I like my floor. Not sure what laserfans floor is.

Orchiddude, do you have any pictures of yours if so I would like to see them, just tying to find the best for my 10x12.

Thanks

I just have a gravel floor. Look back at my pictures under my post and you will see that I use the gray gravel that is about 1/2 inch size. Easy to walk on, drains good. easy to move plants on.

If your greenhouse is little, get some patio pavers and create a floor, or bricks. If I had some free bricks I would do this.

I would really like a concrete floor, easy to clean up, drains well, nice and neat, no weeds growing between your toes.

Hey Orchiddude,

Do you think that a concrete floor is better than just gravel?
What about putting stones on top of gravel would that be a good way to go or is it to much? My GH is a 10x12.

My floor is pea gravel:
- Didn't want to use concrete--too "permanent"
- Wanted to keep the height of the GH to a minimum
- Works nicely with the 4x4 timbers which square & stabilize the HFGH foundation
- Was free! Left over from our road construction!

A solid floor might be better for a number of reasons though then you have to make sure you have the drainage question addressed. But not only is a solid floor be nicer to stand on, it also would hold more of the heat that it would gain during the day--our gravel floor won't retain ANY heat AFAICT.

Here is a link that might be useful: Our 10x12 HFGH

A gravel floor will probably store more heat than an equal mass of concrete, because the heat can enter and leave between the stones. In concrete only conduction helps. If you have lots of gravel you might push air through it from the roof to store and recover heat.

nathanhurst is right.
I use 8" deep "white rock" for my flooring, in a railroad tie frame and it holds heat in winter rather nicely. I also used blackjack sealer btween ties and GH frame. Not the best feeling on bare feet, but with a GH full of cacti, the gravel on bare feet is least of worries. : )

Here is a link that might be useful: my GH flooring

Hey Anya,

I really like the GH, looks really nice what kind of kit is it?

Where can i find the pictures of Laserfan's Floor?

Umm, look at my link?

Re: holding heat, my assumption was that the gravel released the heat very rapidly (TOO rapidly), vs. slow-release for other materials. But I will defer to you guys if your experience is otherwise; I have no experience yet with the GH.

Here is a link that might be useful: Our 10x12 HFGH

pcdur,
My GH is a Rion.

laserfan,
I actually have been out there barefoot at night & Temp wise... Gravel is nice and warm, even with outside temps in the low teen's.

I have a cement floor that is 60-70 years old and very thin. It is breaking up so it is a cross between cement and pea gravel.

I use carpet, old thrown away carpet. Not the fancy wool and natural fibers stuff but the cheap man made fiber stuff.

After 4 years the UV is not breaking it down. Works for me and it was on its way to a landfill anyway.

That our gravel floor is superior heat-retaining-wise to a solid floor is sorta counter-intuitive to me, but it's apparently the truth as I even found a custom GH builder site yesterday that said "It's a fact!".

Well, as I always say, I'd rather be lucky (to have installed gravel) than smart!

Here is a link that might be useful: Look at

I read before hand that concrete flooring was not the best to use for greenhouse flooring. I read the pro's and con's of both it and white rock gravel.
I chose the white rock. The best feature of white landscape rock is that it will bounce back lumens. Anything white in the greenhouse will bounce back incoming light. This can be a great benefit in the winter where I live, when every bit of light that is available is desired.
Not to mention the heat retention and drainage factors.
I personally didn't just get "lucky", I got "smart" and did it the way best suited for me after much research.
Others, well....it is whatever they feel they need to use for thier own reasons.

anya_101

"Anything white in the greenhouse will bounce back incoming light." Very true. (also bounces back IR, heat)

The ideal in a greenhouse is everything that will not retain heat is white, everything that will retain and later release that heat is black.

Going deeper into it, anything in your greenhouse that will not retain heat should be as white or reflective as possible otherwise it heats the air up and causes cooling problems.

Heat sinks should be dark as possible, they absorb and release heat faster.

drainage factors, In a small hobby greenhouse I doubt you will have a problem. The waste water just goes away and there is not that much of it. However, The waste water that just drains away is in many cases toxic waste. Pesticides and fertilizer.

You can't tell the IR response of a material by eye.

nathanhurst

"You can't tell the IR response of a material by eye."

no, I guess not, but if it is made from natural or traditional material you can make a good guess.

