Installing a standing seam metal roof is not as easy as it seems at first. Yeah, you may think: “what’s there to do? just put up those panels”.
Not so easy! Standing seam installation is actually a very tedious work, but lets go about it, step by step.
The most important thing about installing standing seam, is to measure the roof correctly AND precisely. Here is why:
Each standing seam roofing panel is cut to the exact size, and if your panels are too short, you:
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 a 6 inch panels sitting at the ridge of your roof is just as much fun as head-butting the curb 🙂 You would probably want to get at least 2-3 feet long panels for splicing and you also need at least a foot of overlap on each panel.
In either case you will run into additional work and a lot more money to spend then should have been originally.
Step 0 – Before you begin:
Roofing is a very dangerous profession, and safety should be your number one priority. We always use full body harnesses and fall protection systems consisting of roof anchors, 50′ lifeline, and shock-absorbing lanyard.
You can buy these in most Home Depot and Lowe’s stores, or any 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. 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.)
First thing you should do when you get up on the roof, is to install the anchor. You should already be in 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, to get the right measurements, you will actually have to go on the roof and measure every Eave, Gable, Ridge, Valley and Side wall.
Once you get exact to the inch measurements, add 2 inches to each panel for the drip edge, which sticks out by an inch and gets bent back by an inch.
Assuming that your panels will be 16 inches wide, take the wight of your home in feet, multiply by 12 and divide the result by 16. This will give you the number of panels on each side. I like to order my panels at least 1 inch longer than my measurements and also at least one extra panel for screw-ups, which for some reason always happen. I recommend you do the same.
Step 2 – Prepare your roof:
Unlike steel and aluminum metal roofing shingles, standing seam panels should not be installed over existing asphalt shingles. There are two main reasons. First of all, if you install a standing seam metal roof over asphalt shingles, there will be a so called “telegraphing effect” where shingles punch horizontal lines in a standing seam panel. This in neither aesthetically pleasing or good for the metal roofing panels. This gets us to the second reason not to put 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 a Galvalume or G-90 galvanized steel. Well, the truth is such that steel can rust. And if you put steel standing seam over asphalt shingles, which 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 rather than later cause rust spots popping up all over the roof.
To avoid the above mentioned problems, you should tear-off all shingles off the roof, and make sure there are no nails sticking out from the roof deck.
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 old, rotted decking.
Once a 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 A lower slope roofs, we overlap the underlayment by at least 1 foot. On steeper roofs, all you really need if 6 inches.
Run the underlayment on all flat surfaces of your roof. If you have skylights or chimneys, run it to the base of the curb.
Spend extra time wrapping the chimney as it is very likely to leak if you seal it wrong. 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:
This concludes the first part of our standing seam metal roofing installation guide. Part two will be available soon, so you could get to work installing you new metal roof. In the mean time, if you do not feel comfortable installing a metal roof yourself, you should hire a professional metal roofing contractor. If you are located in MA, RI or CT, you can contact us by filling out metal roofing estimate form.