How to Build a Wooden Foot Bridge

Video Transcript

Video Transcript

RON HAZELTON:
Well, today I'm headed to Eureka, California to visit Star and Esther Killian.
STAR KILLIAN:
This is it.
RON HAZELTON:
Well, I can see the problem. I can imagine water rushing through here and also, these banks -- I guess you were telling me, get really slick, huh?
STAR KILLIAN:
Yes, absolutely.
RON HAZELTON:
We don't want to be climbing up and down those. All right. Well --

I have a pretty good idea of what kind of bridge will work best here. It will rest on four concrete blocks or piers, two on each side of the creek. The piers will support two long beams on top of which, we'll place wooden treads or planks. Finally, we'll add a railing.

Why don't we start by pre -- preparing the ground here?

With shovels and hand tools, we begin leveling the ground where the piers will rest. The soil is moist, so the digging goes quickly. Then, we drop our first concrete pier into place.

Did you guys see that little torpedo level anywhere?

We check to make sure the first pier is level.
Not bad, huh?
STAR KILLIAN:
Ohh --
RON HAZELTON:
Huh -- for an eyeball?

Then we dig for the second pier, set it in place and check to make sure it's level with the first.

Wow, I'd say that's close enough.

Now we cross to the other side of the creek and get ready the set the two remaining piers.

Just set that right on top of the pier, would you? And just clamp that --

To locate their position, we lay the ends of two 12-foot planks on the piers we just installed, and extend them across the creek, measuring to make sure the planks are parallel.

Once in position, the ends of the planks will dictate where to locate our second set of piers. A little more digging and leveling and the remaining piers are ready to go.

That looks about perfect. Okay, great.

With all four piers in place, we're ready to build our support beams.

Okay, let's glue this up.

The beams will be 4 x 6 timbers that we'll make ourselves by laminating two 2 x 6's together. First, Star and I apply construction adhesive to the face of one plank, then set a second plank on top.
RON HAZELTON:
Okay, so we've got two pieces of 2 x 6 now that we're going to sandwich together, first with the glue. Now I'm going to bolt these together with galvanized bolts.

Star drills holes every 24 inches. I follow behind, injecting silicone, which will coat the holes and keep water from leaking in and rotting the board from the inside out. Now we drive in the carriage bolts. This combination of adhesive and bolts will give us a strong, stable, warp-resistant beam.

Which way -- we'll go this way? Okay. Okay, time to put some galvanized washers and nuts on these carriage bolts.

We tighten the nuts until the washers just begin to compress the wood.

Do you have any animals on the property?
STAR KILLIAN:
We have an occasional bear --
RON HAZELTON:
Bear?
STAR KILLIAN:
-- and a mountain lion's been spotted up in the back hill.

RON HAZELTON:
All right, let's drop it down.

The piers have metal straps for attaching the beams. After clamping the beams in place, we insert a drill bit into the hole in the metal strap and bore all the way through the beam. A little silicone in the hole and we can drive in our bolts, screw on the nuts and tighten them with a socket wrench. We've purchased pre-cut posts for our railing supports and clamped them temporarily in place.

You know, these pre-cut posts were a great find. Already knots in the bottom, already got champers on the top. And this has made this installation really simple. So let's clamp this on.

We secure them to the beams by once again, drilling clearance holes, injecting silicone and installing carriage bolts. Now we're ready to start on the treads or surface planks of the bridge.

Esther, let's measure the width of these beams now. Start over here at this end, run the tape measure across to the outside. What are you getting there?
ESTHER KILLIAN:
Thirty four.
RON HAZELTON:
Thirty four. Okay. I want to make the treads like an inch longer on either side, so they'll overhang. So 36 inches. Let's go cut some.

I give Esther a few tips on using a circular saw and pretty soon, we have all the treads we'll need.

Now we can make this bridge a bridge, make it walkable, huh?

We're careful to make sure the tread overhangs both beams equally. Then Star attaches it with rust-resistant deck screws.

Our second board here, we're going to have to notch out to fit around this post right here.

To do this, I first line up my speed square with the post.

Put it up against the post, then bring it back just a little bit because I don't want that actually too tight to fit there. This is a spacer. I want to put about half an inch between these treads right here, and that's so that the leaves and debris won't collect on there.

And then we can take our straight edge, run it right along the side of the post -- back it off just a touch and draw this line, okay. Now what we've got is this section right in here, that we're going to cut out. So let's --

The notched-out boards fit nicely into place.

