Bank barn foundation to passive greenhouse?

Hi, everyone!

We are working to put an old family farm from the 1800s back in service. It had once been very large, then not as large, and now even smaller as pieces were sold off to make surrounding housing plans. It's still 5 acres, though, and we are trying to grow as much food as we can.

Apart from the farmhouse and a garage, the land also has most of a pump house (walls, but no roof) and the back wall of the foundation for a bank barn. We had initially thought of rebuilding the barn, but since we can't have animals in this area yet, it seems like that would mainly be an expensive way to protect farm equipment. The back wall is made of massive stones and faces almost due south, towards a forest -- but no evergreens there, just black walnuts. (Good old juglone!) I'd love for it to be further in the sun during summer -- but on the other hand, maybe less sun is actually a good thing in the summer, and the trees dropping their leaves in winter would help with the idea of passive shading in summer and increased light in winter? I suppose we could clear a few trees if we have to; I'm trying not to beat up the forest too much, but I'm also trying not to be too sentimental about any one tree.

I just keep thinking about how much work it would be to make a 55 foot long wall and a flat floor surface anywhere else on the farm, when this one is already there...

Does this sound like a promising start for a passive greenhouse? I can get large amounts of glazing for free, because a friendly local window installer has been giving us vanloads of nice double pane windows and doors that people have been paying him to replace for no apparent reason.

Any thoughts would be most welcome! Thanks in advance!

Some photos would be nice.
But as a long term builder I can say, using something in place always beats starting anew.
Also, I suggest you start small and as money and effort becomes available extend the green house as you can.
That way you dont become dejected because its so daunting.

That sounds like a perfect start to a passive solar earth banked greenhouse!  Where in the world are you living?  You need every drip of winter sun if you want to grow through the winter.  Even deciduous tree shade in the winter is substantial.  

It sounds good. What impact might this have on the foundation of the building?

John C Daley wrote:Some photos would be nice.
But as a long term builder I can say, using something in place always beats starting anew.
Also, I suggest you start small and as money and effort becomes available extend the green house as you can.
That way you dont become dejected because its so daunting.

Oh, pictures! I've attached one. Yes, the area is quite overgrown and the foundation has been neglected to the point that trees were growing in it. But on the other hand, I'm sure it has enough strength left to support the top edge of a greenhouse...

Starting small would be ideal, although this area has a bunch of zoning restrictions such that I'd actually have to ask permission each time I change the size.

Dimensions-wise, it is 55 feet wide and roughly 6 feet tall. It faces south, which is what got me thinking in the first place -- there was a different place where I had thought to put a greenhouse, but it would have ended up more east-facing than south-facing.

Mike Haasl wrote:That sounds like a perfect start to a passive solar earth banked greenhouse!  Where in the world are you living?  You need every drip of winter sun if you want to grow through the winter.  Even deciduous tree shade in the winter is substantial.  

Thanks! We are in Southwestern PA, zone 6B.

John F Dean wrote:It sounds good. What impact might this have on the foundation of the building?

Interesting question. I'm thinking that since it's stout stones, this comparatively small amount of weight shouldn't have that much impact on it?

AS for getting permits, maybe just get one for the biggest size and complete it in sections.
I am suprised you would need approval for that.
Did you say the wall is 55 feet long?

Very nice!
I would want to insulate the green house interior  from the foundation, any plans for that?

I'd actually want to insulate the foundation from the elements so that the thermal mass of those rocks is inside the insulated space of the greenhouse.  If possible...

Now we need more pics!!!  How close are those black walnuts...

John C Daley wrote:AS for getting permits, maybe just get one for the biggest size and complete it in sections.
I am suprised you would need approval for that.
Did you say the wall is 55 feet long?

The zoning situation here kinda is what it is. Thankfully the guy who's actually in charge of that is more reasonable than this all makes him sound, so I'm very thankful for that.

Yes, the wall is 55 feet long! The picture does not convey very well how massive the stones are.

William Bronson wrote: Very nice!
I would want to insulate the green house interior  from the foundation, any plans for that?

... I was thinking of using them for thermal mass, but it sounds like you'd vote against that. Can you elaborate a little?

