Corrugated Steel Roof Panel

[Krugerrand]

I'm getting ready to cut corrugated steel roofing for my small coop. Here is an edited picture from the seller of the plans I'm using as my guide.

The coop is a shade bigger than the plans called for, and I'll be making the roof a bit bigger to which will be one way I'll be adding additional ventilation. The roof will be in the range of 5'x5'. I'm expecting to use 3 of these 24" panels:
https://www.homedepot.com/p/Gibralt...ty-Gauge-Roof-Panel-in-Silver-13513/202092961

I'll be adding an overhang on the high side and a ridge-cap on the top. The ridge cap is something like this:
https://www.homedepot.com/p/Metal-S...lvalume-Universal-Ridge-Cap-4202341/204221815


1) Under the roof: I'll have plywood. Do I need any sort of felt/wrap between that and the steel? I painted the floor with Black Jack 57. I've read some threads where others used that on the roof ... perhaps a coat of that would be sufficient?

2) What overhang should I leave on the A & B sides?

3) What stops water from blowing up the roof and under the ridge cap in high-wind rains? Perhaps that's what the closure strips do ... but while both Home Dept and Lowed have the steel panels in stock, neither appears to sell any closure strip that fits them? Plus, they look more in line to stop bugs than water.

Thanks!

 

[U_Stormcrow]

1) Why????


Metal roofing is designed and intended to be set upon purlins - increases airflow, allows leak inspection easier, no trapped moisture considerations (so no need for roofing felt, black jack, etc. Saves time and money.

2) As much as you can - particularly if it eliminates cutting.

3) Foam closure strips - though it takes a strong wind (depending on the angle of the roof) and very little blows in, even then - certainly not enough to be much concerned about. Check over with the plastic roofing, you may find a shape that works for you. Keep in mind that the closure strips significantly reduce the use of the ridge cap for ventilation, and that coop is already vent impaired, unless you are going to open the top of the wall under the overhang you are adding.

 

[Ted Brown]

While there is no absolute requirement to add something between the metal and the plywood many folks do. I used deck membrane (synthetic waterproof breathable); only issue is it comes in rolls about 60 feet long by 4 feet wide so unless you can buy a small section it would be too expensive.

I used BJ57 on my floor and and am very satisfied with it after two years. One could use it on the roof and it will waterproof the plywood in case of any leaks through (or under) the steel. Some roofers will say that the plywood sheeting should "breath" on both sides but in your application that is not necessary as you will be providing good ventilation for the coop itself.

Your diagram does not provide much detail but the ridge cap you show is intended for equal slopes both side. It is somewhat flexible but the angles will not match what is shown in your diagram; you will have to "force fit" and securely screw it in place.

While it is possible that rain could get forced under the roof the only exposed edges will be on the downside two edges so any that does penetrate will dry quickly given the air flow. I would not worry about it especially with some waterproofing material between the steel and the plywood deck.

The most common overhang that I see recommended on BYC is 12". Be certain that the height of the coop is such that the steel is not low enough for someone to walk into.

Good luck.

 

[Krugerrand]

1) Why????


Metal roofing is designed and intended to be set upon purlins - increases airflow, allows leak inspection easier, no trapped moisture considerations (so no need for roofing felt, black jack, etc. Saves time and money.

2) As much as you can - particularly if it eliminates cutting.

3) Foam closure strips - though it takes a strong wind (depending on the angle of the roof) and very little blows in, even then - certainly not enough to be much concerned about. Check over with the plastic roofing, you may find a shape that works for you. Keep in mind that the closure strips significantly reduce the use of the ridge cap for ventilation, and that coop is already vent impaired, unless you are going to open the top of the wall under the overhang you are adding.

1) no good reason, other trying to somewhat follow the plans - which had a sub-roof. I had cut an extra roof support and will be adding two at the ends. (drawn brown) Can I screw the roof directly to that? Or would I need to add purlins perpendicular on top of those? It seems if I go into that, i could just add some in-line horizontal cross pieces throughout the roof.

2) The plan is to limit cutting. If I put three panels together I should have 64.5" if width. I have to cover 48" of coop. So, I was trying to figure out how wide to make the subroof ... but if I don't have that, I would need to know how wide to frame out underneath it. They're 8' pieces, so I need to make 1 cut across each for the 5' length and one cut each to get something around a foot long for the overhang.

