Lean-to Chicken Coop Roof & Ventilation (w. pic)

[mrtoren]

I'm wrapping up framing for my 4x8 chicken coop and had some roof and ventilation questions. I am in Central Illinois. Cold winters, occasional snow, rainy springs, and summer thunderstorms -- but nothing unusually extreme. We are on farmland with occasional gusty winds during temperature swings.

The coop is pictured below and positioned to try to minimize wind and weather. Our winds come from the north and west. The windows will be above the nesting box facing south. My other ideal ventilation location will probably be the far short side facing east.

I was able to source some Pro-Rib metal roof panels so I will be using those for the roof. Purlins will be installed tonight. The roof panels are a little over three feet wide and provide actual coverage of three feet when overlapped. Going three panels wide will provide me with nine feet of coverage. That's six-inches of overhang on the sides (additional 2x4's for the side overhang and front/back caps the rafters will be installed). Water should not be draining from the side so I believe a small overhang will be sufficient. I will have one foot of over hang off the front and back.

I will be installing two 20x30" windows above the nesting box. I also planned to leave the area where the rafters meet the studs open for ventilation. I am not particularly concerned about weather exposure in the rafter area on the lower side since it is sheltered by the roof. However, I am concerned about weather exposure on the taller side. For those with lean-to coops, have you had rain enter the coop if you leave the rafter area on the taller side open for ventilation? Is it smarter to close the rafter area on the tall side and use, say, four hinged panels (positioned between the vertical studs just under the top horizontal stud) that can be opened and closed for ventilation?

Any ideas for more ventilation? Perhaps along the far short side?

 

[U_Stormcrow]

So, rain will only enter on the tall side if its blowing sideways, and in those cases, its the winds you have to worry about far more than the water. Further, most all of us screen that area with hardware cloth, which does a far better job than it should blocking windblown rains. I don't understand the physics of it.


If its deeply concerning to you, cut an angle on the front of the rafters so the edge is perpendicular to the ground, not angled as it is currently, and face it with a pressure treated 1x or 2x6 - such as the boards used as flooring on a deck. The additional overhange will interfere with air flow, creating a swirl which will further deter windblown rains.

Looking at the framing, your most likely place of water entry will be your nesting boxes - are you planning a top open hinged design? All/Any water blown against that wall is going to want to run right down it, straight into your hinge.

 

[mrtoren]

Looking at the framing, your most likely place of water entry will be your nesting boxes - are you planning a top open hinged design? All/Any water blown against that wall is going to want to run right down it, straight into your hinge.

Thanks for the feedback!

There will be a hinged lid on the nesting box. I agree that a primary point of infiltration could be the gap where the lid meets the coop. I believe the overhang should drop water onto the angled lid which will then run down off of it. If that's not the case, I will install a flashing to protect that gap.

 

[U_Stormcrow]

Its late in the process, and it creates other problems (there are no perfect solutions), but you might consider raising the nesting boxes, and accessing them from the "front/long side" with a bottom hinge access (so it stays open while inspecting and gathering eggs).

My sense its that you would attach it directly over the existing ledger board, then add another ledger to support the nesting box roof, higher up. The problem then becomes location of the roosting bars, which need to be above the nesting boxes to discourage sleeping in them... and, breed dependent, how they get up there.

As I said, no perfect solutions. Given the size of the structure, the current framing is probably the best of a number of imperfect options - but at least you are now aware of the tradeoffs involved.

 

[3KillerBs]

Venting the soffits at the top and bottom of the slope is ideal to create the necessary air movement because heat and ammonia both rise.

Using top-hinged windows rather than single/double-hung windows allows the windows to act as their own awning so that you can adjust the airflow to the current conditions most effectively.

I have bad experience with a top-hinged nestbox leaking and we ended up remodeling those nests into a front drop-down style.

 

[suburbanfarmermi]

I have bad experience with a top-hinged nestbox leaking and we ended up remodeling those nests into a front drop-down style.

We chose to do the side access to the nesting boxes. I was worried about a few things:
-getting a good seal on the top
-having to hold up the lid while accessing the space (especially for my 6 year old)
-my little ones not being tall enough to access the space and or see in.

The side access seemed to address all of these concerns. I did make sure to leave an inch or two of wall to make sure the eggs could not just roll out when I open the door

 

[K0k0shka]

I have the same style coop. It has wraparound vents on all sides where the walls meet the roof. I basically left about 6” between the wall boards and the roof open, with 8” overhangs on all sides. I don’t have a problem with rain blowing in. However, snow does blow in from the tall side, probably because snowflakes are lighter than rain drops and are easier to blow horizontally (the tall side faces south and our main wind comes from the northwest, but in a snowstorm the wind is all over the place). My first winter with this coop, one morning after a snowstorm there was so much snow inside the coop that I had to block off the vent on the tall side completely. Now I cover it with a sheet of plastic (screwed into the coop with furring strips) for the winter, and leave it open the rest of the year.

Keep an eye on your windows though, rain is more likely to blow in through them than through the vents, because they are farther from the overhangs and less protected by them. My run is partially covered, and one of the coop windows faces the covered part, while the other one is in the uncovered part. The uncovered window gets rain blown through it during storms, so I have to close it before any windy storms. It’s a sliding house window. I might give it an awning of some sort, or a top hinged shutter that I prop open just to keep the rain out. It’s closed in the winter so snow isn’t an issue.

 

[Huntmaster]

I had to block off the vent on the tall side completely. Now I cover it with a sheet of plastic (screwed into the coop with furring strips) for the winter, and leave it open the rest of the year.

I have seen on other threads where they use like a furnace filter type material to cover vent areas to block snow and still have some ventilation or air moving through but not snow. Something like that should work.

 

[K0k0shka]

I have seen on other threads where they use like a furnace filter type material to cover vent areas to block snow and still have some ventilation or air moving through but not snow. Something like that should work.

Yeah, I can probably find some material to put up there in winter… maybe a window screen even… I have enough ventilation even without that side, but more is always better, so I’ll think of something, thanks.

 

[Krugerrand]

I built my roof so that it is open on all 4 sides. I added some extra ventilation at the top, and then brought a slight overhang down from the peak so to keep out rain.

The roof joists are attached with hurricane ties:
https://www.homedepot.com/p/Simpson...e-ZMAX-Galvanized-Hurricane-Tie-H1Z/100374935

The cross piece and overhang is attached with Ridge Rafter Connectors.
https://www.homedepot.com/p/Simpson...nnector-for-2x6-Nominal-Lumber-RR-R/313810437

I also went with a flip down egg box to prevent leaks: