Confused about loft area/loading span

[Redbandit98]

Hello all, first time post. I recently bought a house that has a detached "loft" style barn garage. The middle section had decking down and it actually has a door up top to the outside. I removed the decking because it was crumbling..they used MDF in the Arkansas humidity in a non conditioned space. My plan was to replace it with plywood. The problem I have (or I think I have) is the span. According to what I've looked at, the joists don't even seem to be sufficient for the plywood only.

It has 2x6 joists on 24" centers, spanning 20ft. (I didn't know you could get a 20' 2x6). I'm pretty sure the decking was installed by the builders as the notches for the ends where they but against the gable end studs were absolutely perfect on each cut. I think the garage may have been one of those build on site kits. Anyways am I wrong on the span? Seems they wouldn't put a door and decking if you couldn't at least store light items up there. I was gonna sister some additional 2x6s but I don't know if it's worth the time. Some pics for reference.
For the record I just want to store ice chest, luggage etc..nothing heavy

 

[My Old Tools]

span tables say a 2x6 doug fir on 24" centers is good for a 9 foot span with standard L/360 deflection. I wouldn't put much up there.

 

[readhead]

They appear to be attic trusses. But even the center span with a 2x6 seems a little light. How long is the center span?

 

[Redbandit98]

They appear to be attic trusses. But even the center span with a 2x6 seems a little light. How long is the center span?

I'm sorry but I don't know exactly what you are asking. The joists span 20 feet across. There is no center support and the boards are not spliced, they are 20ft long. Is the "center span" a measurement of a section of the truss?

 

[Redbandit98]

More pics

 

[readhead]

You have no joists. You have trusses. The trusses are built to create an attic space. The bottom cord is supported by the vertical members dividing it into approximate thirds. The center span is the center third. How long is it? As MOT mentioned 9' is the maximum span for a DF 2x6 but we don't know what the species is. Where are you located?

 

[Redbandit98]

You have no joists. You have trusses. The trusses are built to create an attic space. The bottom cord is supported by the vertical members dividing it into approximate thirds. The center span is the center third. How long is it? As MOT mentioned 9' is the maximum span for a DF 2x6 but we don't know what the species is. Where are you located?

Ahh got you. Thank you for the clarification. That measurement is 10ft. Unfortunately, there are no markings on the 2x6 to indicate what species of wood it is. I am in the middle of Arkansas..

 

[theoldwizard1]

Hello all, first time post. I recently bought a house that has a detached "loft" style barn garage.

It appears that you have a gambrel roof similar to the roof on this shed.

These are great for storage !

A "truss" is just a way of building a roof structure that distribute the load in such a way as to allow use of lighter building material (hence the 2x6 for the joist. Technically it is not a "joist". It is the "bottom chord" of the truss.

In that picture, you can see that the bottom chord is made up of 2 pieces of wood with a "splice" plate near the middle.


Now on to your question, which is basically how much load will this carry.

Trusses are typically designed to ONLY carry the weight of the roof and shingles. No floor and no ceiling. A GAMBREL ATTIC truss

IS DESIGNED to carry the load of a floor and some amount of live load. The only way you will know for sure what capacity you have is to find the original engineering drawings which should be on file at you city/county building department.

(I will says, that most attic truss garages that I have seen that are designed for storage, have the trusses 16" O.C. 24" O.C. would not carry much of a load and part of that load will be the floor.)

 

[theoldwizard1]

...there are no markings on the 2x6 to indicate what species of wood it is. I am in the middle of Arkansas..

Likely Southern Yellow Pine, not Douglass Fir (common in the NW).

The open span in the center means very little. You need the see what the drawing say. If you are only using it for storage, you can get away with 1/2" plywood for flooring IF you brace it underneath (between the bottom chords) ever 24".