3) I'm find to go without closure strips if not needed. Since the ridge is beyond the top of the structure, I'm not sure closing it up would cost me much.

The ventilation at the top joists will give me 2 sq ft. (That doesn't include the space by the sides at the top which the wider roof will open up and give me about another 2 sq ft (but I haven't calculated that one yet to be sure) The light blue that you see towards the top of the high side will be another 2 sq ft of ventilation. It's also another advantage of the overhang. (I'll be putting the doors on that side, too.)

 

[Ted Brown]

One caution given your location.

Given the amount of moisture the chickens eliminate it is not unusual to get condensation on the underside of the steel sheets in cooler temperatures; can drip and put the humidity back inside the coop. Given the small size of the coop I would add the deck sheeting (either OSB or plywood) and eliminate any chance of this.

While it is true that many outbuilding use purloins only it is also used on homes, etc. all of which will have deck sheeting.

Generally one should have 1 sq. ft of ventilation PER BIRD.

 

[Krugerrand]

One caution given your location.

Given the amount of moisture the chickens eliminate it is not unusual to get condensation on the underside of the steel sheets in cooler temperatures; can drip and put the humidity back inside the coop. Given the small size of the coop I would add the deck sheeting (either OSB or plywood) and eliminate any chance of this.

While it is true that many outbuilding use purloins only it is also used on homes, etc. all of which will have deck sheeting.

Generally one should have 1 sq. ft of ventilation PER BIRD.

I was liking the idea of not needing the deck sheeting.

My calculations put me at about 5 sq ft ventilation for 4 birds of which 1 is a silkie.

 

[U_Stormcrow]

1) no good reason, other trying to somewhat follow the plans - which had a sub-roof. I had cut an extra roof support and will be adding two at the ends. (drawn brown) Can I screw the roof directly to that? Or would I need to add purlins perpendicular on top of those? It seems if I go into that, i could just add some in-line horizontal cross pieces throughout the roof.

View attachment 2649243

2) The plan is to limit cutting. If I put three panels together I should have 64.5" if width. I have to cover 48" of coop. So, I was trying to figure out how wide to make the subroof ... but if I don't have that, I would need to know how wide to frame out underneath it. They're 8' pieces, so I need to make 1 cut across each for the 5' length and one cut each to get something around a foot long for the overhang.

3) I'm find to go without closure strips if not needed. Since the ridge is beyond the top of the structure, I'm not sure closing it up would cost me much.

The ventilation at the top joists will give me 2 sq ft. (That doesn't include the space by the sides at the top which the wider roof will open up and give me about another 2 sq ft (but I haven't calculated that one yet to be sure) The light blue that you see towards the top of the high side will be another 2 sq ft of ventilation. It's also another advantage of the overhang. (I'll be putting the doors on that side, too.)

1) Purlins perpendicular. The roof panel you've chosen has no "flats", so your screws will go thru the lower portion of the "U" directly into the purlin. You've already framed it out, chances are the bottoms of the Us will miss the tops of your existing framing. To save cuts, buy three dog ear fence slats - they are pressure treated, and you can likely buy in a 64" height One top, one middle, one bottom.

2) 8" either side. 48 + 16 (2*8) = 64. No one cares about the 1/2"

3) Good plan.

 

[Krugerrand]

chances are the bottoms of the Us will miss the tops of your existing framing

They weren't going to miss ... I was planning on placing them to line up with the bottoms of the Us.

(The picture is from the seller page. I have the base of the frame built, I have not yet attached the roof pieces.)

 

[U_Stormcrow]

They weren't going to miss ... I was planning on placing them to line up with the bottoms of the Us.

(The picture is from the seller page. I have the base of the frame built, I have not yet attached the roof pieces.)

If you are confident they won't bow between the rafters, you could skip them - I'd use purlins. Will also provide more locations to mechanically fasten to the roofing material.

 

[Krugerrand]

If you are confident they won't bow between the rafters, you could skip them - I'd use purlins. Will also provide more locations to mechanically fasten to the roofing material.

I guess that's where I was counting on the deck sheeting. Plus, with 4 supports, nothing would be more then 1' wide.

Still, I guess there could be some sag with heavy snow load. and it would be easy enough to add a few cross supports.