I was going to do this but while at home depot I found a product that is basically bubble wrap with aluminum on both sides. I figured this would look nicer, reflect more light and be easier to work with.
I bought a 2ft wide roll and cut peices to fit on the bottom half of the greenhouse. I doubled each section up so that it is insulated better. Then I just put them up. The sections fit perfectly between the metal vertical ribs I have. (I have a cross country greenhouse and the ribs are 2 ft apart)
The peices just stuck between the ribs perfectly so I didn't even need to screw them in place or anything.
I just put them up yesterday and need to buy more as I only bought enough for half the greenhouse, as I didn't know if I was going to double up the pieces or not. I am hoping that the reflective properties will help reflect heat during the summer and keep the heat in during the winter.
It came on a roll and they had 2ft and 4ft wide rolls. It was SO much easier than trying to fit a HUGE section of the styrofoam in the car and I put the pieces up in about 10 minutes.

I think this is the product we bought
http://www.radiantbarrier.com/tempshield_single_bubble_double_.htm

It doesn't have as good as an R value as the syrofoam, but I assume that this isn't doubles up like mine.

-renee

We get a lot of sheet foam used as packing at work. I'll cut ti fir and layer it fir insulation.

Orchiddude, I looked at the styrofoam panels but opted instead for the 1"-thick foam panels, foil-faced on both sides. We put these up on the north wall and the north one-third of the east and west walls (I used a polycarb panel as a template). It has held up very well and is a matte-foil finish so is reflective without being blinding.

Someone posted a clever way to add this to the ceiling as well, substituting longer bolts for the short ones that come with the greenhouse so they can go through the foam to secure it to the ceiling.

Diane

I think the best thing to do is use both foam AND the bubble wrap/aluminum stuff. I think the bubble wrap product is good, but I doubt it can have the R value of an inch or two of styrofoam.

The foil faced foam is polycyanurate. It has a great R value (better than regular foam) and is an excellent choice too.

Stuart

"I was going to do this but while at home depot I found a product that is basically bubble wrap with aluminum on both sides. I figured this would look nicer, reflect more light and be easier to work with. "

Interesting posting Orchiddude.Never thought of that.Been thinking about putting a layer of clear plastic up,I would create a 3 inch insulation space between the polycarb and the plastic-but this styrofoam idea sounds pretty cool.I used some of that stuff when I insulated a wall area here in the house and was very easy to work with.

Mark

This is precisely my plan for this winter, but I plan to use the foil-backed polyisocyanurate board instead of styrofoam. SB

Well the idea hit me square in the head while at lowes. I was wondering around and ran into the insulation stuff. Now my gas bill never goes over $90 a month but I got to wondering that if I insulated my north wall, could I get my bill down to $75, or raise my temperature to 65°F. So, I looked at the R-values on this stuff and I found stuff anywhere from 5 to 15. I found 1 inch styrofoam sheets and 2 inch sheets. The 2 inch sheet were $22 each. OUCH!, the 1 inch sheets were $9 each. I am going to look on the internet and see where else I can find this stuff. I worked in retail for 15 years so I know markup when I see it. These babies are MARKED-UP.

My plan was to get these 4x8 sheets, I think I need 6 or 8, and place them between my poly and the metal frame. Now in order to do this, I would deflate my house, slide the sheets into place and then blow the house back up. This would hold the sheets in place and create a styrofoam wall. If I place 2 sheets on top of each other, I can get an 8 foot wall, that would carry it almost to my ceiling, of 9 foot. The beauty of the styrofoam is you can wet it down and it doesn't matter. I looked at other types of boards but found that most had paper or some type of pressed material, if wet, this could be a mess.

The more I think about this the better I like it. I am going to try it and I will post pictures when I get it done. I have my data on gas and heating for the last 5 winters, so I can compare and see if there is a difference or not. With gas the way it is these days, you have to do just about anything to keep your hobby alive. :-)

I've been telling people here to do this for 6 months or more, and got told I'm a git for my troubles... So why do people listen to orchiddude with baited breath and not me?

btw, you could just buy twice as many 1" thick pieces and glue them together. If you stagger the blocks you'll reduce the thermal shortcircuit through the joins.

