Catalog

One of the benefits of using RFPI-Joists in residential floor and roof construction is that holes may be cut in the joist webs to accommodate electrical wiring, plumbing lines and other mechanical systems, therefore minimizing the depth of the floor system.

Rules For Cutting Holes In RFPI-Joists

1. See chart on page 125 for allowable hole sizes and locations the distance between the inside edge of the support and the centerline of any hole shall not be less than that shown in the chart on page 125. 2. Except for cutting to length, NEVER cut, drill or notch I-joist flanges. 3. Whenever possible center holes vertically in the middle of the web. However, holes may be located vertically anywhere in the web provided a minimum of 1/8” of web remains between the edge of the hole and the flanges. 4. The maximum size hole that can be cut into an I-joist web shall equal the clear distance between the flanges of the I-joist minus 1/4”. a minimum of 1/8” should always be maintained between the top or bottom of the hole and the adjacent I-joist flange. 5. The sides of square holes or longest side of rectangular holes should not exceed three fourths of the diameter of the maximum round hole permitted at that location. DO NOT over cut the sides of square or rectangular holes. 6. Where more than one hole is necessary, the distance between adjacent hole edges must be a minimum of twice the diameter of the largest round hole or twice the size of the largest square hole (or twice the length of the longest side of the longest rectangular hole) and each hole must be sized and located in compliance with the requirements of the chart on page 125.

7. Knockouts are prescored holes for the contractor’s convnience to install electrical or small plumbing lines. they are 1-1/2” in diameter, and are spaced approximately 16” on center along the length of the I-joist. where possible, it is preferable to use knockouts instead of field cutting holes. For floor applications, positioning the I-joists so the knockouts are all on the bottom of the joist, may ease the installation of electrical wiring or resi dential sprinkler systems. Do not hammer holes in web, except at knock outs. 8. A knockout is not considered a hole and may be utilized anywhere it occurs. it can be ignored for purposes of calculaing minimum distances between holes. 9. 1½” holes shall be permitted anywhere in a cantilevered section of an RFPI-Joist. Holes of greater size may be permitted subject to verification. 10. A 1½” hole can be placed anywhere in the web provided that it meets the requirements of rule 6 on this page. 11. A group of round holes at approximately the same location shall be permitted if they meet the requirements for a single round hole circumscribed around them. (see diagram on page 125) 12. All holes shall be cut in a workman-like manner in accordance with the restrictions listed herein.

NEVER drill, cut or notch the flange, or over-cut the web. Holes in webs should be cut with a sharp saw. For rectangular holes, avoid over-cutting the corners, as this can cause unnecessary stress concentrations. slightly rounding the corners is recommended. start the rectangular hole by drilling a 1”-diameter hole in each of the four corners and then make the cuts between the holes to minimize damage to the I-joist.

How to Use Hole Chart on Page 161

1. Read across the top of Hole Chart to the desired hole size. 2. Follow this column down to the row that represents the I-joist depth and designation. This number indicates the minimum distance from the face of the support to the centerline of the hole.

Example: Need a 5½-inch hole in an 117 RFPI -400 joist: From Hole Chart, For a 5-inch round hole, the minimum distance is 3’– 4”. For a 6-inch round hole, the minimum distance is 4’– 8”. therefore the minimum distance for the 5½-inch round hole is 4’– 0” (halfway between 3’-4” and 4’-8”).

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March 2022