Measure Deflection In Floor

Measure the static and unloaded position of the floor with a taught wire stretched from end to end of the joist on top of the subfloor.

Measure deflection in floor. Get a ruler and measure the deflection at the center or lowest point typically building codes specify a l 360 deflection limit. For example for a 30 foot span l deflection of up to 1 5 inches in a single floor member would be permissible. I use a dial indicator with a 1 inch travel for measuring deflection accurately. Load the floor with a known load at mid span or uniformly along the joist.

The 2012 international building code ibc section 1604 3 requires floor members supporting dead and live loads to not exceed an l 240 deflection limit. Step 3 determining the deflection limit. For example the maximum deflection for a joist span of 15 is 15 12 360 1 2. Between joists between joist supports wherever.

After you have picked out the species of wood that you ll be using come up with the joist span length measurement by getting the distance between the supports. Relatively longer spans and higher loads have the potential to make differential deflection problems in floors more pronounced. Ft plus any long term deflection due to the weight of the floor. Measure the deflection using your measuring tape.

Floor deflection test molly the deflection has to be measured along any span within the area of the floor. Divide the total span of the floor joists in inches by 360 to determine the maximum amount the floor can give in the middle under a live load of 40 lb sq. This means that the maximum sag in the center of a joist is 1 360th of the length of the joist.