Truss Tuesday: Moving Load

moving load

This week’s truss: Moving Load


This truss has two plate pairs at 101% capacity with a 2000lb concentrated moving load applied to each panel and mid-panel point (i.e. at each vertical and halfway between each pair of verticals or the end of the truss). Without changing the load, how would you modify this truss to bring it under capacity?

Top Chords: Douglas Fir Larch Select Structural
Bottom Chords: Douglas Fir Larch Number 2
End Verticals: Douglas Fir Larch Number 3
Webs: Douglas Fir Larch Number 2

Building Code: IBC 2021

Loads(psf unless otherwise noted):
TC Live Load 20
TC Dead Load 10
BC Live Load 0
BC Dead Load 10
Application: Residential

Wind: 110MPH

The answer will be posted on Thursday! This is not a production truss! This is simply an example for Truss Tuesday conversation.

Passing Moving Load

Updated Thursday, February 22nd, 2024


There are many ways you could fix the issues with this truss, but stacking the webs at the failing plate pairs gives the teeth more area to bite and brings the capacities within acceptable parameters.

What is The most difficult part of any truss repair?

What is The most difficult part of any truss repair?

Roof Construction

The most difficult part of a truss repair is getting the necessary information! Here are the five things an engineer needs in order to efficiently design a metal plate connected wood truss repair:


1. The details of the original truss

Ideally, the original truss design drawings, which describe the assumptions and considerations (such as loading, material properties, etc) that went into the original truss design, would be supplied along with the request for repair. If those cannot be found, a detailed description of the truss in question along with photographs and descriptions of the truss materials will be needed to create a new truss design drawing. From there, an engineer can look at the various forces and design a sufficient repair.

2. Locations and descriptions of the damaged or overloaded portions of the truss

Not all types of damage on a truss can be repaired the same way. A connector plate that has popped off will probably require a plywood gusset repair. A cracked member could probably be handled with the addition of dimensional lumber scabs attached to the front and/or back. Also, there may be repair considerations in one location that are not present elsewhere (see Obstructions or constraints below). Knowing both the location and extent of the damage is critical for designing an appropriate repair.

3. Obstructions or constraints

Some repair designs are impractical if the truss to be repaired is confined to an area where the repair material cannot be realistically installed. For example, a gable truss with a broken web will likely require a beefier scab member attached with more connectors to a single face of the broken piece instead of scabs on both front and back that would be sufficient for other trusses.


4. Available materials/resources to perform the repair with

Knowing what materials are available at the job site will help an engineer design the repair that is most practical to apply on location. Knowing what sheathing material is on hand or if a local truss manufacturer is available can help determine if a replacement or scab truss may be the best option for an efficient repair.


5. Loading and building code requirements

Finally, if the truss being repaired is required to comply with newer loading standards or building codes than the original truss was designed for, an updated truss analysis and design drawing could be needed to understand what reinforcement (if any) is needed to bring it up to code.


Being sure to communicate all of the above information when requesting a truss repair will ensure a better outcome and turnaround time for your repair. If you need to repair a truss and don’t have a truss design drawing or if you need a truss evaluated under additional loading conditions, let Truss Pal create one for you!

Introducing Truss Pal!

Introducing Truss Pal!

Have you ever had a project that required the analysis of an existing structure with prefabricated metal plate-connected wood truss framing? Having trouble tracking down the original Truss Design Drawings? Have the Truss Designs but need to know how they would handle additional loading or modifications? Truss Pal can help!

Instead of relying on manual methods or begging a truss manufacturer to run a design for you, let us provide you with a Truss Design Drawing that matches the trusses you are working with.

Whether you are evaluating an existing structure for retrofitting additional loading like solar panels or a new HVAC unit, or you are attempting to get a sense of whether prefabricated wood trusses are a good fit for your construction project, let us help you by quickly providing detailed and accurate Truss Design Drawings.

We are familiar with the urgency that comes with Truss Repairs. We understand the concern of specifying a floor truss system that could end up being overly flexible or squeaky (but technically within code!). We’ve been involved in conversations about how to make trusses work on a job where the site-built dimensions don’t match the plans. Let us use our experience to help you with your project today.

If you have any truss issues but don’t see what you are looking for on our website, let us know by sending a question to and we will try to connect you to someone in the industry who can help.


Stay tuned as we expand our offerings in the coming months!