Over time, your home’s roofing material will age and break down. While it is unfortunate, every London ON home needs to replace its roofs at some point. Learning how to install metal roofing over plywood is essential in ensuring you have adequate roofing protection against the weather and outdoor elements inside your own home.

As reputable and experience roofers in London ON, we only supply this instruction as a referential material. We highly advise homeowners with little to no DIY roofing experience to only call professionals to address their roofing needs to save time and money.

The Aged Plywood’s Condition

Before starting, make sure to inspect your aged roof’s plywood’s condition. Roof sheathing is made from wood, which is an organic material. While you’re learning how to install metal roofing over plywood, you’ll need to learn how to replace roof sheathing as well.

Fortunately, it isn’t rocket science. However, tearing off the sheathing is the first yet most difficult step. However, SF Gate Homeguides has a great instruction on how to tear off roof sheathing with minimal problems.

If you’re not experienced and comfortable working on a roof, this is a project that is best left to the pros. If you do choose to tackle the project, determine if the existing sheathing is sturdy enough to walk on as the tear-off method starts at the ridge and progresses downward. This allows you to stand on the lower panels as you tear off the upper ones. If the sheathing is not structurally safe, however, construct scaffolding at the roof’s edge to stand on while you tear off the lower panels and replace them with new panels before tearing off and replacing the next higher row of panels. A flat bar, or cat’s paw, is standard for prying up the panels. (Source)

Removed All Unused Roofing Structure

When contractors made your roof, they built roofing structures such as chimneys, vents, and skylights. Unfortunately, you’ll need to remove all these areas before you can apply your learnings on how to install metal roofing over plywood. If you want to remove them without breaking them apart, you’ll need the right tools to do so — which professionals only possess.

Thoroughly Clean Your Working Area

After you’ve removed the aged roofing material and rotting plywood sections, it’s time to replace them. Going back to SF Gate Home Guides, it’s pretty straightforward to install roofing plywood before installing your metal roofing panels:

Sheathing comes in 4-foot by 8-foot sheets to install on rafters spaced 16 or 24 inches apart. The ends of an OSB or plywood sheet align with the centers of the rafters. This is referred to as “breaking on center.” Special OSB roofing sheets contain nailing guides that align over rafters, making nailing simpler. To install unlined plywood, use chalk lines to mark rafter locations. Check local codes for specific nailing patterns, which are generally found in regions subject to high winds. If no nailing code exists, insert one 8d nail every six inches along edges, and one every 12 inches in the plane. Leave a 1/8-inch gap between panels to allow for expansion. (Source)

Once done, make sure to clean your working area. In doing so, you reduce the likelihood of corrosion. Additionally it allows you to make accurate measurements upon installing your roof.

Install The Felt Underlayment Properly

Felt underlayment sheets make sure your new roof plywood isn’t drenched by any gaps or leaks your metal roof panels introduce. True enough, you or any reputable roofing contractor will install them in the best possible manner. However, metal roofs aren’t infallible; some leaks may originate from loosening screw gaskets, which can occur over time.

RoofingFelt.org has a great instruction on how you can install roofing felt in the best way possible before you thoroughly learn how to install metal roofing over plywood. The most important part is knowing how to lay the felt underlayment.

Laying the Felt

The roofing felt should be applied in layers that overlap. Start at the bottom of the roofline and work up so any water that gets through the roofing material will shed down the tar paper and will not go under it.

  1. As you work, the paper can be tacked down in the center so it won’t blow away.

  2. When you arrive at the rake, the paper should be cut flush with a knife and then adjusted to line up with the chalk line. The overhang to the next strip should be 3/8 inch. The paper should then be nailed in or stapled every three to four inches across. All nails and staples should be placed on the lower half of the paper.

  3. Where a roll ends and a new one is begun, the two rolls should be overlapped by four inches.

  4. Valley, ridges and hips should have a 6 inch overlap of paper. (Continued)

Use the Right Tools

Tape measures, metal snips, hammers, having the right-size nails (1/2-inch roofing nails), and other roofing tools are important. Most experienced roofers have invested in top-grade, state-of-the-art equipment, which can be as expensive as a single residential metal roof installation.

The Powerful Use of Chalks

By cleaning the felt underlayment after installation, you can use chalks to mark your metal panel installation areas. Draw lines where the first panel’s edge will rest. Then, you can indicate areas where the screws will stay, and so on. These are useful especially if you’re going to do over your entire roof.

Note the Overlaps

As you install your metal roof panels, make sure they overlap the previous panel by 12 inches. In doing so, you reduce the likelihood of leaks and allow screws to effectively fasten the roof in place.

A Few More Pointers

How to install metal roofing over plywood can be quite challenging in many instances especially for inexperienced homeowners. However, even experienced homeowners in London ON may find trial and error making their success more elusive.

In this light, it pays to work with professionals such as us from Cub Roofing with years of experience and knowledge to help you with all your roofing needs. Contact us today and we’ll get all your roofing needs sorted as fast as possible.