What a team, huh?
STAR KILLIAN:
Yeah.
RON HAZELTON:
We're going to be across this bridge in no time.

After we attach the treads, it's time to coat the cut-ins with wood preservative.

Well, there you go, folks. Who wants to be the first to walk across? [LAUGHS]
ESTHER KILLIAN:
I do.
RON HAZELTON:
Okay. Esther, you go first. Brave, too. I'll come right behind you. Feels pretty good, huh?
ESTHER KILLIAN:
Mm-hmm [AFFIRMATIVE].
RON HAZELTON:
Now that we have tested the bridge, it's time to install the hand rails.
RON HAZELTON:
Okay, Esther, over the top.

Earlier, I drew a line on the post, marking the height of the hand rail. We use a clamp to hold the hand rail in place and secure it with rust-resistant screws.

This really is the last time you have to go into the gully, Esther.

With the last plank in place, and the last screw driven, it's time to enjoy the fruits of our labor.

What a great way to cross this creek and what a perfect spot to watch the sunset. Nice job, guys.
ESTHER KILLIAN:
Well, I can hardly wait to show my neighbors.

Learn how to laminate beams and assemble decking and rails for a woodland footbridge.

Homeowners want a footbridge to help them cross a deep ravine on their property. When the area is dry, crossing the gulley at the bottom requires a hop, but rains and runoff can add slippery banks and rushing water as additional obstacles. Consequently, the bridge will be high enough to avoid the steep banks and any flowing water. Built of laminated four-by-six support beams, pre-cut posts, decking and side rails, the 12-foot length of bridge will span the gulley resting on heavy block piers.

Level the Ground and the First Two Concrete Support Piers
Step 1

Level the Ground and the First Two Concrete Support Piers

Use shovels and hand tools to level areas at the four corners of the bridge for supporting concrete blocks/piers. Position and level the first two piers at one end of the bridge using a bullet level and a bar level.

Use 12-Foot Planks to Position Piers on the Opposite Bank
Step 2

Use 12-Foot Planks to Position Piers on the Opposite Bank

Clamp 12-foot planks to the first two piers, ensure they are parallel and mark the other ends as locations for a second pair of piers. Level the ground, position and level the piers, and temporarily clamp them to the planks.

Laminate Two-by-sixes into a Pair of 12-Foot Support Beams
Step 3

Laminate Two-by-sixes into a Pair of 12-Foot Support Beams

Apply construction adhesive to a 12-foot two-by-six plank and clamp another on top. Pre-drill for carriage bolts every 24 inches, inject silicon into the holes, drive in bolts, and secure them with washers and nuts on the opposite side. Repeat.

Bore Holes in Beams for Attaching Metal Straps on Piers
Step 4

Bore Holes in Beams for Attaching Metal Straps on Piers

Position footbridge beams on piers and drill holes into the wood through the metal strap on each pier. Add silicon to each hole, drive in a carriage bolt, and secure it with washers and nuts tightened with a socket wrench.

Position and Secure Pre-cut Railing Posts with Carriage Bolts
Step 5

Position and Secure Pre-cut Railing Posts with Carriage Bolts

Temporarily clamp pre-purchased railing posts in position along the footbridge. Pre-drill holes, add silicon waterproofing, hammer in the bolts, and secure with washers and nuts.

Measure and Cut Treads for the Bridge Deck from Two-by-sixes
Step 6

Measure and Cut Treads for the Bridge Deck from Two-by-sixes

Measure the distance between the outer edges of the two beams for tread length and add two inches for overhang. Center the first tread across the end of the beams, pre-drill holes, and drive in rust-resistant deck screws.

Notch Treads as Necessary to Fit Around Railing Posts
Step 7

Notch Treads as Necessary to Fit Around Railing Posts

Use a speed-square to mark cut lines on planks that butt into railing posts and notch them with a jigsaw. Space all planks 1/2 inch apart, pre-drilling and securing each while working across the bridge span.

Coat the Cut Ends of the Treads with Wood Preservative
Step 8

Coat the Cut Ends of the Treads with Wood Preservative

Use a paint brush to liberally coat the cut ends of the deck treads with wood preservative to prevent moisture from promoting wood rot. Walk on the bridge to test its sturdiness and balance.

Position the Garden Bridge Handrail and Secure with Rust-resistant Screws
Step 9

Position the Garden Bridge Handrail and Secure with Rust-resistant Screws

Position and clamp a handrail to the railing posts and secure it with rust-resistant screws. Repeat this process for the other side of the trail bridge to complete the project.