Nathanhurst....LOL, Its ok, I really think they listen to you, with all due respect, sometimes you come across a bit more on the technical side than most people want to deal with. But its ok, we need people like you to keep us in line. :-)

I'm a do it your-selfer type of greenhouse guy, I think most people like to see it working and not just hearing that it will work. Keep tossing out the ideas.

It is refreshing to see some new interest in greenhouse insulation and construction as winter looms. (Ignore the Aussies and Kiwis, in a couple of months they will be talking about shade cloth and swamp coolers!)

Without being really boring by going into all the math stuff I think it is worthwhile for people who are adding insulation to do some numbers.

We have all seen and used those "Greenhouse heat loss calculators" and they do work! They work for standard shaped structures, with uniform coverings and tell you what size heater you need.

Anyone who is really interested in this stuff can then expand on the theory and work out where to best spend money on more insulation.

For example, insulating the north wall to R3 may cut your heating cost by 20%. Spending three times that and insulating the north wall to R10 may cut your heating cost by say 22% Is that extra 2% worth the additional cost?

As I say, we ain't going into the math. But if you are serious calculate the heat loss through every wall and roof section and you will see where sometimes a little insulation makes a big difference to your heating requirement then adding more changes it slightly.

I did the math for mine, and throwing more insulation at the walls is going to give me no real noticable change in heating requirement. There is an "optimum" cost vs benefit level of insulation.

P.S.
"btw, you could just buy twice as many 1" thick pieces and glue them together. If you stagger the blocks you'll reduce the thermal shortcircuit through the joins."

Um Nathan, that staggering the blocks to stop a teenie weenie amount of heat escaping is insignificant when you look at the heat screaming out of the south poly!!!!

LOL Chris....Um Nathan, that staggering the blocks to stop a teenie weenie amount of heat escaping is insignificant when you look at the heat screaming out of the south poly!!!!

Your right Chris, the math should be done. I am going to do it for mine, and if I can save 20% on a $90 gas bill that will be a savings of $18, with an end result of $72 a month. I could turn the temps up.

I will work the math on my house and post later today.

chris, yeah, I agree, although if you want 2inchs, with those numbers, getting double in 1inch would be cheaper, and if you are going to do that anyway, then staggering is little extra work.

I've found the most significant effect for heat loss in my greenhouse is air gaps. Even a 1mm gap around a 2' square vent is nearly 4 square inches of air leakage, which is is enough to make a huge difference on your heating bill.

You may be able to find good thick foam pieces near you if you have a Recycle-Rebuild It Center -- our center has a huge stack just sitting there for cheaps.

Recycle-Rebuild It Center

I think nathanhurst is right on the money about air gaps. All the insulation in world won't make much difference if air is blowing in all over the place. One of the reasons that I think my pool cover makes such a big difference is that it blocks any little gaps that I may have missed.

There is one point that needs to be made here. The object of insulation in a greenhouse is not to seal the house up so tight that it cant breathe. If anyone burns a gas heater, that heater needs air. It doesnt need that much but its all based on the size etc.... So with that understanding, one needs to besure they have an air inlet and outlet. If you use some other type of heat source, then you might want to tighten up your greenhouse.

I think aslong as one understands all the elements to the puzzle, then one can understand how to work the puzzle.

Interesting comment there on sealing against drafts, and the need for air. My decision to buy a heater that uses outside air for combustion may prove to have been the best one after all, as we seal the GH for winter.

We used 2" thick Type 250 foam to insulate under the floor, and 2" Type 150 for the kneewalls and beyond, on the ground and out about 2 ft.

(Over 1/2 inch mesh hardware cloth that extends from under the kneewall, out about a foot. I'll have no critters in my GH, unless invited)

I've done some experimenting with foam scraps and discovered that its quite paintable. So far, I've tried several paints and found that priming with Zinzer white shellac works to both seal the foam and present a fine surface for the finish coat; just as it does for stained ceilings.

