Double sheeting (dumb) question

Okay, I need somebody to spell this out for me. If you have double-layered your plastic sheeting - just exactly how did you do it? Did you lay both sheets together on the outside of the frame, or is one on the inside and one on the outside?

If you attached one to the inside, HOW? I have a PVC frame, and for the life of me I can't see how to attach it to the inside of the roof, other than to attach wood furring strips (somehow) and staple the plastic to that.

Now don't snicker too much when you reply, please - I know there's probably a very obvious answer, but I'm just not getting it.

Its not funny,I'm asking myself the same thing,and then we get to the fan question......

Yeah, the fan question is next :)

Although I'm thinking that if these layers are separated by roughly 2" (the outside dimension of the PVC plus furring), do you need a fan?

uhoh.....now im confused....im getting ready to start on my greenhouse.....mine will be wood framed...i was under the impression that both layers go on the outside....and the fan is to make an air pocket between the 2 layers for inuslation.....now im wondering, if both are on the outside, how do you get the air pocket to stay if you have to secure the second layer down?.........oh my...i guess i better do some more questioning of my greenhouse guy that knows bout this stuff.....lol....well ill be watching this one.......:)

cindy

Well, I'm heaving a sigh of relief. Ya'll are voicing the same questions I've been asking myself, and hated to ask because...well, geez everybody seemed to know what to do, and I figured the light would dawn one of these days.

Go vols: WZ'S DN, Dennis here.

I've been been replacing our inter-skin of 6mm. poly on the inside of our GH. The last couple of days.

Our GH is built with 2"x4" roof truses with fiberglass on the outside and 6mm poly(greenhouse quality) on the inside to form a vapor barrier and to hold the heat in from our oil stove.

Made some "clips" to hold poly to PVC for the hoops on our raised beds.

Cans send you a pic and instructions, If your interested.
I think you have our Email address......Dennis

Dennis, that would be great! Gee, it's nice to meet ya! We've..uh...heard a lot about you, LOL :)

Oh my! Both poly layers go on the outside. If you put them one outside and one inside (thereby sandwiching your support) the moisture in-between the two layers will rot out your two-by-fours or other lumber. The two layers will not be attached so tight that they will not be "blown up" when you install the fan. (You'd have to practically put them both more than drumskin tight to stop them from being "inflatable".
As for the fan, it mounts on one of the uprights. A slit (or X) is cut into the inner layer and fitted onto the fan exhaust. I a few minutes the whole thing is inflated. (A very pretty picture!)
Brommon, the air pocket will stay because both layers are secured tight. And, for the longest life of your poly you may want some "leaks" here and there to let built-up moisture escape. Some greenhouses have a release vent in their plastic layers (usually farthest distance from the fan) so they can periodically open it to release moisture.

Okay, Shoe - prepare for the onslaught of questions, buddy :)

1. (An observation, more than a question) Since my GH is made from PVC, so unless I had to place wood on the supports, there's nothing to rot, right? Like I said, not really a question I guess....

2. Okay, let's say I put both layers on the outside. Just how big is this fan? (Not much room to mount it in between these layers, I'm thinking...)

3. This means the two end walls are not inflated, correct? Just the top and the side walls? (Since it isn't one solid piece of poly that covers the entire GH, there ARE those things called seams, LOL)

Okay, that's enough for tonight. As you can see, you have several "newbies" who will be ever grateful for some very basic advice and how-to's here - thanks in advance!!!

They sell a two layer poly covering made for inflating. My friend that has commercial greenhouses has it on two of hers. It is more expensive than the regular single layer poly. The fan that keeps it blown up is a small one.I'll try to find out where she gets it from.

Yep, that is very true snowhermit. Wish I'd had known about them before I did mine. However, we ended up putting one layer on, securing it tight. Then throw another layer over it and securing it not quite so tight (however, we really only gave it probably an inch of slack...that plastic will stretch and shrink).

