Greenhouse connected to home

I've had this idea for a multi-function greenhouse and I wanted to run it by all of you to see if anything stands out as foolish or unrealistic.

I am building a deck off of the south side of my home. I'm looking into installing an 18' x 20' greenhouse on top of it that will open up to the house via a sliding patio door. My goal is to start plants/trees/shrubs for the warm months and extend the growing season in the cold months if not grow year round. I am POSSIBLY even looking at selling surplus plants/trees down the road. An added bonus would be to harvest some of the excess heat in the cooler months to partially heat the south side of the house via the sliding door.

Is there anything about connecting a greenhouse to the home that is automatically a bad idea?

What kind of heat can I expect to generate from solar alone? The greenhouse would be facing south with no obstructions or shade. It would receive FULL sun year round.

Does this seem like a completely unnecessary expense for the result? The system new is looking like about $9000 from Farmtek.

Is a greenhouse really all that necessary/useful in the first place?

For those who have a smaller greenhouse, do you wish you had just sprung for the big one initially?

I am in central Iowa zone 5a

Thanks for your input!

leo Ziebol : It is easy to tell that you are at the early stages of your plans, that is when you can be the most flexible, Rather than building a deck above the earth for
your green house you really should be looking at being tied into the earth, to buffer your temperature swings and help heat your house through the increased thermal
mass rather than the increase in heating load that the increased total surface area would generate, also you need to consider the extra maintenance do to frequent
unavoidable water spills on your deck and the insulation below it ! For the Craft ! Big Al !

We attached a greenhouse that we purchased from Farmtek about seven years ago. We have two decks 12x12 one off of the master and one off of the dining room. There is an open space between the decks that we plant in. I'd do it again. With a newer dedicated larger plant growing greenhouse we end up using the space more for living space and growing herbs and flowers then growing food plants now. Sitting in the greenhouse or opening the french doors in the winter and letting that warm air in does wonders for cabin fever.

See this was my thought on the whole concept as well. I saw a video posted a while back (I BELIEVE it was Sepp) that was saying that for a greenhouse to function in colder weather, you would ideally have it on a raised platform (deck) to allow the cold air to fall below the floorboards. Has this proven true with yours? How cold does it get in your winter? Are you able to grow year round or just extend the season?

Thank you both for your replies!

Can anyone help me and Leo, I don't understand the concept of letting cold air fall out of a building except where you can open the doors to outside after outside
temperatures have climbed from a morning low ! If I have learned anything while collecting information here in these Permies Forum Threads, it is that knowledge
comes only while you keep your mind open ! Big l !

Hi,
This is similar to something we are planning and mentioned under a different topic in this section of the forum. We are planning ground level conservatory attached to our garage (which is being re-purposed). Our plan is to grow year round with the focus for the area to be tropical and Mediterranean; not living space, but included a couple of chairs to relax and enjoy the sheltered view. We are central VA zones 7-8. We are planning to have raised beds inside it so we see a lot of advantages for ground level. On the other side of the house, our deck does not have footings and we can not use it structurally. (It is also the shady side.) We intend to build something else there at a later point. My take is that ground level is better for year round growing; however, a sun room is fine raised.

We had a greenhouse 8'wide x 70' long x 15' high off the side of our house for years. It was great. We gained about four cord of wood worth of heat from the greenhouse. We would open the windows into the greenhouse during the day to gain heat for the house and close them at night. Thermal mass in the greenhouse keeps it warm enough overnight to grow cold season crops. I had huge tomato plants in there - they went dormant in January and February and then picked up production again in March. No air sink in ours but I did use raised beds. Also had rabbits in there under the raised beds. Biggest issue is moisture control.

How did you go about controlling it Walter?

Moisture problems is something Ben Falk has mentioned. Any issue if you're letting in the warm humid air of the greenhouse to your home. OTOH, this is when you'd want humid air, if you heat with wood. I'm not sure if it causes the wood to rot where it attaches to the house, though.

Geoff Lawton has suggested attached greenhouses is a big opportunity in cold climates for the solar gain and double entry. I want it for the double entry because my sliding glass door keeps opening up a half an inch which is hard to notice but if it's really cold out it can effect house temps.

$9000 seems like an awful lot though.

Leo Ziebol wrote:How did you go about controlling it Walter?

I built an air exchanger that brought in fresh air through the earth air tubes and then exhausted the moist air recapturing heat. Extremely effective. See:

http://SugarMtnFarm.com/earth-air-tubes/

And if you need rocket engines for your wood shed...

http://SugarMtnFarm.com/launch-tubes/

(A little silly post that came up when I looked for the other one.)