So: What about thick, dense foam panels, cut to fit between the "studs' or whatever uprights are in the GH, sealed with a really good primer, then painted an easily washed gloss white, or even gloss reflective silver?

I admit that I'm as much into asthetics as anything else, and if the white would do pretty much the same job, I'd use it.

Nathan: comment please?

You led us into weeks of digging, hauling extra materials and insulating down and out, and as much as it delayed our getting my Cross Country up, I'm grateful for your insights, because the extra time and work should prove more than worth it in the end.

So how about some insight on colors?

I agree you need air, but you need very little compared to most greenhouses. Especially if you have a 'ventless' heater. Commercial growers often seal their greenhouses and burn something to provide the required CO2, but to do so requires good CO2 monitoring equipment to prevent killing your plants with CO2.

birdwidow, yes, taking outside air, burning it and then venting _through_ the greenhouse is probably the best solution. Even better (in very cold climates) is to recover the outgoing heat by heat exchanging it with incoming air. You can build such a device using 'fluteboard' or whatever it's called (the cheaper plastic they use for signs, much like twinwall PC) stacked in lots of layers.

Not worth the effort in my climate.

Nathan:

The gas heater I chose for my GH does the heat exchanging in its double chambered flue.

But I would still like to hear your opinion regarding the notion of painting insulating foam panels, and if white would do as well as silver, or nearly so.

re: heat-exchanger flue: nice.

white paint is negligably better than black paint for stopping heat transfer. To stop thermal emission you really do need metal. I wonder if you could glue al-foil on easily enough.

Nathan: Yes, I could glue alum. foil onto the foam panels.

I even know where to buy especially heavy duty, extra wide foil, that would eliminate seams on 2' wide panels and hold up well: Restaurant supply store.

But, in an asthetic passion for my new GH; may I ask if the aluminum must be exposed to effectively stop heat transfer?

Would it work as well, if the foil was then covered with something more attractive?

Also: is the thickness of the alum. an issue? Would lightweight alum. sheetmetal work even better? Or does it make no real difference?

You did say heat transfer; not reflection, or am I confusing them?

It's just occured to me, that I may have asked a foolish question about aluminum and covering over it.

The foam insulating panels sold for use under siding are aluminum faced, but are not at all exposed after the siding has been installed.

Yet, they are labeled for R Values and supposedly do insulate. If they don't, we wasted money when we put them under the vinyl when we re-sided our house.

So did we waste money? Or is the aluminum foil on the insulating panels as much for vapor barrier as a barrier against heat transfer?

Why would metal, that is such a good heat-cold conductor, be better at preventing heat-cold transfer, than any other impermeable material?

Am I missing something? Or am I asking the wrong questions?

Good night - Orchiddude is still alive and kicking!! What the world is going on.....have you graduated yet? Univ. starts Monday and it is also the end of the fiscal year next week....have a new President, VPAA/Provost and my department head....I wonder what it would be like to have a "normal" academic year start-up (big lopsided grin on that one)! Did you ever plant those pepper seeds, and do you still have a banana pup for me?

We have covered the north end of one of our ghses with foil-backed insulation board(have pictures, will have to fine them). Then we also have a layer of bubble-pack plastic that is dropped from the ceiling about 1' which, even though not a sealed chamber/pocket, gives us a somewhat "dead air space". Before using the bubble-pack, we had used 6 mil plastic in 10' widths. Both work.

Nathan, yes you sometimes are more technical that most of the people who are here always want or need to hear (a few of us are commercial growers), but your advice and information is great, well-intended, and apprecited. As some of the people get more experience, I think they will remember something you may have posted and go back and reread your info which will make more sense to them at that time. Please, keep sharing the information you have!