Mike Haasl wrote:I'd actually want to insulate the foundation from the elements so that the thermal mass of those rocks is inside the insulated space of the greenhouse.  If possible...

Now we need more pics!!!  How close are those black walnuts...

Right, that's what I was thinking, but insulating those -- ah, you said from the elements. There'd be no need to attempt to get insulation behind the stones themselves, right? How would I go about trying to make a decent-ish seal where the roof would meet the ground, behind the top of those stones?

More pics: looking back through my pictures, I seem to have been demonstrating why I did not become a photographer. =) They are all from the same perspective, just turning to the left and right. I'll try to snap some more on Monday, Lord willing.

Black walnuts: I'm assuming I should be focusing on the south side, right? North of the wall they're quite close. I should measure instead of estimating here. The closer ones on the south (maybe 25-30 feet from the wall) are not very large and I'd be OK with taking those down. But tall ones might be 50 feet away, guesstimating?

Yes, I'm thinking some sort of insulation that continues from the roof over to the soil behind the rocks.  It doesn't have to go down the back side of the rocks underground, it can go horizontally to the north of the rocks a few feet.  See the purple in this crude sketch below:

Nice diagram Mike!
I was thinking that insulating the foundation and wall would require lots of digging.
Would you suggest  a horizontal apron of insulation around the foundation as well as the wall?

You can go 4ft horizontally from the back of the wall to insulate or even further and backfill on top.

I'd try to imagine the insulation of the greenhouse and its foundation to be a hat (maybe a stocking hat or a cowboy hat).  So the mass and everything can be inside or outside the hat as long as the hat is continuous around/over the greenhouse.  I think the architects call it the "conditioned envelope" of the building.

So logically the walls would want to be insulated.  The glazing is a crappy insulator but it's the best you can have and still let light through.  Where the walls and roof meet the foundation the insulation would ideally continue through/over/past the foundation and to the soil.  In my area the frost depth is 4' so I did my insulation 1' deep and then 3' out.  The 4 feet doesn't have to be straight down, frost still has to travel 4' to get under the footings or to the foundation.  

There's a point at which it's useless to keep insulating the ground around the greenhouse.  You have constant heat coming up from the core of the earth.  By putting a greenhouse over a spot of the earth, that heat can get closer to the surface (yay!).  So insulating under the greenhouse doesn't make too much sense to me.  I welcome that 45 degree heat source (yours may be warmer).

So I'm not sure if I answered your question William?

Better late (sorry!) than never, here are some pictures of the area with the foundation behind me. This one is looking directly out.

This one is with my back to the foundation, looking to my left.

And this one is with my back to the foundation, looking to the right.

So there's plenty of smaller stuff that should probably be cleared, and I'm fine with that. I'd like not to clear out too much of the larger stuff in the forest, though. Apart from being a really beautiful part of the ecosystem, it's the hunting perch for the hawks and owls that prevent the bunnies and rodents from completely overrunning the place.

I think it depends upon your goals.  I don't think you could grow much there from mid fall through mid spring due to shade.  Unless you remove a lot of trees.  Or have lots of grow lights.  The shade also cuts down on the passive solar element so it won't collect as much heat as it could.

Charles, If your place is truly a farm (an agricultural business) there may be exemptions carved out vis-a-vis land use, animals, construction of agricultural structures. Having a hobby farm in a residential setting you run into residential zoning/permitting rules.
It's also too bad that the old barn is completely gone. Often having a structure to "repair" or "remodel" is looked at differently than "new construction". Not sure if just a foundation counts.

You could also take a step North, and put the greenhouse above the wall (mostly) and have the space below the wall be the cold sink. Maybe with a solid roof (or like a berm shed) it cold double as a root cellar?
The wall would be in the center of the structure, sort of a split-level thing, with a narrow opening over the top of the wall joining the two spaces.

Will the stone wall remnants constitute as enough parts of the barn to repair it?

Mike Haasl wrote:I think it depends upon your goals.  I don't think you could grow much there from mid fall through mid spring due to shade.  Unless you remove a lot of trees.  Or have lots of grow lights.  The shade also cuts down on the passive solar element so it won't collect as much heat as it could.

