One of the easiest ways to change the look of a room is to change the artwork hanging on the walls. Purchasing an art print and frame is a relatively small investment compared to buying new furniture or spending hours painting the walls. A wall shelf to display artwork is another simple way to transform the look and feel of a room. New artwork can bring lasting enjoyment - provided it has been mounted properly.

You may not realize it but there is a science to hanging objects off your walls. Just ask anyone who has had a frame come crashing to the floor or hammered a nail into a water pipe! There are three main considerations before starting a project:

Type of Wall Surface

Is it drywall, wood paneling, brick or concrete? Is it hollow or solid?

Size and Weight of the Object

The weight of the object will determine the type of fastener required. If you are building a shelf, be sure to weigh the shelf plus all the objects that will rest on it. When buying fasteners, read the packages to find the maximum weight specified by the manufacturer.

Force

What types of forces will be applied to the object? Will there be any outward pulling force (tensile force) or will the major force be gravity (shearing force)? It is also wise to be prepared for unexpected vibrations from slamming doors or earthquakes (not to mention curious felines).

Once you have considered these factors, you will be able to determine the best fastener for the situation. If you have a light-weight item but you wish to add extra stability, use the fasteners recommended for medium-weight objects on your wall surface. Likewise, for medium-weight objects, use heavy-weight fasteners.

Hollow walls (drywall or paneling)

The walls in most homes are built with wood studs (commonly referred to as 2x4's) spaced at regular intervals. The space between the studs creates a cavity that can be used to run electrical wires and plumbing pipes. Before you start hammering or drilling fasteners, try to find out if anything is behind the wall.

Some important clues to look for are the position of electrical outlets, sinks and radiators. Try not to hang artwork directly above any of these items. Electrical wiring and pipes may run vertically from the ceiling. If the wiring and pipes run horizontally, they will usually be below average waist height therefore much lower than most people would hang artwork.

Once you have found a safe location to hang your artwork consider the weight of the piece. For light-weight artwork you can use small finishing nails, hook-type hangers that spread the weight of the item over a larger area, or plastic screw anchors that fit into pre-drilled holes. As you twist a screw into the plastic anchor, the bases of the plug spreads out and locks against the perimeter of the hole. This is one of the most secure options for light-weight artwork, however, plastic anchors will create a larger hole in the wall than hook-type hangers.

To hang medium-weight items on drywall or paneling, ask for molly anchors (or hollow-wall anchors) at your hardware store. These anchors combine a casing and screw similar to the plastic anchors mentioned above, but are more sturdy than plastic. As you tighten the screw, the casing around it collapses against the inside of the drywall. For the best result, pre-drill a hole for the anchor rather than hammering. Molly anchors will provide protection from tensile and shear forces.

Heavy-weight objects such as large pieces of artwork and shelves cannot be mounted on drywall alone. Gravity and vibrations can eventually dislodge them likely damaging your wall in the process. You will need to secure heavy objects to the wooden studs or joists behind the drywall.

In order the find the stud or joist, you can use an electronic "stud finder" - a gadget that measures the density of various points along the wall. When you pass the stud finder over wood, which is denser than drywall, the machine will indicate the location of a stud. If you prefer a low-tech approach, use the location of electrical outlets as a clue. Outlets are usually attached to one side of a stud for stability. The electrical wiring typically passes through a hole drilled in the cross-section of a stud. Tap your fist against the wall on either side of the outlet and listen to distinguish between hollow and solid sounds.

Once you have located the stud, use toggle bolts or molly anchors to hang artwork. Toggle bolts have spring-loaded wings that expand inside the wall and provide added stability.

Solid walls (brick or concrete)

The benefit of solid walls is they can hold heavy artwork; the downside is the challenge of installing a secure fastener. In order to drill into brick or concrete, you will likely require a carbide masonry bit. This type of bit is designed to drill a clean hole in a hard surface. If you are drilling large holes (over  ½" diameter) start with a smaller bit and work up to the desired size.

For light-weight objects, you can use plastic anchors or masonry screws. To use the anchors, pre-drill a hole, blow out the dust (goggles and a face mask are recommended), and tap the anchor into the hole. As you twist in a screw the anchor will expand as much as possible and fill the hole. When using masonry screws, pre-drill a hole that is exactly the size of your screw. A hole too small will not accept the screw and one too large will result in an unstable mount. Drive the screw by hand for the best result.

For medium and heavy-weight objects, you can use large masonry screws or spread out the load by using two or three normal size screws. Another option is the sleeve anchor. This anchor has a steel sleeve that expands in the pre-drilled hole. Tighten the bolt to expand the sleeve but be careful not to over tighten as this may crack the brick or concrete.

Whichever your wall surface and artwork, one of these methods is sure to provide a stable mount that will stand the test of time.