Quick guidance on installing metal roof

[Squeaky_Alexander]

First off I want to say thanks for the advice I got in this previous thread on getting some 6x6 support posts installed. Now that the posts are done I'm moving on to my garage roof.

The roof is already sheathed in plywood, most of which is still good. My plan is to tear off the shingles and install the metal roofing right onto the plywood.

I get the general gist of installing the panels, but I can't find answers to some of the details. Here's a few of my odd questions.

1. Do I need any sort of underlayment?
2. How the heck do I do sidewall flashing with a metal roof?
3. Should I install a gable end overhang or not?
4. How big of a rolloff should I get? (I can do the sq ft calculations but hearing experience is useful)
5. If the job takes me a few weeks, can I reasonably keep water out by using tarps? Or is this asking for trouble?

I'm guess on this piece of sidewall (below) I can run the metal roofing under the existing flashing, but the area that concerns me is the other side of it, second pic.

I'm not an expert, but this area looks pretty poorly done. When I replace, should I install step flashing that goes under the siding and on top of the roofing? And kind of wrap it around the gable edge?

Speaking of, it seems like many modern houses/garages don't have gable or rake edge overhangs. But my thought is that since the house has a bit of an overhang (see first pic) it would be better to keep a similar style on the garage. On the other hand the garage roof is not that noticeable from the road or most parts of the property. And I've never really tackled a DIY project this big, so maybe I should just keep it simple and do away with the overhang? I dunno.

My father was an electrical contractor for a long time but also has done full house remodels, so he'll help me out once I get all my materials and plan in place. He is just honestly awful at explaining things. So any thoughts to help me along would be awesome. Then I can order my materials, get a dumpster, and start tearing up shingles. Got a quote from a roofer of around $4,000 for this job. Doing it myself (well, with help) should only come up around a third of that. We'll see.

 

[Squeaky_Alexander]

Back view for shits and giggles. Also an idea of size, each side is about 13'x24'.

 

[jonesg]

Sounds like a ludicrous price on a metal roof.
I was quoted under 1000 for a single car roof. Amish steel up in Maine.

 

[Kaizen]

You tube metal roof. Theee is a company that did some good videos esp on flashing. Yes there is a recommended underlayment to allow panels to move. Not tar paper. Not sure if I'm going yo use it. Laying metal goes fast. Shouldn't be more then a weekend job to strip and lay. I have one foot overhangs with crown molding. I'm overhanging my metal about an inch over the dripedge.


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[Charlie51]

If I were doing a tear-off, I would do the gable overhang. It will help a lot in the appearance and give a bit of protection to the siding and windows directly under it.

 

[Firebrand]

Quote is way high! If you DIY, get an 11 yard dumpster. Yes to overhangs. You'll need to order special formed metal parts to make the flashing happen for your roof intersections at the siding intersections. Ask your roofing supplier when planning your order. Metal goes down fast-wear gloves! Make sure your surface is flat with no metal sticking up before installing your underpayment. The new stuff is a synthetic: longer lasting, lighter weight, and much easier to install than tarpaper. Once that's down, the hardest piece is the first, just to make sure it's set straight as the rest have to follow. Good luck!

 

[yeldogt]

Why do you want a metal roof? Are you going to replace the house w/matching?

I'm not sure how people are giving you any idea on price since you don;t say .. what type of metal. I could never get a proper metal roof installed on that garage for 4k around me.

I love metal roofs -- I'm doing a zinc one on my new build .. but you have to plan to make them work correctly. You are going to hear the noise from the metal roof .. what about gutters?

Yes on underlayment -- that's what give you the working time to get the roof on -- if you are going to heat the space -- I would do a strip of ice shield if in a cold climate.

Personally -- I don't see the benefit of metal on the project. Get a nice 30 year shingle -- forgiving product .. easy to install.

My guess is the step flashing is along that wall -- be careful and reuse.

 

[texas webb]

Where do you live and what kind of metal roof are you talking about?Standing seam...corrugated...v-crimp...R or M panel?

 

[matt_i]

Grace has a peel & stick (the ice + water shield) specifically for metal roofs. It carries the -HT suffix which I think is for "high temperature". I think there have been issues using the standard peel & stick under metal roofs.

For that "wedge" you showed, I think the proper thing is to build a "cricket" which is basically a very small ridge that intersects the main roof over near the corner. Its a ton of detail work/hand fabrication/cut & measure but imo that's the right way to do this.

Something also doesn't look right to me in the way the roof was flashed to the wall. Imo it should be step flashings that go up under each and every shingle. That looks like a single piece of bent metal which looks great but has very low weatherproofing value. Hopefully its a counterflashing over top and the steps are just hidden underneath. Also its useful to spend some time understanding how a kickout flashing works...you don't have it either, and they kind of got lucky they could just notch fully thru the lower edge of the siding as to not create a water pocket...but a kickout flashing would be better there imo.