Mary

Hey Mary! So good to hear from you. Yes, I am on my way to teaching next year. I will have a classroom in the fall of 2007. I am working on my last 2 classes right now. I started those last week. Student teaching in the spring. Fun, Fun. I am excited. Its been a short 3 years but school has been fun. The graduate program is next, I suppose. Peppers...well, I dont think I planted them, if fact I am not sure where they are. If I find them, do you think they would still be good. Yes, I still have a banana for ya. LOL :-)

I hope I will be hanging around here for a while, unless school gets tight.

Good to hear from ya.

Thanks mary for your encouragement, sometimes I need it!

BirdWidow: It's quite surprising - heat radiation (as discussed in another thread) occurs at frequencies we can't see. At these frequencies normal paints all look 'black', only metal looks 'white'. The aluminium reflective surface must have an air gap. If there is direct contact it does nothing (and loses its R-value), indeed it is worse because it conducts the uniform heat coming through into the cold spots better(though this is fairly negligible in practice).

I think you could put something nice in front of the foil, but on spacers so the foil-air surface isn't totally covered. I think if you have an inch or two of foam the value of the foil is fairly low.

in summer foil outside works by reflecting the visible light, but that is best done on the outside because the glazing will trap a goodly chunk of the reflected heat.

Nathan:

You wrote:

"I think if you have an inch or two of foam the value of the foil is fairly low."

---------------------------------------------------------

I think I understand. The foil works, but if it's sealed under another material with no space between it and the cover material, the properties of the foil are pretty well negated.

Ergo: insulating material such as dense, 2" foam, even if not metal wrapped, would still provide the labeled R-Value.

Yes? No?

It should or why would they have it rated in the first place.

Orcharddude:

That's what I thought, and why I considered cutting 2" thick, Type 150 foam panels to fit, then sealing and painting them to both preserve them and make them more attractive and easy to clean, but was confused by the reference to foil.

Nevertheless, Nathan has been an inspiration for me, and has given me a lot of useful information regarding the insulation of my GH foundation.

And yes, after recieving information from him, we spent far more time and money on the foundation than we had expected, but I will always be grateful, because he led me to where I needed to go to do the job right to begin with.

Once we have the structure completed, going back to mess about with the foundation is NOT an option.

Experimenting with different approaches to additional insulation for the walls is however, and I'll be watching for more suggestions on this forum.

The problem is that the rating system assumes a certain configuration, if your configuration is different the rating will be irrelevant. We know why foil works (it reflects heat and doesn't emit heat) so we can work out what sorts of topologies provide the best bang for buck. The best insulation we know of consists of lots of layers of fine foil separated by very small gaps (5nm). Practically, this is only useful for cryogenics.

For me, that means single wall poly carbonate on the sunnyside, with spaced extra layer of very thin shrinkwrap film to give me a low bridging double glazing (and low cost too), careful control of air intakes, a large thermal mass and foam insulation on the shady side. If you don't like the look of bare foil, don't bother with it. Painted foil is basically worthless. Instead, get some stucco mix, and make a nice cement rendered wall, hang some wallpots on it , paint it or oxide it a nice colour and grow moss and ferns on it.

Rebuildit Centers are popping up all over -- they are places where people take house parts from houses that are being torn down, remodeled, and so on.

The one near us has hundreds of doors, bathtubs, toilets, knobs, bath/kitchen cabinets, fireplace surrounds, sliding glass doors, old wooden and newer aluminum/vinyl windows, railroad ties, lighting fixtures, tile, carpet, linoleum, and so many other things!

Kind of like a junk-yard, but much better since they are somewhat discriminating in what they will accept. Prices seem really reasonable too.

:)

FYI - I don't know if this makes a difference in a green house or not - I did a google on insulation panels and saw this -

Disadvantages of Foam-Core Panels:

Fire safety and insect problems are the two greatest problems associated with foam-core panels. The concern over fire safety mostly concerns EPS panels. Polyurethane and isocyanurate burn like wood, remaining intact until it burns through. EPS, however, can begin to deform at temperatures as low as 167°F (75°C), melt at around 200°F (93°C), and flow at around 250°F (121°C). In addition to causing structural failure, melting polystyrene can actually fuel a fire.

