The gentle drumming of raindrops on a metal roof is a sound unlike any other, often bringing back memories of childhoods spent on farms or watching the rain from a covered back porch.
Metal roofs are rising in popularity with residential and commercial property owners alike, due to their long-lasting durability and high rating for energy efficiency. However, no roof is immune to leaks. Flat and corrugated metal roofs are prone to rusting and weakening at the seams over time, and this can cause rainwater to permeate your roof.
If you have a metal roof on your home, don't panic! SEMCO Liquid Membrane is the perfect tool for fixing a metal roof leak. In this piece, we'll walk you through every step, from how to find a leak in a metal roof to how to go about fixing it so that you never have to worry about the potential of water damage.
What Causes Leaks in Your Metal Roof?
Although metal is one of the most durable and long-lasting roof materials, there are opportunities for leaks to occur — especially if the roof is old or poorly maintained. There are other factors to look out for as well.
For example, if you live in a humid climate or one with a lot of rainfall, you should expect your metal roof to rust faster. If you move into a house with a metal roof, there's no guarantee that it was installed with the level of quality that would allow you to reap the benefits that a metal roof is intended to provide.
Here are some of the most common sources of leaks for homeowners with metal roofs:
- Improper installation
- Issues with fasteners
- Panel damage
- Open headwall or flashing
- Missing trim
- Loose gutters or downspouts
- Gaps in seams
- Rust damage
Wondering why these same spots keep leaking even after a repair? See our breakdown of why metal roof coatings actually fail, covering fastener back-out, capillary action at seams, and the other root mechanisms behind repeat leaks.
How to Find a Leak in a Metal Roof
If your metal roof is leaking, naturally, you'll want to have it fixed before water damage occurs. The first step is finding the leak. Here are some of the places to look when trying to find the source of the issue:
The Roof Body
A visual inspection may be able to help you detect leaks in the body of your roof, especially if the leaks are major. Check for:
- Holes from weather or debris
- Rust damage
- Missing, loose or overly tight screws
- Shifted metal roofing panels
Connection Points
Seams and joints are common places for leaks to start due to loosening screws or water buildup. Check for:
- Missing sealant or tape
- Loose trim or gaps
- Missing, loose or overly light screws
- Misalignment where panels overlap
Roof Openings
Most roofs are built around other ventilation, piping networks, and other systems (skylights, chimneys, etc.), which create opportunities for leaks to form. Check for:
- Cracked seals on flashing
- Gaps in trim
- Rotting sealant
Roof Edges
The edges of the roofline, including where the roof and gutter are attached, are also prone to leaks and should be part of your inspection. Check for:
- Gutter damage
- Flashing damage
- Rotting sealants
- Cap issues
How to Approach Fixing a Metal Roof Leak
Now that you found the source, it's time to go about fixing the metal roof leak. Before you pick up the phone, call a contractor, and spend thousands on repairs, you should know that SEMCO Liquid Membrane Waterproof Sealant enables you to do the job yourself without compromising quality.
Step 1: Prepare the Roof
The first thing you'll want to do is make sure your roof is 100% ready to treat. Before you do anything, tighten or replace any loose or damaged screws and fasteners. You want your seams to be as tight as possible before sealing the roof for the best results.
Remove any loose debris off the roof. Then clean it with Prep D: Nu-Lift Cleaner to lift oxidation and residue, then Stone Soap, rinsing with clean water after each. Make sure the surface is completely dry before applying fabric or membrane.
Step 2: Fortify all Seams
As mentioned, you won't get the best results with loose or open seams on your roof paneling, flashing, or joists. Lay down strips of Fabric Reinforcement to cover cracks and seams.
If the gaps in the seams are large, use a metal-safe polyurethane based caulking on remaining cracks or seams, making sure to smooth the material before moving on to the next step.
Finally, apply Fabric Reinforcement around vents, flashing and protrusions, smoothing it tightly down before moving onto the next step.
How to apply the Fabric Reinforcement :
- First apply a generous coat of SEMCO Liquid Membrane on the areas where the Fabric Reinforcement will be applied to
- While the coat is still wet, apply the Fabric Reinforcement and press it flat
- Any excess coating that comes from underneath the Fabric Reinforcement, spread it evenly with a brush or roller
- After 10-15 minutes apply a thin coat of SEMCO Liquid Membrane over the Fabric Reinforcement to embed it.
Not sure which fabric roll size fits your roof, or when it's actually required versus optional? See our guide to what SEMCO Fabric Reinforcement is and when you need it for the full breakdown.
Step 3: Apply SEMCO Liquid Membrane
Now you're ready to seal your roof and prevent leaks! Using a brush, roller or heavy-duty airless sprayer, apply SEMCO Liquid Membrane Waterproof Sealant in an even coat over the entire roof. You need to apply multiple coats, so make sure you're letting the prior coat dry completely first.
You need a minimum of two full coats to waterproof, each at 15 to 20 mil, at about 200 sq ft per gallon.
Wondering whether a water-based membrane is really the right chemistry for a leak-prone metal roof, versus a silicone-based or rubber-based coating? See how the three compare on odor, cure time, and flexibility before you commit to a product.
Enhance the Impact of Your Roof Sealant
SEMCO Liquid Membrane waterproof roof sealants are one of the top-rated products designed to help you repair existing leaks and prevent new ones from getting the chance to form. There are, however, some steps you can take to increase the effectiveness of your project:
- Use Fabric Reinforcement, the same tape you used on the roof seams, to patch holes and cracks before applying sealant.
- Wire-brush areas of significant rust back to sound metal and reinforce them with Fabric Reinforcement before coating. No primer is needed.
- Be sure to apply sealant in the best environmental conditions. It shouldn't be exposed to heavy wind, rain, or excessive heat or sunlight while it's drying. Pick a dry day between 50°F and 85°F, out of direct sun.
- On corrugated metal roofs always calculate an addition 25-30% additional to your surface area as it is not a flat surface. This will avoid running out of materials during the application.
- Keep it dry for the full cure, 7 days minimum.
Related reading:
- EXPLORING ROOFING MATERIALS : A GUIDE TO SEMCO LIQUID MEMBRANE SOLUTIONS
- Metal Roof Leaking? How to Find and Seal It Before Winter Rain
- Roof Leak Checklist: What to Inspect Before the First Freeze
- SHIELDING YOUR INVESTMENT : THE KEY BENEFITS OF WATERPROOF SEALANTS FOR METAL ROOF MAINTENANCE
- THE PRICE OF REPLACING A ROOF OF A RV