Do you mean 'look the characteristics up in a book'? Charcoal and iron oxide(II) both look black, but one absorbs TIR and the other doesn't.

chris_in_iowa,

All I can say is my flooring of white rock is nice and warm in coldest of nights & yet it can be HARD at times to keep it cool during a sunny day, even this time of year.
Therefore it would be very stupid of me to have anything dark colored for flooring material.
So go with your finding and I will stick to what works for me.
And drainage is very nice to have and the whiterock both absorbs it and dries it up fast. Last thing I need is a "humid enviroment" in my greenhouse. It is full of cacti.

pcdur...when I built my floor, I wasnt worried about the heat part. The thing I looked at was the walkable-bility of the floor on my feet. Gravel for me was good cause it was easy to walk on and had good drainage without doing plumbing work etc...Now that I have had gravel flooring, I am going to the next level in my next greenhouse, and that will be a concrete floor with cermic tile, once again, I am not worried about the heat on the floor, but I do want a floor that is easy to walk on, and will be easy to keep clean. There are lots of different floor types, just pick one that you like. One is not better than the other, its the way you use it that makes it the best for YOU!

I started out thinking brick over gravel for a heated GH in a cold climate, until Nathan disabused me of the notion, with lectures on ground mass, heat loss and insulation.

I'm can't say for sure how our bright young Aussie friend managed to convince a pair of old Illinois farmers to embark on such a time and labor intensive project, but he came across as if he knew exactly what he was talking about and in the end, it turns out- he did.

I can stand barefoot in my GH in sub-freezing weather with no more discomfort as in my basement laundry room. I tested it at 22 deg., just to see how it felt.

For our "base" we started with a treated 4 x 6 set upright and bolted to concrete footers, then dug down about another 6" inside, so by the time it all got back up to the top of the base timber, which also serves as the door threshold, the entire foundation under the floor is actually about a foot thick.

We also dug a narrow channel around the inside next to the base timber and put 2" foam insulating panels down about another foot, and where the concrete footers interfered with a tight seal, used expanding foam to fill in all the gaps.

On the outside, we laid the same foam out 2 ft., all around the base, with a slight downward slope. There too, wherever it wasn't a perfectly tight fit, filled in with Great Stuff.

We surrounded the exterior foam on all sides with timbers laid to the height of the GH base timber and filled in the space with decorative stone.

(That surrounding area keeps everything tidy, adds a nice finished look to what is as much a garden feature as a working GH, and the large sized decorative rock is easy to keep clean, as it's too heavy to be lifted by a blower/vac.)

Inside, from the bottom up: about 4" of medium river rock, then limestone screenings, packed and sloped front and back to center in a very shallow V, to a channel drain spanning the width of the GH. The drain runs to a sump under the sink, which pumps it out to a long, deep, gray water drain.

We laid a nylon mesh reinforced vapor barrier over the screenings and up over the both the base timber and the 2 additional ones, that create the kneewall, then laid down 2" Type 250 foamboard over the vapor barrier on the floor.

Over that, 3/4" OSD, to give more rigidity to the finish floor, which is 12" quarry tile, then 3/4" concrete board, which serves as a base for the tile.

The tile runs up the side of the kneewall, which was also insulated with foam under concrete board, so at need, I could literally power wash the floor and kneewall.

I guess I'm among the "Nathan Convinced and Converted".

If you want to heat a GH in sub-freezing temps. and not break your wallet on fuel costs, start with the MOST foundation you can afford and are willing to sweat over to construct, and go from there.

Regardless if any GH is home built or a kit, the foundation is the one part of it most difficult if not impossible to go back and do over.

Gads- I'm exhausted just describing it, but now, so very glad we took the time, made the effort, and spent the extra, that will repay itself, every winter.

Thanks for the kind words birdwidow (and just because I sound knowledgable doesn't mean I am - judge the ideas themselves, not the people who give them. Sometimes I talk crap, and invariably someone picks me up on it :)

Anyway, the general principle is to insulate as much ground under the greenhouse as possible, because that is free thermal mass. Unfortunately, as with the gravel vs concrete argument, the problem is how to get that heat in and out. solid soil will quite a while to change temperature. earth tubes are an easy way to get considerably more heat transfer capacity.

And think hard about your design before putting it in the ground, because it is hard work and expensive to change once you've put a greenhouse on top.

I'm thinking we should start a wiki or something on important ideas in making and running a greenhouse. Thoughts?

Nathan:

You knew far more about it than either of us did, so I followed your advice, and it worked.

As elaborate as it sounds though, it really was more time and labor than money.

