My truss system above my garage is used for storage. My ceiling is starting to crack and I am concerned, what can I do in order to use the space for storage again?

Q: My truss system above my garage is used for storage. My ceiling is starting to crack and I am concerned about storing things up there now. I have some numbers on a truss 020022 / 30 / common. What can I do in order to use the space for storage again? I thought about using 3 – 28′ I-joists to support beneath the nail plate supported on each end.

What is your thought on this?

 

A: I always like questions people have about getting more out of there current truss design!

The first thing I would ask is whether or not your trusses were designed to support additional storage loads in the first place. The marks that you say are written on a truss really don’t help me too much but seeing that they are for a garage, I would imagine that they are just common trusses designed to carry only minimum snow and dead loads.

Placing any kind of additional load on a truss whether it is permanent or temporary, can adversely affect the performance of the roof system. Trusses are designed with safety factors which help them to survive occasional temporary overloading due to construction loads while being installed but, any kind of additional load that is applied long term will definitely affect the truss system and cause things like cracks in the ceiling.

If a truss is originally designed with extra storage capacity, then it will perform as intended and provide years of trouble free service. All trusses are engineered components and are far more complex in their design than simple rafters. For this reason they must not be altered in any way either by cutting, drilling or adding additional loads!

Now, to answer your question about what can be done to “stiffen up” your ceiling. Possibly adding more support under the trusses could be a solution but I doubt that a 28’ I-Joist would be a good choice. Again, I-Joists are an engineered product and must be designed to carry loads. As the I-Joist would be used in conjunction with the existing trusses, only an engineer would be able to help you with that solution. Possibly the self weight of the I-Joists might add to the problem. That is a very long span for an I-Joist and its deflection would be fairly high. This is what you are trying to correct – not make worse!

I would suggest that you remove as much of the “storage load” that you have in the attic to allow things to get back to normal for a bit, then call an engineer in your area that specializes in roof trusses and have him come out and take a look at your situation. He will be able to come up with a solution that can fix your problem.

I hope this information is helpful for you and that you can continue to enjoy your storage space – crack free!

 

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