What Is Behind Drywall: Guide to Wall Studs and Framing

Drywall framing, including two-by-four wall studs and drywall sheets, is vital in any home building or renovation project.

Knowing what is behind the drywall, the distance between the studs, and the presence of wires and pipes, makes a difference when doing anything from hanging a picture to building the room itself.

Drywall

Drywall is the rigid gypsum-based board that forms most walls in homes. Often called wallboard, drywall is 1/2-inch thick but can be 5/8-inch thick for ceilings and fire-prone areas like furnace rooms or between the garage and the house. Drywall is either screwed or nailed directly to the wall studs.

Wall Studs

A load-bearing wall supports the weight of the house above it. A non-load-bearing wall supports only its own weight.

Load-bearing wall studs are usually 16 inches apart, on-center. This predictable spacing lets you easily find studs when trying to hang a picture, install shelves, or put in new kitchen wall cabinets, among other projects.

Non-load-bearing walls can have vertical studs spaced as far apart as 24 inches, on-center. Since non-load-bearing walls only bear the weight of drywall and some electrical and plumbing work within, it is possible to have wider apart studs. In some homes, load-bearing walls are 24 inches apart, on-center.

Insulation

Exterior walls usually have fiberglass, cellulose, mineral wool, or foam insulation. Older homes may not have insulation behind the drywall.

Interior walls usually do not have insulation but sometimes they may have it as a soundproofing device.

Headers

Headers are horizontal members that run across the top of doors, windows, and entryways. Headers are important because they support the weight that ordinarily would have been supported by vertical studs in that space.

The wider the header above the window, the larger the window. Thus, you receive more air and light. Also, within the house, a sturdy header above the door between the kitchen and living room can help tie the two rooms together.

Wires

Electrical cables are usually behind drywall, either running horizontally through holes in the studs or stapled vertically up the sides of studs.

Outlet cables tend to be about 12 inches high. Light switches are around 48 inches high, so expect to see electric cables around that area. You should not find loose electrical wires: only wires bundled together as either metal- or plastic-sheathed cables.

Loose wires are not allowed by most electrical codes. In some older homes, though, you may encounter loose wires called knob-and-tube wiring.

Pipes

Plumbing pipes of PEX, copper, or galvanized steel are found behind walls mainly to serve kitchens and bathrooms.

Pipes will run vertically more than horizontally through walls. A common example would be a blue PEX and a red PEX pipe running vertically up from the water heater and main water supply in the basement.

Fireblocks

Fireblocks are short horizontal studs added perpendicular to the wall studs to slow fire movement.

Many fire codes require fireblocking, which is a simple, effective fire barrier between floors. It can seal vertical and horizontal concealed draft openings.

Vermin and Insects

Even the tightest wall may end up with spiders and cobwebs. Rats and mice die within walls and remain there until found during remodeling projects.

Construction Debris

Careless builders sometimes let construction debris fall down wall wells. There is a good chance that you will encounter some screws or nails.

If the wall is made of plaster, the plaster will have squeezed through the metal or wood lath to create necessary knobs called keys. Keys sometimes snap off on their own and fall into the wall.