Poly Mil vs. Polycarb

I'm on the hunt for a hobby greenhouse kit. I want something that can be heated during winter months... if I choose to do so. I had my heart set on a kit with twin wall polycarbonate covering. I'm thinking this would be the most efficient to heat and be the most durable. Now DH & I are bickering about the cost.

The greenhouse I have now is like the "instant garage". The covering is shot now - but this really has been nothing more than a giant cold frame for me. I've used an electric heater during April & May to keep seedlings from freezing on cold nights. The frame is still good and DH thinks we should just recover this one add a couple vents and a decent door.

I'm not too keen on this idea. He's also questioning the snow load the twin wall can handle. I would like to hear some pros and cons from people that have one or the other. If I were to purchase a poly twin wall kit ... would it be worth the savings in heat cost? I'm stubborn. And it's what I want! I need some ammunition for argument!

Sue,does your "instant garage" have the curved roof or the V roof.Mine, (that is still waiting to go up),is the V kind.I bought the Uv plastic,but I'm thinking that I can get the twin or triple and do a section each year,by the time my plastic is shot,I should have it all covered.I too am worried about the snowload,but if its heated ,it will melt,or ,thats what I've been told.....

It has the V roof. I think it's a galvinized steel frame. The snow pretty much slides off it. It will definitely need new plastic if we go this route. There's a fella near hear that builds greenhouses. I think he makes them with the steel ribs and then builds the ends with wood. If we decide to re-do this one I think I will call him. It will take another 6 years of nagging to get DH to do it. I want to get the project done so I can use it next winter. I need a floor too. Right now it just sits on the ground. I have a tarp down and then lay cardboard on top ... but it seems the weeds make their way into it anyhow.

I'm still investigating what to do about the floor.I want it raised up,but I don't want to go thru the expense of pouring footers and putting cinderblocks up,but I need something heavy to hold it down.One of Chucks freinds had his staked down but the wind blew it over anyhow.I was thinking 4 X 6's with rebar stakes pounded in the ground thru them,fill the area with sand or gravel dust,cover with landscape fabric,and the someone mentioned indoor outdoor carpet.......

CC - Mine came with achors for the ground. Did yours? Their flat and get pounded deep into the ground. When you pull up on them they twist so there's no chance of them coming out. I haven't had any trouble with wind and this has been in the same spot 6 or 7 years.

I don't know,I have not opened the box,the last tree to be cut(this one needed a proffesional)is coming down tomorrow at 9am,We got over a foot of snow today,WHERE IS SPRING???Chucks freind said his was staked down,I wonder if it was with ones like your talking about.

My greenhouse is a "hoophouse" style...metal ribs like poppysue mentioned her friend builds, and I build the ends with wood. I've got the 6 mil poly plastic on it, two layers that are inflated with a fan. On the ends of the greenhouse I have corrugated vinyl, which I'll never use again. Altho it was supposed to last 20 yrs it has become very brittle in only 5 or 6 yrs, and yellows. (Once it is completely shot I'll remove it and put the poly-plastic on the ends.
We've had several good snows on it. It usually just slides off however, it collects on each side and once it gets build-up on the sides (this past yr it was about 3 or 4 feet high) it needs to be shoveled away because the weight pushes in on the plastic.
All in all I like it very much. The double layers really help to keep in the heat, much more so that vinyl would seem to.

Is there anyone here who has the twin-wall polycarbonate glazing on their greenhouse?

I just got a double coldframe with twin wall, and I was sort of disappointed at the quality. It has all the substance of a potato chip, and they sent double face tape to secure it to the aluminum frame. All the time we were putting it together, I was thinking about the stiff wind we get almost all of the time here and wondering how it would hold up.

I was looking at a twin wall greenhouse too, but now I don't know what to think, especially when they want well over $1000 for them.

Comments? Opinions?

the 65 year old green house i have now is glass and is the typical peeked roof style. I have been contemplating rebuilding it a bit a year. heated of unheated the carb honeycomb should hold a better snow load then the plastic sheeting but i have alot of tropical stuff that has to be warm so i heat mine all winter.i want to go with the carb because it is more durable and will last longer than plactic sheeting and will hold up to the local kids throwing stones alot better.(see story at bottom) also the carb is a bit more expensive but worth the energy savings. as my heat costs are $40-$70US per week avg for kero the greenhouse is also 19x23 and about 12 at the peak also the carb should available from a local greenhouse supply for around $80US for a 8x10 spx. sheet.i would have to cut it into 18 inch strips to fit in the groves the glass comes out of. also the ribs are wood and after 65 years alot of the wood needs to be replaced anyway but but anyway i like the carb better

now for the story
a few years ago i was sitting in my greenhouse planting seeds and next to me the glass pops. this i thought was realy wierd but did not think to much about it.then a few min. later it happened agian. i walked out and around the greenhouse just in time to see a kid winging a stone i yelled and took off. after hurdling the first3 foot high fence they (there were 2 of them) took off in different directions as i hurdled the 2nd fence they picked up the pace a bit i decided to go after the heavier one a block later i cought up to him and he folded on his buddy rather quickly after threat to call the cops. then he also gladly gave up his mothers phone number and i made him sit in the greenhouse till i got ahold of her and drove him home and have not had any problem with kids and stones since.

So if I want a glass greenhouse I have to do sprint training first?????