What is pipe deflection?

Pipe deflection is the bending of pipe either under its own weight or under the weight of a load or support. Here's an explanation of the two types of pipe deflection:

Self Deflection

This is where the weight of the pipe by itself causes it to bend. Since the pipe is so heavy, it tends to bend on its own, horizontally. Lengths in these sizes should not bear the additional weight.

Load Deflection

This is the bending of horizontal pipe when external weight is applied only. This size and length of a pipe that does not bend under its own weight and is ideal for weight-bearing structures that will have persons/items placed upon it.
Load

How to use the Load Deflection Chart:

  1. Determine the size of PVC you want to use for your structure.
  2. Create your design and determine the lengths of pipe you will need.
  3. Use the chart below to see if your pipe lengths are Self Deflecting () or Load Deflecting ():
    • If your segments are self deflecting () the number listed is the total number of inches deep the center of the pipe segment will bend from fully horizontal under its own weight.
    • If your segments are load deflecting () the number listed is the maximum weight in lb. (load) before the pipe begins to bend.
Horizontal Span Length (ft.) 1/2 in. Size 3/4 in. Size 1 in. Size 1-1/4 in. Size 1-1/2 in. Size 2" Size
1' 18 lb. 28 lb. 40 lb. 50 lb. 58  lb. 70 lb.
2' 5 lb. 10 lb. 24 lb. 35 lb. 45 lb. 55 lb.
3' 3 lb. 6 lb. 11 lb. 20 lb. 30 lb. 35 lb.
4' 2 lb. 3 lb. 6 lb. 11 lb. 23 lb. 28 lb.
5' 0.25" 0.25" 5 lb. 10 lb. 16 lb. 22 lb.
6' 0.50" 0.75" 0.25" 0.25" 0.25" 12 lb.
7' 1.00" 1.00" 0.50" 0.25" 0.25" 6 lb.
8' 1.75" 1.25" 0.75" 0.25" 0.25" 2 lb.
9' 3.00" 2.00" 1.25" 0.75" 0.25" 1 lb.
10' 3.75" 2.25" 2.00" 1.25" 0.50" 0.25"

What about the load on a PVC pipe vertically?

Since the wall of a PVC pipe is stronger in the vertical position, you can multiply any horizontal load numbers by a factor of 2.8. As an example, a vertical 3-foot length of 1-1/4" PVC pipe will hold:

20 lb. x 2.8 = 56 lb. vertical load

Basic Load Guidelines

For Load Deflecting pipe, you can estimate the total horizontal load a PVC structure can bear by adding up all of the segments that will have a load applied to them to find the total weight that the horizontal element(s) of the structure will bear. This is only in situations where the load is even across the surface.

While this does not mean that the structure can only support the weight shown, it does provide a conservative estimate of the total load the horizontal structure can bear.