When a new metal roof starts to leak shortly after it was installed, you will be justified to feel upset about the whole “Leaky Roof” situation, especially if you’ve just recently paid many thousands of dollars to a shady crew for your new Forever Roof. As a specialty metal roofing contractor, I often get calls from concerned homeowners and businesses who have a fairly new, yet already-leaking metal roof that requires a professional repair to remedy the situation.
When asked whether they have called the company that installed the roof in the first place, I usually get one of the two responses; The contractor will not return the calls, or the company is out of business. Go figure! – This situation plays out over and over again, with all sorts of residential and commercial metal roofs that were installed by regular roofers. From a leaky metal shingles roof that was installed over some four old layers of asphalt, to standing seam panels that were not properly flashed at the ridge using a z-bar flashing, or copper pans that were not properly soldered, I’ve seen it all! 😉
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Now, normally, you should not really ever have to repair a metal roof that was properly specified and installed correctly, but we live in the real world, and whenever you have a regular roofing crew install a metal roof, they often (not always) do not really know what they are doing in terms of proper installation of all the components and flashing details that make a metal roofing system leak-proof for many decades.
Identifying the Causes of Premature Roof Leaks
Improper Roof Slope
First and foremost, make sure that a roof has a sufficient slope for the metal roofing system that has developed a leak. You will find that most metal shingles roofs require a minimum slope of 4/12 or four inches of rise for every 12 inches of roof run. If you see a metal shingles roof on a roof that has a slope of less than 3/12, you will know why you have a leak. With a standing seam, you will usually need to have a minimum slope of 3/12 for most architectural standing seam metal roofs, while many commercial systems can be installed on a roof that has a slope of 2/12 or greater, while some mechanically locked standing seam roofs can be installed over a roof with a pitch as shallow as 1/12.
Improperly Locked / Poorly Secured Metal Panels
Aside from an improper/insufficient roof slope, there could be many other causes of a leaky metal roof; some may be quite obvious, such as a roof leaking due to metal shingles or standing seam panels being blown away by the wind during a storm. — This happens quite often, actually, especially to the roofs that were not properly installed, nor properly secured to the deck with appropriate fasteners, in the first place. – If this is the case, you will need to assess the damage to see if the roof can be repaired by sourcing the same type of panels and replacing all the missing panels with new ones. You will also need to identify what caused the failure as most metal roofs are rated for wind uplift of 110 mph or greater. – For instance, you may find that the metal panels were blow away due to improperly interlocked metal panels, or due to the fact that panels were not properly secured to deck with appropriate fasteners. You may also find that there were one too many layers of shingles underneath a metal roof.
Leaky Chimneys, Skylights, and Roof Penetrations
But, what do you do in less obvious cases? What are some common sources of leaks in metal roofs? In my experience most metal roofs will often leak due to the fact that they were not properly flashed around critical areas such as vulnerable roof penetrations, especially around old sky lights or complicated brick chimneys. These are the usual suspects. I would start out by examining the flashing details around chimneys and skylights, especially if that’s the area where the roof seems to leak.
To repair a leaky flashing detail on a chimney of a skylight you will need to use a special silicone such as solar seal. On a chimney, apply a bead of solar seal above the metal flashing around the chimney. For a leaky skylight, inspect the metal flashing to make sure it was properly installed. You may want to lift up the rubber gasket around the skylight to see if the underlayment and metal flashing are sufficiently high. – Apply a bead of solar seal around the corners, and anywhere where you may see cracks in the old silicone. You may also want to apply some silicone around the corners under the rubber gasket, especially on the upper side of skylight that is facing the ridge of the roof.
Leaky End-walls, Side walls and Valley flashing
Another common area where metal roofs may develop a leak are end-walls or side-walls and valley flashing. With the end-wall flashing, you will want to make sure that the end-wall or sidewall flashing rises up to about five or six inches from its base. Keep in mind that you will not be able to see how tall it is, as most of the end wall flashing will be concealed by vinyl or wood siding. So you will have to stick you hand under the siding to find out how high it rises up from the base level. Should you find out that it only rises up one or two inches, you will know why you have a leak! Replacing the end-wall or side-wall flashing will usually solve the problem, but the job may be very tedious. So good luck!
With the valley flashing, look for an improperly flashed metal valley flashing where it meets the ridge line of the dormer on both sides of the ridge line. If it’s just one side of the dormer that is leaking (usually it will be just one side), you may be able to identify obvious problems including improperly bent metal flashing at the meeting point, at the very top/starting point of the metal valley flashing. Hopefully, you will not find any other obvious issues such as nails through the metal flashing that you can see in plain view. – You should not be able to see any nails penetrating the metal valley flashing. If you do see the nails, then you will know that the metal roof was installed by an ignorant hack. – I have seen a few of those. A less obvious one would be improperly installed metal shingles or metal panels that seem to be poorly installed or have a lot of unnecessary wiggle room, which would indicate that it’s a structural problem with the installation, often due to poor measurements.
For some roofs, especially for lower-slope commercial and industrial standing seam steel roofs that have leaks or a fairly severe case of rusting, elastomeric acrylic and urethane metal roof coatings may hold the key to stopping both rust and sealing the space where leaks occur. In my experience these specialty coatings can be very successful at stopping leaks, especially if the leaks are caused by the space that is created as a result of two long standing seam panels that are part of the same super long panel, joined together with a small overlap – one over the other, which is often the case on large industrial and commercial standing seam metal roofs. – Due to low slope on large commercial and industrial roofs, wind driven water can often sneak under the panels at the point of overlap, which is the weakest point in the system where a single panel was not long enough, so an additional panel had to be used to cover the whole length of the roof span.
By properly applying special membrane in combination with a roof coating, you can effectively seal the space created by the two panels overlapping and thus stop the leaks. – The coatings can also be helpful where a metal roof is rusting away, and needs to be coated in order to stop the spread of rust. It’s an added plus that modern metal roof coatings are also energy efficient.
R panel and U panel metal roofs are also great candidates for metal roof coatings, because they have screw-through, exposed fasteners that over time can become loose as long metal panels expand and contract due to temperature changes, and the neoprene washers in contact with the screws drying up and cracking over time. – These are the places where leaks are likely to develop eventually, and properly applied coating can help stop the leaks and greatly extend the lifespan of your system. You can learn more about applying roof coatings in this helpful article by Bill Hubbell.
Repairing a Leaky Copper Standing Seam Roof
With a copper standing seam roof, you will want to inspect all the seams to make sure that they were properly soldered. If they were not, you may have to redo it. Remove the copper panels, apply caulking such as solar seal in between the seals as necessary, and then properly solder the seams.
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