Although all plastic insulations emit toxic gases while burning, experts believe that toxic gases released by carpets, furnishings, and foam-filled furniture appear more dangerous than the foam insulation hidden behind drywall and composition board. When installed according to manufacturers' recommendations, EPS panels pass the American Society for Testing and Materials (ASTM) tests and meet national building codes. Polyurethane/isocyanurate supporters nonetheless claim that the ASTM test (ASTM E84) for flame spread and smoke is not appropriate for testing EPS. There appears to be a consensus among the testing community to change the test so that it more realistically duplicates EPS burning patterns. Such a change is likely to raise the EPS smoke and flame levels. EPS panel manufacturers, however, maintain that fire testing of EPS panels should deal with assemblies (for example, the walls) made up of panels.

Now my GH never gets that hot ---- but I do have an open flame -ie my gas furnace -

SO I suggest care is taken when using these panels.

Mike

The EPS I used is made with a flame retardant. You might have to ask your supplier. Practically, in a greenhouse, things tend to be quite damp and hard to burn, once it reaches the point whether it could burn you're stuffed anyway.

I also put stucco over all my PS, the cement will certainly give a significant extra margin of error.

I've asked about the styrofoam panels a long while back. One of the concerns that was brought up then was about moisture that may get trapped between the panels and the glass or poly...since this area would receive no circulation. Any thoughts on this?

I'm near the completion of my structure and I need to start thinking about this as well. Everyone has raised a lot of good points. On price...my consideration would be to arrange and secure the panels in a manner that I can reuse them year after year. So gluing is out of the question. How to store the panels after the season is another consideration. I thought about making some sort of platform hanging from the ceiling of my garage to stack the panels on.

My thoughts were to cover only the top half of the ceiling with the panels...not the entire ceiling. Since the sun is so low during our winter months, it would only really be coming in thru the lower portion. I considered setting up the lower half with some sort of thermal blanket that could easily and quickly be pulled up and away. Probably won't be time or funds for that. But I would think that any insulation would have to be better than none! As for the side and front walls? I was thinking of just using the clear plastic heatshrink film with the doublesided tape for them...just to create a dead space. I want to keep my view unobstructed.

But!! A second thought is that I'm so darn tired of spending my entire spring and summer building this thing, that I may do nothing insulation-wise this first year. I need a break! It could provide the break I need as well as a base-line on the heating costs. The structure itself is well insulated from footer thru the kneewall. Thermal breaks and double pane insulated glass. Yeah...sounds better and better already....

I plan on placing the 4x8 1 inch panels on my north wall, beause they are styroform, they are a form of plastic or something water proof. That means while they may get damp in the winter, I hope they do. It also means they will dry out during the summer. So all in all, I think it will work out for me. I still need to run the numbers just so I can see the difference it will make.

OJ, that's what I did...I did not add any extra insulation the first year. I didn't keep it as warm in the GH, maybe mid 40s, but I was able to get a feel for the little microclimates and temperature swings.

This year, of course, I'm shooting for min 60F and I've already started fitting the north wall with removable sections of rigid foamboard, R-6.3.

SB

the heat shrink extra glaze idea is good. That's what I do for the clear parts. Even two layers is practical instead of shade.

As for being removable, I helped my brother put foam panels in his shed roof and we just put fencing wire across and used that to hold the panels firmly against the roof.

SB...what kind of foamboard are you talking about. Where did you get it, how thick, price. etc....

spill the beans.

Thanks

I could not get foil-backed 1" foamboard locally. What I got was 1/2" R-3 foamboard which, I think, is styrofoam (I'll have to double check that). It is the pink stuff you see at HD. I am doubling that with 1/2" foil-backed polyisocyanurate (sp?) board, R-3.3, facing inside.

