Ok, you brug greenhouse owners, I need advice

I have noticed that alot of you brug fanatics have greenhouses. I posted a couple questions on the g-house forum, but didn't seem like many people must read it, so I'm posting here because it seems like you folks know what you're doing re: greenhouses. Here is a "Cliff's Notes" on what we're doing. We're remodeling a 30x120 building that used to house hogs into a greenhouse. We are going to put polycarbonate paneling on the south roof and the south wall. (Hopefully the triple wall paneling.)We are seriously considering the spray-on foam insulation for the north wall and roof. Now comes the question...........in a greenhouse book I have it says that"if the roof were insulated more than a quarter of the way up from the eave, the rate of production decreased. Phototropism (the bending of a plant toward light) occurred when the north roof was insulated, even though the insulation was reflective." I don't plan on starting plants in this greenhouse, I am going to board already established plants here, I have no desire to get into retail and sell, I just want to "plant sit" for those people who have tropicals and patio plants and have no place to put them. So, if any of you have any suggestions re: insulation on the north roof, I'd appreciate it. I'm going to post a photo of what the inside of the building looks like right now. All replies learned by the University of Hard Knocks will be seriously considered. I should add here that the north roof is 17 feet long, if that makes any difference. TIA

Anna Zettle WI

This message was edited Thursday, Jun 13th 11:31 PM

Oh man - you lucky duck!!to have such a big space!! I'd love to be able to help but I don't live in a cold zone. But would I ever love to have a place this big.

I suppose I should mention also that at this point in time we are only going to do half of the building, so it will be 30x64. Most everything else will be up to a point that we can add the polycarbonate paneling and insulate quickly if we find the first of Sept. that we need the extra space. It took Spouse 8 1/2 hours to pressure wash the whole building down.

Anna, I'm no expert on large greenhouses and this would probably be a good question for Cala but what I see in the picture is a lot of wood. With all the beams in the roof it will cut down your light quite a bit.I'm not familiar with the foam insulation so I don't know how much light it will cut out. Are you taking the wood boards down under the windows in your picture? Are these the walls that will have the polycarbonate paneling? You are going to have a huge greenhouse when you are done.I agree with Liz, I would love this much room for my plants. I just couldn't afford to keep it heated up where I am.

Let's see if I understand this: You are taking out the south side and roof panels and replacing with polycarbonate(that stuff is so expensive, but lasts for 20 years) and are leaving the other walls. I think that will be enough light for wintering tropicals, but they may stretch in the spring when the temps get warmer and the sun gets stronger. You aren't talking about putting foam insulation on the polycarbonate are you? I think that would ruin it, plus if it's double or triple walled, it is already insulated.

Cala, no, good heavens, not gonna put foam on the poly paneling!!!!! :>) We were also wondering about maybe putting in some horizontal strips of poly paneling on the north roof, would be kind of like skylights. Any thoughts on this? Or perhaps grow lights if needed in the spring when the sun would be more intense to counteract any plant bending. But, we realize we will have to sacrifice some light in order to keep the heat in. And with the south roof being 15 feet of poly paneling and the south wall at 8 feet of height with the poly paneling, there is going to be ALOT of light, and it will get to the back of the building in the middle of the winter.

suggestions...skylights on the north roof especially for winter light...be sure they are operable skylights as you have to consider heat build in the daytime, venting, and air circulation. insulate the north wall to at least to R20 if possible to compensate for heat loss in winter. you are zone 4, so consider removeable insulated panels for south wall for the night time to keep heat in and compensate for heating costs. interior retractable shades for south roof also needed for night heat loss in south roof...if at all possible use the eastern portion of the entire structure rather than the western side...eastern light is best for younger plants and western light will scorch plants in late afternoon.

hope this helps.