How Much Weight Will An Old Work Box Support?

Dennis Howard
by Dennis Howard

Remodeling is always a challenge, especially when adding new light fixtures. Adding a light fixture or ceiling fan where there is no electrical box requires some forethought. One question to consider is how much weight will and old work box support.

An old work box will support up to 50 pounds of weight as long as it is attached to a support, however, if it is only attached to the sheetrock then the weight-bearing limit is zero. The weight limit is different depending on the manufacturer, so it’s best to double-check the limit for your model.

Choosing the style of workbox that you install determines the weight you can hang from the workbox. Some old workboxes are rated for fifty pounds of hanging weight. These types of old work boxes require special installation steps. Understanding old work boxes is critical before installation.

Do You Need to Hire an Electrician?

Get free, zero-commitment quotes from pro contractors near you.

Old Work Boxes: Standards and Ratings

There are several different categories and styles of old work boxes suitable for hanging fixtures or ceiling fans. It is important to match the type or style of the old workbox with the intended application.

The problem with choosing an old work box for your remodeling project is the variety of manufacturers in the market. Each of these manufacturers has their style of old work boxes and assign their weight ratings to the old workbox. Some don’t give weight ratings for liability reasons.

Weight-Bearing Old Work Boxes

Typically, an old work box designed to hold weight requires attachment to something more substantial than the sheetrock. These weight-bearing rated old work boxes have nails or screws that allow mounting the box to a ceiling joist.

Attaching this style of the box means a trip into the attic to attach the old work box to a ceiling joist. If there is no access to the area above where the box is needed, another solution is necessary

Into the Attic

If there is no ceiling joist in the spot where you want to locate the old work box, you must place a supporting member between the ceiling joists. The supporting member is usually a length of 2×4 cut to fit tightly between the joists and securely attached.

No Access, No Problem

When there is no access to the attic above the ceiling where you want to install a new weight-bearing box, you may need to use a brace box. These boxes install through the hole in the ceiling for the fixture

Installing A Brace Box

Installing this type of brace box is easy. Some of the steps differ from manufacturer to manufacturer. Be sure to follow the directions with the box you purchase. In general, the steps involved in installing a brace box are:

Step 1: Locate and Cut the Hole for the Box

Locate the position for the new box. Using a sheetrock hole cutter or sheetrock saw to cut out the hole. Reach up through the hole and locate the ceiling joists on either side of the hole. Mark the edge of the hole showing the direction to install the brace. Remove any insulation above the hole.

Step 2: Install the Brace

Follow the manufacturer’s instructions to install the brace properly. Generally, the brace slips into place and a mechanism is engaged to clamp the brace into place between the joists. Take care not to tighten the mechanism too much or you risk bending the brace.

Step 3: Pull the Wire through the Hole

Pull the wire through the hole. Put the wire through the box before you install the workbox on the brace.

Step 4: Install the Box on the Brace

The box should slip up into the hole and attach it to the brace. Follow the manufacturer’s instructions when re-installing the box to the brace.

When the New Service is a Ceiling Fan

If the new fixture is a ceiling fan, you should choose a brace style box. Even boxes that attach to a ceiling joist on one side can tip and rock with the weight of a ceiling fan. Brace style boxes specifically for ceiling fan installation are available.

Non-Structural Weight-Bearing Boxes: Be Careful What You Install

Some manufacturers advertise non-structural weight-bearing old work boxes. These boxes depend on the structural strength of the sheetrock for support. Most of these old work boxes rate for 10 pounds or less weight when mounted properly.

The downside is the ceiling sheetrock. Old sheetrock that has degraded may not handle the maximum weight for the box. Another consideration is how well you do the installation. If the lugs on the box aren’t supported enough around the box, you lose capacity.

Non-Weight-Bearing Old Work Boxes: Don’t Be Tempted

Don’t get tempted to put in an old work box that doesn’t have a weight rating or even states that it has no bearing capability. You are asking for trouble down the line for yourself or the next person who owns the home.

The fixture you hang from the non-rated box may be light enough not to cause a problem. However, you can never be sure. There is also the possibility that someone living in the home later may want to install a different fixture. You don’t want to be responsible for a preventable accident.

Other Considerations: Getting the Big Picture

There are other considerations beyond the problem of hanging a heavy fixture from an old work box. You may run into roadblocks if you do the job improperly.

Inspection Problems

If the work you are doing during the remodel requires code inspections, the inspector will require that the appropriate box for the application. Better to do the proper job in the beginning than to redo a job at extra expense and time.

More Inspection Problems

Selling a house usually involves having a home inspection performed before the sale is final. It may not be likely that a home inspector finds the wrong old work box installed unless there is a clear indication that the installation is questionable.

A sagging or poorly fitted fixture may tip off a good home inspector that something is amiss with the electrical box. Well trained home inspectors look for these kinds of clues. Failing to install the right box in the first place can have you making repairs in the future.

Insurance Considerations: When a Claim is Made

Should the installation of the wrong box result in an accident, if the insurance adjuster who inspects the damage finds that the old work box was improper for the installation or was not installed to specifications, the insurance company may deny the claim.

When you do the proper job, in the proper way, with the proper parts, you are protecting yourself as well as your home. It pays to do it right the first time.

Be Careful What Ever You Do

Whenever you are working with electricity, you must be cautious. Following a few simple tips to ensure your safety will pay off in the long run.

  • Make sure the power is off to any circuit with which you are working
  • Be careful when cutting into walls or ceilings. Other things may lurk out sight.
  • Wear appropriate safety gear including eye protection and gloves
  • Use the right ladder if working on the ceiling

Do You Need to Hire an Electrician?

Get free, zero-commitment quotes from pro contractors near you.

Old Work Boxes: Make the Right Choice

If your remodel involves adding new fixtures, you must select the right old work box to install. Don’t make the mistake of taking the easiest or cheapest route for the project. A little bit of time and extra effort will make sure that the job is safe and secure.

We hope that this article has answered your questions about the weight-bearing capabilities of old work boxes. Always follow the manufacturer’s instructions and recommendations when installing any equipment. Good luck with your projects.

Dennis Howard
Dennis Howard

Dennis is a retired firefighter with an extensive background in construction, home improvement, and remodeling. He worked in the trades part-time while serving as an active firefighter. On his retirement, he started a remodeling and home repair business, which he ran for several years.

More by Dennis Howard