Porch roof

[MossflowerWoods]

Rember that with a shallow roof, the edge tends to hold water and if you don't have a good drip edge, water will want to hold onto the edge and come back under the roof and behind the fascia. This is VERY COMMON, and a big reason that people call me out. The fascia and soffits are rotting out and they don't understand why. In every case, it's because water is coming back under the roof.

Eddie

Eddie,

I'm thinking about metal roofing on a run-in shed for my horses. It will also be a fairly shallow pitch roof just because I need it to be easy to build by myself... I'm thinking a 1:12 or a 2:12 pitch (Please advise what pitch you think, we do get snow here, just not tons usually).

How do I prevent the water coming back under the roof problem.

Thanks in advance,

David

PS - Prokop, Please forgive the hijack of your thread...

 

[chopped]

I have a few roofs with the membrane and also shingles.in fact one leaked and I pain-stakingly removed the shingles ,saved the nails and then reapplied over the rubber membrane. I will use this membrane for all roofing int he future.its simple double protection,

198 sq. ft. Grace Ultra Self-Adhered Roofing Underlayment-5003000 at The Home Depot

Thank you, Steve,

That metal roofing looks just like MasterRib, but MR has minimum pitch 3:12:

MasterRibｮ Metal Roofing Panels - Install Metal Roof Panels - Union Corrugating

I wonder if doing a membrane and shingles on top of it will make it last longer, since shingles will protect it from the sun?

Thank you all for suggestions, TBN helpful as always :thumbsup:

 

[czechsonofagun]

Eddie,

I'm thinking about metal roofing on a run-in shed for my horses. It will also be a fairly shallow pitch roof just because I need it to be easy to build by myself... I'm thinking a 1:12 or a 2:12 pitch (Please advise what pitch you think, we do get snow here, just not tons usually).

How do I prevent the water coming back under the roof problem.

Thanks in advance,

David

PS - Prokop, Please forgive the hijack of your thread...

Hijack what you want

I used metal roofing on the tree house - it was challenging

Probably the same stuff you are planning on using - MasterRib from Culpepper/Marshall Coop - i think MR supplies the whole Virginia.

 

[GLyford]

How do I prevent the water coming back under the roof problem.

Most home stores sell "drip edge flashing", which is either "L" or "T" shaped, and the leg that hangs down has an edge that sticks out to shed droplets. The plain unpainted stuff is about $3 for a piece 10' long. If you have fascia boards, it's usually installed between them and the roofing (panels or shingles). Otherwise, you could just put it up over your purlins. I'd put a piece over the ends up the sides, too. Then install your roofing, with maybe a 1/2" overlap past the flashing (for the L) or nearly flush (T).

When running paper and shingles, the bottom drip edge usually goes under the paper (or ice-and-water shield) so that anything running down the paper under the shingles will still go over it. On the sides and top, they usually get nailed over the paper to help keep the wind from getting under the edges.

 

[MossflowerWoods]

[I used metal roofing on the tree house - it was challenging

That is an awesome picture Prokop!

How did you get off the roof!

David

 

[MossflowerWoods]

Most home stores sell "drip edge flashing", which is either "L" or "T" shaped, and the leg that hangs down has an edge that sticks out to shed droplets. The plain unpainted stuff is about $3 for a piece 10' long. If you have fascia boards, it's usually installed between them and the roofing (panels or shingles). Otherwise, you could just put it up over your purlins. I'd put a piece over the ends up the sides, too. Then install your roofing, with maybe a 1/2" overlap past the flashing (for the L) or nearly flush (T).

When running paper and shingles, the bottom drip edge usually goes under the paper (or ice-and-water shield) so that anything running down the paper under the shingles will still go over it. On the sides and top, they usually get nailed over the paper to help keep the wind from getting under the edges.

GLyford,

Awesome post... I helped my buddy (who was just starting out with his own roofing company) roof my very first house I ever bought back in 1990... But I was not much help honestly, and that was a LONG time ago...

David

 

[czechsonofagun]

That is an awesome picture Prokop!

