Wood or Metal?
Wood is definitely the sturdier of the two materials. Metal appears to be flimsy, but once the drywall is screwed to it, it is strong and rigid.
There is some debate about whether or not metal is suitable for hanging cabinets or heavy mirrors. Canadian contractor and construction expert Mike Holmes (Holmes on Home, Holmes Inspection) says absolutely NO WAY. While I have read other opinions on the subject that say that it is possible, I haven’t actually tried this myself. Personally, I certainly would feel more confident with a 2 and a half inch screw biting into solid wood than I would with a screw tapping into thin metal.
When using wood, it is possible to add structural support. Metal can only be used for non load-bearing walls.
Metal can be cut using aviation snips, which means no sawdust. However, gloves should be worn to protect the hands from sharp edges and care must be taken to clean up any small pieces that end up on the floor, lest they migrate into your foot..
It is also possible to cut steel studs using a miter saw with a metal cutting blade, making it easy to cut multiple studs at once.
With wood or metal, eye protection is a must. Always wear safety glasses.
What is the cost of using wood versus metal? As a general rule, building a steel stud wall is more expensive because of the cost of fasteners and other specialized materials. However, steel stud walls can be built faster so there is savings in labor costs, which can balance out the material cost difference. Do-it-yourselfers, of course, are already saving labor costs anyway.
Make a mistake in measuring? Stud not vertical? Since metal studs are attached with screws removing and moving studs is simple.
Wood is prone to twisting and warping; metal is not. Wood also wicks moisture which can lead to mold growth and rot; metal does not. However, metal does rust. A vapor barrier or sill gasket should always be used between the bottom plate and the concrete floor regardless of which material is used.
Carpenter ants and termites can severely damage wood construction, but, as far as anyone knows, they have not yet developed a taste for metal.
Metal framing has sometimes been promoted as an environmentally friendly alternative to wood. However, both materials have their positive and negative points. Wood comes from trees, and cutting down trees is generally seen as bad for the environment. However, wood is a renewable resource and we are getting better at managing our forests. Wood scrap is biodegradable and smaller pieces can be composted, but it takes a while to wood to break down and most scrap ends up in the landfill anyway. Metal is recyclable, and while recycling is generally seen as good for the environment, the recycling process is not. Basically, either material can be seen as better or worse for the environment than the other, depending on your point of view.
Wood burns, metal does not. A wall built with metal studs is virtually fireproof.
Metal conducts cold. Metal framing next to an outside wall (ie the foundation wall in a basement) will transfer the cold. Beyond the obvious comfort issue, this may cause condensation on the walls in the stud locations. The condensation can attract dirt which will lead to dirty stripes on the walls. Therefore extruded polystyrene insulation should be considered between the outside wall and the metal to act as a thermal break. I did not take this step but did not notice any major problems. With wood, cold transfer is less than with metal, but it still exists.
Having worked with both materials, I believe that both have their positive and negative attributes. It basically comes down to personal preference.
Installing Metal Studs
Metal studs come in the same dimensions as lumber. The system consists of two main components, the track and the stud.
The tracks are usually installed first fastened to the floor and the ceiling– in the case of a basement, to the slab using concrete screws, and to the ceiling joists. The studs are then inserted in the tracks and twisted in place until they are square. Wafer screws or framing screws fasten the stud and track assembly together. The studs and track can both be cut to size using aviation snips.
Because the metal tends to be somewhat flimsy, we found a “third hand” to be somewhat beneficial. Small vice grips held the track and stud together while the screw was driven. This stopped the screw from pushing the stud away, and it saved our fingers.
For framing around windows and constructing headers for doorways, the track material has to be dog-eared.
The track is cut about a foot longer than the space between the two studs. The sides of the track are cut so that the track can be bent and fastened to the studs as shown in the picture. For doorway headers, two tracks are installed. The track attached to the ceiling faces down, and the track for the top of the door frame is installed so that the channel faces up. That way vertical studs can be installed between the two tracks for attaching wall material.
As previously mentioned, metal studs require specialized device boxes. Shown at the right is one such box inside vapor barrier. This particular box has a front piece that clips onto the stud and gets screwed into place. There is also a strap that bends around the stud and gets fastened to the back.
These additional fastening points do present a problem when installing the electrical box in vapor barrier on exterior walls. The vapor barrier isn’t’t exactly air tight with holes for the wires and holes for the straps. The best solution is to use acoustical sealant to seal any points of penetration.
Insulating and Attaching Vapor Barrier
Because the studs are essentially hollow, standard insulation is too narrow. Be sure to use insulation specifically designed for metal studs (a full 16 inches wide)
In wood construction, the vapor barrier is attached with staples. Staples will not work with metal studs. The solution again is to use acoustical sealant to attach the vapor barrier to the framing. Continuous beads along the top and bottom tracks will keep things air tight (in fact this should be done with wood framing as well). Dollops of sealant spaced 6 inches to a foot apart on the studs will hold the barrier in place. The sealant is messy stuff, so you will want to get the vapor barrier in place the first time.
My method was much less elegant. I cleaned off the studs and used double face carpet tape to help hold the vapor barrier. The top and bottom of of the vapor barrier were taped to the tracks with the same tape I used for sealing the seams (Tuck Tape). My vapor barrier was airtight, but I wish I had known about acoustical sealant at the time because it sure would have been faster and easier.
Hanging Drywall and Trim
Be sure to use fine threaded drywall screws for hanging the gypsum. Trim screws that have very small heads are used for attaching the trim. Screw holes can be filled with wood filler or caulking if the trim is painted. For stained trim, you will probably prefer to use nails, which is still possible with metal framing. Fasten a strip of OSB or plywood that is a little narrower than your molding and the same thickness as your drywall to the metal. The wood will provide a nailing surface for attaching the trim and the trim will cover the seam between the wood and the drywall.
The bottom line
Moisture is the enemy of both wood and metal. In both cases, structural damage can result if steps are not taken to prevent moisture from contracting either material. With wood, you also have to contend with the added bonuses of mold and insect damage.
Cold transfer is a concern with metal when used for perimeter walls but this problem goes away if a thermal break is installed between the exterior walls and the framing. This step will add to the overall cost of the project, though having additional insulation can lead to some long-term energy savings.
Trakloc is a product that is worth a look. The telescoping studs (no need to cut to size) simply twist and lock in the track without the need for fasteners. The cost of this product is higher than conventional metal framing, but offers savings in time and therefore labor costs. Company president Todd Beasley explains the math:
As for cost, here is a rule of thumb for comparing Trakloc to other metal framing. The ratio between labor and material to install conventional steel framing (that has to be measured, cut to length and attached to the top and bottom track with fasteners) is approximately 3 to 1. Trakloc costs about 25% more than conventional framing but can save on average approximately 35% on labor costs. So with Trakloc the materials (25% of the cost) go up by only 25% but the labor (75% of the installed cost) goes down by 35%. Therefore the cost of the average job, when considering both labor and materials, can be reduced by anywhere from 15% to 25%.
As of December 2013, the company only manufactures in California. They hope to get a plant up and running on the east coast soon which will be helpful in getting their product into major national chains. Initial talks with Home Depot and Lowes have taken place. Meanwhile, they do sell through distributors that are open to the public including Allied Building Products (AMS), Westside Building Materials, L&W Supply (Calply), Great Western and some others. [Please note that I am NOT paid to promote Trakloc, although if someone at the company were to cut me a check, I wouldn't turn it down!]
You may also be interested in The Basement Renovation where most framing was done with steel studs.
And you may also want to check out my cost comparison of metal versus wood framing.