Just sent you an email with an article on greenhouse flooring. A 7 ft. x 9 ft. granite well cover sounds like a quite a challange. If you are looking for heat storage, water is the best option for a barrel.

Martha: If you are planning to cover your GH floor with a solid slab of granite and to use a hole in it to lead to a dry well, may we presume it's channeled to the hole? If not, I am confused, because with an impermeable surface, the only way to affect drainage is to slope the floor to a drain.

Otherwise, putting a barrel under it to serve as a dry well would work, presuming the soil is permeable enough to allow it to drain quickly.

That last is really the most vital part of planning any type of drainage, or structure for that matter: know both the premeability and stability of the soils under it.

If you aren't sure, before you commit to any specific type of drainage system for your GH, check with your local Soil & Water Conservation district. They will give you all the info you need to avoid making a mistake that might end up with water where you don't want it.

Channeling the slab to the hole makes sense. It is not now, but could be channeled easily. And I appreciate this information. However, the question in my mind,(and the debate with the person doing most of the work) is about using that hole for a cold sink. This greenhouse may only be in place for a few years, so we have chosen not to put in a four foot down-past-the-frostline foundation. As of today, there is a 9x11 hole about a foot deep, filled with granitestones, which are 1-2" big, so that it is flush with the surrounding ground. 2 2x12" PT wood bolted together and set on edge sit on top of this. The GH sill sits on top of that. One opinion is that 2" styrofoam should be laid on the floor surface and vertically on the inside of the wood. Then the granite well cover (7'w x8'L x 4"D) plus another smaller slab set in the middle of that. Then more crushed rock poured around the edge.
I live in Maine, and I find it hard to comprehend that there will be enough warmth in the soil 1 foot down in January to transfer to the slab to warrant not putting styrofoam under it. I may be wrong, and feel free to correct me if so. I don't intend to use it in the summer, only for starting seeds in the winter and overwintering some marginally hardy perennials, so I'm not concerned with too much heat in the summer.

I also intend to use black jugs of water. I tend to use every possible available method no matter if it only helps 1%. To me, any amount is helpful.

So:
Issue #1 Cold sink: I would like a cold sink if it is going to make ANY difference at all. I hate the cold, I hate cold feet, this is my bit of warmth in the cold dreadful winter. Will the cold sink down into that hole in the well cover (2'diameter)? Will the cold also sink down into the 4" trough around the interior edge.

Issue #2 If the 6" trough has styrofoam under it, can it still be effective as a cold sink. I'm questioning whether the styrofoam should maybe just be under the slab and vertically. And if so, should the vertical styrofoam extend lower than the 12" wood perimeter?

Here are three new photos. The last one is of the well cover. We are fortunate to have access to a limitless supply of granite and a few of these well covers.

{{gwi:304301}}

{{gwi:304302}}

{{gwi:304304}}

I too hate cold feet and as I use my GH as a tropical fish room, I'm tramping out there in my robe and slippers at dawn to feed and when I have fry, may repeat the trip 10 X daily, regardless of cold and/or snow and acting on the advice of a very clever young scientist who sadly, has been MIA from this forum for a while now, I insisted on Type 250 construction foam under the floor, around the perimiter down to 3 ft and in addition, out 2 ft.

My reward for persistance is cheap heating bills and warm feet in the coldest weather, often bare, because in the early mornings especially, I'm invariably too lazy to change from my Wicked Good's to protect them from the water I slop all over the place, to slip into the rubber clogs I keep out there, so kick off the warm slippers and end up padding around in bare feet. But I also cheat. I hit yard sales and used joints for all cotton throw rugs and in winter, my GH floor looks like a hareem, with different colored rugs everywhere, but they serve as a barrier against any cold on the glazed quarry tile floor and when they get wet, a quick toss in the dryer gets them back in action PDQ.

As for your dry well/cold sink: Any hole will help for drainage but do lay a piece of small mesh hardware cloth over it to trap solids, or eventually, enough will work it's way into the stones to clog it.

However, once the outside temps drop below about 25 deg., I seriously doubt that enough cold air will sink into either the dry well or perimiter to warm the GH and the problem with black jugs of water as a heat source is that you need to have daytime air warm enough to heat the water in them, then need so many to give off enough heat at night to actually affect the ambient air in your GH, you would have little room remaining for plants.

If you want to keep any GH warm in bitter cold weather without breaking your bank on fuel costs, the only real solution is a lot of insulation, both in and outside, top to bottom, and a fuel effecient heater.

Insulate under your GH floor and around the perimiter, line the interior with 1" bubble wrap and wrap the exterior with a clear solar pool cover, and you will do far more to keep it warm than if you filled every cubic inch of it with jugs of water.

THANK YOU! Your feedback helped. I hear what you're saying about the jugs. According to info on the FAQ (if I am calculating correctly), my 8x10 GH has roughly 300 sf of glazing, multiplied by 2-3 gallons H2O per sf means 600-900 gallons of water!! Yikes! I can get plastic 55 gal barrels, but to fit in 12-18 of them?? Where would I even stand!

I am also planning to look for a pool cover. We do have Ocean Job lots here which is one source mentioned for them. We have heavy winds most of the winter, but I'll try to strap it down somehow. And I have access to quite a bit of BW. I'm assuming double sided tape will be good for attaching this?

BTW, the present area filled with stone is hooked into a brand new "french drain" that is under the drip line.
{{gwi:304306}}

Martha

Martha:

I do understand that you are likely operating on a tight budget. Otherwise, I presume you would have just hired pros to construct the greenhouse of your dreams, then simply cut a check to pay for it, all fitted out and ready to use. I expect that virtually all of the posters to this forum are DIY'ers. The very wealthy who hire architects to design then supervise the construction of home GH's don't tend to come here seeking advice.

