Installing a standing seam metal roof is not as easy as it may seem at first. “Yeah”, you might think: “What is there to do? Just put up those panels!”.
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Not so quick, now! Standing seam installation process can actually involve a lot of tedious work, so let’s cover it in a step-by-step fashion to see some of the challenges it may entail. Shall we?
1. Basic Preparation for the Job
The most important thing about installing standing seam, is to measure the roof correctly and precisely. Here is why; Each standing seam panel is cut to the exact size, and if your panels are too short, you will run the following costly issues:
A) If a panel is only 2″ short, you may not be able to use your ridge cap as it will not cover the ends of the panels. In this case you will have to get or make a wider cap. In this case it will go from 12 to 16″ wide cap (remember – panels are 2” off on each side, so we add 4″ to the ridge cap)
B) If panels are short by 4-6″ you may not be able to get a cap that wide, so now you have only two options: Ether panels are useless, or you splice them. Splicing 6-inch metal panels, while sitting at the ridge of your roof is about as much fun as head-butting the curb! 😉 You would probably want to get at least 2-3 feet long panels for splicing. You will also need at least a foot of overlap on each panel.
In either case you will run into additional work and will likely have to spend a lot more money compared to what should have (and could have) been originally spent.
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A few words of advice before you get started:
Roofing, by its very nature, is a very dangerous work, and hence your safety should be your number one priority. We always recommend using a full body harnesses and a properly set-up fall protection system consisting of roof anchors, 50′ lifeline, and a shock-absorbing lanyard.
You can buy these in most Home Depot and Lowe’s stores, or any local roofing supply place, or online.
Using heavy duty steel screws or 3″ framing nails with a double head for easy removal, install your roof anchors over the ridge, so each “ear” of the anchor is located on different side of the roof.
The best way to install it, is to find roof rafters and put your nails into them. This will give you the best hold-down on the roof.
When attaching the lifeline rope, always make sure that the arrow on the lanyard’s self-tracking rope grab points up, toward the roof anchor. Otherwise, it will not hold you in case of a fall.
You should always have at least 3 anchors for an average size home. Each person on a roof should be tied off to his or her own anchor. You should not have more than one person tied to one anchor (unless it is the end of the job and all other anchors have already been removed.).
The very first thing you should do when you get up onto the roof, is to install the anchor. You should already be properly wearing a body harness and have a rope with you. Once the anchor is securely attached to the roof, snap on your rope, and now you can start measuring your roof.
Step 1 – Measuring the roof:
So, in order to get the right measurements, you will actually have to go up onto the roof and measure every Eave, Gable, Ridge, Valley and Side wall.
Once you get the exact to-the-inch measurements, add two inches to each panel for the drip edge, which sticks out by an inch and gets bent back by an inch.
Assuming your panels will be 16 inches wide, take the width of your home in feet, multiply it by 12 and divide the result by 16. This will give you the number of panels required for each side.
I like to order my panels at least one inch longer than my measurements, and also at least one extra panel for any screw-ups that for some reason always seem to happen! 😉 I recommend you do the same.
Step 2 – Prepare your roof:
Unlike steel and aluminum shingles, standing seam panels should not be installed over the existing asphalt shingles. There are two main reasons:
- First, if you install a standing seam metal roof over asphalt shingles, there will be a so called “telegraphing effect” where shingles can punch horizontal lines in standing seam panels. — This in neither aesthetically pleasing nor good for the metal panels.
This gets us to the second reason not to install standing seam over shingles:
- Since most contractors and homeowners are looking to spend as little as possible, they usually choose to install a Steel Standing Seam, which is usually made of Galvalume or G-90 galvanized steel.
Well, the truth is that steel can ultimately rust and corrode, especially if its coating wears off.
And if you put steel standing seam over asphalt shingles that are covered with stone granules, the expansion and contraction of the metal will rub the underside of the panels against stones on the shingles. — This will sooner or later cause the protective coating to wear off, thus inviting the rust spots to start popping up all over the roof.
To avoid the above-mentioned problems, you should tear-off all the old shingles and make sure there are no nails sticking out from the roof deck, before installing standing seam.
