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Why Does a Metal Roof Deteriorate?

Metal Roof Repair You Can Trust

You can have major problems with a new metal roof if mistakes are made in in its design as well as its installation. The selection of the system is not an area where such problems will typically occur. A major part of the problems that lead to leaking in metal roofs, have to do with the details used for finishing the roof system. When a roof is first installed, these mistakes may not be immediately evident, as they can take some time to develop.

Ann assessment of a metal roof will bring up the most common five problems that are encountered.

Horizontal Seams Openings

You will rarely get metals roofs that in length span the full length of the rafters. Some project designers limit the length of the roof panels to take in both expansion and contraction.

This restriction of the panel length then makes it necessary to have horizontal seams in the roof system. These seams run horizontally, and are perpendicular to the other standing seams in a metal roof.

These horizontal seams do tend to separate over time. Where the metal roofs are hydrostatic, this results in openings being created, that allow water falling on the roof to enter the building that it covers.

Penetration Flashing Openings

Commercial Metal Roof Replacement ContractorsAll metal roofs will expand and contract with the temperatures they are exposed to. This causes movement of the roof panels. This in turn leads to the attachment points and the penetrations getting stressed. This stress causes the flashing at the points of penetration to breakdown and then cause the roof to leak.

The construction of a metal roof system involves the attachment of individual panels by bringing them together at the seams. Once this assembly is completed it is not easy to disassemble these panels or remove them.

In an asphalt shingle system you can disassemble the shingles to allow for any repair to penetration flashing. You cannot do this with metal roofs, which makes any repairs to flashing, difficult, and even more so, if this penetration installation work is carried out after the roof is installed.

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Metal Roof Oxidation

A variety of materials are used for manufacturing of metal roofs. These are aluminum, steel, copper, tin, and zinc. Some of these materials can combine with the oxygen in the air and cause oxidation. The sheet metal of most metal roofs are given a protective layer. This layer can wear away after some time and this will leave the metal exposed to oxygen and that can cause oxidation.

When metal roofs suffer surface oxidation, it can lead to several problems. If the roof system is structural, there can be structural failure. Oxidation can also lead to difficulties in repair. If this oxidation occurs at the places where fastener heads are exposed it then becomes difficult to apply any sealants.

Fasteners Backing Out

A typical metal roof system will involve both concealed and exposed fasteners. You can use either screws or nails for this fastening. Most fasteners that are exposed will have washers made of neoprene that allow the sealing of fastener heads to the roof.

After some time, these fasteners do tend to back out from the position they are seated in. One reason why this happens is wind uplift, which causes the metal panels to vibrate and thus dislodge the washers from their seat. The neoprene washers can also dry out and allow water to enter. Come winter, this water can freeze and this expansion can lead to a further backing out of the fastener.

Open Ridge/Headwall Flashing

Roof systems do need to end and come into contact with other building surfaces. Roof systems can end into a rising wall, like where it ends into any rising wall in a shopping center below a sign band.

This is a point where the roof system can be weak. This is often a result of poor detail in the original installation design. It is necessary to have closure strips to see that water does not blow back into the detail. Many installers or contractors do not install these closure strips. The underlay acts initially to waterproof the roof system, but as it ages, it can lead to moisture penetrating the roof.

There are other reasons why a metal roof system may leak, but those given above are most common and must receive any initial check. Your battle against leaks is already half won, when you know where to look.

Armadillo Roofing & Exteriors, 512-333-7663, provides commercial metal roof replacement and commercial metal roofing services to Austin, Texas and the surrounding Austin area communities.

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