Modern Double Sliding Gate

Estimated total project cost: $350 USD (I did not pay for any cedar, though)

Estimated total project time: 3 days

We live in a mid century ranch (on the left) with a side door that is about 15 feet away from our fenced in back yard. We don't have a door that directly opens into the back yard. We do, however, have both a pre-schooler and a dog - both of whom are independent enough to hang out in the back yard on their own (or together), so long as they are not distracted by the outdoor cats that hang out across the street. I wanted to build a gate across the driveway such that the dog and/or pre-schooler could be allowed to go outside with substantially less supervision than is currently required. Our neighbor's bushes (on the right) provide enough of a deterrent to both the dog and kid, so we didn't really need a fence to run along the side of the driveway, just a gate with full coverage across the driveway.

There were a few design constraints I had to keep in mind when designing this fence. They were as follows:

• My wife wants to be able to move our grill to the driveway near the side steps, but city regulations prohibit a visible grill. The fence needed to be tall enough to hide the grill.
• The maximum allowable height for a fence without a permit is 6' in our city
• Our driveway is quite steep, making it extremely difficult to design a swinging gate that opens uphill
• While we do not park a car in our driveway, the pre-schooler's grandparents frequently do. If I built a swinging gate that opened to the downhill side, our driveway is not long enough to have space for both a car and opening the gate.
• Along the lefthand side of the driveway, the side door steps protrude 2 feet out into the driveway. Along the righthand side, our neighbor's bushes flop over into our driveway space. Sometimes they get a little out of control between trimmings. As a result, I wanted the opening to be centered on the driveway.
• Our driveway is 9 feet wide
• My wife very clearly said, "THIS IS NOT THE PROJECT YOU GET TO TAKE A WELDING CLASS FOR". So....no metalwork.

Based on the above constraints, I decided to design a gate with the following characteristics:

• Industrial - modern design aesthetic
• 5 feet tall
• Centered opening
• Sliding mechanism for gate opening
• Because the opening was centered, I used a double gate. This maximized the size of the opening I could construct.

Tools:

Measurement Basics

• Tape Measure
• 4 ft Level
• Carpenter's square
• T-Bevel (useful for copying angles if working on a sloped surface)
• Cabinet Clamp (not necessary, but makes life easer, especially when working alone)
• Clamps

Power Tools

(Full disclosure, I have completed many many projects with just a circular saw. You could totally do this project with a power tool inventory of just a circular saw and a drill. But here are the tools that I used - and that make life easier)

• Drill
• Kreg Pocket Hole Jig (not a power tool. Also not necessary, but pretty much my favorite little gadget.)
• Miter Saw
• Table Saw
• Hammer Drill with 6 in long, 1/2 in diameter bit (only necessary if you have to anchor posts to pre-poured concrete)
• Palm Sander (for painting / sealing prep)

Supplies:

Anchoring

• 4 Simpson Strong-Tie 4x4 Post supports (I got the kind with the 1 inch offset above the pavement to keep my posts dry)
• 4 5 inch long 1/2 inch retrofit bolts with washer and nut (sold immediately adjacent to the post supports, as these are how you are supposed to attach the supports to your concrete)
• Concrete adhesive

Lumber

• 4 8' long pressure treated 4x4's
• 6 8' long pressure treated 2x4's
• Salvaged interlocking cedar boards (I demo'd a cedar closet and saved these, so I have tons sitting in my shed. If you're buying new and trying to copy this design, I wound up needing about 60 2 ft long pieces of 3.5 in wide cedar for the dimensions of my driveway)

Aesthetics

• Exterior paint (I used a little less than 1 quart of Behr Peppery exterior paint+primer to do a single coat. Two coats would probably have been better, but man I hate painting.)
• Cedar Semi-Transparent Seal (about 1 quart)

Gate Hardware

• 4 unidirectional 2.5 in casters (the one direction aspect is quite important)
• Lag bolts to attach casters
• 4 1/2 in diameter, 24 in long galvanized pipes
• 8 1/2 in diameter galvanized pipe caps
• 12 eyebolts where the hole is large enough for the galvanized pipe to slide through, but not so large that the galvanized pipe has a large amount of play

Misc Other Supplies

• Screws (I used 1 1/4" and 2 1/2")
• Exterior paintable caulk (for sealing gaps)

This could vary wildly depending on where you are putting your sliding gate. In my case, I needed to affix the posts to a concrete driveway that had already been poured (and had been described as "wow, this is super hard" by the guy who cut a hole in our driveway to add an egress window to our basement). I divided the driveway up as shown in the attached diagram and attached 4 Simpson Strong Tie 4x4 supports.

First, I had to drill holes. I used a 1/2 in bit in my hammer drill. Remember - when the bit gets hot, it no longer works as well. Since I work from home, I just spaced this drilling out over the course of a work day. I'd drill for about 5 mins, then go back to work. The next break I had, I'd go drill for another 5 mins.