Once the tear-off is complete, repair and replace all rotten wood. You do not want to put a brand-new lifetime metal roof over an old, rotted deck.
Once the tear-off is complete, install a waterproofing underlayment, which will protect your roof in case it rains during the installation of your new roof and will be a second waterproofing barrier once the main roof goes on.
I recommend using GAF DeckArmor breathable synthetic underlayment, and strongly advise against Felt or tar paper, both for safety and performance reasons.
Mask sure you start installing the underlayment working your way from the bottom up. On lower slope roofs, we overlap the underlayment by at least a foot. On steeper roofs, all you really need is 6 inches of overlap.
Spend some extra time wrapping the chimney as it is very likely to leak if you seal it the wrong way. Start at the bottom of the chimney with a piece of underlayment that is 4 feet wider than the chimney, so it will have a 2 feet flap on each side.
Run underlayment 6 inches up the wall on the chimney and nail the flap to the roof along the straight line of the fold.
Put only two nails for now, at each end of the fold line. Cut the corners sticking to the sides of the chimney at 45 degrees from the roof deck and wrap them around the chimney. Install your side flashing in the same manner and then the top flashing.
Run a bead of caulking (we use Solar Seal 900) between the chimney and top 1 inch of the underlayment flashing. This will make your chimney watertight, and even if it rains, the water won’t get through.
Here is what your chimney flashing should look like:
2. Necessary Tools, Materials, and Supplies
A roofing hatchet or a carpenter’s hammer. I prefer a hatchet, but in some cases you do need a claw-hammer of some type to pull out nails. You can also use a flat bar, but it’s not always convenient to have too many bulky things on the roof.
Utility knife. After trying out more than 50 different utility knifes, I came to a conclusion to use the single-use knifes with blades that are long and you just brake off a dull piece of the blade and the next on is sharp. You can buy them at a Dollar Tree – 3 knifes for $1. They are light and I don’t care if I drop or lose one.
Carpenter’s pencil and/or Sharpie permanent marker. You can buy these at Home Depot or Lowe’s
Sheet Metal Snips – I prefer the 3″ snips (with yellow handles) from Sears – they last the longest, cut easily while staying sharp, cost only $16.99 and (very important for me) have sharp, pointy tips that make the cut very clean, without ripping the metal.
Tape measure. There are many and many people have their own preference. For me, I find the best tape measure is the one from Lowe’s, that costs $9.99. It’s green and has a black release button. I like it so much because when you pull out the tape, does not retract back, but stays until you press the release button. All other tape measures work in the opposite manner, which I find VERY annoying.
Again, just as with tape measures and many other tools, there are so many choices, but a good belt can make your roof installation as pleasureful as one can be, while a so-so tool belt will make your life hell and you will probably hate any kind of construction work for the rest of your life :).
My personal preference is a $45 plus tool belt from Home Depot. It is made of blue heavy duty synthetic cloth. It has a metal ring (hammer / snips holder) on each side, large pockets, a special place to put a bulky tape measure, and is otherwise rate small, compared to other full size tool belts.
It is also light and somewhat comfortable to wear on the roof. You can also take it apart – i.e. remove one of the pockets which will make the tool belt only “half the size”. The Velcro belt also makes it easy to put on.
Sheet metal hand seamer / folder. This tool is invaluable for any metal roofing work. In fact, when I just started installing metal roofs, hand seamer, along with the above tools where the only tools I had and needed to install a metal roof.
Everything else is just for convenience / speed. With the hand seamer / folder, you can make such complex flashing pieces as chimney collar, sidewall, etc. You will find it very useful and essential to the installation of a metal roof.
The above-mentioned tools are the bare essentials you’ll need to install any metal roof, whether metal shingles or standing seam.
Drill/Driver: Aside from these, you will need a cordless drill. I recommend an impact driver with Lithium-Ion batteries, and all my power tools are made by Hitachi.
I used to work with Craftsman and still own them, but they are heavy, loose power fast, and break, while Hitachi ones are light, strong, have log battery life and do NOT break!
Wood cutting: For minor wood repairs, a cordless Sawzall such as the one by Hitachi will be more than adequate. Actually, I rarely bring my corded tools to a job site anymore.
