How to Seal a Metal Roof | 2024 Guide
Well-designed metal roofs are durable, safe, and energy efficient, lasting up to 70 years. Despite requiring relatively little maintenance, they need sealing to shield against moisture, prevent leaks, and extend their life span. In this guide, we’ll explain the benefits of sealing a metal roof, how to seal a metal roof, and how to maintain it.
Compare Quotes from Roofing Specialists
Just answer a few questions, and we'll take care of the rest.
Metal Roof
Metal roofs cost, on average, between $7,081 and $110,150.
Tile Roof
The NRCIA reports that the average tile roof cost is $8,000 to $23,000.
Shingle Roof
Shingle-style roofs cost, on average, $5,000 to $18,000.
What Are the Benefits of Sealing a Metal Roof?
Sealing your metal roof protects both the roof’s material and the structures below it, such as your rafters, attic, insulation, and home ceilings, which could be damaged by water or pests. By sealing and resealing your metal roof, you can keep your home safer and extend its life span.
Here are a few benefits of sealing a metal roof:
- Extend the overall life span of the roof.
- Increase curb appeal of your home.
- Make the roof more reflective, resulting in greater energy efficiency.
- Prevent damage that could lead to costly roof repairs.
- Protect the panels from corrosion and water damage.
- Watertight or waterproof seal helps keep water out of your attic and walls.
Additionally, sealing a metal roof can save you money in the long run by helping you avoid costly repairs and premature replacement.
Safety Considerations
If you decide to seal or reseal your metal roof on your own, there are several safety considerations to keep in mind. Consider the height and slope of the roof, how to handle sharp or heavy materials, and how to deal with wind or bad weather conditions.
Follow these safety tips if you perform your own roof work:
- Avoid hazards such as power lines: Assess your roof’s proximity to power lines, utility poles, and trees so they don’t catch you off-guard during the sealing process.
- Never work alone: Always work with a partner. Ideally, you would have an additional person on the roof and someone on the ground.
- Read the manufacturer’s instructions for sealing materials: Before you begin the sealing process, ensure you have the right sealing materials and follow any safety requirements listed.
- Reschedule work around windy or wet weather: Wet roofs are slippery, and high winds can knock you or the materials off the roof. Wait for a clear, sunny day to perform work.
- Wear safety equipment: Protect yourself during the sealing process by wearing protective eyewear, kneepads, gloves, and a safety harness.
If your roof is very steep or you don’t feel comfortable sealing your roof as a do-it-yourself (DIY) project, hire a commercial roofing professional to complete the task for you.
Tools and Materials Needed
Before you can seal your metal roof, gather the following tools and materials:
- Caulk gun for applying beads of metal roof sealant, silicone sealant, and/or liquid rubber
- Nonslip shoes for walking across the roof surface
- Paintbrushes or paint rollers for applying the sealant
- Pressure washer for precleaning the roof
- Protective gear, such as gloves, kneepads, and eye protection
- Safety harness for heights
You’ll also need the sealing materials themselves:
- Roof caulk: Choose a caulk designed for metal roofs and flashing seams. Depending on the type of metal roof, you may have more or fewer exposed edges than others, which can affect the total amount of roof caulk you need.
- Sealant: Choose the right material for your region’s weather hazards, the metal composition of your roof, and your style preferences.
Preparing the Metal Roof for Sealing
Preparing the roof surface before you start the actual roof sealing process ensures that the roof is in good condition for an optimal seal.
1. Clean the Roof
Remove dirt, dust, organic matter, twigs, leaves, and other debris on your roof. Depending on the tools you have, you can pressure wash or scrub the roof with a mild metal roof detergent.
Thoroughly clean every exposed surface of the roof, including any raised lips or panel edges. You can also clean the surfaces of your gutters, gutter guards, and downspouts. Once you have cleaned and rinsed the surface, let it dry for at least 24 hours before continuing.
