Q&A / 

Joist Hangers

DEAR TIM: The carpenter that built my deck used joist hangers to hold up the joists along the house and at the end of the deck. Are these steel joist hangers approved and will they stand the test of time? I’m worried that the joists will fall out of the hanger or pull away from the house. Is there a right and wrong way to install these framing connectors? Is there a way to build without using joist hangers? Sally P., Richmond, IN

DEAR SALLY: If the joist hangers your carpenter used are approved for use with the newer ACQ treated lumber, you should have nothing to worry about. These metal framing connectors have been around for years and they are code approved. The biggest problem I’ve seen with joist hangers of all types is using the wrong nails when installing them.

This joist hanger is made from galvanized steel and can support a significant amount of weight when installed correctly. PHOTO CREDIT:  Tim Carter

This joist hanger is made from galvanized steel and can support a significant amount of weight when installed correctly. PHOTO CREDIT: Tim Carter

All too often rookie carpenters or do-it-yourself homeowners will install joist hangers using roofing nails. That’s a recipe for disaster as roofing nails are not structural nails. They don’t have the inherent strength to support the weight of a deck or any framing member. Not only are the shafts of roofing nails too small, but the heads of roofing nails can also easily pop off when subjected to low amounts of tension.

Most of the manufacturers of high-quality joist hangers sell their own approved nails. Not only are the nails heavy duty, but they also have a special galvanized coating that’s designed to resist rust and corrosion from chemicals found in modern-day treated lumber. I would have your carpenter show you the box that the nails came in to make sure they’re approved.

I can see why you might be concerned about the joists pulling away from the house. The small metal pocket that each deck joist rests on seems insufficient. The truth be told, that’s plenty of support assuming that your deck is built correctly.

If your carpenter used high-quality decking joist hangers and the correct nails, you’ve got no problems. You should be able to see on the face of the joist hanger that’s on the actual joist several small holes. These holes are punched at an angle and are meant to accept 3-inch galvanized nails that pass through the joist into the structural band board that’s bolted to your home.

As these nails are installed on each side of the joist, they create an anchoring effect because the nails are driven at opposing angles. The key is to make sure the carpenter used 3-inch or longer nails. I would randomly remove several to make sure you have the correct length.

If you want to buy joist hangers to see all the different sizes, shapes and configurations, I would visit a traditional lumber yard. You can find them at home centers, but some of the most unusual hangers, including stainless steel joist hangers, can often be found at a full-service lumber yard. You may even find large timber joist hangers for massive pieces of lumber.

Joist hangers give carpenters all sorts of flexibility. They allow you to install floor joists in the same plane as a beam. There are ways to do this without joist hangers, but it can be more time consuming.

Perhaps one of the most traditional ways to frame without joist hangers is to have the joists rest on top of a beam. There’s nothing wrong with this method, but realize the top of the beam will be at the bottom plane of the floor joists.

You may have this situation inside your own home where you have two rooms that have a partial wall between them. At the ceiling you’ll notice a short wall that hangs down about a foot. Often this is a beam supporting the floor joists above.

Using joist hangers you could possibly tuck this beam up into the ceiling making for a much cleaner look with a continuous ceiling plane going from room to room.

Be careful about installing joist hangers and nailing both sides to the band board without the joist being in place. It’s easy to install the hanger too tight and you can’t get the joist into the hanger. There are special tools that create the correct spacing.

Installing the hangers before the joists are in place can also cause height issues if the joists and the beam are not the same heights. Believe me, there can be up to one-quarter inch in difference. Welcome to the world of rough lumber!

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One Response to Joist Hangers

  1. Why can't galvanized screws be used instead off galvanized nails for joist bracket fasteners in wood structure and still meet code?

    The shear strength of a structural galvanized screw is higher than the nail. It is also had a greater pull out strength as well as better expansion and contraction characteristic over time.

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