Hey guys, I post so infrequently but I have a question with regard to a certain type of greenhouse material. I'm looking to build a walipini (underground greenhouse) and wondered if anyone has any experience with this stuff . It's a double wall 10mm 4'x12' polycarb sheet. They run around 150 American right now and I was wondering if anyone had any experience with them, and how well they work? Any info at this point would be good, because my only source of data is from the manufacturer. Thanks in advance guys.
Have a look at this thread, see if it has something you can use. The Walipini | Survival Monkey Forums
No experience with earth bermed greenhouse, site not suitable for one, but have had great success with the twin wall poly carbonate on the end of my greenhouse. It is brittle and expands and contracts so I have had best luck drilling a larger hole and putting a screw with a sealing washer over the hole so it can move a bit. There is a tape for the ends that allows it to be vented and yet keeps insects our and the metal fasteners for joining and sides and ends work very well if you again allow for expansion and contraction. The ones I got 10 or so yeas ago had good instructions and they are meant to be followed, not just to be taken as a suggestion.
The double and triple poly sheets work great. I used them on a 24x72 greenhouse in 2001 or 2002 and skinned the whole thing in them. By the time you figure the cost of the Poly Sheets and the U and H channel it gets expensive real fast. That being said the sheets I used are said to have a 40 year life. I am guessing the life will be much longer as they tend to rate the life span based on the most extreme conditions. 17 years in and no major problems or drawbacks with the sheets. The minor drawbacks the cells tend to get condensation in them in high humidity areas and if not allowed to vent out you get mold and algae that will take up residence. DO NOT run a bead of caulk ir other sealer in the U or H channel the sheets have to be able to breath to expel the moisture and they will get hot enough if the cells are sealed to blow the cells open, if the heat can't vent out (Think of a pressure cooker ) Cost wise if you are going to use the structure for a long time they are the lowest cost and most durable option in the long run. Over 40 years I would change greenhouse film at least 10 times at a cost of $1400-$1600 per change so looking at $14,000-$16,000 VD around the same material cost for poly sheets initially, the poly sheets win....... The greenhouses and tunnels I have been swapping film on every 3-5 years are going to all get converted to poly sheets over the next 5 years. I am getting on in years, help is getting harder to find and the maint. that used to be no big deal when you are 10 years younger........ gets to be a big deal. I would suggest anyone new to greenhouse or high tunnels should start with Film and run that its 3-4 year lifespan and see if it is something you will stick with before investing a much larger amount of money into the channel and poly sheets. Walipini's are great if you are in the right environment for them. Used one when I was farther North 20 years ago and loved it. 200 miles South and tried it again and ended up with a covered pond, due to a higher ground water level and considerably more rainfall. It did make a nice stock pond though once the top was taken off