After drilling holes (note that if you are using a 5 in long bolt, you will need a hole that is deeper than 5 in to allow space for dust, the concrete adhesive, etc.), I installed the posts following this video. (OK, full disclosure, I first tried to do it my way, and I really jacked up the bolt for the post installation. Then I watched the linked video and did it right. Then I had to go to a hardware store and buy a new bolt to fix the first failure. So you should just watch the video and do what the guy says, rather than listen to any advice from me on this step).

Remember how I said our driveway is steep? In a perfect world, I would have installed the Simpson Strong Ties level, but I couldn't figure out how to do that given the location I was working with. Instead, I cut the 4x4 posts at a slight angle on the bottom so that they were perfectly vertical when set in the Strong Tie bracket. From the photos, you can see that I used a level and a T-bevel to mark the angle. Then I cut it with my miter saw.

After cutting and affixing the posts to the Strong Tie brackets, I measured and cut 2x4's to create two nice rectangles for the side panels. I used my pocket jig to attach these butt joints, but there are an infinite number of ways you could probably figure out how to attach them.

Make frequent use of a level in this step - you want to make sure everything is squared up. At this point I also sealed the butt joints with exterior paintable caulk. Not necessary, but I wanted the frames to look as smooth as possible.

For my design, I wanted the far left and far right of the gate to overlay the inner 4x4 posts, as shown in the dimensions figure above. So I measured off the post positions to figure out exactly how large my two gates should be, then cut 2x4's to create appropriately dimensioned rectangles. Again, I attached the butt joints using pocket holes and squared things up using a cabinet clamp.

**Make sure that your gate panels and your side panels wind up being the same height by comparing the heights of your casters to the heights of your post attachment. In my case, the unidirectional casters and Simpson Strong Tie offsets were the exact same height. This was dumb luck rather than careful shopping. But make sure your gate is going to line up at the top with your side panels. It is far less important that it lines up at the bottom, aesthetically speaking.

I wanted to be sure that our casters were meeting the driveway squarely. I used my bevel T to find what perpendicular was at the point on our driveway where the casters would be gliding, set my table saw angle appropriately, and ripped a very thin angled cut along the bottom 2x4 for each gate piece. If you are working on a flat space, this step isn't necessary.

After ripping my bottom 2x4, I attached the casters using lag screws.

At this point, you should have 4 rectangles that look pretty good standing together. Line them up, pull out a level, make sure you don't need to make any adjustments. If you're satisfied, this means that the basic structure of the gate is done. Congratulations.

I wound up needing 15 cedar pieces per panel (60 total). I measured each of my rectangles to figure out what size I would need, then set up a block with my miter saw so I could quickly chop them all to size.

As far as attaching goes, for the gate pieces, I just screwed them in on the back so the sizing was flexible. For the side panel pieces with the big chunky 4x4 posts, I didn't want my cedar to be backset so far, so I ripped some leftover 2x4 to make like a picture frame (shown in the picture) and just attached the cedar to those picture frame pieces instead.

Do some sanding. Then put away all the fun power tools and get out your paint brushes. I used Behr one-coat exterior paint (the color is "Peppery", chosen to match our composite decking material) for the treated lumber and semi-transparent cedar stain for the cedar pieces.

Because I used interlocking cedar pieces (purely by virtue of what I had salvaged. I think this project would have gone just fine with some plain cedar boards), I slid the pieces together and then attached them on the back as shown in step 5. Attaching would have gone much faster with a nail gun, but I was worried about rust from the nails marring my beautiful cedar. It also would have been easier to screw stuff in from the front, but aesthetically, I wanted the screws hidden.

I locked the cedar pieces together (just like in Step 7) and just screwed in the boards from the back to secure them.

This is the real magic. I got the idea from this video, but that guy only does a single gate and it is quite a bit shorter. Because my fence was taller and double, I thought it would be important to have sliders at the top AND bottom - just so the gates don't start flopping around.

You will wind up installing 4 eye bolts into each sliding door and 2 eye bolts into each fixed panel. It is very important that the 3 eye bolts across the top and the 3 eye bolts across the bottom are level with each other, as the galvanized pipe that slides through them needs to remain level so you don't have any sticking issues.

From left to right, a full slider assembly is:

Galvanized cap, Gate eyebolt, Side panel eyebolt, Gate eyebolt, Galvanized cap, with a galvanized pipe running through it all. The caps are very important as they serve as stoppers at each end.

I put slider assembly at the top and one at the bottom of each gate. I am pleasantly surprised by how stable the gate panels are in both the open and closed position. I was worried they would be a bit floppy, but they really aren't. I think it's because of how little play the galvanized pipe has within the eye bolts.

I don't have any great advice here except - take your time. It's important that stuff lines up on this step to ensure smooth operation of the gate.

I purchased a latch for the back side of the gate and screwed it in near the top (out of reach for the pre-schooler). I also purchased gate handles and screwed those in on the front of the gate.

Here are a few more pictures of the final build. The dog is insulted (pictured). The pre-schooler loves it (not pictured, as he is busy playing in the backyard like a "big boy", all by himself).