When designing the honey house we knew we wanted a green roof to increase garden space and replace the lost green space taken up by its footprint. The honey house also faces West and overlooks the bee yard which we felt would make a nice sitting spot in the evenings. This structure is quite small but the roof has a lot of dynamic loads to contend with. In addition to the dead weight of the garden and the decks, it carries the live load of fluctuating water burden and the likes of us tromping around on it when it suits us. Below is the photoblog of the build. Again, we did our research. Make sure you do your own. To do this on a larger scale you may consider seeking an engineer’s advice. Enjoy!
First the trusses were slatted with new 1x4 lumber. These were placed with a gap between each board to allow for swelling. Then the side fascia board was put in using 1x12 screwed to the end grain of the trussses. We had to trim off the end of each truss to get a series of perfectly aligned plumb faces. The fascia board was attached so as to space from the base of the trusses allowing for a depth of roughly 6″ for the the garden soil. We then covered the entire roof with a plastic waterproof membrane designed for green roofs. We got ours from Nilex in Burnaby. It was called the Enviroflex 30mil LLDPE. It was reasonably priced, about 100$ for this project, and so far it has worked flawlessly.
The plastic was stiff and a little tricky to get it to sit nicely. We spent a lot of time fussing with it to get it to fold tidily in to the corners. The towel in the photo above is trying to protect the plastic from injury by the ladder. We clamped the membrane in to place and then locked it down with some capping strips that we milled from 2x4’s. We learned something important here. We installed the membrane in the day, in the sun, and got it all beautifully seated. The next day we came back to work on the roof and found that the plastic had shrunk when the temperature dropped over night. It never re-expanded so now the membrane is pulled off the bottom of the roof at the front. Functionally it works fine but if we were to do this again, once we got the membrane placed nicely, we would weigh down the bottom creases around entire edge of the roof with timbers weighted with rocks. Either that or lay it in to place well after dark. Live and learn.
The excess membrane was then trimmed off and we finished the fascia board joints with some custom made corner caps. The exposed wood was then given two coats of primer while we waited to decide on a final paint colour. We still haven’t decided. We’re open to suggestions!
Then the tricky part! We knew we wanted some sort of deck platform on this roof. We thought for months and months about how to do this without compromising the water seal of the roof. When it came time to build, the solution came to me out of the blue! The decks would just float on top of the roof, held in place by their weight. So simple! Why had I not thought of that in the first place? We designed the decks using Sketchup to ensure that they would sit perfectly flat on the sloped roof and that their weight would rest directly over the trusses, so as not to rely on the flimsy 1x4’s for support. The deck footings rest on strips of rubber that we reclaimed from the horse stalls when the rubber mats were replaced. These worked great as water tolerant soft tiles to disperse the weight of the decks and prevent the membrane from puncture.
Excess membrane was used to fashion a water barrier skirt around each of the platforms. Our hope was that this would protect the wood from direct contact with wet soil. We overlapped the membrane pieces as we worked our way around the four sides. We built one big platform for sitting on and 4 little ones as pavers through the garden for weeding. Then we pre-stained the 2x6 decking and screwed in to the platforms.
Excess membrane was used to fashion a water barrier skirt around each of the platforms. Our hope was that this would protect the wood from direct contact with wet soil. We overlapped the membrane pieces as we worked our way around the four sides. We built one big platform for sitting on and 4 little ones as pavers through the garden for weeding. Then we pre-stained the 2x6 decking and screwed in to the platforms.
We put in two drains on this roof, one on either end of the low end, which punch through the fascia board. I thought we took photos of them but I can’t find them. If they turn up I will add them to the post. For now, refer to the diagram below. In essence, the drains were made with 1 1/4 inch ABS pipe (PVC would work fine too, I just liked the black of ABS) forced through a tight hole cut with a hole saw right through the fascia and the membrane. To keep the drain from pushing through and out the other side, we ABS-glued a straight ABS connector on the garden side of the drain. Then we pressed the connector up tight against the membrane and siliconed it all together. The drains sit about 2″ off the bottom so that there is a layer of standing water on the back of the roof most of the year. This keeps the back of the garden happy.
Once the drains were in, it was time for the garden soil. We did this in layers. First we used shredded wood that came from cleaning up the fallen tree branches around the property. This, we hoped, would act sort of the same way as the wood in the hugels. Then we put in whole branches, again, for the same reason as the hugels. Use dead wood if you can help it. Our green poplar branches grew! We got all of this up on to the roof by way of 5 gallon buckets on long ropes. Ryan would fill the buckets on the ground and I would pull them up and dump them. Worked great. You can really see how the membrane shrunk in these photos.
We made our own soil using a mixture of rotted horse manure and perlite at a 2:3 ratio. This had worked well from a weight and drainage perspective on the garden wall so we went with it. The plants seem to like it so far too.
By the time it came to planting, it was autumn and most plants at nurseries were on sale. We got a lot of plants for not a lot of money. We also took cuttings of sedums and other plants from the wall green roof and around the property. We planted an assortment of different plants, some of which have done well, others which haven’t. We planted a lot of different strawberry varieties, some dwarf blueberries, dwarf sage, dwarf rosemary, some culinary herbs, and lots of sedums, all of which are thriving. We also planted pansies that reseed in the spring and scattered some wild flower seeds and bulbs. There are some dwarf sunflowers and fall blooming perennial daisies that still seem happy a year later. Things that haven’t done well are mosses and other more delicate plants than don’t like the dry heat up there. Since the roof drains to the back, the back of the roof stays damp much longer than the front. We do have to water with a drip hose in the summer sometimes. The drains seem to work well. The roof is entering in to its second winter right now and so far has been holding up well. We get a lot of humming bird traffic up there as well as chickadees and bush tits. We put little humming bird feeders up there and now they are quite used to being up there with us. The roof gives views of the horse fields, the barn, and the bee yard as well as beautiful sunsets. It is, in our opinion, a lovely place to unwind after a long day of hard work on the farm.
The next problem was figuring out a more permanent way of getting up there….
nice photos
Thanks 🙂