Options for insulating small greenhouses

[Rivka]

So im putting in a 4x10 lean too greenhouse against two brick walls of my house, the long side has a sliding glass door on it, o the greenhouse will in a way be a extension of that room.
It is sitting on a painted wood deck, with pretty open slats ei very good drainage and probably upwards airflow.

The exposed sides point North and West the 10 foot side is North. So 2 story walls on the south and east sides. Not perfect, but its what I have.

The greenhouse is build with 4mm double wall Poly, and i am in a 7a area, the winters can get down to freezing for a while and snowstorms can happen, though last year for instance it only snowed one day. but also had 3 days of 15f.

I am probably planning to pulling my orchids back inside the house if it gets like that this year. But as long as i can keep things decent out there, i would like to keep most of them in place.

So what types of things work for extra insulation to make it easier to heat and a more stable temp?

A few things i have read about here and found online, would love folks opinions on their effectiveness

1. Insulation grade bubble wrap good because it still lets light in, does this stuff rally work, and i wonder how hard ti is to keep clean in-between it and the glass, were the bubble protein points, algae hell?? 2 rolls of this stuff would easily cover all poly surfaces. taping the seams of this might be a good thing to reduce air leaking out the top, but might make condensation bad.

2. Reflectix easy to get locally, might this be good for the back wall side? to maybe bounce light back into the greenhouse that hits the brick wall? or am i better to leave the brick exposed cause it could serve as a heat sink and stabilize things?


other ideas?


3. and for heaters, is there a functional difference between types of electric heaters? or is cost just a funtion of durability of they are all listed as "greenhouse" or "outdoor" heaters?
is something like this actually worth the extra money? is it cheeper to run, more safe or capable to run all night and day? than the standard $60 or $70 ones?


4. since we have at least one power outage each winter, fun fun, suggestions on a back up LP heater? I so wish i could run a gas line for this whole thing, but alas i am renting so that is out of the question.

5. general question about airflow, do you think that as long as i seal up the top of the greenhouse well, that i can control the air coming in from the bottom? i can seal that up, cause it is my drainage, and i thought about putting a matt down to slow the air down like astroturf, but I'm guessing that would cause damage to the wood by trapping moisture, so i think i have to let it be open and dry able.

[WhiteRabbit]

good luck!

[Bolero]

You might be surprised but if you can find a way to line it with bubble wrap, the kind you use to pack boxes for posting it does an awesome job of insulating a green house.

[Rivka]

Anyone know if this thicker stuff is any better? Or just a gimmick to charge more? Frankly I'm not surprised it works so well, I have used reflectix a number of times on things to keep heat out and find it impressive.
What I would love is if this larger stuff was dual smooth walled like reflectix is, the exposed bubbles on one side concerns me on both a insulating level plus a cleaning one.

Anyone know of a brand of clear large (or small i guess) bubble wrap that had flat sheets of plastic on BOTH sides?

[Ray]

Tackling the simpler issues first - check out Farmtek.com or other sites, and look for a radiant heater that mounts directly on a gas grill-type propane tank. Simple, cheap, and a single burner will be plenty for that volume.

Unless you're willing to pay a great deal to heat that space, and supplement the humidity in a big way, you're going to have to seal that floor. No matter what you do to insulate the upper part of the structure, if you've got direct communication with outside air, all of your heat and humidity will be going right out that way. Don't forget that you're not only dealing with convection, which keeps warm air up in the structure (something partially defeated by fans), but air conducts heat as well.

The idea behind all insulation is to provide pockets that don't communicate with each other, so that the heat in one can be restricted from being rapidly transferred to others.

Your idea of double-faced bubble wrap is a good one, but I've not seen that anywhere. However, two layers of ordinary stuff - both facing out to the glazing - is an excellent idea and actually has more insulating value than 2x a single layer.

[RosieC]

I've used the large size bubble wrap, looks about the same as the stuff in your link (they sell both sizes by the metre in my garden centre). I think it works well, I find the greenhouse hold's the heat much better once it's in place. I take it down in the spring, wash it with the hosepipe and a garden brush if necessary, then store it in the loft. I'm due to put it back up again soon. I've not really had any problem with Algae.

Only think I wasn't sure from the picture was if it's the stuff that has connected bubbles rather than discrete ones. I think the insulation effect is less if they are connected bubbles than if they are discrete. Mine is a large version of the small bubble wrap with discrete bubbles and that works well.

I agree with Ray however. That floor immediately strikes me as the place you are going to loose a LOT of heat and it seems a waste insulating the top and leaving the floor open. I remember one of our members designing a greenhouse a couple of years back and he put deep foundations as it made a major difference to insulation to have good insulated foundations. Without at least sealing the floor you are going to have problems keeping it warm I think.

[dounoharm]

i agree with all the above comments....you have to do something about the floor or you are spinning your wheels....i use a real heavy duty bubble wrap sold as a solar pool cover, found at any pool supply and cut to fit....i use mine on the outside of the gh, as it was too complicated to drape it inside......gl

[Rivka]

ok well i could agree on the floor in a lot of ways, but im pretty limited because it is a deck at a rental house, what do you suggest i do to slow down air circulation thru it, while still maintaining drainage and not destroying the painted wood?

[silken]

Could you lay sheets of plywood on the deck just for the winter and store them upright somewhere in the summer. Or even large firm slabs of foam insulation would be warmer. Since its not a huge area it shouldn't be too horribly expensive.

I have seen several guys in Europe on this forum who use the bubble wrap on the outside of the structure in the winter. Can't think of his name but we saw lots of pics when he was building his. I think he is from France. Also Kelo a member in Sotland I think here just built a greenhouse so he may have some ideas too.

I think the bubble wrap would work well.

I think its Kavanaru who uses the bubble wrap in france.

[DelawareJim]

If your deck is elevated, your best option is to buy rigid foam insulation, cut it to the width of your deck joists and attach it underneath between the joists. The thicker you stack it, the better your insulation properties will be. Unfortunately, that requires a lot of crawling under the deck on your back.

Cheers.
Jim