To properly install a metal roof, you will need a properly attached underlayment and properly flashed and sealed roof penetrations. After trying out many products, I have my favorites that I now exclusively use on every job:
Underlayment: We use GAF DeckArmor breathable underlayment on every one of our roofs. Why? Because it is the best we found at reasonable price (there is a similar product, but it costs 4 times more and is not any better in actual performance).
DeckArmor is durable, slip resistant, watertight, light-weight and comes in 4’6″ wide rolls which makes installation much faster, compared to 3″ rolls.
DeckArmor prevents most moisture problems associated with the synthetic underlayments, where the moisture is trapped between underlayment and roof deck, and makes the wood rot, causes mold, mildew and problems for contractors using them.
Deck Armor works like a human skin, by letting the water vapor molecules pass through, while keeping the water out. This way, any moisture from the inside escapes and runs down, between the underlayment and the actual roofing material, instead of being trapped inside.
You can easily walk on the underlayment, after securely attaching it to the roof deck, and you can leave it exposed up-to 6 months and not worry about leaks.
Nails: We use 1 1/2″ plastic cap nails to attach the underlayment to the roof deck. They are rust-proof, lightweight and will not damage the underlayment, unlike regular roofing nails. You can buy a large bucket of these nails at Home Depot or Lowe’s, but I recommend not to get 1-inch nails, which the above-mentioned stores usually stock. Get the longer ones, and it will be much easier for you to work with them.
Sealant / Caulking: Each roofer has his/her own preference when it comes to sealants, and my love goes to Solar Seal 900. I found it to be the best caulking that is water-tight, cures fast, has very strong adhesion, is rather inexpensive and comes in a variety of colors.
3. Standing Seam Metal Roof Installation Process
Step 1 – Installing the drip edge
Installation of the drip edge is usually a rather simple process, but for a novice roofer it can be a challenge. I’ll take a step back to the first part of this guide – when prepping your deck, make sure that the old drip edge is completely removed, and all rotten wood (boards or plywood sheeting) is replaced.
There are several opinions as to whether install drip edge under or over the underlayment. In theory if you install drip edge over the underlayment, then run-off rainwater may get underneath it. In reality, metal drip edge gets installed so tightly, that water just rolls over it. Therefore, I always install underlayment first, and then go over with the drip edge.
Advantages of installing drip edge after the roofing underlayment has been installed, are as follows: You do not waste any precious time during the installation of the drip edge; when and if your roof is open and it rains, you may not have enough time to cover it, that’s where having water and vapor barrier in place really comes handy. Second reason is the safety.
When I install underlayment, first I can trim the edges as I please, in case that a hang off portion of the roof is too lengthy. If your drip edge is already in place, and underlayment hangs off it, trimming it may be rather dangerous, while sitting on the edge of the roof.
Lastly – it really does not make much difference in terms of performance. A properly installed metal roof will keep the water out, and the only water on the underlayment will be condensation.
If rainwater does get onto the underlayment after a metal roof has been installed, then you have bigger problems to worry about! 😉
Install your drip edge using either screws or nails about 8-12″ On center (O.C.) in a staggered pattern for optimal rigidity. Overlap individual sections by at least 2″ and don’t forget to open up the lip of the overlapping section for a better fit. Install the drip edge along all eaves (horizontal ends of the roof).
If you have a hip roof, trim your drip edge so it overlaps the batting section.
Note: Usually you will receive a drip edge with 1 1/8″ face. You can optionally order 2 1/8″ face or any other size as well as vented drip edge in case you want to do the soffit / ridge ventilation, and you don’t have any soffits.
Depending on your metal roofing supplier, you can order pretty much any type of a trim detail custom made to your specifications. Unless you specify, you will usually get the standard trim that your supplier has.
I once got a 2″ face drip edge while I was expecting a 1″ and 2 inches did not work, so I had to exchange them. Think about such things ahead of time, and you won’t be wasting your time and money – always specify what you want to get. Most fabricators / suppliers will accept your drawings, even hand-drawn on, a piece of paper.
