I used that tin-foiled bubble sandwich insulation in my HFGH and I'm wondering if, when the sun hits it this winter, it'll COOK my plants. After all it'll reflect back the sun/heat right on the plants. I bought white spray paint but haven't sprayed it yet. I was going to spray just enough to cut the glare.

Sheri:

I went back to re-read that thread, because in the year since, I've tried, failed, tried again with some if not total, then at least partial success, and in doing so, became more than a bit frustrated over so many conflicting opinions.

I finally came to the conclusion that sans a wood framed, triple glazed GH, set on a heated foundation, nothing will make my GH as weatherproof as our home, so I might as well just do what I could with what I had, and enjoy it.

Yes, painting the reverse side of a double foil might negate some of it's insulating qualities, but if the material you bought is foil only on one side, and you want to make it more attractive on the outside, go for it.

Try Zinzer shellac base primer on it. It will seal against moisture and at the same time, do a great job of covering the printing. Then finish with whatever color appeals to your asthetic senses.

If your GH ends up making you feel as if you have imposed something ugly on your neighbors, you will not enjoy it, and why bother, if you can't enjoy?

Thank you both!

Greenhouser, IÂve wondered about that too. The polyisocyanurate foam sheeting IÂm looking at has a slightly matte foil, not quite as shiny as the foil/bubble wrap material, but IÂm not sure I wonÂt find some reflection problems when itÂs in place.

So far IÂve only found one thread that mentioned foil reflections causing hot spots. In this thread, the original poster did paint the interior foil side of his insulation to correct the problem (melting plant trays, yikes.) Did the paint lower the effectiveness of the foil insulation? My fuzzy guess is probably, somewhat, but no one really says.

That poster mentions this happened on "2 trays in the corners on the top shelf where the light would get concentrated," and not a problem throughout the entire north wall. So, IÂm figuring people may have different results depending on sun orientation, shelf locations, etc. I have no shade trees and full hot desert sun. (I might be a good test rat for this question.)

I'll install mine in the coming weeks and see what happens. My greenhouse will still be empty for a while, so I could put a bunch of cheap thermometers in various locations. I had the exact same thought you didÂdusting with white spray paint to tweak the problem areas only as needed. (Maybe mask surrounding areas with newspaper to be sure no paint overspray drifted onto the poly panels.) IÂm also thinking that shadecloth would affect foil reflection problems, and I havenÂt even purchased that yet.

Birdwidow, thanks for your thoughts. As you said, IÂve searched high and low, but I havenÂt found a really clear answer on the foil-painting issue. I do want a greenhouse that works, but I also want one that pleases me when I see it, and that other folks wonÂt mind looking at. YouÂre right; the point is enjoyment!

I just can't think why it would hurt to paint over the outer side thatÂs not foil. Thank you for the recommendation on the Zinzer product.

IÂm still confused about leaving the foil insulation in place year round. Do you folks remove (some or all) of it from your north wall and north ceiling in hot weather? If possible, IÂd love to know before I install it if IÂm going for a permanent install, or one that could be more easily removed and stored. Any thoughts from anyone who's had it up a while?

Everyone has a little different circumstances because of where you live and if you use the GH 12 months a year.
I use my GH in the late winter early spring to start flowers from seed and after mid April the GH sits empty.
Most of the time I'm heating only the last few weeks of afternoons do I need to run the exhaust fans.
I have 2" expanded poly foam sheeting on the north wall and 4 feet up both side walls with bubble insulation on the rest of the walls and roof.
I painted both side with white paint was no way that I was going to put it up with the ugly blue printing on it neither inside or out.
Been that Way since spring of 2006 NO problems looks good works good. My GH also has a thermal blanket on the roof and it heats pretty easy so heating cost it very reasonable.
I leave the insulation up year round works great for what I want to accomplish your mileage may vary.

I ended up going with very heavy, large (1/2") bubble and used it to line the entire interior of my GH, ceiling to floor. It's proven pretty effective and while it may not be quite as insulating as foam, it's pretty clear, so still leaves the interior with a soft, diffused light all over, which is whay I wanted a GH to begin with.

Otherwise, for the cost of the GH, I could have just built a large, heated, AC, insulated shed, with lots of thermopane windows and some skylights.

I'm planning on spending far more time in it this winter than is really necessary to maintain my tanks and plants. It will be a sop to winter blues, and rueing my not having made a stronger argument for dumping this place when we retired, and moving to AZ.

