each side of the joist). This will let you rest the joist on the support beams so that you can fasten it to the support beams. After fastening the joist to the support beams, you can easily unscrew or hammer off the scrap piece of wood. The joist trick looks like this:
As mentioned previously, for the actual fastening of the joists to the support beams I used both screws and joist hangers for added redundancy and increased strength. From my Connectors & Fasteners post, you will need the LUS210Z Simpson Strong-Tie Face-Mount Joist Hangers for 2×10 Nominal Lumber, the 8 inch Simpson Strong-Tie Timber Screws, and the .148 x 3 Inch Simpson Strong-Tie Nails.
First, use the timber screws to initially secure the joist to the support beams. I used four timber screws per joist (for 2x10s, use at least three; four if you want a little extra strength and support), like this:
Second, with the joists screwed in place, you can easily nail in the LUS210Z joist hangers. The underside of the joist/support beam connection should look like this:
Step 5: Add the Bridge Joists
Playground bridges might seem like a difficult engineering feat, but the beauty with this playground design is that the process for adding bridge joists is identical to the process for adding tower joists. The only difference is that the bridge joists now go in between the towers, and get fastened to double 2x support beams that are on opposite towers.
I used a bridge that was 3 ft. wide. It’s a great width for comfortably allowing two lanes of traffic to pass on the bridge, but still making it narrow enough that it seems like a bridge. With an 8 ft. tower deck/platform, a perfectly centered 3 ft. wide bridge would start and end 2.5 ft. from the edges of the tower. With my 12 inch joist spacing, this means I had four bridge joists at 2.5 ft., 3.5 ft., 4.5 ft., and 5.5 ft. Here is a visual diagram showing bridge joist spacing (tower joist spacing is also included for your reference):
As with tower joists, to fasten the bridge joists to the double 2x support beams you will need the LUS210Z Simpson Strong-Tie Face-Mount Joist Hangers for 2×10 Nominal Lumber, the 8 inch Simpson Strong-Tie Timber Screws, and the .148 x 3 Inch Simpson Strong-Tie Nails. First screw them in, then nail on the joist hangers.
After adding the bridge joists, you’ve now completed the main structural frame of the towers and bridge. The playground should look like this (these photos were also at the beginning of this post):
Step 6: Add Joist Flashing Tape
This step is optional, but recommended. In the next post, we will add deck boards on top of the tower and bridge joists to create a deck/platform surface that you can actually walk on. Small gaps naturally occur in between deck boards and joists/support beams. Moisture, rain, or melting snow can easily build up in these gaps, which can lead to wood rot and weaken the playground structure.
Flashing tape is a self-adhering, waterproof strip of tape that is designed to protect joists and beams from water damage and rot. In the picture below, the joist flashing tape is the black strip of tape that runs along the rock climbing wall/step ladder joists:
From my Materials & Tools post, you will need the Flashing Tape (1-5/8” x 50’). Use a step ladder, and simply apply the flashing tape to the top of the joists and support beams. Flashing tape cuts easily with a pair of scissors.
Next Step
Congratulations! You’ve now completed the main structural frame of the towers and bridge!
In the next post, we will add deck boards on top of the tower and bridge joists to create a deck/platform surface that you can actually walk on.
Did you find this guide useful? Have you built a playground or play set? Let me know in the comments below!
Read the other posts in this series: Step 2 – Deck Boards, Step 3 – Bracing and Blocking, Step 4 – Swings and Monkey Bars, Step 5 – Railing, Step 6 – Rock Climbing Wall and Step Ladder, Step 7 – Step Ramp, and Step 8 – Staining Wood.
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