When some homeowners decide to invest in the longevity and beauty of a metal roof, a common question is whether they can install metal roofing directly over their rafters.

You can install metal roofing directly over open rafters. This combination is fitting because they are durable and long-lasting. Moreover, metal roofings need a sturdy but underlying structure such as open rafters to anchor them properly. 

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Can You Put Metal Roofing Directly on Rafters?

Metal Roofs Directly on Rafters

Yes, you can install metal roofing sheets such as copper and aluminum directly over open rafters as they are relatively lightweight materials.

It is advisable to consider some factors before installing your metal roof on rafters. Metal roofing sheets fit into almost any roofing style.

You can consider installing your metal roof with or without insulation. However, I recommend installing metal roofing sheets on rafters with insulation.

This option helps to keep the temperature of your building optimal at all times, as metal roofs absorb heat.

Insulation also helps in reducing noise pollution, especially when it rains. So if you want your home to be quiet, warm, and cozy, you should consider installing metal roofing sheets with insulation.

It is important to check with your insurance company to see if your insurance will cover the cost of the second layer of protection for your home in case of unforeseen circumstances due to poor installation. 

Metal roofs are more expensive than other roofing materials and would require more maintenance when installed directly on rafters.

How to Install a Metal Roof over Open Rafters?

Almost anyone can install a metal roof over an open rafter system if they know the right steps and the proper way.

The steps to properly install a metal roof over open rafters are;

  1. The first step in installing a metal roof over open rafters is getting the proper tools and materials such as safety goggles, gloves, roofers safety harness, caulking gun with roof caulking, etc.
  2. Lose the insulation with the vapor barrier facing downwards.
  3. Using galvanized nails, attach the insulation to the first rafter.
  4. Lose the insulation further, stretch it, so it does not get damaged, and attach it to the next rafter. Do this for the next rafters to avoid the insulation sagging between the rafters.
  5. Align the first metal panel with the eaves and use the screws to attach the metal to the rafters. Apply caulking at the edge of the panel and place the next, ensuring it overlaps the first panel. Screw this panel securely into a rafter and repeat all across the building
  6. Caulk the next row of panels across the top of the existing panels. Follow this procedure till you cover the whole roof with metal panels.
  7. Place the ridged panel where the two sides meet atop the roof. Caulk the point where the ridged panel touches the corrugated panels. Screw it into place, and you have finished the installation of your metal roofing sheets.

Can You Screw Metal Roofing Directly to Rafters?

It is impossible to screw heavy metal roofing sheets such as steel to rafters because the roofing screws do not hold well onto the wood.

The holes on the rafter might not expand enough for the screw heads to fit after you fasten them through the metal roofing sheets.

Fastening heavy metal roofing sheets directly to your rafter may void the roofing warranty issued when you originally constructed the house.

You should install your metal roofing sheets according to the instructions in the installation manual.

Metal roof battens provide fixing points for roofing materials, including heavy metal roofing sheets.

A more logical connection will be to use metal roof battens to provide a nailing surface instead of just attempting to fasten it directly to the wood. 

Afterward, you can use two and a half inches or three inches of countersunk galvanized lag bolts to join the metal roofing sheets to the bracket while installing your metal roofing sheets.

You can also use a header or a gusset plate to fasten your metal roofing sheets onto your rafter.

The metal piece will be attached to both the roof and the rafter distributing the load evenly through the beam and increasing the load capacity of the roof structure.

Notwithstanding, if your metal roofing is a lighter material like aluminum, you may be able to screw it directly onto your rafter.

Whatever method you choose, it is best to consult a roofing contractor to ensure that the metal roofing installation is done properly and securely.

Tips to Put Metal Roofing on Rafters

Proper roof installation on the rafters will ensure that your metal roof remains watertight for many years.

In the long run, it would save you a lot of trouble should you want to sell your home one day.

To better assist you in properly installing your new metal roof, here are a few tips to help you along the way;

  1. Get a skilled professional to do the job. A skilled installer will do the job properly and avoid potential problems.
  2. Choose the right material for your roofing sheets. When choosing the material for your roofing sheets, ensure to choose the appropriate material for your rafters.
  3. You will need to have your rafters inspected to ensure they can handle the loading of a metal roofing system. Inspecting your rafter to ensure it can carry the weight of a metal roofing system is one of the most important aspects of installing metal roofing sheets on an open rafter system. 
  4. Ensure you get your roof measurements correct. You want to double-check that what you measure from the top of the rafter is exactly the height of the roof you have ordered, including overhangs, before you cut the first piece of metal. Getting this measurement wrong can cost you money in roofing waste later down the road.
  5. Always seal your flashing with caulking or silicone before putting the screws in to hold it in place.
  6. Install plastic or a bitumen base sheet when installing your metal roof. A base sheet protects the purlins which support the rafter from water.
  7. If you are installing your metal roof with insulation, ensure your insulation is 50mm below the roof. You can use metal roof battens to measure the area between the roof and the insulation.
  8. Put furring strips across the rafters to provide a space for panel attachment.

Metal roofing may be a good option for your home if it is suitable for the location you are building it. Taking these tips into account will help make the process easier and ensure a successful installation.

Pros and Cons of Installing Metal Roofing over Rafters

Metal roofs are popular because they have many advantages, but they also have drawbacks. The table below highlights some of these pros and cons;

Metal roofs are durable.Metal roofs are noisy when installed without insulation or a noise barrier.
They are heat resistant.Metal roofs are very expensive.
They are generally lightweight materials.Not all metal roofs can be screwed directly to rafters.

Final Thoughts

Installing a metal roof over rafters can be tricky for someone without knowledge of roofing as its instructions involve many details on its installation methods.

It is advisable to employ the services of a professional roofing company if you are a newbie to ensure the installation of the metal roofing sheets is done properly.

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