2. Repair Damage
As you clean the roof, inspect it for damage before sealing it. Here are a few signs that your roof needs repairs:
- Dents or holes in the roof panels from hail storms or branches
- Loose panels and flashing from missing gaskets or improperly tightened fasteners
- Missing flashing to metal shingles
- Rust spots on the roof panels or flashing
- Leaky patches inside your attic
Repair any of these problems before continuing. If you notice severe roof damage, such as broken shingles, water damage, or clogged gutters, schedule a professional inspection or hire a certified contractor to make the repairs.
3. Ensure the Roof Is Dry
Your roof must be dry before you apply the sealant, or it won’t bond properly with the roof. Wait a day or two after cleaning your roof to seal it, and check the weather for misting or rain storms—even lingering dew can risk the effectiveness of your seal coat. Schedule the project for a warm, sunny day for the best results.
How to Seal a Metal Roof
This basic process includes applying a thin layer of sealant across the main surfaces, sealing the edges and fasteners for extra protection, and inspecting the roof after it dries. The steps are detailed below.
1. Apply the Sealant
Read the manufacturer’s guidelines and follow the listed instructions. Start applying the sealant with a roller brush or paintbrush from the top down. Work in vertical sections of shingles or panels so the sealant doesn’t become patchy or uneven, and apply a single thin layer at a time.
As you work, check for drips or missed patches. Reroll or brush over completed layers on windy days to smooth out any drips or unevenness.
If your roof is too big to seal at one time, plan a few stopping points. For example, you might complete one side of a gable roof and the other. This planning will help the finished product look more cohesive.
2. Seal Seams and Fasteners
Once you’ve sealed the main surfaces, use a paintbrush to apply a sealant to vertical or curled lips, exposed fasteners, and flashing. These exposed metal planes would have been difficult to reach with a roller brush.
You can also apply caulk sealant (rather than the liquid paint-like sealant) during this stage. Apply a thin bead of caulk to any joints or overlaps in the panels. Water can slip between these surfaces, so ensure there’s an unbroken caulk line over every potential gap.
3. Allow the Sealant to Cure
Depending on the chemicals used, you may need to let the metal roof seal cure for 48 hours or 96 hours (four days). Try to schedule your project for a week of dry weather. Generally, the warmer the weather, the faster your roof will cure. Once the sealant has cured, go back on the roof to check the surfaces and caulk.
How Do You Maintain a Sealed Roof?
You should replace roof sealants every few years, though some types can last up to 10 or 20 years. Here’s how you can protect your roof between sealing projects and extend the life of the seal coat:
- Clean out your gutters to reduce the risk of pooling water and damage.
- Every few years, touch up the sealant, or apply a new layer to select panels or the entire roof.
- Have an annual roof inspection.
- Maintain a high-quality roof coating to extend the life of your roof.
- Routinely clear away debris and dirt.
- Stay off the roof unless you’re making repairs or inspecting it.
- Stay vigilant for leaks on and inside the roof.
Following these steps and conducting routine maintenance can help minimize costly repairs and roof damage.
Our Recommendation
Metal roofs should last for decades, and you can maximize your roof’s life span by sealing it with additional roof sealant and touching it up whenever you detect signs of wear. Along with sealing the roof system, we recommend cleaning it every year and monitoring it for potential damage along the seams. While you can complete this project on your own with the proper safety steps, consider hiring a professional roofing contractor if you don’t have the necessary tools and expertise to perform the task.
Compare Quotes from Roofing Specialists
Just answer a few questions, and we'll take care of the rest.
How to Seal a Metal Roof FAQ
Can I seal a metal roof in cold weather?
You can seal a metal roof in moderately cold weather. It’s more important that the weather is dry when sealing metal roofs, though applying the sealant in above-freezing temperatures is best. The sealant should also be around 70 degrees Fahrenheit, so homeowners should store roofing materials inside before starting.
How do I know if my metal roof needs to be sealed?
You’ll know if your metal roof needs to be sealed if you see gaps in the panels, worn sealant, corrosion, or damaged fasteners. If it’s been a few years since you last applied sealant, consider resealing your roof.
Can I paint my metal roof after sealing it?
You can paint your metal roof after sealing it, provided the sealant has cured and settled. It’s best to paint during spring or fall with periods of dry, temperate weather. Additionally, ensure your paint is compatible with a silicone-based sealant or polyurethane coating.
