This article is an informal walk-through of the steps taken to design and fabricate a Little Free Library with a Green Roof for a client. Hopefully, it is informative for all knowledge/skill levels. But probably the most useful part is how to make a green roof (garden top) that doesn’t create problems by rotting out or leaking into library. Maybe it will help you design and build a little free library with a green roof.


Estimate and Contract Phase

We had a pretty rough idea of what CRWD wanted, as they found inspiration in this Green Roof Free Little Library online. Basically, it was a wood library with angled top planted with Sedum. I did some early SketchUp models so I could think through this piece and figure out materials and time for the estimate.

Once we agreed on the materials and the materials cost, and once I estimated labor, I was able to write up the estimate to their liking. We signed a contract, and now we had only about 3 weeks to get this done.


Design Phase

The first thing we did was draw up plans in Sketchup. They would take a look and respond with ideas about what I should change, like the dimensions or which way the door swings. Some critical things worked out easily in SketchUp were how the steel post interfaced with the wooden library, and how the garden-top would be removeable in winter and route water away all summer. There was some back and forth for a few days, but soon, we arrived at a nice design.

We would use SketchUp throughout the job to make changes and do more detailed design on some elements. For instance, I needed to design a pamphlet holder yet, but it would be easier to design it once the library started to take shape. And since I’d still have to run it by the client, I’d draw it up in SketchUp at that point. So really, the design phase is never really over, it just begins before the fabrication phase.

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Fabrication Phase

The Steel Pole

The first thing we had to get going was the pole, as it would need powder coating. The design was to have the pole 42″ in a cement footing, and sticking up roughly 30″ above grade. The pole was a 3″ square 12 gauge hot-rolled steel tube. I welded 8″ square 1/4″ thick mounting plate on to the top of the pole. There was an identical companion plate I would embed into the bottom of the wooden library. All this I got at Coremark Metals (formerly Discount Steel) in Minneapolis. They are a great company and easy to work with and have an excellent customer service team. Anyway, they have bins of mounting or caster plates of various sizes with holes already laser cut for hardware, so that’s what I used for the 8″ plates.

Powder Coating

I got the pole and plate welded up, cleaned it up a bit and took it on over to Rob Broker at Adrenaline Customs. He’s a top notch powder coater. He cleans up and sand blasts everything, and does a flawless powder coating job that will last. He said I had done more clean up that I needed to. So next time I can be quicker. I got the pole back in a week. It looked nice with the particular black we specked together.

The Box

The next thing I did was build the box. I used 2 layers of 3/4″ MDO Plywood (Medium Density Overlay) so it was going to be sturdy for sure. Another reason I used 2 layers was so that I could nail on the tongue and groove cedar siding with out nails popping through interior walls. MDO is a cabinet grade marine plywood with a resin infused paper face. It’s always flat and doesn’t come warped like more common plywoods. In my region, Menards is a good place to get it.



Corner Boards

After I got the basic box built, I made some corner boards out of Cedar. I could not find 8/4 stock cedar, so I bought 4x4s and ran them over the table saw to get the L shape I needed.  I then drilled some deeper 3/8″countersunk holes to attach the corner boards. Deeper, I mean, so I could wood-plug the holes and 3/8″ because that’s the size of plug I wanted to use. These plugs, you cut from your material with a plug cutter. I got a good one at Rockler Woodworking. Buy a good one, because the plugs have to work just right. Finally, I glued and screwed 3 of the corner boards. The 4th one that the hinge would attach to I left unglued and unplugged because I wanted to be able to mortise out for the piano hinge with a router, and that wouldn’t work if it was attached. But I screwed it on temporarily so I could fit the rest of the siding and the door.

Cedar Siding

I had to match the cedar siding to the style on the building. It was tongue and groove, but had no V-cut. I needed square edges. I could not find anything like it quickly, so I bought the V style at Siwek Lumber and basically remilled the tongue and groove on the table saw, getting rid of the V. I then dry friction fit all the siding, because I would need to bring it to the laser engraver for some detail work, and a laser bed is only so big.


I wanted a really sturdy door. That meant, not using cedar because the frame styles and rails were just a 2-3″ wide. I decided on African Mahogany, which wasn’t cheap but I didn’t need much. African Mahogany is pretty resistant to rot. Not as good as cedar, but pretty good. But it’s a hard, heavy and strong wood. And I was using 5/4 stock so the door would be 1″ thick, not 3/4″ thick. I got this at Siwek Lumber too.

Window/Door Joinery

I have a trick for making window or paneled door frames that just uses the table saw and a tenoning jig you can fashion yourself. Think of the 5/4 stock (finished at 1″ thick) as 16 16ths. From the front of a door stile or rail, the first 6/16″ is the backer (like a fixed bead) for the glass or panel and the 11/16″ left over holds the glass or panel along with the bead that holds it in, whether that bead be wood or glazing. My plexiglass was 1/4″, so 4/16″ more would leave 7/16″ for the bead. So you take your 4 lengths of wood (2 stiles, 2 rails) and either dado or table saw out that 11/16″ off the back of an edge. You end up with a fat-bottomed L shape. Assuming then that you have square ends on these 4 lengths, hold them like your going to attach the end of a stile to the side of a rail, and you’ll see what you need to cut out of the end of the stile to make them nest into each other. You’ll be putting the stile vertically in the tenoning jig and dadoing out that 11/16″ to the depth needed.


