Building a deck or a house that does not have a concrete slab will require the use of metal joist hangers to attach the floor joists to a girder joist. Metal joist hangers are commonly constructed with galvanised sheet metal and are have pre-stamped mounting holes located to provide maximum support for the installed floor joist. It is important to use the fastener specified by the metal joist hanger when attaching it to the framing of your home. Using the wrong fastener can lead to the metal joist hanger failing, which can lead to injury to you or others.
Measure the width of the metal joist hanger with the tape measure. Make sure you measure the width at the bottom of the metal joist hanger, where the two vertical legs of the joist hanger meet the bottom connector of the hanger.
Place a mark on the girder joist 1/2 the width dimension of the metal joist hanger on either side of the centerline of a floor joist with the carpenter's pencil. For example, if the metal joist hanger is 1 1/2-inches wide, place a mark 3/4 of an inch on either side of the joist centerline.
Extend each mark by placing the bottom of the carpenter's square on the bottom of the girder joist and aligning one leg of the carpenter's square with one of the one-half dimension mark you placed on the girder joist and dragging the carpenter's pencil along the aligned leg of the carpenter's square. Then switch and repeat this step on the other one-half dimension mark located on the opposite side of the joist centerline.
Put on your safety glasses.
Align one side of the metal joist hanger with the line you marked with the carpenter's square and align the bottom of the metal joist hanger with the bottom of the girder joist.
Place one 8d nail into one of the metal joist hanger's pre-stamped mounting holes located on the aligned side of the metal joist hanger with the hammer. If the metal joist hanger calls for a fastener other than an 8d nail, use the specified by the metal joist hanger manufacturer.
Align the other side of the metal joist hanger with the other line you marked on the girder joist and make sure the bottom of the joist hanger is aligned with the bottom of the girder joist before you place a fastener on the other side of the metal joist hanger.
Place one 8d nail or approved fastener into each pre-stamped hole of the metal joist hanger to complete the installation of the hanger. Repeat the process for each floor joist you need to connect to the girder joist.
Slide the joist in the secured metal joist hanger. Make sure that the joist rests firmly on the bottom of the metal joist hanger.
Place one 8d nail or approved fastener into each stamped hole in the metal joist hanger resting against the side of the wood joist. Repeat the procedure to secure each floor joist to each installed metal joist hanger.