Monitor Barn with Greenhouse - worrying about snow breaking the greenhouse roof

I am building a monitor barn in Wisconsin (as a house) and it includes a greenhouse all along one side. A monitor barn has a two story middle with a single story wing off each side. My worry - when snow slides off the middle section, how can I keep it from breaking through my greenhouse roof below?  I was thinking of using double-wall poly as the roof material. This is a wood framed building. Any ideas?

Neat idea for a home!
Very exciting, it gives me all kinds of ideas!

Now first of all I believe  snow guards  are the conventional solution.
These are "racks" that hold snow on the roof until it melts.
Commonly used on metal roofs, which are extra slick.

Now on to some crazy ideas!


If you had an uninsulated roof or used electrical melting cables, you could keep the monitor design, no problem.
Since you are enjoying a living space in a greenhouse, I doubt you want to spend thermal energy that way.


If you center roof has a steep enough angle, there shouldn't be any accumulation of snow on it.
That creates other complications, but it should work.
A Gothic arch or gambrel roof might do the trick.

Alternatively, you could skip the monitor design, while keeping the flanking greenhouse.
Instead of the greenhouse roofs being lower than the center roof, they would start right where it ends.
Essentially you would have a standard gabled roof, but the lower half on each side would be glazing instead of opaque.

You could even extend the roof like all the way to the ground, so basically you would have two story house built into an A frame.
The space that is usually "wasted" in an A frame would be your  greenhouse space, and  A frames are considered excellent for dealing with snow loads


You could have a flat roof in the center section.
Your roof framing and decking would need to be very strong, and you would want parapets all the way around, but snow would accumulate and not fall, plus the roof could be used for gardening ,etc.

Most simple of all, maybe you don't need glazing on the greenhouse roofs.
Winter sun is low in the sky and mostly should enter via the vertical glazing.
By using a conventional opaque roof on the greenhouses , you can insulate it.

You could even make them flat roofs,build the greenhouses as elevated decks, accessible from the second floor of the  center monitor section, enclosed with glazing underneath.
The deck can stand up to ice and snow, and an under deck drainage system keeps rain and meltwater out of the greenhouse.
Any snow that piled on top of the deck would be extra insulating!

Ok, enough crazy ideas for now, thanks for the prompt, I really enjoyed it!

I like the idea. A couple suggestions would be to bring the roof of the wing higher so that there is not so much space between the main roof and the wing roof. The shorter the distance, the less speed the snow builds up between roofs and the less force when it hits. As was already suggested, you might be able to build the greenhouse roof stronger, perhaps even not have glazing on the roof.

Another crazy idea (though it would take more lugging up and down stairs) would be to put the greenhouse on the second floor and use the wings for more living space. At least in our climate we want heat and moisture in the winter and you could setup a fan to blow the warm moist air from the second floor greenhouse down to the living space. And on cold, less sunny days... the heat of your living space would help heat the greenhouse floor. With this option you would probably not get much build up of snow, but if you did it would be coming off a greenhouse roof onto a regular roof that should be able to handle it better.

William Bronson wrote:
Most simple of all, maybe you don't need glazing on the greenhouse roofs.
Winter sun is low in the sky and mostly should enter via the vertical glazing.
By using a conventional opaque roof on the greenhouses , you can insulate it.

I have seen barns like this before, but did not know they had a special name!

Lots of good ideas here.  Based on living for many years with snow sliding off of a house with a metal roof, I can say that ~90% or more of your snow will land within 4' of the house siding (assuming ~18" soffit).  If your greenhouse will be sticking out from the main house structure by, say, 12 - 20 ft, you probably could get away with having 8 ft of solid roofing on the greenhouse most close to the house siding.  The remainder of the greenhouse roof approaching the drip edge could be your poly twin-wall (GE Lexan being a common standard).  As William B. notes here, depending on your location in Wisconsin, you will be getting low solar gain from above in winter and most will be coming through the sidewalls anyway.  But with a "half-solid, half-transluscent twin-wall" roof, you could still enjoy some extra ambient light and feel more confident that ice chunks won't be coming through your greenhouse.  All of this said, it may be worth giving the roof of the greenhouse a good tilt since the heat from the greenhouse will locally thaw any large accumulation of snow that can't otherwise run off of the roof.....freeze-thaw cycles are hard on seams, joints, and fasteners.

So excited! I am finally getting permits and closing on the loan on this project THIS WEEK! We've already set forms for pouring concrete so we are rolling!