Vols, I was thinking about your pvc also. I'd still put both layers on the outside. That pvc may become brittle pretty fast if confined in the two layers of moisture. Also, for ease of hanging the plastic...it's gonna be much much easier to throw an extra layer over the first layer than it will be to fit the plastic INSIDE the g-house. Just think how difficult that could get. Securing it to the pvc pipes...lots of hardware needed there to keep it from just hanging loose, and a big headache compared to only a matter of a few minutes of installing it outside, then just go along the bottom of your gh and stapling it down.
As for the fan, it is only 6" by 5 " and can be installed in a corner out of the way, even under a table. It has a ring/gasket that comes w/it and secures it to the plastic. (Last I saw they were anywhere from $25-40.)
As for the two end walls...unfortunately my ends are corrugated vinyl, something I'll never do again. When I replace them it will be with double-layer poly. Your end walls will also be inflatable vols. What you do is either buy a "jumper hose" or make one (cutting up an old vacuum cleaner intake hose into 18" pcs). One end of the hose hooks up to the side wall, the other end to the end wall and it allows air to inflate the end wall. Do the same for the other end wall.
Hope I've been good at s'plaining this but if I've only confused you more please hit me again!

This message was edited Tuesday, Mar 26th 11:23 PM

besides Vols you will want to hang baskets of the pipe inside the green house i seen this yesterday and was hoping shoe would come along he's better at explaining things than i am have fun with your new house
dave 719

You guys (and gals) are great! I can see we'll be "tweaking" some things late this summer, before our weather turns cool.

okay, now I'm confused. If I'm going to use bubble wrap instead of using the fan, do all three layers go on the outside????? Sides will be wood.
and we're using PVC for the top, Terry, where did you find clips, I can't find that thread.

i have most of my greenhouses double layered....
if yall want, I'd be happy to do some sorta article on various greenhouse topics.

ohh, and yeah, lay both over the top.

drew

tiG, here's where I got my clamps:

ACF: http://www.littlegreenhouse.com/accessory/pvc.shtml

This place has 'em too: http://www.snapclamp.com/prices.htm (but I didn't need 100 of the 4" ones - I think I ordered 50 or 60 of them, and that seems to be doing the trick quite nicely.)

And here's a "clamp central" site that lists several sources, but to be honest, I didn't find all the links worked, or that all the sources listed actually carry the clamps: http://www.pvcplans.com/pvc-suppliers.htm

I read somewhere if they don't seem snug enough, you can always use self-tapping (I suppose) screws to attach them, or even drill a whole through them, then slide a lag/carriage bolt and attach it on the inside to ensure they aren't going to pop off.)

It took me a while, but I did figure out that indeed, all layers go outside the frame :o)

Look under packing materials in your Yellow Pages to find sources of bubblewrap - I found a place nearby that will sell 1/2" thick x 4' wide x 125' long for $37 + tax. The next-best price I found on the web was 2' wide x 250' long for $36, plus $20-some in shipping (4' wide rolls would have cost $70-$130 in shipping because it was oversized. Ouch!) I'm waiting until I need to make a trip to N'ville to pick it up, as they are open to the public, and have it in stock all the time - no need to make a special trip until I'm ready for it anyway :)

Guys, If you check out the sites that Manufacture andor sell Greenhouses, you can pick up a bunch of information. Crop King comes to mind, but there are a whole lot more. Do a google search, and you'll find enough to keep you reading for ages! (Do greenhouse commercial or greenhouse hobby or you will be wading through a bunch of greenhouse effect stuff, believe me!)

The blower fans cost about 52.00 here and Ive been told will only cost about 6.00 a month to run 24/7.This will be my first winter to go all the way with it. We have it on its own meter and I will let ya know if it holds true.Ive been told by alot of people around here that inflated is the way to go if ya dont wanna spend $$ to heat.Geez Im just kinda worried about those staight line winds.Kinda like having your first baby.Just a little nervous!