There are two tricky parts which I haven't worked out completely yet. At first I thought I would just stick them to the window. I may still do that. But the greenhouse design prevents me from sticking a piece against the glass and covering all of the glass at the same time. So far I have solved this problem by taking the first 1/2" piece an maximizing the horizontal coverage, and then on the second 1/2 piece I'm maximizing coverage in the vertical direction. I may solve this problem another way, by moving the pieces away from the glass a bit, creating an air gap. This would allow larger pieces and insulate better, but I would have to redesign shelving and move a lot of stuff around. Still experimenting. The other issue is that of the metal frame being uninsulated. I am thinking about a single layer of poly with a slight air gap around the metal frame pieces, with the edges tucked behind the foamboard. It would be better than nothing.

Anyway, sorry to ramble. I hope that is not too unclear or confusing. Suggests are welcome.

SB...it really sounds like a lot of trouble if you ask me. LOL. I would rather take pictures of my orchids than have to mess with do this or that....LOL

Well, I have one of those little 6x8 HFGH greenhouses, so one sheet of 1" foil-faced foam board covered the entire north wall - not as unattractive as I thought it would be, so I've left it in place through summer. The two panels that I cut to cover the north 1/3 of the east and west walls I did take down and they're set on their sides under the bench along the north wall - out of sight and safely out of the way until needed again.

Di

OD...of course it's a lot of trouble! If it was easy...none of us would be doing this!!!! :) Not laughing...crying. SB...I understand what you are saying. We can get the 2" thick foam pieces. I'm wondering now if using the heat shrink on the entire roof might not be a bad idea. Might be more costly than the foam though. I haven't priced that stuff in ages. I can only imagine what removing that would be like. One shot deal too. Damn, nothing sounds like any fun that's for sure. I've got a lot of roof to consider. I'm just too pooped to care right now! Keep me informed what measures you guys take and how it works out. Thanks, J

I attach PVC shrinkwrap with silicone. It can be removed with a window scraper. The film cost me 70cm/m^2 and out of UV should last indefinitely. Let the silicone cure completely before heat shrinking.

Hi,

I'm a daylily grower and I need to build a greenhouse that will keep my more tender plants and seedlings at a minimum temperature of 45 during the winter months. I'd like to make it 16 x 20 and have a 3ft high kneewall to prevent snow from coming in. I've been considering a Quonset style GH but I also wanted to be able to have a solid insulated north wall. I've been doing a lot of reading on this subject and I think I know the steps I have to take in building this thing but I'm having a problem locating a local supplier for the film. I live in the greater Rochester, NY area. Does anyone know of a supplier out this way? I've found online sources but shipping cost almost double the price. I did find an online source for a metal frame (Mortons $400. for a 16x 20 H series) but again I'd rather get it locally than pay for shipping. Does anyone know a source or can suggest an alternative way to build this thing?
Heat will be my next consideration. We had been planning on installing an outdoor wood furnace for our house and running a line from it to the greenhouse. Now the need for a new truck may have wiped out the furnace for this year. What options are there for heat.I don't have access to natural gas lines. I can get electric or propane. How many btu's would a structure 16 x 20 x 6 ft high require to maintain a minimum of 45 at night in up to -20F (a possible extreme) weather? Also snow load is another factor. Do I need a minimum slope? We average 5 ft of snow over the winter.
If there are archives that would help pointers would be appreciated.

Thanks for any help with this project.

Molly

What I find that works great is foils faced bubble insulation. The foil reflects the heat back inside so it's not lost, and the bubble insulation is an R 15 in less than half an inch. It's more efficient than foam. You can buy it at Lowes, but it's cheaper to buy it online. I'm posting a link.

By the way, the same company has a 95% reflective cloth that might be a good use as a shade cloth.

Here is a link that might be useful: Innovative Insulation Inc

This product from Inovative Insulation, what do you think of the Temptrol? it sounds good and seems easy to use.

lj1,
Don't know yet. I am still waiting for my sample. I had tought it would get here Sat. but for sure today. It sound good, but I guess we will never know until someone bites the bullets and buys it and trys it. Who want to be the guenia(sp) pig? There is a lot of good information on the web site to help and understand insulation and I did learn a lot from that.
1eyedJack and the Dawg