Duct Web Opening Charts

The versatility of the TrimJoist® is unmatched by any other pre-engineered wood joist product. The open-web nature of the TrimJoist® is ideal for plumbing, electrical, and A/C duct work. Need to get a perfect slope on a drain line? TrimJoist® is the Right Choice.

Trimjoist Duct Web Opening Chart

Notes on Opening Sizes:

  1. All opening sizes given are in inches and denote maximum expected clearance.
  2. Rectangular opening R1 is provided at centerline of stock length (except 4-foot length).
  3. Only a single opening D available in 4-foot stock length.
  4. Only opening R1 available in 6-foot and 8-foot stock length.
  5. Openings R2 and D not applicable in shaded areas (S) adjacent to rectangular opening.
  6. The shaded openings (s) are available for smaller pass-throughs such as electrical, plumbing, vacuum, etc.
  7. PVC materials should not be allowed to freely rub against the wood structure of the joist. PVC is notorious for squeaks and should either be held well away from joist contact or secured to the joist with appropriate fasteners and padding such as felt (see below).
Trimjoist Opening Sizes Details.png

Uniform Loading Charts

Although Uniform Load Span Charts are available on all engineered joist products, they actually contain very little beyond comparative data. For example, the charts below tell you how our products perform at their maximum spans for a given depth and spacing. However, the charts say nothing for how they perform under more typical loading and support conditions. Only a computer analysis can provide more exact performance data for a given condition. This is true of all engineered joist products on the market.

We also provide a description of floor loading terminology. For unusual loading and/or support conditions, consult our engineering department.

J12 (11-7/8″) Uniform Load Span Chart: 

Trimjoist J12 Uniform Load Span Chart

J14 Uniform Load Span Chart: 

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J16 Uniform Load Span Chart: 

Trimjoist J16 Uniform Load Span Chart

J18 Uniform Load Span Chart: 

Trimjoist J18 Uniform Load Span Chart

Important Notes on Span Tables:

  1. Spans are based on uniformly loaded joists and include allowances for repetitive use members.
  2. Live loads of 40 psf assumed. Additional dead loads are due to various combinations of construction materials.
  3. All TrimJoist® products are cambered to compensate for dead load deflections. Do not install them upside down.
  4. Deflections shown assume a 3/4-inch-rated subfloor that has been both glued and nailed.
  5. Total deflections are limited to less than L/240 as required by code.
  6. Indicated spans are full member length, including a minimum bearing width of 1.75 inches on each end.
  7. TrimJoist® products are designed for clear span applications only. Do not apply center supports, cantilevers, or concentrated loads without first consulting a TrimJoist® representative for a free computer analysis.

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