When it comes to stud material for building interior walls, there are two distinct options available to homeowners: wood and metal. Both materials have their advantages and disadvantages. This page offers an analysis of the pros and cons of each material and presents a brief guide to metal stud construction. This article refers to the light gauge metal framing that is widely available in building centers designed specifically for partition walls. It has no structural strength and cannot be used for supporting walls.
Wood or Metal?
Strength: Wood is definitely the sturdier of the two materials. Metal tends to be flimsy, but once the drywall is screwed to it, it is strong and rigid. However, 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. But I have read other opinions on the subject that say that it is possible. 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. Metal is only suitable for partition walls. With wood, is is possible to add structural support.
Convenience: Metal wins here, hands down. It is lighter than wood and since it is not a solid material, two metal studs only take up the space of one piece of lumber. This makes for easier transporting. Metal is 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.
Cost: The cost of both metal and wood can fluctuate. In determining the actual cost, the homeowner must consider that electrical boxes for metal studs are more expensive than the standard boxes, and plastic grommets are required for running standard electrical wires unless shielded BX cable is used. Metal also requires wafer screws for construction, and trim screws for attaching moldings.
Forgiveness: Make a mistake in measuring? Stud not vertical? Since metal studs are attached with screws removing and moving studs is simple.
Stability: 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 vapour barrier or sill gasket should be used between the bottom plate and the concrete floor regardless of which material is used.
Insect damage: Carpenter ants and termites can severely damage wood construction, but, as far as anyone knows, they have not yet developed a taste for metal.
Environmental Concerns: 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 amd 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 recycling is generally seen as good for the environment. However, the recycling process does generate a certain amount of pollution. Also, the ore has to be mined and refined to produce metal, and that negatively impacts the environment. Basically, either material can be seen as better or worse for the environment than the other, depending on your point of view. Further perspectives on reducing the environmental impact of home construction and renovation can be found elsewhere on this site.
Fire Concerns: Wood burns, metal does not. A wall built with metal studs is virtually fireproof.
Cold Transfer: Metal conducts cold. Metal studs on an outside wall 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 one is not necessarily better than the other. 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 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.
Doing things the hard way:
Because the studs have to be screwed in on each side, we were presented with a problem when we did the exterior walls– we obviously could not attach the screws from the wall side without room to get the drill in between the wall and the track. We did not even think of attaching the screw from the inside of the stud.
Instead, we framed the wall in place without fastening the bottom track to the floor and only temporarily fastening the top track to the joists. We attached the the studs to the tracks from the front, then moved the assembly out from the wall, again temporarily fastening the top track to the joists. We were able at that point to attach the screws from the other side. The entire assembly was moved back in place and permanently installed. It was suggested to me after the fact that using a crimper would have made this job much easier. However, the strength of crimped joints is questionable, and in some building codes this method may not allowed at all.
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.
Trakloc is a newer product on the market. 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.
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 vapour 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 vapor barrier on exterior walls. The vapor barrier isn’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 hollow, standard insulation is too narrow. There is 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. Contiuous 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.
I took the extra step of installing fire and noise insulation in the interior walls. At the doorways where I had two studs close together, I thought it would be easier to fill the cavity with expansion foam.
Voice of experience here: Expansion foam is not recommended for filling narrow cavities between metal studs!
The bottom line
For me personally, the biggest advantage of metal framing is the stability over time. As a do-it-yourselfer and an expert procrastinator, I tend to work slow. There have been many times that I have purchased wood studs only to have them laying around for a few weeks. When I finally had enough time or ambition to start the project there wouldn’t be a straight board in the bunch.
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 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, but having additional insulation can lead to some long-term energy savings.