It is common for the modern roof to come with several layers. Now, if your plywood roof is currently sagging or rooted, there’s a great chance you have to fix it as soon as possible. The guide below will tell you how to install metal roofing over plywood.
How to Install Metal Roofing over Plywood in 8 Steps
You may wonder why you should use metal roof replacement. Metal is seen as a wise roofing material choice nowadays, considering its visual and functional aspects.

The metal roof needs to have a solid deck structure. Plywood is what do you put under metal roofing to support the metal panels’ weight. However, it would help if you made sure first that the plywood is free from raised nail heads and clean enough.
Read also: How to Build a Metal Roof Over a Deck
Follow these steps on how to install metal roofing over plywood after you make sure it is already clean and all the nails are hammered down.
- Set the waterproof plywood on the flat surface of your roof. Each row must be overlapped by a couple of inches and cut to fit the protrusions’ base. Secure with nails and hammer.
- Calculate your roof edge’s length. Then cut the metal flashing and install it on the roof perimeter by using a nail and hammer. Install the gutters according to the fitted size, then secure them by using a hammer and nails.
- Draw a vertical line about 0.25 inches away from the rake edge. Work by starting from the left to the right side of the roof. Set the metal panel on the bottom corner to the ridge of the roof, with 1-inch overlaps between each edge. Then use a galvanized metal screw to secure the roof panel to the deck, in the distance of 16-inch or 12-inch between each other.
- The next step on how to install metal roofing over plywood is to line up the second panel over the first panel straightly. Their edges must overlap by about 12-inch. Secure the metal roofing panel is in the distance of 16-inch or 12-inch between each other to the deck using a galvanized metal screw.
- Continue step 4 until you arrive at the roof’s peak. Calculate the length required to reach the last upper panel and mark it by using a pencil. Then cut the metal panel accordingly.
- Come back to the bottom corner of the roof. Start to install another metal roofing panel row. Set the rib on the left part of the metal panel to the right part of the next installed metal panel’s rib.
- Again, continue step 7 for every row until you have completed the installation for all panels.
- Finally, set the ridged metal on the highest point of your roof, and install kits of pipe boot throughout the vent pipes.
Prefer not to use underlayment will only save you some budget on short-term, from several hundred to one thousand dollars – depending on your house’s size.
If you follow the steps on how to install metal roofing over plywood, you might be able to save thousands of dollars in the future instead.