Having expressed that thought, I'll go to another that may seem in conflict, but I truly believe it's good counsel.

If you have to compromise on other things you want to buy, don't skimp on the insulation or get trapped into a cheaper up-front but more costly to operate heater or you could find yourself with a GH you can't afford to use except in the mildest days of late spring and early fall.

Every extra penny you spend now in tight insulation and a fuel efficient heater will pay back in dollars every year you use your GH and with the cost of energy rising so quickly, the pay backs are coming just as fast.

For a solar pool cover in a very cold and windly area, I highly recommend Diamond Clear. It's not the cheapest, but is exceptionally sturdy and will last for many years. If you bought one large enough to literally bundle your GH, it would seal it up against the worst a NE winter could throw at it.

To hold a solar cover in place, you might do as we did, starting with fairly heavy guage eye screws set into the wood base, to attach the hooks at the ends of long lightweight tie-downs; the kind sold to hold cargo onto PU's. If you ran two of them over the top, then another around the base, with a pool cover large enough to leave some extra at the bottom, your GH would be bundled up snugly. Then, cut out for the door, leaving the material intact at the top of it. With your GH door facing so close to another structure, it should not be subject to too much wind.

Hint: once you have the cover positioned exactly as you want it, if you use a marking pen to ID each corner, fitting it back on each fall will be a quick job.

However, if your GH panels are polycarb, DO NOT use adhesieve or double faced tape to hold bubble wrap against it on the interior because any residue will become a permanent mar on the surface, as you can't use any of the compounds used to dissolve old adhesieve on polycarb.

Charlie's Greenhouse sells clips to hold bubble wrap on the interior of aluminum & polycarb GH's that fit into the aluminum channels. I've never tried them, but other posters here have used and praised them.

BTW: I too have a curved eave GH and as much as I love the looks of it, the curved ceiling did present a challenge when we were trying to get the bubble to stay up on it and my solution was small tension, spring loaded curtain rods. They fit between the polybars and hold the bubble in place against the polycarb panels and the rubber bumpers on the ends of the rods don't scratch the finish on the polybars. We then sealed between each sheet of bubble with clear, heavy packaging tape to seal the bubble wrap without leaving any goo on the polycarb.

I hope my notions will be both useful and practical for you, but other posters will have their own to impart and many of them have far more experience in home GH projects than I do, so keep checking back on your thread. You will likely receive many more.

I've seen the Diamond Clear also. Glad to get your recommendation for it. It comes down around the straight ends also? Is it round or rectangular? Why doesn't the end of the ridge poke thru the plastic? I'm going to have to start reading the many posts about these. This is one area I've not researched at all.
As for the BW, from your description I'm envisioning the sheets of BW taped side by side with a space in the middle of the tape to accommodate the glazing bar?
Thanks, Martha

Martha:

To answer your questions in order: The pool covers come in different shapes. Rectangular, Oval and Round. To have it large enough to really wrap a structure, you need one large enough to accomodate the height as well as width and length.

To determine that, measure the distance from the center of the roof down to the bottom of the wood base on your GH. Then double it. For the length, measure the height from the top of one end, also to the bottom of the base, double it and add the length of your GH.

Those two totals will determine how large of a cover you will need to be able to completely wrap it, rather like a package. The overlapping ends not only make it easier to get it wind proof, it adds additional insulating. I say to the bottom of your base, because the most important area to seal against cold is along the sill and you can winch a tie down strap to the inth around the wood base with no danger of putting too much torque on it and possibly warping any of the aluminum aluminum frame or marring the polycarb.

No, the aluminum ridge pole doesn't tear the plastic because the tightening is at the base. The cover is loose enough over the roof to avoid any sharp projections on it from piercing the cover.

The polycarb panels in my GH are 2 ft. wide and when I was planning my bubble wrap, I wanted to keep the channels on the polybars open to allow me to add or remove any bolts, so bought the bubble in a 2 ft. width.

The bubble fits exactly between the bars and is held in place by the tension rods, so all that remained after they were in place was to seal over the polybars and we did that by running the tape on the face of the bubble wrap, just to the outside of the channels. In areas where I would not be using the channels, a third strip of tape was applied over the inner edges of the two already in place, creating a true seal.

However, my ability to both seal up my GH like a tomb and still be able to use it without keeling over from gas fumes is a dual combustion, direct vent gas heater that burns only fresh air, pulled in through a double walled pipe that heats the fresh air as it comes in, thus affecting greater fuel effeciency.

But my GH is not only larger (12 X 16 X 12h) it houses tropical fish, so must be maintained at a reasonably steady 72 deg. through the bitterest cold and I live in the territory of one of the most rapatious electrical providers in the US, so I had to have a powerful nat. gas heater.

If you insulate your small GH well enough and don't need temps much over 68 deg., an electric baseboard heater might be just the ticket for you. It really depends on your fuel rates and which type of fuel will provide the most BTUs for the least cost.

Again: Don't skimp on the insulation, in coverage or quality. It really will make a huge difference in the cost of operating your GH through this and many more winters to come.

I provided a link to the best price I found for the Diamond Clear in another thread but will repeat it:

http://www.poolsupplies.com/covers/diamond-solar-covers.asp

But I bought mine 2 years ago, so don't presume that it's still the very best deal. Once you determine the size and weight you need, do some web searching by brand name. You may find another seller with even better prices. Diamond Clear is a copywrited name, so every seller offering it will ship the identical product.

Birdwidow, Do you still have the owner's manual for your GH? Do you have any photos of it?

Martha