 

[TractorJeff]

Put metal roof on which will last 40 to 50 years. 30 year Asphalt Shingles no longer exist! If they did, there would be no such thing as water resistant underlay (IMO). As far as noise, they aren't that loud if there is a wood barrier they are laying on. My house has tin, garage has tin and my new shop has tin. Yes on a 10 or 11 yard Dumpster as far as size. Couple of guys start stripping in the morning, you'll be laying sheets on one side by Noon!
Key is the first sheet, but I did have a conversation with a Roofer once on it. He said to put the first couple of sheets on with only top screws, put sheet screws on the ridges of the sheets to tie them together, then re-measure to check square. If it is off, remove the top screws, move the sheets(which are tied together with the ridge screws) to square up, then re-fasten the sheets.
Make sense?

 

[readhead]

The roof to wall flashing is not correct and will need to be raised to work with metal. The garage to house connection should be reworked to eliminate the dead end rake into the side wall. Remove the siding and repair the water damage that is almost certain to be there.
Overhanging the metal at the gable rakes is very common but not a good idea. Proper rake flashing will close the gap and look better. Eave trim should be installed also.
Talk to a real metal supplier that has knowledge about proper material and installation practices rather than a big box store. A knowledgeable salesperson can save you a lot of headaches down the road.
To do the job properly you will need to remove some siding so be prepared. The sidewall flashing should be spaced out past the face of the siding so you have a kick out at the eave. Also be prepared to repair the damage behind the siding.
I sell metal roofing and siding but no longer install. I deal with mostly DIY customers and most really have no idea what they are in for. Most have the idea that all they have to do is throw some sheets down and put some screws in and they are done before lunch. The tricks of shrinking and stretching and flashing details are unknown to them.
It isn't difficult but watch some videos, check out some websites for install tips and think through some of the details before you start. Do the easy left side to get your feet wet before you tackle the other side. Do some math because you may have to rip the first sheet to come out right on the other end.

Andy

 

[Greyhorse]

Not sure why you would strip the shingles off, seems like extra work/expense if you are going to put metal on.

 

[yeldogt]

Put metal roof on which will last 40 to 50 years. 30 year Asphalt Shingles no longer exist! If they did, there would be no such thing as water resistant underlay (IMO). As far as noise, they aren't that loud if there is a wood barrier they are laying on. My house has tin, garage has tin and my new shop has tin. Yes on a 10 or 11 yard Dumpster as far as size. Couple of guys start stripping in the morning, you'll be laying sheets on one side by Noon!
Key is the first sheet, but I did have a conversation with a Roofer once on it. He said to put the first couple of sheets on with only top screws, put sheet screws on the ridges of the sheets to tie them together, then re-measure to check square. If it is off, remove the top screws, move the sheets(which are tied together with the ridge screws) to square up, then re-fasten the sheets.
Make sense?

What are you talking about -- 30 year shingles exist ? And how does that have anything to do with a water resistant underlay. And -- the biggest complaint about metal roofs is the noise (rain) ... and the OP has a dormer next the garage roof.

Doing corrugated on a barn w/o gutters is much different vs doing a proper standing (even with snap locks) roof on a house. .

As I said -- love metal roofs .. but they are not always the best for every project and not the easiest for a first time roof project. If the OP plans on doing the rest of the house -- the dormer may be a problem depending on his choice.

 

[finn]

I don't see the advantage of doing a metal roof on that house.

A good architectural shingle will be easier and quicker to install, and in my opinion, look better.

Metal is a bi##% to install on any roof with valleys or transitions. Straight runs like a ranch house or shop building are ok. The metal will tear in valleys if you live in snow country.

 

[readhead]

I agree that shingles would look better on the house. I would still rework the flashing details and fix the dead end rake.

 

[Tejay]

If you get any amount of snowfall I see many issues surfacing in your future with a metal roof.

 

[finn]

If you get any amount of snowfall I see many issues surfacing in your future with a metal roof.

Yup!

Contractors around here discourage metal roofs for anything other than a roof with no interruptions.

Talked to a guy a couple of weeks ago who has been gathering pictures of snow and ice damage to metal roofs with "features". He says people don't listen, but after they see the pictures, they'll go conventional.

He does both, by the way.

 

[readhead]

Done correctly, ideally with standing seam, metal will work fine. It's the correctly that is a problem. The paranoia that some people have with getting snow off the roof puzzles me. I don't know if that is the case here. I sell metal roofs and I took the metal off my house and installed shingles.

 

[matt_i]

I put Grace triflex on my roof as an underlayment with the orange cap nails on the "X" marks which are preprinted. I lapped it over the peak to be cut open when I was ready to install the ridge vent. I was thoroughly impressed how weather resistant it was, thru several drenching rainstorms, I couldn't detect a drop of water that had penetrated the sheathing. I was probably open in some form or another for ~30 days as I pecked away at the roof. One caution is that I found it very slippery when wet on a 6:12 roof. I waited for any moisture to dry off in the sun before going up there. Most of the work was standing on existing shingles with plenty of traction but I had the bundles stored up near the peak.

I would invest in some new drip edge all around. Also you should check your pitch. That looks to be about an 8:12 by guess which would be tenuous walking in the driest conditions...

 

[Whitworth]

Never done a metal roof, so I'm curious as to the answers to your questions as well.