I should add that this door had an angled top, so I had a little more figuring to do to dado out the joinery. But, it’s just a little more work. The photo shows the simple tenoning jig. It’s basically a sled around the fence with a vertical that you can clamp boards to at whatever angle you need.

Once I had the stiles and rails fashioned, I used a doweling jig and 3/8″ dowels to join them together. This makes the door very sturdy without doing a full mortise and tenon. The main trick here is make sure the doweling jig is in fact putting the holes exactly in the center, and that since there’s two dowels per joint, they are an exact distance apart. My doweling jig was a bit wonky, so I had to make 2 exact flat shims to center the hole jig. Maybe if it was oiled better, the jig would automatically center, but mine isn’t real consistent.



The hinge, and a bunch of other hardware I got at McMaster-Carr online. They are the best for all kinds of hardware and less common materials.

To make this door real sturdy on the hinges, I used a stainless steel piano hinge because it has lots of screw holes and seals pretty well. The one thing is, be sure you’re getting it on straight by screwing in the end screws first, then closing the door to check its fit. If it’s off, take a screw out and use the next hole up (or down), and repeat. When good, put in all the screws into virgin holes and put the off ones in last.

In my case, I mortised out the door and hinge-side corner board for the hinge. Once I got it attached as described, the door shut well and I could install handle and magentic clasp.

Door Plexiglass Window

This assumes you’ve cut the plexiglass to fit the opening. What I did was lay a bead of silicone in the frame, and put the plexiglass in and squish/suction it down. Then I had African Mahogany strips that matched door wood, and siliconed those in. I used painters tape on door frame in and out so I could minimize clean up.


Rooftop and Garden Tray Top

The garden tray top is removeable, so that it can be brought in over the winter. Under that, the rooftop of the actual library is cedar. I suggested a aluminum sheet over the cedar, but the client wants to see how the cedar will hold up. The aluminum can always be added on.

The angle on the top, or the roof pitch is 6.5 degrees, enough to drain the water, but not so angled the potting soil would want to slide down the pitch. The basic shape of the garden top was that of a slanted tray 2 1/2″ deep inside, with a 3/4″ bottom and sides that extended another 1 1/2″ down below bottom to nest around the roof. The entire garden top was cedar. The bottom was wide enough to require two boards of width, which I dowel jointed together. You could just as effectively biscuit join the top.

The “downhill” end of the garden tray has a scupper to let the water drain out. (A scupper what you’d find on a roof or shipdeck to let water exit a short wall.) It is important that there is no dirt or water sitting in direct contact with the cedar, as with any wood. Over time, even cedar would rot. So the cedar that forms the scupper wall above the gap was faced with a 1/4″ aluminum slat about 1 3/4″ wide. Additionally, I carefully lined the whole tray with 1/16″ EPDM rubber from McMaster-Carr, not unlike the type they use on flat roofs. I folded the corners tidily like you would wrap a present, rather than cut them and introduce a spot for water to escape. The rubber extended through the scupper, being sure the edges curled up on the tray’s inner walls as much as possible, and extending an 1 1/2″ off the end of the overhang. This way, the dirty water would drain well away from the side of the library.

To keep the rubber in place, I captured the top edge of the 3 non-scuppered sides with 3/4″ aluminum angle stock and mitered them at the 2 common corners on the high side. I drilled some countersunk holes and fastened them down with stainless steel screws, making sure the rubber was held tightly and folded up nice at the 2 high-side corners. Finally, I used a little clear silicone to seal up the corners on the aluminum angle miters. 

Library Interior

If any moisture ever ended up in the interior, it would likely be due to condensation. Nonetheless, you wouldn’t want that pooling up. In order to insure that wouldn’t happen, I angled the cedar interior floor at 2 degrees so any potential water would run forward and drip out behind the door. Then I fashioned a pamphlet holder with cedar and a piece of plexiglass. It held the pamphlets leaning back at about a 10 degree angle, still very visible through the door glass.

Laser Engraving

There was a handful of critter icons used in the scavenger hunt that we wanted laser engraved into cedar siding. I had dry fitted the siding for this reason. So I was able to temporarily mount it on backer boards so it would fit onto a laser bed. I had Modest Laser in Roseville, MN do this job and it turned out great for a reasonable price!


The cedar was sanded and sealed with a clear exterior wood preserving finish. The interior had a cedar floor which was also cleared. And the African Mahogany was cleared the same way. The interior walls and ceiling, we painted with an exterior enamel blue that matched their building. I usually like to get these products at Hirshfields Paint. The folks there really know their products.


Pouring the footing around the pole was pretty straightforward. I dug a hole 12″ diameter 42″ deep plus a couple more inches for a gravel base. For this kind of footing, a sonotube isn’t necessary, and in fact, it will be sturdier without a form, because the concrete fills every nook and cranny and sits solid against the dirt walls. The irregularity of the footing will make it sturdier. A sonotube needs to be backfilled and will never be as sturdy unless backfilling is packed in tight. Over time, that will happen of course, but the use of sonotubes underground can sometimes be an OCD issue on part of the installer, and not really help anything. On the other hand, a sonotube does guaranty that the footing is a certain diameter and a certain depth. So, hey, it’s up to you what you think is best.

At any rate, if your footing is to be proud of the grade, then you’ll need a form or piece of sonotube for the top 4-6 inches so that the footing has a clean finish. So maybe, in this case you might as well use a form that extends the height of the hole. Whatever the case, you should cover the cement with plastic to keep it wet for curing.

Completed Little Free Library Pictures

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