We’ve got a metal roof on one of our outbuildings, but have never considered it for the main house. Apparently, it lasts forever but does present some unique challenges when it comes to fitting effective guttering.
Gutters on a metal roof should attach to the fascia board, not the roof deck. As rain and snow slide off a metal roof faster, the gutters need to be stronger than traditional systems. Depending on the climate, experts say metal roofing panels should overhang the gutters at between 1 to 1.5 inches.
Join me as we discover whether putting gutters on your metal roof is a good idea, how to fix them on – and what gutter alternatives there are for homes with metal roofing…
Should You Have Gutters With a Metal Roof?
Yes, you should have gutters or an alternative gutter system. Gutters prevent erosion around your house, they protect your garden beds, they prevent foundation damage, they protect the siding on your house, and they protect your roof. Metal roofs don’t need so much protection – not like traditional roofs – but everything else still does.
Metal roofs are having a moment, and no wonder. Metal roofs are surprisingly cost-effective. Sure, the cost up front is higher than traditional roofing but metal roofs last much longer. Warranties are typically 30 to 50 years. Traditional roofs last up to 15 years but a metal roof lasts up to 3 times longer – but metal roofs don’t cost 3 times as much.
In fire-prone areas, metal roofing can save on the cost of home insurance. They can also lower your cooling bill – metal roofs are reflective. Experts say that a metal roof can lower your cooling bills by 20%.
Gutter systems on a metal roof have special challenges. A traditional gutter installation company may have installed a system in the traditional way on a metal roof, resulting in big problems.
Problems occur during severe weather – heavy snowfall, rainfall, or excessive ice. Improperly installed, the excessively heavy gutters will rip off the metal roof, causing damage to the roof.
Another problem with guttering on metal roofs is water overshoot. Shingles, whether they are wood, clay or asphalt, tend to slow water down. Not so for metal roofs. Water sheets down fast and then shoots off the edge.
How Do You Attach Gutters To a Metal Roof?
Gutters for metal roofs should attach to the fascia board, not the roof deck. Because rain and snow will tend to sheet and slide off a metal roof (fast!), the gutter system needs to be stronger than a traditional one.
Metal roofs should not have a guttering system attached in the same way as a traditional roof. In a traditional roof, gutters are attached to the roof deck with metal straps or brackets. The gutters snap onto the brackets.
How Far Should a Metal Roof Overhang The Gutters?
Metal roofing experts say that the panels should overhang the gutters from 1 to 1.5 inches. But it depends a little on your climate, how big your roof is, the pitch of your roof and the type of metal roofing.
The gutter system on a metal roof needs to be designed to fit your climate. If you have heavy rainstorms, water may overshoot gutters that are too narrow and installed too low.
Ideally, a metal roof gutter system will be designed to handle the volume of snow or rain and the velocity of the water. The velocity of the melt water or rain depends on the pitch of your roof and the type of metal roofing.
Given all these factors, the overhang and the gutter need to be perfectly paired for your climate and your roof.
Are There Alternatives To Gutters on a Metal Roof?
Gutters catch rain but other junk as well. Gutters get holes and the brackets break. Standing on ladders to clean them out can be hazardous. Sure, you can have a service do it, but that’s expensive. Experts say there are several alternatives to guttering, like rain chains, drip paths, rain dispersal systems, French drains, and drip edges.
Rain chains are beautiful but effective too. You can feed a rain chain directly into a rain barrel or cistern. Rain chains replace downspouts on traditional gutter systems or pair up rain chains with rain dispersal systems.
Drip paths are impervious to the erosive effect of water sheeting off your roof. Drip paths are constructed of large rocks, bricks, or pavers. They are located directly below the roof edge where water runs off.
The drip path paver or rock system is strong enough to dissipate the force of the falling water and then channel it away from the foundation.
Rain dispersal systems divide up the water flow to non-damaging flows – down to just droplets. There are a variety of DIY systems you can buy online or at your hardware store. Designed by engineers, these systems direct rainwater away from the side of the house.
French drains are a great way to direct large volumes of water away from your house. Install a French drain at the drip line. Drip paths and French drains are a great combination.
Drip edges can also prevent water from running down the side of your house, damaging the side of the house and the foundation too. Experts recommend drip edges for all roofs if you live in an area with wind-driven rain. Drip edges can be installed by themselves or in addition to gutters.
In 2012, the International Building Codes (IBS) began requiring drip edges for shingled roofs. A drip edge is the flashing installed at the edge of your roof. The drip edge directs water off the roof.
Flashing is a thin, metal strip that channels water away from building joints. Typically, builders use flashing to join two other materials in a weatherproof way. Flashing prevents water from dripping in between the joined materials, which are often wood. Builders use flashing around chimneys, vents, windows, and walls.
The IBS requires drip edges on any shingled roofs. The drip edges, installed along the lower edge of the roof, cover the gap between the shingles and the roof deck (usually plywood). The drip edge prevents water from channeling right into your attic or pooling between the wood layers, resulting in rot.
Metal roofs don’t have shingles and many experts say that a drip edge is not necessary for a metal roof. They say that if you overhang the metal roofing sheets at least an inch, then you shouldn’t need the drip edge.
However, you may want a drip edge anyway. A drip edge on a metal roof helps protect the fascia, it seals up your attic from “vermin“, it protects your home’s exterior, and it gives the exterior a professional look.
Here’s a great reference for drip edging and flashing.
How Do You Install a Drip Edge on a Metal Roof?
Follow these simple instructions to install a drip edge on your metal roof:
- Install the drip edge before the metal roofing.
- Measure, measure, measure. Measure your eaves for how much drip edge you’ll need. Drip edges are typically sold in 10-to-12-foot lengths. Plan for overlap – 2 inches is code for shingle roofs.
- When shopping for the drip edge, experts recommend buying at least 36-gauge aluminum edging. Overlaps come as L-Shape (aka L-Style or Type-C), T-Shape (aka T-Style or D-metal), or F-Style (aka Gutter Apron).
- If your drip edge has a plastic film, remove it.
- Start at a corner. Lay out the piece with the corner an inch away from the edge of the fascia board. Mark the inch on the underside of the drip edge.
- Use tin snips to cut the drip edging. See the video at the end of this section for instructions to cut and fold the extra inch of drip edge. Be sure to protect your hands with a good pair of sheet metal gloves.
- Hold the flashing down tight against the roof line. The drip edge should be installed under the underlayment, not on top of it. Next to the fascia board, you should be able to fit a finger between the drip edge and the fascia board. This will keep the water from dripping onto the fascia board.
- Nail or use a low-profile metal to wood screw every 12 to 16 inches, starting 8 inches from the corner.
Here’s the how-to video.
You can (and probably should) fit gutters on a metal roof, but remember they need to be stronger than on traditional roofs because rain and snow will just shoot off your metal roof at higher velocity than tiled roofing.
This means you need strong gutters attached to the roofing fascia, and the metal roof panels need to overhang them by between 1 to 1.5 inches to be effective (depending on your climate and level of precipitation).
Like all big jobs outside your home though – if you’re unsure about fitting these yourself or are scared of heights – then it’s always better to hire a local contractor to fit your guttering for you. 🙂