Gardenerwantabe, first I need to thank you for all your great posts on modifying the HFGH 10x12. They have been a huge help to us as we found our way through the kit. I think I have your greenhouse memorized. :-)

I'll use my greenhouse year round, so cooling will be a challenge. We're zone 8a; Average Jan/Feb low 27°, average June/July high 94°. I'm growing cacti and succulents. I'm hoping to keep the greenhouse above 45° in the winter, and below 100° in the summer. My greenhouse receives full south and east sun, and is sheltered on the north by our house.

Our greenhouse is still going up, but I'm figuring I'll need a 16" exhaust fan, shadecloth, and some screen panels to keep it from soaring over 100° in there. In winter, I'll use two 1500w electric heaters, and possibly a solar pool cover, to help retain heat.

Anyway, I sure wouldn't want to leave up any insulation that would increase my cooling problems in summer, so that's why I asked. I'm looking for any tweaks I can find to keep it cool. As you can tell I'm not very good about intuitively knowing how to best manage hot or cold air.

I'm happy to know I'm not the only one who'd rather not look at big blue printed letters on insulation!

Birdwidow, at first I didn't want to make any walls opaque; I love the idea of diffused light on all sides. (If you could see our harsh New Mexico sun, you'd know why.) But, some of the good posts here that calculate heat costs pushed me to the foil-faced insulation for the north wall.

For the first winter, maybe I'll do the north wall in foam sheathing, and the north roof in large bubblewrap. You've given me more good food for thought. It's hard to know what to do, right out of the chute. I know trial-and-error is a good teacher (so are high heating bills.)

Actually, Arizona sounds pretty good to me too, they have much better cactus nurseries there than we do! :-)
Sheri

Sheri Glad that some of my posts were of help.
You are right about the fan, the sites on the internet will tell you that a 12" fan is enough for a 10x12 but I use a 16" and it runs nearly all the time on 80 degree days with the stat set on 85.
When I put the painted foam in my GH it made it much brighter inside the sun will bounce back off the north wall so adding the foil does the opposite of what some thing it will be very bright in the GH.
Every one has their own climate to deal with but I think your challenge will be trying to keep it from over heating.
You may need to hang something like 70 percent shade cloth on the west wall to help cool in the afternoon.
Talk to some local people who run nurseries they have experience with that climate.
Here in the spring on a sunny day with 40 degree temp my GH will be 80 degrees without any heat other than the sun.
When it warms up to the lower 70's I use a shade cloth to help keep the heat down but what I have in the GH much over 85 and the flowers suffer.
Good Luck with whatever you decide on.
While I was typing this we had a storm blow through with tornado warnings and they said we had 80mph winds here.
My GH is fine it has been through several severe storms since I put it up. Glad I did the mods and sit it where it has a wind break.

Thanks for the thoughts on the fan gardenerwantabe, any confirmation of our plans is a relief. We have no experience with any of this, so all of our info comes from information people are kind enough to post. Asking local nurseries about shadecloth density might be a good idea. That part is purely a shot-in-the-dark guess for me.

If your greenhouse can be 40° hotter than the outside air, imagine what mine would be on a day when the temps are 100°! Fortunately most of my plants can take 100° for short periods...but not 140°. Cooling will be a battle.

Winds are a second challenge here, which is why I was so glad to see the strength modifications you and other folks made. We have those mainly completed. If any of our greenhouse lands in the next county, I will be very surprised, and it's nice to not be anxious about that. Now I can be anxious about the rest of it! ;-)

Sheri:

If you can, you would benefit by raising the roof on your GH with a kneewall. I know it might not be as easy with an HFGH, because I don't know if you could drop the door, but even a foot higher would help in summer.

It might mean a step up in & out, but might also give you that bit of extra height you would need to be able to mount a ceiling fan under the roof vent.

Sheri
Here is a link that will help you to better understand what you are going to see as temp in the GH.
While I'm concerned with mostly heating you will need to worry about cooling.
The GH temp will really soar when the summer sun is on it.
I fear that you will need a evaporator or at least a mister to control the temp in summer months.
I have a 52" ceiling fan in my GH but I use it while heating it keeps a uniform temp in the GH and keeps the heat from collecting on the ceiling.
I think it is better than HAF fans it is quiet and costs less to run than HAF fans.

Here is a link that might be useful: COOLING INFO

Birdwidow, the greenhouse frame is already up, but it's the same as gardenerwantabe's (HFGH 10x12) so it does have a lot more room overhead than the HFGH 6x8. Since he managed to fit one in his structure, I think we could too. I had about decided on two small HAF fans, mounted high, one at each end, pointed slightly down, to try to get the air moving in a circular pattern. But, I've also read your posts about ceiling fans, as well as gardenerwantabe's. We're still a bit muddled about which way to go.