I've calculated that we spent about $400.00 more than we would had we just laid brick or concrete pavers over gravel and considering the cost and size of the GH, that's not really a great amount, relative to the entire project.

The channel drain was pricier than a single center one would have been, but we just couldn't get the limestone scrrenings sloped to a center as one could with poured concrete, so we went with the clannel, because it allowed us to just run 2 straight slopes from each end- to it.

It only slopes about 1/2 inch, but for an 8 ft run, that's enough, and not to having to deal with valleys sure made laying the foam, OSD, concrete board and tile a lot easier. The quarry tile was a closeout special and even with the mud and grout, cost no more than concrete pavers would have.

We exhausted ourselves for nearly 6 months on a project that would have taken far less time 20 years ago, when we had a lot more energy, but all it has to do is cut our annual winter heat bill for the GH by just 20%, and it will pay back in 5 years.

Meanwhile, my GH floor is also attractive, easy to clean, drains perfectly, is fairly indestructable, and just looking at it makes me feel good.

A "wiki"? Is that one of those Aussie terms you need to explain to us Yanks?

Important GH ideas. Me? Oh my no. Not yet.

But I would reiterate the importance of hardware cloth under the edges of any GH foundation that isn't poured concrete- out at least a foot.

I like little critters, in the field, where they belong. I also like snakes. They keep the mice out of our hay loft, and they can stay there.

However, I don't want the little critters OR their natural predators in my GH.

I shouldn't complain though. I understand that you get wild critters that make ours seem like house pets. Or, has the PBS series "Nature" been putting us on?

Wiki is a colaborative website: http://en.wikipedia.org/wiki/Wiki

It allows everyone to improve the description.

We have many nasties in australia, as Steve Irwin discovered to his surprise. However, where I live we don't have any aggressive nasties - The most I worry about digging in our garden is perhaps tetanus or red back spiders. We certainly don't have rabies, or lyme disease or anything nasty like that.

I used 3/4" salt and pepper gravel and then laid mats in the walkways. The mats are rubber, about 1/2" thick, 3' x 4' and have 1/2" hexagonal holes in them. They are used over hard surfaces for people who stand a lot. I have perfect drainage and it is very comfortable to stand on. I know two people who have concrete floors. They get moss and get slimy. I fell at one and busted my behind!
Jim

birdwidow,

"It only slopes about 1/2 inch, but for an 8 ft run, that's enough, and not to having to deal with valleys sure made laying the foam, OSD, concrete board and tile a lot easier."

What does OSD stand for?

I just got the building permit for my 8x16 lean-to GH yesterday, and started removing sod from the location today. So I am very interested in the recommended techniques for preparing the foundation area. My guess is that OSD stands for OutSide Drain, but that's a pure guess.

From what I have learned so far in this forum, I plan to excavate at least a foot down, place a little sand, put hardware cloth over that (to stop the varmints), a little more sand, some Landscaping Cloth, some crushed rock, and some pavers on top of that. I'm wondering if I should bury some PVC drainage pipe in with the crushed rock.
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This is a crude Photoshop simulation of what the GH will look like against the house. A door opens from the lower level into the the GH and a crank-out window also can open into it, which should let the GH be a "parasite" to the furnace room for at least some warmth. Initially the upstairs electric clothes dryer vent also opens into the GH. The dryer has a lint filter, but if lint starts to become a problem, I may do something about that.

This is in the backyard and the greenhouse faces south, so it should get about as much sun as is possible in this location. The house will shelter it from north winds. However, our winter days are quite short here in Maine, so I may supplement them with fluorescent lighting.

MM

maineman: that's a fantastic looking plan. I'm a big fan of house attached greenhouses, especially when used to provide suplementary heat to house. You might consider putting a thin (say 6 inch deep) 'solar collector' on that big expanse of wall and move the heat into the greenhouse. You have a lot of house surface there, and you'll reduce the heat loss through the wall. To make this you would use polycarbonate sealing a shallow space, perhaps some shadecloth to absorb the light and a simple fan arrangement to move the air. (In summer it will be shaded by the eaves and not contribute to the heat)

I think the most important other step is to put in your in ground insulation as deep as you can stand. A foot doesn't sound very deep for Maine, how deep is the frost line?

