The final stage of a house construction is a laying of the roofing system and the exterior coating. It is it that will take on the main load from precipitation, therefore, only the best materials available should be used for this purpose. We will tell you how to install metal roofing over plywood step by step with your own hands.
Metal roof is not affected by fire, and its life span exceeds 40 years and more with proper care. The only fire hazard comes from wooden beams, but if treated with flame retardants, they also cannot catch fire or support combustion.
How to Install Metal Roofing over Plywood
Once you’ve removed the old roofing material, it’s time to install a new, beautiful metal roof. Nevertheless, it is extremely important not to rush through the preparations or skimp on materials. Thus, you can provide a solid and reliable new metal roof for many years to come.
Tools needed for DIY work:
- Push broom
- Roofing felt
- Slide sheet
- Universal or roofing knife
- ½” roofing nails
- Metal scissors
- Tape measure
- Metal flashing
- Gutters (as needed)
- Chalk and a chalk box (it should be roomy)
- Drill / Screwdriver
- 1 ½” galvanized metal screws
- Sets of rubber tubes (for each vent)
- Companion (when you work on the roof, it’s better to have a second pair of eyes and hands to avoid accidents and injuries)
- Roofing harness; again, safety comes first
Step One: Prepare the Plywood Decking
Before proceeding to install the panels, check the condition of the existing plywood flooring for any damage. In the case of deformed or broken tiles, replace them. Remember that the plywood should be at least 15/32 inches thick. Repair flat roof leaks.
Also make sure that everything is fixed as firmly as possible. The nail heads should not stick out of the plywood. The surface should be flat, smooth and undamaged. Raised nails can be dangerous both for you and for the roof. Badly hammered nails are loosened more easily. Begin installing.
Step Two: Install Waterproof Felt and Slip Sheet
It is not recommended to lay roofing panels directly over plywood, it is better to use a special protective layer as a barrier to moisture. And roofing felt can be used as such a material.
Roofing felt should cover all areas of the roof panels. In some places, its overlap might be in two inches. To make sure the material is really level, carefully cut holes around pipes, chimney, and vents. Protruding sharp parts and raised nail heads can damage the roofing felt. When the roofing felt is smooth and flat, secure it with 1/2-inch roofing nails.
Next, it is recommended a slip sheet be installed over the underlayment (felt paper or similar) for metal panel roof systems.
This helps protect the felt from sticking to the metal panels of the roof. The slip sheet can be secured with anything you have on hand, such as the same nails.
Step Three: Install Flashing and Gutters
Use a tape measure to determine the length of the entire roof edge. Cut the flashing material for roof’s fasteners to size with metal scissors and secure along the roof’s edge of the entire roof with roofing nails 1/2 inch.
If you decide to install gutters at the same time as well, which is very wise, this is done at this point. Cut the gutters with scissors to the size you want and secure them in place with ½-inch roofing nails.
Step Four: Install the First Metal Roof Panels
Moving on to the next step, take a box of chalk. Now you are ready to install metal roofing. It’s best to do this from left to right and from bottom to top. Mark a small vertical line with chalk and measure 1/4 inch from the edge of the roof with the chalk box.
This side slope of the roof should protrude enough over the edges of the house. This will help drain the rainwater away from the side walls of your house.
So, we start at the bottom and left side. Install the first panel so that the edge protrudes one inch below the roof, making rake edge for water run off.
Better yet, have your buddy hold the panel while you fasten it with 1 ½” galvanized metal screws to the deck. The distance between the screws should be 12 to 16 inches.
Make sure you carefully align the first panel, because this affects how neat you end up with the roof as a whole.
Step Five: Installing the Rest of the First Column
When the first panel is secured, you can move on. The next step is to install the second bar on top of the first. Move up to the roof’s peak. You may have two or three pieces up, depending on the design and length you prefer. Then go back down to start the next column.
Align the other first panel directly, covering an area of about 12 inches. Secure the next panel with screws in this way, in the end, just as you did with new panel.
Do not stop installing the panels in this way until you somehow get to the top of the roof with roofing material.
Note: Cut the top panel at the peak of the roof with the metal scissors. Leave as much free edge as will fit on your roof ridge.