I will admit that some of this air circulation stuff is sort of like black/magic voodoo to me...I read all I can, and then it will just be a leap into the world of trial and error. I know HAF fans are well regarded, but since both you and gardenerwantabe seem very happy with your ceiling fans, I suspect that either solution would have a degree of success for us.

Thanks for the link, gardenerwantabe, it's a good one. I'm worried I might need an evaporative cooler too, and one of my friends suggested that. I am (stubbornly) hoping to avoid that expense/complexity, and we'll try other simpler methods first, but that'll be Plan B.

In addition to the 16" exhaust fan, four roof vents (I know they won't be much help in really hot weather), some type of ceiling or HAF fans, and some undetermined type of shadecloth, we're going to try to incorporate a lot of screens.

I'll use the screen-building supplies at Home Depot to build screen panels to replace some of the poly panels in the summer, and we'll make some sliding screen doors to go inside the greenhouse, and those would serve as the vent for the exhaust fan. My thought was to have it function (sort of) like a shadehouse with an exhaust fan. As long as I can keep it within a few degrees of the outside air, that would be fine.

Looking at the dark-colored fiberglass screen material HD sells for these DIY screens, it occurs to me that they would have somewhat of a shading effect, although probably not as effective as real (good) shadecloth.

Somewhere around midnight last night I had the wild idea of using Aluminet shadecloth in these screen frames, to just pop them into my greenhouse openings as needed. Midnight ideas are usually dumb, but it would be cool to be able to provide ventilation and heat reflection in one fell swoop, and then I wouldn't have to figure out how to keep Aluminet on the outside in 40mph winds. Do either of you think Aluminet could be built into screen frames? Is it too fragile? I've not seen it in person yet.

Thanks for all your thoughts, they are much appreciated!
Sheri

SHERI
I think the aluminet is an outstanding idea it would not only provide ventilation but block some of the sun. I think that you will still need it on the roof but if you did that o the west wall and then just use what ever was cheapest on the east wall.
Try your idea and let us know what you think I'm sure this will work. GOOD IDEA go with it.
When I mentioned my GH going to 80 on a 40 degree day that is with it closed tight and very well insulated but even with the door open and the exhaust fan on it will run much above the outside temp.
That is why I posted that link so you could see the effect of shade cloth and fans.. Heating is much easier and cheaper if one need to run a cooler.
Strange thing about all this is I'm not really interested in flowers or the GH but my wife is so I do the grunt work and she takes care of the flowers and she is very good at it.
I have a show car and I'm going to leave soon for a evening show my hobby is building and showing fast and unusual cars.
Building greenhouses is easier and cheaper than building show cars L.O.L.

GARDENER: Show cars? Interesting. It was an old car that arrived here as a basket case on a flatbed, followed by spousal guilt over the time and cost to restore it that gave me my GH. Care to guess what kind of "Bird" widowed me? LOL!

SHERI: Roof vents can be lifesavers, but are also passive, meaning that they will release hot air, but unless it's quite cooler at the floor than the ceiling, the actual air movement through them is very slow and why Gardener and I at least, advocate ceiling fans, to forceably pull the air UP and OUT, regardless of any or no temperature difference between floor and ceiling, although cooling the floor is relatively simple.

You could pave your GH floor with semi-premeable blocks, such as innexpensive concrete pavers over hard packed sand. Soak the pavers with cold water and with a ceiling fan under a roof vent, I believe you would get some real cooling benefit in the middle.

I also agree about swamp coolers. For a GH the size of yours, one would not be expensive to buy or operate and in a hot, dry climate, quite effective.

Building greenhouses is easier and cheaper than building show cars L.O.L.
Good heavens, that pretty much guarantees you won't find me building show cars. I hope you did well at the show!

I'm glad you think the Aluminet panel idea might have some merit. I will let you know what happens.

OK, that makes four people who've suggested swamp coolers for our situation. I know they work well here, since we have two big ones on our house roof. I think I've been slow to leap to that solution because I've been thinking of them as huge, noisy, ugly things that gobble electricity. I need to research smaller units, including portable ones like the one you mentioned recently, birdwidow, in another thread. I'll elevate that to the Serious Consideration list.

It makes sense to me that a ceiling fan located at the peak would help the roof vents work more efficiently, too. Also on the list.

