Framing
Metal vs wood studs for interior walls
Steel studs are the norm in commercial interiors and still unusual in houses. Each has a place, and the drywall goes on both, with different screws.
Two systems
Wood studs are 2 × 4 or 2 × 6 lumber, nailed or screwed to wood plates. They are the standard for houses: familiar, forgiving, easy to cut and fasten to, and every trade knows how to work with them.
Light-gauge steel studs are C-shaped channels of galvanized sheet steel that sit in a U-shaped track at top and bottom, screwed together with short pan-head screws. Interior, non-structural studs are thin, commonly 25 gauge, and come in widths of 1-5/8, 2-1/2, 3-5/8 and 6 in. They are the standard for commercial interiors, and the usual choice in basements where moisture and termites are concerns.
Compared
| Wood | Steel (25 ga, non-structural) | |
|---|---|---|
| Straightness | Varies; can twist, bow and shrink | Straight, does not shrink |
| Moisture, rot, termites | Vulnerable; pressure-treated plate on concrete | Immune |
| Weight | Heavier | Light |
| Tools | Saw, nailer or drill | Snips or chop saw, drill, clamp |
| Drywall screws | Coarse thread, 1-1/4 in for 1/2 in board | Fine thread, 1-1/4 in, pass 3/8 in through the steel |
| Hanging things | Screw into any stud | Needs wood or steel backing for heavy items |
| Doors | Doubled studs and a header | 20 ga or doubled kings at doors; header from track |
| Nail pops | Common as lumber dries | Rare |
| Fire | Combustible | Non-combustible |
The same wall in each
A 14 ft partition, 8 ft high, 16 in on centre, one door
- Wood: 17 studs, 19 with waste (92-5/8 in precuts), 42 ft of 2 × 4 plate, one 37 in header
- Steel: 15 studs, 16 with waste (3-5/8 in, 25 ga, 8 ft), 4 pieces of 10 ft track for the plates and the header, about 68 framing screws
Steel studs are not doubled at the ends or at tees as wood is; the end stud is screwed to the track and to the wall it meets. The metal stud calculator and the wall stud calculator count each.
Building with steel
- Track first: screw the bottom track to the floor and the top track to the joists or ceiling, plumb above it.
- Studs in the track, open sides all facing the same way, twisted into place and screwed through each flange at top and bottom with 3/8 to 1/2 in pan-head framing screws.
- Doors: kings turned to face the opening, often 20 gauge or doubled, especially for solid-core doors. The header is a length of track cut 8 in longer each side, the flanges bent down and screwed to the kings.
- Electrical: the studs have punched holes for cables, with plastic grommets to protect them.
- Heights: light-gauge partitions are limited in height by the stud width, gauge and spacing. The makers publish limiting-height tables; check your wall against them.
Hanging drywall on steel
Drywall goes on steel studs with fine-thread, sharp-point Type S screws. A screw must pass at least 3/8 in through the steel, so 1-1/4 in screws suit both 1/2 and 5/8 in board. Hang each sheet so its edge lands on the open edge of the stud first, then the closed (web) side; screwing the web side first deflects the flange. Screw spacing is the same as on wood: the guide to screws per sheet and the screw calculator cover it.
Sound
A steel stud is less stiff than a wood one, and that flexibility helps sound isolation: walls on light steel studs often test several STC points better than the same board on wood studs. Commercial sound-rated partitions are built on them for that reason. The guide to soundproofing a wall covers the assemblies.
Hanging things on steel
A thin steel stud holds a screw poorly compared with wood. For cabinets, TVs, handrails and grab bars, install backing before the board: a wood block screwed between the studs, or a steel backing plate made for the purpose. For lighter items, toggle anchors through the drywall or into the stud work well; the anchor weight calculator rates them.
When to choose which
- Basements: steel, or wood with a treated bottom plate; steel does not mind damp or termites.
- Long straight walls, soffits and ceilings: steel stays straight.
- Walls with heavy cabinets or many hung items: wood, or steel with planned backing.
- Small DIY jobs: wood; the tools and techniques are familiar.
- Exterior walls: wood in most houses. Steel conducts heat and needs continuous insulation outside it.
The steps for building a partition, in either material, are in the guide to framing a partition wall, and the partition wall materials calculator lists everything for one.
Mixing the two
Many basements and remodels use both: wood for the bottom plate’s neighbours where cabinets hang, steel for long runs and soffits, or steel studs with wood blocking where anything heavy will be mounted. That works as long as each wall is fastened as its own material asks: coarse-thread screws into wood, fine-thread into steel. A steel wall meeting a wood one is screwed to it through the end stud.
Shrinkage, pops and straight walls
Kiln-dried lumber still loses moisture after it is enclosed, and as it shrinks, screw and nail heads can push out through the finish. Steel does not shrink, so pops are rare, and steel studs come dead straight, which shows on long walls and ceilings under raking light. Choosing straight lumber and letting it acclimatise before the board goes on narrows the gap.
Safety
Cut steel edges are sharp; wear gloves. Snips are quiet; a chop saw with a metal-cutting blade is fast and throws hot sparks, so eye and ear protection and nothing flammable nearby. Steel studs are not load-bearing unless specified as structural framing with heavier gauges and an engineered design.