How to Install Metal Roofing Over Shingles
If you begin to have problems with your shingles or they are showing wear and tear, replacing them with other shingles is not your only option. Instead, you can consider an upgrade to metal roofing, which is known for its durability, environmental friendliness, and sleek appearance.
Additionally, you can usually just install it over your shingle roof. The only things you need to consider are whether the roofing is in decent condition and not overly heavy. Of course, this is usually not something you can do alone, but it might be fine on smaller projects or with others.
The Best Way to Install
If you want to install metal roofing on top of a shingle roof, the best way is to use battens. Battens are strips of wood (though they can be other materials) that help you maintain a gap between the shingles and the metal roofing.
Take your battens, which should be 1×2 or 2×2 boards, and place them on top of the shingles. They should be placed horizontally and parallel. Doing this allows the roofing to contract and expand with the weather and ensures that there is no major build-up of moisture between the layers.
The Deal With Damaged Shingles
While using battens is great, you cannot ignore damaged shingles. If they are leaking or not in good condition, you will need to remove them first. While many people want to place metal roofing on top of a shingle roof because it needs to be replaced, they need to be stripped.
In part, damaged shingles need to be replaced because adding weight on top of them will eventually cause them to collapse. Moreover, damaged shingles might have an underlying problem or damage underneath, so keeping them on is not an option, no matter what.
Therefore, you will need to have them stripped, and any joists showing damage or decay will need to be replaced. After that, the metal roofing can be placed onto the framing.
The Role of Underlayment
Underlayment is often used, but it is not mandatory, especially if the shingles are in decent condition. If it is added, putting it down before the battens and roofing is a good choice. Doing this helps with unwanted moisture and the prevention of leakage. Moreover, it is an inexpensive way to add a barrier of protection, even if it is not a must.
Keep in mind that you might see something different done by contractors. Some place plywood on the battens before nailing the felt on top of that. Then, the roofing can go down atop the other layers. However, doing it this way means adding quite a bit of weight, so it is not always used.
Installing Metal Roofing Over Shingles
While the process is not complicated and was discussed a bit above, it is important to go step by step when installing metal roofing over shingles. To start, you will be getting the battens and underlayment (optional) in place, followed by securing the panels to them. Finally, you will add closure strips and flashing to complete the job.
Battens and Underlayment
Assuming the shingle roof is in good condition, you can immediately place the underlayment down, unrolling the felt over the roof. Remember that underlayment is optional, though it is a good choice for extra protection. Once the underlayment is where you want it, nail it into the plywood layer beneath the shingle roof.
After the underlayment is nailed down, place the battens atop it in rows. Remember to place them horizontally and parallel to one another as you nail them in place. Getting the battens right is the only vital part of this, so do it carefully. And remember, if the shingles are damaged, they will need to be removed before the battens go down.
Secure the Metal Sheets
It is not easy to secure the metal sheets alone, especially since you have to haul them onto the roof and screw them into place. Therefore, you might want to get help or have professionals deal with securing them onto the battens or subroof. The sheets are heavy and hard to maneuver, so do not get frustrated if they do not line up immediately.
When laying down the panels, the grooves must be exactly level when placed beside one another. If they are not, they will need to be cut in such a way that the seams match.
Closure Strips and Flashing
With all of the metal sheets in place, you want to go to each seam where two sheets touch and add closure strips to keep water out. Next comes flashing, which means a drip edge on the edges of the roof. It also means a ridge cap at the peak. Make sure to screw the flashing into the battens or edgings to ensure it is firmly in place.
The last thing you want to do is apply a rubber grommet atop each screw or nail to avoid leaking through the minuscule gaps. And that is it.
Doing the Work Yourself
Now that you know what is involved in the process, you might be thinking it is an easy project you can take on yourself. However, without previous experience, it is not a great idea. Roofing can be dangerous, especially alone, and metal roofing is particularly risky. It is heavy, requires special equipment, and doing it incorrectly can cause a disaster.
However, if you have experience, you can give it a shot. Just keep in mind that it will cost between $15,000 and $60,000, which will depend on the material and how much space you need to cover. Though, the good news is that metal roofing can last upward of 50 years.
The only exception to the experience recommendation is if you are working on a particularly small project. That includes something like a shed, where there is not much lifting and falls are unlikely.
Do Not Forget a Permit
If you do the work yourself, you will probably need a permit since it is illegal to install such roofing without one in most places. That might not be true of small things, like minor repairs, but for big roofing jobs, you will want to contact your local building department.
Additionally, some places do not allow those without a contractor’s license to do their own roofing work. Therefore, even if you decide to go with a professional, ensure they are licensed to do the work.
Metal roofing comes with many benefits, but there are also some disadvantages. One disadvantage is that there is an added weight that can be a problem over time. Homes are designed to handle a single roof. Moreover, as time passes, degradation can occur in the joists, subroof, and shingles.
Ordinarily, the weight is not a problem since metal roofing is usually lightweight, which means a single layer of shingles will not lead to buckling or damage. But that is not always the case, especially with old homes, which carry the possibility of already having old shingles underneath the current layer.
Metal roofing also tends to be expensive. It comes with increased durability and a higher effective lifetime, but it does mean eating the initial cost. Some cheaper options include aluminum and galvanized steel, and for small projects, corrugated steel is the least expensive option.
Finally, you will likely notice some noise when it rains. The shingle layer helps to reduce that noise, so it should not be significant when you are inside, but there will still be some sound.
Bumble Roofing Can Help Install Your Metal Roofing
6800 Owensmouth Ave STE 410, Canoga Park, CA 91303, United States
With over 12 years of construction industry experience, David Bitan specializes in restoring, inspecting, maintaining, and repairing roofs for residential, industrial, and commercial properties.