We're on the same page on the floor idea...we're going tomorrow to get the 12" square concrete pavers; they'll be used in all the walkways. The sand is already in place since our entire yard is nothing but deep sand. Soaking the pavers for cooling is something I hadn't considered, thanks for that!

Got the bench supports in the ground today, so on to the floor. As soon as (most of) the hard physical stuff is done we can put in the panels. We wanted to work in the open air as long as we could before we warmed up the interior. Thanks again for all the good help!

Concrete pavers are cheap enough. Pave the entire floor with them and expand the area that will retain the cool moisture. The water will run right through the sand and it's cooling properties will be lost almost immediately, while the pavers will hold it, if not forever, then a whole lot longer.

I neglected to say, in the areas under benches we plan on using several inches of gravel. You're right, the sand would be a poor surface. I thought the paver/gravel floor would be a good start, and more pavers could be added later. If my good husband would only purchase a car to restore, I would have a better supply of spousal guilt to allow for more splurges right off the bat!

I hope you did well at the show!
Yes I won best of show but it was just a small show.

If my good husband would only purchase a car to restore, I would have a better supply of spousal guilt to allow for more splurges right off the bat!

I can help with your problem I have one I will sell.

Back on topic I would use paver's on the entire floor. I did in mine I used the 16" imitation brick it looks nicer than stone or gravel easier to keep clean plus has the added benefit of thermal storage.
During the day the concrete will absorb the heat making the GH cooler and in the evening when the air is cooler they will give up their heat and warm the GH saving you paying for that heat.
Only a few dollars more and when you want to store something under the benches you wont be dragging gravel out on the paver's when you need to use them.
I put insulation under my paver's to prevent the heat from going into the ground while my heaters are on.
We start using the GH in late Jan. and it is very cold here that time of year.

Ladies,
My GH is still under construction. A homemade one that I sometimes call "The Greenhouse from Hell". I am using or planing to use foundation vents for my intakes. They are relatively cheap at $13.00 a pop and are made to fit in the same space as a concrete block. The neat thing is that they also are somewhat automatic. They open at 72 degrees and close at 38. I standard block is 8 x 12 and I plan to use 6 in my 6.6 x 15 foot. I will be using a 16" exhaust fan with louvers. I have no roof vents but the exhaust fan will be moounted high near the rood of the rear wall. I also am worried more about summer than winter.
1eyejack and the dawg

Gardener, best of show is best of show, regardless of show size. Good for you. My husband says he'll pass on the car, but thanks for trying to solve my problem.

Your GH floor looks good. Yesterday we used your photos to determine a solution to the entry level problem. We've planned an outdoor threshold to the level of the floorplates, but I kept trying to figure out how to do the same thing on the inside...a step...or a slope...to ease the transition down. Finally decided to just leave the interior floor completely level, as I think you did, with a small step-down on the inside. Much better.

I can make a presentation to the Finance Committee regarding paving the whole floor. They seem a bit cranky lately but I have no idea why.

Ole dawg, good price on those foundation vents, but is 38° too cold for your vents to close? I suppose you could cover them manually before that temp, though, if your plants need more protection. Are you having fun yet? I am, but my brain hurts a lot from all the stretching.

Something I forgot to mention to both of you- Ole dawg and Sherri both: 2 ft. wide hardware cloth.

Unless you want small burrowing critters and their natural, slithering predators moving into your GH, lay no larger than 1/2 inch mesh wire just under your foundation timbers and out, securing it to the ground at the outside edges with heavy U shaped staples, timbers, rocks- whatever.

Screen your intake vents too, or they will suck in every small flying insect that comes close to them.

The aluminet shadecloth has another great property. If you lay it over the vents loosely, with the stretchy part running top to bottom, the vents will open under it and it will also serve as an insect screen.

I can make a presentation to the Finance Committee regarding paving the whole floor. They seem a bit cranky lately but I have no idea why.

I bet you know how to make him see it your way.
I did the same on the inside as out. Nothing fancy but it is easy to get in and out of the GH
I think Maldive has screens that he puts in place of the panels for hot weather but your idea of shade cloth will allow air to blow through but have the added feature of cutting down on the sun that will definitely lower the temp.
I really like that idea.
Only thing is as hot as it Gets where you live I think during the hottest day's you will need to close it and run a cooler.
In the spring most days all I need to do is open the three windows that I put in the rear wall and open the door.
The wind blows through it and keeps it from overheating but you have a much hotter climate than me. I worry more about heating than cooling.

