Making Green Houses

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Michael_Rudmin's picture
Status: Platinum Member (Offline)
Joined: Jun 25 2014
Posts: 772
Securing acrylic

If securing acrylic is a problem, I would suggest mounting the acrylic in a wooden or metal frame, with a double-layered gasket of bubble wrap all around, sealed with silicone caulking if necessary.

The wood or metal can be screwed securely, and can be large enough to securely hold the acrylic. The bubble wrap gasket will prevent a concentrated load.

Krystof_Huang's picture
Status: Bronze Member (Offline)
Joined: Jan 7 2017
Posts: 25
PPPS--correction of

PPPS--correction of correction--I guess it is 1-in poultry fencing I am using for roof or quasi-horizontal regions. 2-in will work and will allow more light but may be less likely to have insulation value.

For vertical areas I do not use poultry fencing, but instead use vinyl film--held down by battens made from ripping studs down to "2x2" = 1.5x1.5. Thus creating 1.5-in spaces between each vinyl film layer. Also, an extra vinyl film runs from top of one 2x2 to bottom of next 2x2. So effectively 2 air spaces are created with each layer of 2x2 battens. (R value maybe 2 per layer.) For strength, I do suggest chicken wire over the final layer, followed by polyethelene or vinyl. The outermost layer will be replaced much more often, thus I suggest the cheaper polyethene--and which also blocks more light so the inner layers will then last the longer. However if you want to impress your friends and family with something like a clear view then use vinyl.

The above "vertical" or "wall" method can also be used to super-insulate horizontal skylights. Skylights usually being relatively a small or limited surface area, chicken wire is not necessary and also would block too much light. So instead, use the 2x2 battens to create multiple air spaces. Oh and rip a 1/4-in thin batten down the center of each sklight for each batten layer. This enables you again to create 2 air spaces for each 1 batten layer. (I can post photos if anyone is interested. Note: no screws needed. Use Lexel to attach everything without making holes in the factory-made skylight.)

(Please note that Lexel caulk is "liquid Lexan" and is much more reliable and durable than "100% silicone" caulk--even though they may look similarly clear in the tube. Also note that under full sun, bubble wrap will deteriorate in a few years. Bubble wrap is thus not a sensible sealing material for acrylic panels which are costly and last for decades.)

If the skylight is fairly horizontal (shallow sloping roof) then in northern climates, one layer of chicken wire is needed under the topmost layer of 6mil vinyl--not for insulation but to prevent a possible snow load from stressing the vinyl film. But it will look much better and be worth it not to use chicken wire--but to spend $60 or so per skylight for thin rigid acrylic panels from Home Depot as the final layer--covered with one more layer of vinyl to prevent aging. In summer, be sure to put opaque plastic over the skylights--not only to reduce heat, but also for the vinyl to last much much longer. Crystal-clear "packing tape" can be used to hold the summer shading. For this temporary use, black plastic mulch or a black trash bag will do, although white plastic will look better and allow a nice bit of light. The ideal summer skylight covering is aluminized mylar "emergency blanket" or "space blanket" often sold for $1 each. This mirror-like ultra-thin mylar reflects all the heat while also allowing you to see out and a bit of light in, and can look impressive if just trimmed nicely with the scissors.

LesPhelps's picture
Status: Platinum Member (Offline)
Joined: Apr 30 2009
Posts: 722
Cement Block Raised Bed Garden

Mark suggested that I share my April 2016 raised bed project.

As background, my wife and I snowbird in South Central Arizona and live in Central Wisconsin.  Last winter, I found these "recreational" raised beds at a community garden in Green Valley Arizona.  I say recreational, because they are obviously tiny. Never the less, they further encouraged me to consider alternatives to wood for raised beds.  

These are made from poured concrete.  I decided to go with cement blocks for a variety of reasons.  First, it saved me from building forms, mixing concrete, etc.  Overall, perhaps, an easier process.  Second, if I ever decide to move or get rid of the raised beds, cement blocks will make tear down easier.

My goals in a garden were low maintenance and comfortable maintenance in an ascetically pleasing garden.  I was willing to invest more time and funds than some might consider reasonable for a vegetable garden, in order to meet these requirements.  Here is what I came up with.

The beds themselves are made of three courses of conventional concrete blocks.  The bottom two rows are typical 8X8X16" blocks with holes.  The top row is made up of 4X8X16" solid blocks, to cover the holes in the lower blocks.  The concrete blocks are not cemented together.  Weight alone keeps them in place.  I covered the walkways with paving stones to minimize weeding and surrounded the garden with a 5 foot tall fence to discourage deer.  Our neighborhood does not have a lot of rabbits, but does have deer.

What I wound up with is a low maintenance garden that is pleasant to maintain.  the height of the beds, makes maintenance and harvesting easier.  The walls around the garden are ideal height for sitting while working on the garden, an important feature for people who are older than the dirt they are working on.

A large part of the effort involved with this project was painting the blocks.  The paint consists of a coat of filler, followed by two coats of paint.  Part of the impetus to do this is that my well water has a bit of a rust tint.  The garden is within my yards sprinkler system, so the garden is automatically watered along with my yards.  I did not want to be looking at rust stained unpainted cement blocks 5 or 10 years down the road.  So, I painted my garden rust colored.  :-)  I will say, however, that, given the way it came out, the effort was worth it, regardless of the well water issue.  People have commented on the beauty of my garden.  That has never happened with any of my previous gardens.  IMHO, it adds to the appearance of my property.

The beds are 4' wide by 25' long.  I will guess that the project cost in the ballpark of $750.

Down the road, I may add two to four more rows.

I'd love to have a greenhouse, but as long as we are snowbirding it is impractical.  We don't get home until late April.  That is too late to start seeds.


Krystof_Huang's picture
Status: Bronze Member (Offline)
Joined: Jan 7 2017
Posts: 25
Suggest Lexel to adhere blocks, flooring, many other things

Very nice raised beds. Just want to suggest using a dabs of Lexel caulk to adhere the blocks. ( = Liquid Lexan "bullet proof glass" = liquid polycarbonate. Also available in gallons under different trade names.)  Not to be confused with "100% silicone" which can look like the same ultra-clear tube but does not have the same properties. "Lifetime caulk" may last a lifetime but not necessarily stay stuck on. Lexel stays rubbery and adheres for decades--thus holds up better than grout, especially flexing against frost heaves when there is no foundation--and at any time can be peeled apart with a crowbar for disassembly. Also much better than traditional adhesives for vinyl floor tiles. Moderate dabs of old Lexel can simply be peeled off--no scraping, sanding or chemicals. Makes it super easy to repair, change, replace or remove. Often favored by professional roofers over silicone.

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