Using the greenhouse as a solar booster is a great idea, and it has a further benefit - it will filter the air and remove both CO2 and also many harmful gases such as plasticizers, formaldehyde and NO2. You should think about a way to move stale air from the house into your greenhouse to push the air into the furnace intake. You can control this by measuring the temperature in the greenhouse and only running the fan when the greenhouse is warm enough (thermostat).

Pity you couldn't make your greenhouse the full length of the house, though I think you'll be very pleased with the results.

maineman: I think OSD is an acronym for Oriented Strand? It's a composite of wood flakes running in all different directions, as strong as plywood, yet per thickness for 4 x 8 sheets; cheaper, and unlike ply, won't delaminate.

It's pretty tough stuff and has pretty much replaced exterior plywood for sheathing. Your house appears fairly recent and I would bet if you get up into your attic and look up, you will see it.

We added the OSD under the concrete board to give the quarry tile the firmest base we could over the 2-1/2" thick foam and also laid the sheets of OSD and concrete board in opposite directions to avoid seams over seams.

The concrete board was laid over and attached to the OSD with exterior glue and screws. Then we taped the seams, sealed them with concrete morter, let it cure overnight and sanded it. (Pretty much like taping and sealing plasterboard.)

I wish I'd had a place to connect my GH directly to our house, but didn't, so had no choice but to go with a freestanding. I'd give a lot to be able to be able to wander in and out of my GH anytime I felt like it, dressed for the weather or not.

Or, just dressed- or not. LOL!

OSB is oriented strand board.

I had a post written with a guess that OSD was oriented strand board, but then I didn't post because I didn't think that could be right!

OSB is basically flakes or chips of wood pressed into sheets, but the grain of the chips is "oriented"...you can see this if you look closely at the sheet.

OSB to my knowledge is not approved for any ground contact applications. As far as I know, it is rated for dry applications only. It will most definitely fall apart in a ground contact situation. Here are pics of a couple of sheets of OSB I put down in front of my greenhouse a couple of years ago just to keep my feet clean. I think you can see that there is not structural support...it is only keeping the grass from growing there.

{{gwi:310601}}

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Birdwidow, other than the OSB, I really like what you are saying about your floor/foundation. However, I'm having a hard time visualizing the whole thing. Do you have any way of posting a schematic showing the layers?

Thanks, SB

OSD? OSB?. Oh my; did I get the two mixed up? Sorry. Well, at least we are talking about the same stuff, and we wern't concerned about weather or moisture, because it's sealed between the vapor barrier and the concrete board.

A schematic. Yes, I could draw it out on some graph paper to show the layers, run it through the scanner and convert it to PDF, but don't know how to post it. I've learned how to attach them to emails, and that's as far as I've gotten.

Help?

BW, I'd be happy to post it for you if you want to email it to me. ;-)

Otherwise, scan it in, convert it to a file type that photobucket or webshots will take (if needed), and upload it just like you would upload a picture. Photobucket won't take pdf files, but they will take jpg, gif, png, bmp.

If you're handy with paint programs, you could just draw it there and those files should upload, I've done that several times.

Nathan,

Thanks for your kind words about the plan. Now that you mention it, I think our frost line does go well below 12 inches, so I will definitely excavate the foundation deeper than 12 inches. We have quite a bit of crushed rock left over from a previous project, so I will try to use that all up.

I would like to have made the greenhouse longer than 16 feet, but several things prevented that. The most important thing was not to block the visibility of the backyard from our two south facing kitchen windows. Also, Essex Greenhouse considers attached GHs longer than 16 feet as "custom" and they cost disproportionately more.

MM

You could build two greenhouses, leaving a gap between them for the kitchen, and each would be less than 16' :)

When you insulate your foundation, make sure you use something that will not wick water - wet insulation tends to not work very well. This might mean painting it with thick paint, or plastic film or asphalt sheet.

Nathan,

"You could build two greenhouses, leaving a gap between them for the kitchen..."

At some later date I may build a second greenhouse. I'm sure there is a "learning curve" to this, and if I do build a second greenhouse, I want to be able to apply my "lessons learned" to the second project.

In our case, leaving a gap for the kitchen isn't really applicable, because on the other side of the kitchen window area there isn't a suitable place to locate a greenhouse, unless it was decided to remove the upper story deck, or re-floor it with polycarbonate.

For the time being I am very excited about the prospects of completing this project and starting to use the greenhouse. I wish I could wave a magic wand and have the thing finished today. I am thinking about starting some seeds indoors under fluorescent lights in the next few days to have them up and growing in case the greenhouse project goes faster than I expect.

MM