Building a loft

[Bojans]

We are currently building a new home and I am trying to plan out my final garage layout. We will have 13' high ceilings in the garage so usage of the vertical space will greatly increase my storage. My question is with a truss built roof can I hang the outer edge of a loft from the trusses?

My plan to make one section of the garage have a 20'x4' loft about 8' off the ground. Only the back edge of the loft will be attached to the wall, the front and sides will be free floating. My thought is to build this out of 2x6 framing, 16" oc with 3/4" decking. I would support the outer edge with chain every 4 feet attached to the horizontal portion of the truss. I don't want to put supports to the floor as the garage is not very deep (24') and supports would need to be right in line with where the cars would be parked. I have no structural background so don't know if hanging the loft from the trusses is acceptable. I had thought about putting some 4x4's up there to span the trusses and spread the force out. As for what I will be putting on the loft - I don't know. I know it won't be any 4 wheelers or snowmobiles but I can only guess that the weight that will ultimately end up on the there will be more than I currently think. My biggest concern is not doing anything that will compromise the structural integrity of the structure.

Thanks
Scott

 

[kbs2244]

Tell the truss co what you plan to do and they can design the truss to take the load.
They will want to build the special ones for you. That is a good thing, because then your inspector will know they have been designed right.

 

[Hatman52]

Are you using a General Contractor for this job? If so, tell him what you're looking to do and let him come up with the best way to do it.

If you're doing it yourself, I'd look to an engineer or an architect for some help. In most areas you're going to need the stamp/signature of one of the two in order to get your plans approved and a permit issued anyway.

Trusses are designed to work as a complete unit. Hanging weight that will be concentrated in very small areas (the loft "hanger" mounting points) is not what they are designed to do, and no structural tables or software programs will be able to spec a truss for the job. Call any truss company, tell them what you're trying to do, and I guarantee they will tell you there trusses are not designed or approved for that.

Any chance you could change your design to run the loft area from one exterior wall to the other? Then you could simply tie into the exterior wall framing, doubling up or tripling up on studs as needed. Even if you attach it to one exterior wall, that would add a bunch of support and leave you with just one corner to support with a truss. At that point, if you ran two 2x4s or 2x6s up to the center point of the truss (which is it's strongest part), you'd *probably* be okay. It's still concentrating all the weight on one truss, so I wouldn't store much more than light boxes up there.

 

[sneezer41]

Take a 4x8 sheet of plywood and cut it into 4 triangles[2 4x4's, then zip diagonally]. Before sheetrock, screw and nail one of the triangles to a stud every 8 feet, the bottom being level at the 8 foot high mark. Build the 4x8[minus or plus whatever] deck for every one and screw/nail glue the deck between these braces. Plywood is very strong in tension, and if you screw the deck to the wall, the braces are only holding half the weight. I just finished a narrower version in my garage, and my boiler and water heater have been on a modified arrangement for 4 years.

 

[Bojans]

Thanks for the advise guys. Since the trusses have already been constructed I don't think I can modify them, but thinking now maybe I will do a combo of what sneezer suggested and tie the top of the loft back to the wall with chain. I wish the roof were being stick framed but this is the way the builder has speced it...

 

[kbs2244]

The chain idea scares me.
You are concentrating the load into too small an area.
If you go with hanging chain supports, wrap them around an at least a 2 inch or better pipe spanning 3 or 4 trusses to spread the stress around.

 

[Chris J]

Unless called out otherwise, the bottom cord dead load is usually designed at 10 pounds/sq. ft. This is sufficient to hang sheet rock and lay insulation. It is NOT sufficient to carry storage loads of any size, let alone any live load. Do not do it!

If you can pull the load back to the wall, you can probably come up with something that will work. But DO NOT load the truss! (And if you do, do not let your insurance company ever find out or they will deny your roof collapse claim.)

 

[6768rogues]

Chris is right. The bottom chord of a truss is not made for more than 10 lbs./square foot of loading, dead and live loads combined unless you specified otherwise. A concentrated load is bad. An engineer can design a modification to the truss to carry your intended load. It is likely that your chain idea will pull the bottom chord off, or split it in two. The bottom chord is there for a horizontal tension load, keeping the walls from spreading. It is not meant for a moment load, as a beam.

 

[Matti]

At this point in time you are probably better off to add horizontal trusses/beams (like for a floor) and integrate them into the walls. I imagine you will need vertical supports added into the wall framing for the trusses to sit on.

 

[Bojans]

glad I checked here. So bottom line is no weight hanging from the trusses.

Thanks guys