Installing Engineered I Joists

I joists are somewhat tender. In other words, they derive an enormous amount of their design strength from the top and bottom flanges. For this reason, you must never cut, drill or notch a top or bottom flange. The only time you can cut a flange is when you are cutting the I joist for length.

Storage and Handling

When you receive the I joist shipment, look immediately for the written APA installation guidelines. Read these and make sure the lead carpenter has a copy at the jobsite at all times.

Don't store I joists on their sides. Keep them standing upright and in their original bundles until such time as you need to use them.

Make sure the joists are not in contact with wet ground or soil. Unload them onto pallets or 4x4's well up off the ground.

Keep the I joists as dry as possible. Cover with plastic, but do not allow the plastic to make a tent that traps water vapor from the soil!

Do not handle or carry the I joists flat, This is their weakest orientation. It is very possible for you to crack one if carried in this fashion.

Absolutely NEVER use a damaged or field repaired I joist. Cut out the damaged section and use the remaining pieces for small joist locations.

Exterior Applications

You can't use I joists where they will be permanently exposed to the weather such as a cantilevered deck or where they will achieve a moisture content greater than 16 percent. In other words, don't use them near swimming pools or large hot tub areas. These environments pump massive quantities of water vapor into the air around the joists.

Bearing Points

I joists need a minimum of 1 and 3/4 inches of bearing at each end. Multiple span joists - those that stretch through a house must have an intermediate bearing point of no less than 3 and 1/2 inches.

Prevent End Joist Rollover

Where joists rest on a foundation wall and terminate, they must be blocked to prevent them from falling over. Traditional floor joists are simply nailed into the band board. You can't do this with I joists! You solve the problem by installing a special APA Rim Board or I joist blocking panels in between each joist.

Cutting Holes in the Webs

ALWAYS refer to the Hole Cutting Guide in the enclosed installation instructions!

Always attempt to center the holes that are cut into I joists. This will balance the forces within the joist.

Believe it or not, the maximum sized hole you can cut into an I joist web shall be equal to the clear distance between the top and bottom flange minus 1/4 inch. This hole must be centered so that 1/8 inch of web material remains between the hole and the top and bottom flange.

The factory pre-punched knockouts are not considered a hole. You don't have to figure these things into hole spacing calculations.

Holes must be neat and circular. Use a compass, bucket, paint can, pipe fitting or other perfectly round object as your layout guide. Cuts must be nice and neat.

Only cut as large a hole as you need. Never overcut a hole!

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