Thanks folks, I really appreciate all the good tips. I plan to order some Aluminet to experiment with. It's good to know about the stretching ability over the vents, too.

I'll be sure to post any results regarding the Aluminet screen idea (good or bad).

Sheri:

The Aluminet stretches in one direction only, so when you order it, make sure you have the fabric cut to stretch in the direction it will hang from top to bottom. When the sales rep from IGC (where I ordered mine) told me the vents would open under the fabric, I was a bit doubious, but she was right. The key is to mount the fabric without stretching it tightly.

My husband was concerned that the corners of the vent windows might punch holes in the aluminet fabric and wrapped rags around them. So far, even with the vents opened full and pulling the fabric, no holes, but I'm looking for a more elegant solution. Fat, self adheseive foam bumpers come to mind.

But I didn't suggest that you use the aluminet AS a screen, only that when it's draped over the ROOF vents, it serves as one, which I found ironic, because we made screens for the roof vents, that will soon serve as storm panels for winter, as we can use them to hold bubble wrap in place under the vents.

For your intake vents, use standard screening material, in a frame.

To screen the powered intake vents on my GH, we used white vinyl house trim materials to create a box frame, 5- 1/2" deep, to allow the vents to open out, then just made screens using the screen channels, corners & spline sold in any home center.

The box is made of 1 x 6 vinyl trim board, (actually 3/4 X 5- 1/2) so the edge facing out is wide enough to accomodate the screen frame, that is mounted to the box face with screws.

To give a surface to mount the box to the GH, we used vinyl brickmould. The box sits inside brickmould, attached with small screws. The brickmould was fitted tightly around and to the fan frame, sealed with silicone.

Once we fiddled the design, they were pretty easy to make and give me the ability to both remove the screens for cleaning, and in late fall, when we seal up the GH for winter, we can seal the vents by placing insulation in the boxes, then use the screens to hold it in place.

My inspiration was shadowboxes, which, when you look at them, are no more than a picture frame with a second frame inside of it that projects out, with another frame on it's face, to hold the glass.

From the craft shop to the GH. LOL!

Birdwidow, I was considering asking you how to know which way the Aluminet stretched when ordering, and here was your post! Thank you.

No, I know you didn't suggest using Aluminet as a screen...that is my own hare-brained idea, and one I'll explore for some of the wall panels (using those screen-building components at HD.) If I could make some summer wall panels that provide ventilation (like regular screen fabric) and reflect some heat (like Aluminet) all at the same time, I think it might be worth trying.

Even if that idea works, I'll still need shadecloth for the roof, which is why I was glad to know that Aluminet could stretch over the vents. I may order an ample piece for roof coverage, and extra to experiment with for wall coverage in other areas, in screen frames.

Instead of building traditional screen vents in the front wall, we're thinking to build an additional set of sliding screen doors that will hang on a track inside the greenhouse. This would give us two sets of doors...the polycarbonate doors that slide on a track on the outside, and a screen set that slide on a track on the inside.

The size of the cheapest screen doors at HD ($20) would work, but they may be a tad too heavy, so we may just make our own.

I do like the methods and materials you used to build your vents. It's nice you can remove your vent screens for cleaning and winterizing.

I guess everything is fair game when it comes to inspiration for ideas. I have now memorized the innards of most of our hardware stores and our local ReStore as I brainstorm ideas. Now you have me thinking what material to use to cushion the window vent corners, under the Aluminet. Ack, it never ends!

Our floor is in, the major bench supports are in place, the electric and water are stubbed in, and we insulated and stabilized the steel base. Tomorrow we may install the roof vents and roof panels, if we are not too sore to climb the ladder.
Sheri

Sheri:

You will try a lot of things before you have it all just right. I think everyone on this forum has at one time or another, and that may be part of the fun. But as much as others here are glad to pass on their own lessons, in the end, you, your location and your GH are unique, so what worked well for me or any other poster might not be quite right for you.

As long as you are willing to try, fail, and try again, you will very likely succeed.

But one thing that always seems to work for me at least, that I would encourage anyone to try, is to look outside the "box". There are loads of products and materials available that while not intended or advertised for GH use; may prove perfect for YOUR needs, in YOUR GH.

Don't you just love just being able to say it?

MY greenhouse. My very OWN greenhouse.

Birdwidow, well said! And, thank you for your time and kind encouragement.

We got the roof vents up today, as well as the north wall of panels. I soon noticed a familiar line of dog nose snurfle marks on the shiny new polycarbonate. Apparently it truly is OUR OWN greenhouse. :-)