Arg. Well, I'd rather hear it honestly than build it and find that it doesn't work.

Just to be clear, when you mention removing a lot of trees, you don't just mean the closer-in ones, right? I'd be fine with removing them if that would help -- but getting a clear line to the horizon isn't feasible there.

There is enough clear land here that if grow lights would be needed there, it's just not the right location.

Kenneth Elwell wrote:Charles, If your place is truly a farm (an agricultural business) there may be exemptions carved out vis-a-vis land use, animals, construction of agricultural structures. Having a hobby farm in a residential setting you run into residential zoning/permitting rules.
It's also too bad that the old barn is completely gone. Often having a structure to "repair" or "remodel" is looked at differently than "new construction". Not sure if just a foundation counts.

You could also take a step North, and put the greenhouse above the wall (mostly) and have the space below the wall be the cold sink. Maybe with a solid roof (or like a berm shed) it cold double as a root cellar?
The wall would be in the center of the structure, sort of a split-level thing, with a narrow opening over the top of the wall joining the two spaces.

The goal is for it to be a true farm, not necessarily the only source of income for the family but a place where we would grow more food than we can eat, so that we can sell crops. We are not there yet, of course, but that is the goal. Being a farm does get us certain privileges in the process, you're right, although the main thing it would probably gain us with this specific question is a friendlier response if asking for a variance. It helps that all of the places I'm considering for the greenhouse are far from the property line, and it seems like much of what the zoning board deals with involves people debating exactly how close things should be to their own property. Here, it's 100+ feet away and the adjoining things in that area aren't houses anyway.

Having two technically separate buildings is a very interesting idea and one that might actually help with zoning, though. Maximum height was going to be a problem, because of how it defines height (basically from highest point to lowest point above ground). I think that part is a little silly (since it would essentially also define the farmhouse's basement as its first floor), but they didn't ask me =)

... And using the cold sink as a root cellar, that's a neat idea.

John C Daley wrote:Will the stone wall remnants constitute as enough parts of the barn to repair it?

The zoning folks are actually more flexible than I'd feared they would be, but no, I don't think enough is left that they'd call it a repair.

Charles Rehoboth wrote:Just to be clear, when you mention removing a lot of trees, you don't just mean the closer-in ones, right? I'd be fine with removing them if that would help -- but getting a clear line to the horizon isn't feasible there.

It's hard to tell from the photos.  If you like apps on your cell phone, you can get a sun tracking app that will show you the sun angles at any time of year.  Then you can look through your phone and see which trees would be blocking the sun in December and January.  Then you'd know how many would need to come out.  Not all, but many that block the sun in winter would need removal (I think).

For reference, in the attached photo my greenhouse (top center) sees excessive (ie total) shade from the white pines (yellow stars).  The maples with the pink stars are annoying but not enough to cut them down.  Now I am a bit farther north than you.  This picture was taken in April (I'm guessing) so it's around the spring equinox and you can see how long the shadows are at that time.

I am just outside Manchester in the UK and have a lean to greenhouse attached to a stone wall. Firstly it is brilliant and we grow peaches in it every year. What I would say is if your climate is similar to mine then forget all about insulation your problem will be keeping the greenhouse cool. I have an autovent in the roofwhich works well. As for the trees I doubt whether they will have any significant effect as they seem to be quite a distance away. Maybe thin out every other tree if you have a problem.

Southwestern PA, even though it is considerably farther south than Manchester, will get much colder in winter due to the continental climate, and stay that way sometimes for weeks at a time.

I would love the stone wall inside the greenhouse as thermal mass, and support the idea of putting the growing beds on top of the wall and to the north a bit. I would berm up behind that on the north side, perhaps with a small pitched roof facing north for insulation from a direction that gives little solar gain, and a large pitched roof going down over the stone wall a few feet such that all the stone gets solar exposure. Then a short wall on the south side bermed in front, and maybe some more cold-tolerant plants can grow in the lower level. This all requires experimentation. If the stone wall is 6' high and you have a 2' berm in front of the south wall and a ridge 8' above the ground behind the wall top, you might be able to call it a 4' + 8' total height... 12' doesn't seem like it should be out of bounds zoning-wise.