Step 2 – Gable / Rake trim:
With standing seam metal, there are at least two ways to trim the gables of your roof with many variations; using a special gable trim or a regular drip edge. I prefer using a special trim as it is easier and safer to install.
Installing your gable trim may have to be done either in the beginning or at the end of the roof installation. This will depend on how you plan to layout your metal panels. If you start with a full or partial panel at the gable, then you can put up the gable trim as soon as your first (and last) panel is installed.
You will need to bend up 1-1 1/4″ lip on the outside edge of your panel. This will serve as a hook for the gable trim. Optionally, you can cut out the outside part of a double lock on the panel itself if you are using a full panel.
If you will be bending the lip, you can either use the hand seamer / folder or a special roller (which costs about $500, and you may not want to invest into it if you are only doing a single job).
If you use the hand seamer / folder, your panel bend will not be perfectly straight, but do not worry about it as the gable trim will hide any imperfections. This will be a very tedious process, especially on a longer panel.
If this will be your last panel, measure the distance between the edge of the roof and the edge of the last full panel – this will be the pan width of your last panel. Add at least an inch to this width for your fake lock.
Make sure that you measure both top and bottom of the panel, as this width tends to be slightly off due to framing being out of square and panel creeping. You don’t want your panel to bump out by an inch or two!
Once you have prepared your first and / or last panel and you’ve created the fake lock to hook your gable trim into, you can then line the panel up so it is flash with the rake board.
If this is your last panel, and you measured everything right, the panel will be flash with the rake board or you may have it bumping in or out by 1/8 – 1/4″ – this is normal and will not be noticeable.
Hook your gable trim into the fake lock, pull it down with your fingers and drive in the color matching hex screws with rubber gaskets, approximately 12″ on center to secure it.
In some situations, mostly for aesthetic reasons, I measured 2″ from each end and measured the remaining distance for equal spacing of screws (which usually came out to about 10″ oc).
In some situations, you will be required, or may choose to use a drip edge as gable trim. In that case, instead of bending up 1 inch of fake lock, bend down about 7/8″ lock to a 90-degree angle. Hook that side lock to the drip edge and fold in down with your fingers. Use hand seamer to tightly crimp the lock.
All other trim, besides the drip edge and on some occasions the gable trim, will be installed as you get to it with your panels.
Step 3 – Installing your first panel.
Whether you are using gable trim or drip edge for your rakes, the first panel will be the most important, because it will determine if your roof is squared, if any penetrations line up in the center of a metal pan or on a rib / lock.
You definitely want to avoid having any penetrations lining up with the lock, because it would be quite challenging and problematic for a first-time installer to flash it properly. — This should be solved ahead of time by making sure that your first panel has an appropriate width, so that you end up with a panel layout where you have all the penetrations through the center of a panel.
Assuming you have the correct width of the first panel, and that all the drip edges are installed, you will have to create the hook-lock at the bottom of each panel. This hook / lock should be 7/8 of an inch wide and folded down (see photo below).
Also notice the little “ear” sticking off on the side of the double lock. You will need to make this to wrap it around and crimp once the panel is installed.
Hook the first panel into the drip edge, align it flush with the rake board and install 1 screw through the pan, all the way at the top of the panel (about 1 inch from the upper edge of the panel). This screw will hot it in place while you are installing clips.
Space your clips 10-12″ OC, and using special flat-head screws, attach the panel to the roof deck. To avoid dents in the panel, install screws into outside hole of the clips.
If you are located in high wind area, you may want to put two screws into each clip, but I would actually increase the number of clips to 6-8″ on center instead of using two screws.
Never put two screws if you have boards instead of plywood. Two screws will split the board, which will cause the panel attachment not to be secure.
Once the first panel is installed, snap on the next panel. I found that the easiest way to do this is to hook the loose panel into the drip edge and insert the tip of a single snap lock into the double snap lock, then push the panel all the way up, and only then start putting the lock together. See the video bellow:
Use a rubber mallet or the rubber handle of your hammer to snap the seams of the roof panels. Using your palms will begin to hurt after just a couple of panels. Make sure that whatever you use is soft as to not dent the metal panels.
