Garage Loft design

[RyanDan]

I was looking to get some opinions for the loft i built a few winters ago. Basicly concerned about the added weight of the structure and and maybe if making some modifications or slight additions would be helpful. Let me know what you think.

The garage is Reverse gable with 10 foot wall studs and a 7/12 roof i believe. It was built with traditional rafters with 2x6's at 16" on center. 2x6" Rafter ties were used at 48" on center. The rafter ties span the 22' exterior wall length with about a 21 feet unsupported. They do rest on the top plat.

On 1/2 of the garage i added 2x6 rafter ties sitting on the top plate to every rafter. Giving me 2x6 rafter ties at 16" on center spanning 21 feet. Each rafter has a strut down to the rafter tie at 8' from the wall. I did one hanger from the center at the top of a rafter and was going to do more but i am unsure if its a bad idea structurally. I sheeted the top lightly to reduce load. I've installed insulation and will be using iso foam panels for the ceiling to avoid the weight of dryway. While walking in the loft it does feel rock solid. Nothing moves or bends when you step. I am just worried the struts are going to cause the roof to sag over time. Maybe i should double up some rafters? Thoughts?

Thanks

 

[RyanDan]

Thanks for looking.

 

[firebirdparts]

What are you planning to do up there? a 21 foot 2 by 6 wouldn't carry much, but the ties you have will help. The insulation worries me a little. Are you building an office up there?

 

[RyanDan]

Insulation is the loft floor (garage ceiling). Just trying to keep the propane usage down. The loft is storage only. Mostly kids toys, bikes, ect. Seasonal stuff.

 

[firebirdparts]

That's a pretty difficult structure to assess, really. It would not bother me at all to put my Christmas decorations up there, but I don't have any idea just what it would really hold as designed. If it doesn't deflect much with you up there, then that's a good start.

 

[RyanDan]

I appreciate you taking a look.

 

[matt_i]

A 2x6 bottom chord @ 48" oc is not a very big timber. So it probably needs the support of the rafters.

Just comparing to my attic truss which is a 2x10 @ 24" oc, over 26 feet of span.

So, depending on what you store, its going to transfer additional loads to the rafters. Which they can handle some...but how much is a question that's tough to answer.

It is challenging to sister rafters due to the roofing nails that inevitably poke down from above (thinking classic shingled roof) and you Do Not want to pound them back upwards to gain clearance. But you could use a smaller timber, eg if you had a 2x6 top chord/rafter, use a 2x4 sistered, and pickup strength in the assembly by using construction adhesive to promote load transfer. But the construction adhesive may not cure in such low temps as we have right now.

 

[RyanDan]

Thanks. The Garage was 48" on center with the ties but i added a bunch and made them 16" OC. I appreciate you taking a look.

 

[Natty Bumppo]

I think for kids' bikes, seasonal bins, and stuff like that you're more than fine with what you have. If you start storing spare engine blocks that might be a different story.

 

[RyanDan]

My spare engine block days might be behind me. Engine Blocks were replaced by radio flyer wagons and little tikes play equipment.

 

[Innovate1]

That's pretty light joist for the span. Best simple improvement would be to tie the middle of the span to the peak of the roof like you did in one spot. It's easy to pile up more stuff than you realize over time.