How to run pipe through a tji joist

Updated February 21, 2017

The TJI, or wooden "I" joist, has been used in construction since the 1970s. It is composed of an Oriented Strand Board centre with two 2-by-3 sections of lumber fastened to the top and bottom. This combination makes a strong floor joist that has a long span. They also resist warping, twisting and shrinking that is common with conventional floor joists. When building a house it is necessary to cut holes in the joists to run plumbing and gas pipes. There are special rules for making these penetrations in TJI Joists.

Determine the starting and ending point of your pipe run by looking at the building plans. Choose the most efficient route between the two points, keeping in mind the allowable hole locations by the TJI joist manufacture. Consult the Resources section below for information regarding acceptable hole locations for your size of joist.

Chalk a straight line along the bottom of the joists on the path you would like to take. Measure up from the bottom of the joist the distance to the centre of the hole and mark with a pencil. Repeat this process to mark the centre of each hole.

Position the saw on the centre of the marked hole. Drill the hole through the joist, keeping the drill as level as possible. Repeat this process to drill a hole in each joist.

Slide the pipe through the holes to make your run.

Things You'll Need

  • Chalk line
  • Measuring tape
  • Hole saw
  • Drill
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About the Author

Bob White began his writing career in 2006. Working in sales, he was a technical writer tasked with responding to requests for proposal. White has a Bachelor of Arts in computer science and a diploma in home inspection. He has also worked in construction, landscaping and the pool industry for more than 15 years.