Repeat the process until all panels are installed. Measure and install your last panel as described above. Repeat the process on the other side of the house.
Step 3.1 – flashing a vent (stink) pipe.
If you have a vent pipe (most likely you do), you should have ordered an appropriately sized pipe boot with a metal/rubber flexible adjustable bottom, designed for corrugated sheet and standing seam metal roofs.
I hope you aligned your panels so that the stink pipe lands between the ribs. As you approach the stink pipe in your installation of the panels, getting as close as possible with the last full panel that does not require cutting, finish installing it, and then measure the distance from the bottom to the center of the pipe, and from the side where the last panel is.
Locate the spot where you will be cutting in a hole in the panel for the pipe, and make sure to cut the hole such that it would be 1/2 – 3/4″ wider than the pipe.
As you can see in the picture above, we actually had the rib sitting 1″ away from the pipe. We could not avoid this and had to deal with it, but for you, I strongly recommend spending 5 extra minutes measuring and not doing it the hard way.
Once you cut your hole in the panel, put it up, install the clips, and now you should be ready to install the pipe flashing. Put your pipe flashing on, align it with the panel, use pencil to mark the location of the flashing and pull it off.
Apply a thick bead of Solar Seal 900 or an equal exterior grade sealant / caulking within the perimeter of the flashing. Then, set the flashing back in place so that its base is completely sealed by the caulking. Finally, fasten the flashing down with the hex head rubber gasket screws, spacing them about 1.5-2″ apart.
Once again, in order to avoid the situations where roof penetration lands in the center of the lock, measure carefully beforehand!
Step 4 – Installing Z-bars and ridge caps
If you are using the ridge/soffit vent systems, make sure you are not installing it on a low slope roof, as water may get inside through the perforated z-closure.
Cut your z-bar to the width of one panel. Make sure it fits tightly, but not too tight as to scratch the locks of the panel. Usually go about a 1/4 less than nominal width of the panel. This gives you enough room for a snap lock of the next panel to fit in, and it will help you to end up with the minimum gaps between the edges of.
Cut a small piece of ridge cap (about 2″ wide), align in so that it is in the center of the ridge, laying perpendicular with the locks. Mark the outer edges on the top of each rib. You will align your z-bars and the ridge cap to these marks.
Use the first piece as a template and cut enough z-bars to accommodate every panel on your roof (both sides). Using double-sided peel-n-stick foam or some type of exterior grade caulking such as Butyl, Urethane, or similar sealant, caulk the connection area between the panel and the z-bar.
Attach the z-bar with 3 screws, and caulk the side gaps so that any wind-driven water would not be able to get in. As for the caulking type of choice, we always use a clear (or color matching) Solar Seal 900. It works awesome!
Once all your z-bars are up and sealed, take a section of the ridge cap, and cut a 2-inch line down the center bend, on the end of the cap. At the same end, cut off 2 inches of the lock and bend down the two flaps. This will be your end-piece.
Align the flaps you’ve just created with the gable trim and hook in one side of the ridge cap into the z-bar. If your z-bar is spaced too widely or narrowly, you can bend it in or out so that it fits your ridge cap.
Hook the second (unclosed) lock into the opposite z-bars all along the length of the cap. Once it is completely clipped in, use your hands to close the opened lock (lip) on one side of the cap, and then using the hand seamer crimp both sides of the cap.
Take the next section of the ridge cap, and cut of about 3″ of locks at one end of the cap. Do not cut along the center.
Apply two lines of caulking where the connection between two pieces will be made and install the second piece the same way you did with the first, using the end where you cut off 3 inches of lock, to overlap the 1st piece. Do not use any screws. The connection should be watertight, and it will not leak.
Once all your ridge cap is in place, your roof is pretty much complete. If you have the stack or bathroom vent pipes, I will show you how to flash them the right way in the next post.
In the meantime, if you live in the snow country, you may want to have some snowguards installed. Visit Berger, to find the style of snowguards you like, and locate the supplier to buy it from.
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Hope you enjoyed reading this post, and that you found the information helpful. As a word of precaution, always remember to safety-in using a proper fall arrest equipment and anchoring methods. Never ever work alone.
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