Step 7: installing the greenhouse roof

The roof material is called Polygal; it is plastic with 1 cm by 0.5 cm channels.  There is even a double channel version available if you needed more insulation.  I ran the channels vertically but seems like you could run in any orientation.  There is an outside and inside to the panels, so pay attention when you remove the protective cover.  The outside has UV protection of some sort.  It is held in place by screws drilled through aluminum brackets.  The screws have a neoprene washer to provide a water seal.  Puckett Plants & Green Houses (http://www.puckettgreenhouses.com/) did a nice job of preparing the panels and brackets, although the shipping cost was almost as much as the material.  The brackets or holders are aluminum H-channel to join two (2) panels together and J-channel for the ends.   

There are other roof materials but I have been very impressed with how easy Polygal is to work with and how well it functions.  During kiln operation, you can feel the heat come through the insulated walls while the roof is cool to the touch.  It also seems very durable as it got whacked by a significant hail storm this spring with quarter-sized hail with no apparent damage.

I also put self-adhesive weather stripping between the frame and roof to reduce air leaks although the stripping did make it a little more difficult to slide the roofing panels into the brackets.  I beveled the edges very slightly with a utility knife and the panels slid into the brackets a little easier.
<p>Thanks. Even before your own sawmill, you could purchase green wood from a local sawmill as I did. It is good to support those local businesses. My local sawmill had his own solar kilns and helped me understand how to operate them properly. All the best.</p>
<p>This is so awesome!! I always wondered how you could kiln dry green wood at home without a big gas kiln... if I ever get the sawmill I want then I would definitely build this!! Thanks for posting!!</p>
<p>wow great project. So many people want to build this (including me), but you did it.</p>
Thanks for the kind words.
Could you modify to dry/ fire clay?
Hello - It may be possible but I think it would depend on the temperatures you need to achieve. 150-170 F are the warmest temperatures I have seen to date with this configuration. Another clay artist described a Japanese firing method where they built a fire at the base of a hill and the clay &quot;oven?&quot; extended up the hill. You may be able to use a solar collector in a similar configuration and use the naturally-rising warm air instead of fans. It would be an interesting experiment. You may also want to contact Dr. Brian Bond at Virginia Tech (VT) Department of Wood Science since they developed the wood kiln design and may know of other designs/examples that would suit your uses better. Good luck and send any info on your build.
also one cud use solar powerd fans
wud be good for drying food too
Was thinking of making something like this for drying painted parts in the colder months <br>great job
Good idea. I think the kiln could be used dry anything. PS. I have just ordered a solar panel to run the DC fans and make it completely solar. Good luck on your build.
As they say aboard ship, &quot; belay my last.&quot; I found what I needed here at Instructables. Who'd a thunk it? <br> <br>
Glad you found the information. And in answer to your question, yes, the kiln could be modified to heat other structures. I positioned a side door of the kiln to allow a duct to be constructed to blow heated air into the adjacent workshop, without interfering with any workshop posts or purlins. If I got really fancy, I might blow the air through some concrete blocks to create some thermal mass and direct the air flow at the concrete floor. Many possibilities.
What exactly is a pop can collector? I know I could look it up on line but I would rather hear it from other members of the Instructables family. <br> <br>I am wondering if this unit could be modded to become part of a heating system for a small shop or maybe even a green house.
Cool build! I've seen solar kilns in woodworking mags before but I like the looks of this one better. As I read this I had a thought. Have you ever thought about useing something like the popcan solar heater on this? Depending on the size you could generate more heat and use heat convection to move the air around and maybe not need the fans. Just a thought, but some reworking of the design may be needed for best results.
You and Bob from Kansas Wind Power are thinking alike. A pop can (or soda can depending on where you live) collector would work well, especially if constructed below and in front of wood box. Refer to my reply to sam D. <br><br> I used the metal roofing because it is somewhat easy to remove panels, if needed, and I was able to salvage scrap roofing from a friend's metal roof project.
Gday - great instructbale. I want to build one to dry clothes!<br> Have you thought of placing a cheap / removable reflector in front of the unit to increase the light capture?<br> People are doing this for solar panels - a kiln would make sense too. I have put a picture of a concept on my blog - sorry for relinking! <a href="http://samdidgaf.blogspot.com/2011/08/solar-concentrator-linear-reflector.html">http://samdidgaf.blogspot.com/2011/08/solar-concentrator-linear-reflector.html</a>
Gday also. Interesting idea on the additional reflector. Only my guess but seems like a reflector would work better with photovoltaics than a solar collector. The best answer would be to test with and without.. In a similar vein, Bob at Kansas Wind Power made the suggestion of putting the collector below and in front of the wood container and allow the natural rising of warm air to dry wood and not even use fans.
Good question; I did not mention exhaust. Currently, moist air exhausts through one of the side doors. The VT plans call for vents on the lower side of the back doors. I may need to add vents there also.
Thanks for posting I've been wanting/needing to build a kiln for some time. But I must have missed something, where does the moist air exhaust?
Thanks for compliment; I put a lot of work into it.
That is such a great idea! Thanks for sharing how you built this kiln.

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