Step Six: Finish Installing the Remaining Roof Panels
Next, you need to install the following first panel columns. Start at the bottom of the metal roof panels from smooth building paper.
There you need to fix it so that it is just above the other panel. You need to place the first panel left edge of the new panel on the last right roof’s edge of the adjacent installed panel.
Step Seven: Finishing Touches
Continue to cover the whole roof with this technique, which we have told you about. Next, you need to place rubber pipe boot kits and install gutters. After that, your work will be ready.
Enjoy your work done! To further improve your attic, consider installing solar-powered fans. For more details, welcome: How to Solar Attic Fan Installation: The Gadget That Saves Your Money.
To sum it up
|Job Step||Basic task||Needed materials|
|#1 Preparing plywood||Check the plywood to make sure it is flat and smooth||Push broom, ladder, hummer, nails|
|#2 Moisture-proof layer||Roll out roofing felt and slip sheets||Hummer, nails, utility knife|
|#3 Installing flashing and gutters||Finishing roof edges and installing gutters||Tape measure, scissors, hummer, nails, metal flashing|
|#4 Installing the first panel||Align it carefully so that it’s hassle-free with the next ones||Chalk box, screws, drill|
|#5 Installing the panel upwards||Overlap the bottom panel with the top one by 12 inches||Screws, drill, metal scissors|
|#6 Installing other panels||Aligne the rib of the next panel with the previous one||Screws, drill, metal scissors|
|#7 Final finishes||Put a roof ridge and seal vent pipes with rubber gaskets||Sets of rubber tubes|
Types of Metal Roof
Metal roofs are used for industrial buildings, residential buildings, outbuildings, and small architectural objects: gazebos, and canopies. Knowing how to install metal roofing over plywood makes the job a lot easier on yourself. There is also the option of installing metal roofing over old shingles.
In the classical form, the building material consists of slip sheet, some of which are covered with a polymer layer or paint. New metal panels are produced from alloys or non-ferrous metals for slip sheets: copper, aluminum, titanium-zinc, steel.
For now we plan to make a post on the average cost of each type of roof. Stay tuned with Repair of the Attic.
Copper and Zinc Roofs
The golden-red color of copper on the roofer felt will gradually turn brown. And the shine will also go away. Therefore, we must be prepared for such a turn. After a few years of operation, the roof’s panels will become black or greenish.
At the same time, uniformity of color should not be expected. All this happens under the influence of oxygen and humidity.
This type of roof slip sheet has impressive advantages:
- Anti-corrosion resistance.
The least popular option is metal snips, since they are not particularly resistant, and they are inferior in price to other materials. Sometimes used in old houses.
Roofs made of steel are very diverse. They are distinguished by their long service life. Such a metal roof panel can last more than 40 years. Metal snips also has a good price.
Many modern molds and construction crews work with this type of metal.
Comment: Nonmetal roofs have their own advantages, see for yourself in How to Install Rubber Roofing: DIY Guide for Homeowners.
Can you put metal roof directly over plywood?
Metal roofs can be installed on top of metal roofing over plywood, but you should inspect the plywood in advance for damage and perform any repairs. Your metal roof panel is likely to last 70 years, so make sure you don’t start with rotten or damaged plywood.
What underlayment should be used under metal roofing?
As the market has developed, synthetic hairs have become more affordable at a price equivalent to a 30-pound felt.
These underlying layers are light in weight and very durable. The rolls are usually available in 10 square rolls (1000 square feet) and are very light in weight.
Can metal roofing be installed over OSB?
OSB often serves as a roof decking or a bottom layer that is on top of the frame of the house. Roof decking is also known as sheathing.
This is crucial for the process of installing an existing plywood roof. It holds the roof beams and trusses together, forming a solid structure.
Assume that after reading these instructions on how to install metal roofing over plywood, some will turn to professionals. Well, there is some truth in that. It is not enough to understand how to do, you need to have enough time, skill and tools as well.
For those who do venture out on a DIY journey, we have a useful video. Check it out to borrow a great idea on how to make the edge of the roof straight. It’s a really handy trick with panel alignment.