But based on 13 by 24 feet times 2 size, if using 3 tab shingles I could do that in my sleep. Maybe 7 days working by myself (including tear-off), or 3 days work with a good helper.

 

[brownbagg]

if you do screw the metal down, some do. one tip is aline all your sheeting on the ground stack on top of each other, and pilot drill through all of them with a 1/8 bit. then all your screws will line up perfect.

 

[Tejay]

Here's what I see from your photos. Siding is right down to your roof when it should be 6" or so up to be able to flash properly. The lower end empties into an existing hole in the siding -definitely a wet spot behind that siding. You have a 90 degree corner that the snow will push on and most likely rip off and or inject water into that area. When the snow does decide to let go it will slide off and take out your stairs below or at very least create an area that you really don't want or need to be shovelling as it will set up like concrete.
I don't get why people want to create issues for themselves - leave the snow on the roof!!!

 

[DTE]

Here are some good videos from Union steel on installing a metal roof. http://www.unioncorrugating.com/installation-videos.html

 

[yeldogt]

Corrugated roofing relies on rubber gaskets and caulk for water tightness -- it's not a roof suitable for a dwelling unless it has an "under" roof for long term water tightness. Even some of the "better" systems will tell you in the fine print ... they drip. Especially in cold areas.

 

[Squeaky_Alexander]

Wow, thanks for all the feedback. I am in Southern VT so I get a decent amount of snow during the cold season. This area pictured here does become a huge mess with ice formations coming off the house roof connecting with ice buildup on the garage roof.

And the way I came to think about doing a metal roof was that, when we bought our place last December, realtor and inspector were saying easiest route for redoing the roof would be putting metal over the shingles. But then when I actually got a quote roofer said shingles were too far gone, and given there was a lot of trim rot too, that they would have to come off. There does seem to be a lot of stuff growing in them, so I can see that would be problematic if we just put metal over.

My plan was to use the cheaper ribbed steel roofing, not standing seam. But I did a quick estimate on shingle cost for the roofing area and I think it would be around the same as cost for ribbed steel. I guess I'm going to have to re-consider which roofing type will be best for me. I thought metal would be better for dealing with snow and last longer, and be easier to install. But I have no plans to re-do the house with metal.

Here's street view of our place, as you can see garage isn't very noticeable. And with the dormer and porch roof I don't think I would ever try to put metal roofing on the house. But, standing on the back porch you're eye level with the garage roof surface so had concerns with metal being reflective and maybe not as appealing from there.

I think I got the message that it's fair to ask for installation advice from my hardware store. With whatever roof type I get I'm going to have to probably talk with someone in person about getting the right flashing for the intersection with the house sidewall, and will prob have to do some repair work as, yes, I'm sure water has been getting behind my siding. Other option is to see if I can get a contractor to come in just to get the flashing installed right, I don't know if someone would be willing to do just that but why not?

I think I'm going to have to break job down into:

1. Tear off shingles/put down underlayment (ensure temp water protection)
2. Repair any water damage behind my house siding
3. Replace any rotted sheathing
4. Build and install my overhangs, redo eave and gable fascia
5. Redo flashing on sidewall area
6. Install drip edge and main area roofing

Feel like I'm leaning more towards asphalt now...

 

[Squeaky_Alexander]

Here's where my back porch is in relation to the garage. Would asphalt be nicer than metal given how in-your-face the roof is when you're hanging on the porch?

 

[yeldogt]

From what I can see you have two different types of siding -- AL on the bottom. Something else on top when the dormers were installed?

In the old days when AL was installed guys normally had at least one person making all the bends and flashing and they knew how to do it .... the flashing along the roof maybe fine. Bending a strip like that is not unusual around me .... I can't see what's under that other small connection point. It's a poor idea from the get go.

I don't think you understand why people don't use the "barn" type corrugated metal on houses.

And yes ... asphalt will look better ... what's on the rest of the house... match that

 

[6768rogues]

I would just strip it and put architectural shingles on it. Then you can step flash intersections. No need for gable trim pieces and trying to keep bees from nesting in the corrugations. The noise from rain will be loud enough to keep you up at night. I like metal roofs for outbuildings, but not for anything near where I sleep. I am 65 years old and with a shingle eater I could have that garage roof stripped before lunch and the whole thing done and cleaned up in a weekend.

 

[matt_i]

Asphalt shingles are easy to cut, bend, use. They're heavy...that's the only downside.

I'd make a bigger project of it. If you go architectural shingle, I think those look much better and they are thicker so last longer. Obviously redoing the garage that way would force the house to be done as well. Properly done you're into a good 30 years of happiness.

The kickout flashing can be ordered. The step flashings can be made from trim coil or bought from big boxes. Anywhere that's iffy, use ice+ water shield. I'd make sure that cricket gets built.

I would try a local roofing + siding yard over a hardware store...they will have more products stocked, more suggestions on installing it, basically more of what you need. They also might point you to a number of contractors who will do a good job. They probably know over time whose work stands out as reliably good, who orders "better" materials, who wants the absolute cheapest they can get, and whose work has to be redone by others.

The biggest issue to DIY that I see is I don't think the roof pitch is walkable. You'd have to use toe-boards & brackets. But, that's just another step in the process...