Where we last left off, the skeleton of the shed extension was more or less entirely in place, from floor to roof. So let’s jump right in:
I ordered the siding in a big bulk purchase with the longer (i.e. 12-ft) lengths of lumber, the roofing, etc – all the stuff that was too large or unwieldy for my car. Therefore, I picked the siding out from descriptions on the website. I thought I was buying textured plywood that matched the existing structure. I did not read closely enough. What I actually bought was a “Brown Engineered Siding Panel.” (no wonder it was surprisingly cheap…)
These engineered panels seem pretty tough and they have good reviews. However, I was really worried when I first touched them – they almost feel like tough cardboard or fiber board. I’ve witnessed the latter practically dissolve when hit by water.
Although it’s normally a good idea to seal wood projects soon, I was careful to immediately work on these panels to protect them. First, I caulked all the seams and nail holes/heads.
Then everything got a nice coat of Kilz, inside and out (since I didn’t have the roof on yet). I’m happy to say that the panels seem to be holding up really well so far.
This stage is finally when everything started moving a little bit more quickly, not in the least because I was excited about the polycarbonate panels.
I chose these specialized panels (ordered from Greenhouse Megastore) because they advertise “high impact resistance, excellent heat retention and 80% light transmission.” My other option was the standard polycarbonate ridged panel found at most big box stores. I opted against those, however, because the ones I’ve used on chicken coops tend to get brittle after a year or two under the subtropical sun. I’m hoping these hold up better.
As you can see in the photo above, installing them is more complicated than nailing siding to studs, but not by that much. Seal the top edge with foil tape (the silver roll) and the bottom edge with dust tape (the white roll) to keep out dirt and insects. Then plastic caps go on the top and bottom – but before the bottom cap goes on, drill a few tiny holes in it for condensation to drip out.
Panels like these will tell you which side needs to face out (otherwise the protective qualities won’t work) – they’ll have different colored film on either side. On these, the blue side faces the outside world.
Finally, secure the panels in place with roofing panel screws that have self-sealing neoprene washers to keep the water out of the screw holes. If you’re lazy like me, you might not always stop to pre-drill holes, but it’s especially important to do so here. If you don’t pre-drill, you risk cracking your fancy new panel – ditto if you over-tighten the screw.
Place your screws wisely – the more holes you add, the less insulation your panels provide. These panels seem pretty tough, but they aren’t provided structural support. Therefore, the screws are mostly there to make sure the panels don’t rattle or fly off in high winds.
Unless you’ve designed your structure to match the panel dimension exactly, you’ll need to cut them at some point. Fortunately, there are blades designed for this delicate task. You’ll want a fine-tooth blade designed for plastics, plexiglass, etc. to reduce the risk of cracking. This one worked fine for me.
Now onto the roof! (shrieking, gnashing of teeth, general terror)
I read up a ton on whether or not it was okay to install metal roofing over shingles. The most frequent opinion I saw was, “Technically it’s fine, but ideally, remove the original roofing.” I tried ripping off the old shingles, but those suckers held on tight. Meanwhile, the sun beat down on my poor little back and sweat made tools slip right out of my hands. If I wanted to finish the project, I needed to give up on removing the shingles and focus on the new install. (I justified this laziness because it’s an outbuilding. I like to think I would’ve completely removed the shingles on a residential roof.)
Step one of covering up my past is a nice layer of tar paper, tacked down with roofing nails.
Although the above photo makes the roof look tiny (instead of stretching back 12 feet), it does a good job showing how awkward it was to maneuver around. My ladder’s sticking up through the rafters. I have the chicken coop on one side, the resin shed around back, and a fence on the third side. Above, a live oak tree was always trying to smack me in the face with branches. For normal shed usage, it’s plenty of space, but for roof work and ladders, it’s irritatingly tight.
On top of the tar paper went metal roofing panels, secured by the same neoprene washer-screws as the polycarbonate panels. I needed about three little plastic boxes of screws for this whole project, and I chose the 2-inch ones to make sure they plunged all the way through the shingles and plywood.
I chose metal roofing panels over more shingles for a few reasons. First, they’re lightweight and easy to manage. Second, I’ve toyed with the idea of adding some gutters onto the shed and collecting water in a rain barrel to use on the garden. I wouldn’t feel as comfortable doing that if shingle dirt was in the water.
Due to the combination of tight spaces, squishy ground underneath ladder legs, and a fear of heights, the most worrisome part of this whole project was adding the roof ridge. I used the same galvanized metal ridge for the whole shed, including over the greenhouse portion.
The roofing panels extend at least a few inches beyond the edge of the shed on all sides. I also replaced some of the drip edge under the new metal roofing. I didn’t install drip edge under the polycarbonate panels because there isn’t a plywood substrate to worry about. I have some extra, though, if water dripping inside becomes an issue (we’ve had several summer storms, though, and the inside of the shed remains dry).
One of the most recent steps involved repainting the whole shed from tan to light green. The color is “Ballroom Dancing” by Valspar, and I love how refreshing and natural it looks, especially with the white trim and the “frosted” effect of the greenhouse panels.
So am I done?
…er, well, mostly. I’d argue that construction/projects and writing share something in common: they’re only ever done when you decide to stop working on them. I’m frequently going back and tweaking existing projects, just as a writer will return to revise a piece over and over.
In terms of this project, there are a few smaller things that need finishing. If you look carefully, you may notice missing fascia (the horizontal facing board) underneath the greenhouse roofing. I’ll need to add that at some point to keep out critters and to help insulate the shed/greenhouse a bit better.
I also need to go back and seal up the areas between polycarbonate panels, the meeting point between the metal and polycarbonate panels, and the gaps between the roof ridge and the panels. For larger spaces, I have sealing spray foam – that stuff is messy, but I love how easily and quickly it fills gaps. Then, for the smaller spaces and perhaps over top of the spray foam, I’ll use clear silicone caulk. Manufacturers of polycarbonate panels will specify which sealants can or cannot be used with their products – make sure you check before buying!
As far as the inside, I’m working on that as I go. The first thing I knew I wanted and needed were some nice shelves for potting and storage. Fortunately, I overbought plywood, so those were relatively easy to whip up and put in place. I also had spare shelf brackets from an earlier house project, which certainly helped.
It’s not perfect, but it’s functional and I love it.
Future ideas for the inside include building more shelves (whoo, storage) and maybe a flip-down workbench in the “shed” part of the shed. I’m also considering adding some plastic sheeting to separate the shed from the greenhouse and concentrate the heat and humidity in the latter portion. However, as it’s still summer and highs are around 90F, I have some time to get there.
Overall, this shed extension/greenhouse addition was a monster of a project. Summer was not the time for this kind of build in south Louisiana, but I’m glad it’s (mostly) done. My “new” shed is extremely spacious. I no longer have to worry about balancing trays of seedlings on scanty window sills inside my house, where one of my cats could easily take a wrong step and flip potting soil onto the floor. I’d say that alone is a win.