Metal framed buildings have been constructed in the southern regions for years. The popularity of metal as a framing material was desired in these climates due to high risk of termite and rot damage. Metal studs were more prevalent in commercial construction, but have since shifted to residential. It is estimated that between 10,000 and 15,000 metal framed homes were built in 1993, and that number is expected to more than triple by 1996.

As the use of metal studs spread to the northern regions, some problems have arisen. Many carpenters and builders have not had the proper education or training with respect to proper installation methods. These are a few areas to inspect for structural inadequacy:

• Proper fastening techniques to areas such as roof trusses, are necessary using techniques such as, metal tie straps or spot welds. If the trusses are only merely screwed to the top plate, high winds could lift the roof system from the house.
• Exterior and load bearing walls should have a heavier gauge steel channel, than nonload bearing walls. Bridging in the wall cavities, can help to prevent stud movement.

Floor systems that use channel steel require bridging to prevent racking and crushing to the web. Bridging should be used in the center of the spans and also below load bearing points, such as where a load bearing wall rests on a main girder. Another area to reinforce would be a parallel wall bay. This could cause sagging between the joist unless properly supported. This can be supported by installing bridging 24" oc., or installing two parallel joists offset from the wall, one on each side.

Another point of contention is thermal conductivity in the northern regions. This is where outside air temperature is transferred through the metal stud to the inside and warmer air. This is referred to as thermal bridging, resulting in condensation forming inside the wall. This can be evident by streaking showing through the drywall. The streaks are lines reflecting location of the metal framing in the wall, and may be vertical or horizontal. Frost and mold can form inside the wall cavity as well.

Metal conducts heat and cold 300 times faster than wood. This drops the R-value of the wall significantly. There is research being conducted on proper remediation and installation techniques to deal with this issue.

This situation can be aggravated by using hardboard wall sheathing such as oriented strand board. One recommended procedure is to install extruded polystyrene foam over the studs on the cold side to reduce the chance of a condensation problem. This is referred to as a thermal break. One problem with this method is that the fasteners conduct the cold to the stud and the problem can still exist.

Another method of prevention being studied is the use of horizontal "hats." This is a channel ran across the studs that break the thermal bridge. Some companies have developed studs that have an opened webbing, as opposed to solid. These studs are supposed to significantly reduce thermal bridging.

Any areas susceptible to air infiltration should be caulked or spray foamed. There is other research going on including the use of wooden washers and other methods.

If these conditions are not rectified, the condensation could lead to rusting and possible failure of the metal studs and the walls. Further evaluation and monitoring is recommended.

Eventually a system will be worked out so metal studs and applications will have guidelines to prevent such problems. A professional should be consulted, if you suspect a problem.