How did you get off the roof!

David

The window helped some but I had a rope from the tree to hold to and for other places ladder with hook for the ridge. Day work on a ridge like this felt like giving birth

 

[ETpilot]

I built a 14x30 flat roof behind my house. I used grooved plywood with the groove face down, very short nails that would not show and flashing at the roof joint. First roofing job was shingles. I used a double coverage felt paper under the shingles. This lasted quite a few years but then a leak developed by one of the nails. Eventually I had to repair the plywood and redo the roof. The second go around I used roll roofing since I got it free. If I recall correctly I used the double coverage on both the felt and the roofing material. I also used a drip rail and Hardie Plank for the fascia. It has been up there for about 10 years now and no problems.

If you go shingles or roll roofing look into doing a double coverage. It is more work and takes more material but I have been pleased with my end product. If I had to choose between shingles and roll roofing I would go with the roll roofing.

 

[EddieWalker]

Eddie,

I'm thinking about metal roofing on a run-in shed for my horses. It will also be a fairly shallow pitch roof just because I need it to be easy to build by myself... I'm thinking a 1:12 or a 2:12 pitch (Please advise what pitch you think, we do get snow here, just not tons usually).

How do I prevent the water coming back under the roof problem.

Thanks in advance,

David

PS - Prokop, Please forgive the hijack of your thread...

The flatter the roof, the harder it is for slow moving water to fall cleanly off the edge. Heavy rains are never an issue, it's the slow moving water that gets to the end of the roof and then comes back under and either holds there, or actually follows the bottom of the roof to the soffit or whatever barrier it hits. Flashing gives you that sharp downturn to your roof that the water cannot get around. 4:12 pitch roofs are steep enough not to need it, but shallower roofs do.

I don't live in snow country, so I can just guess. My thought is that with snow sitting on the roof and slowly melting, you will have that slow moving water problem to deal with more so then where I live.

Flashing is cheap and easy to install. I use it on all my gable ends and valleys.

Eddie

 

[MossflowerWoods]

The flatter the roof, the harder it is for slow moving water to fall cleanly off the edge. Heavy rains are never an issue, it's the slow moving water that gets to the end of the roof and then comes back under and either holds there, or actually follows the bottom of the roof to the soffit or whatever barrier it hits. Flashing gives you that sharp downturn to your roof that the water cannot get around. 4:12 pitch roofs are steep enough not to need it, but shallower roofs do.

I don't live in snow country, so I can just guess. My thought is that with snow sitting on the roof and slowly melting, you will have that slow moving water problem to deal with more so then where I live.

Flashing is cheap and easy to install. I use it on all my gable ends and valleys.

Eddie

Thanks Eddie!

 

[tcreeley]

View attachment 272097To do flashing, drip edges this pdf link may be helpful.
http://www.metalsales.us.com/files/installation-guides/Application%20Manual-West%20Coast.pdf

You have to study it a bit to make sense of the design drawings. When I did my barn- I learned later that snow blows in where the metal roof goes up and down (corrugations). They sell foam strips that match the profile to install when you put it up. Be careful of using spray foam because it will expand and lift your panel unless it is down pretty tight.
I used drip edge to match and side drip edge. My roof was not insulated, so I applied the panels right on the 2x4 cross framing. But first I put down the bottom drip edge, then the side sloping drip edge, then the roof panel and finally the eve cap. Foam at top and bottom is good. Also I used this air vent stuff for ridge vents sold in 50' roles at home depot. Goes under the ridge cap. I cut the 12 inch wide piece into 2 -6" wide pieces and lay them on top of the foam . The air can get in/out, but snow doesn't com in that I see.
Maybe you can blow up the barn pic to see where I used drip edge. The stuff on the bottom is different from the edge on the side. Different profiles. Over the door I used cedar shingles on top of the drip edge- ran out of metal panels to cut down.View attachment 272098

 

[MossflowerWoods]

To do flashing, drip edges this pdf link may be helpful.

Thank you. That is a helpful document and your barn is VERY nice looking sir!

Thanks again.
David