Would Installing Additional Bracing Between Rafters and Rafter Ties Increase Load or Negatively Impact the Structure?

[mountainmaverick90]

My garage was built in the 70s.
Rafter ties are 24" on center, currently there is no sagging.

I'd like to place some items up for long term storage (empty coolers, backpacking/camping gear, water ski, etc.,). In total it's probably about 200 lbs max worth of items spread out closer to the walls and spanning much of the (perpendicular) length of the rafter ties.

I'm wondering if the additional beams (in red) might help keep things stiff (and ties from sagging down), even if installed on every other rafter or 48". I've seen a similar design in several garages around my area, some where the rafters are only 2x4.

Forgive my paint design

 

[MadScientist3019]

What's the span of the rafter tie (ceiling joists)? I can't imagine that putting what little you're talking about will affect it at all if you put a few boards up to go over the top spreading the load to a few of the joists. I mean it'll probably be fine with you walking up there on the joists and the amount you quoted, about 200 lbs, isn't much.

 

[dcg9381]

The piece of missing data is the ceiling joist span, but span tables (assuming the span is within length) have 2x6 at 24" OC being within spec for an attic space with storage load. I doubt that 200 lbs spread out is going to bother it much. How much load depends on the span and grade of lumber.. Older lumber is probably better in this case.

Tie it in like that and you're transferring load to the roof, which again, may be OK... Worried about it, I'd just put anything "heavy" as close to a wall as possible. I wouldn't tie it in over 200 lbs.

You are sorta building your own "truss" here. Usually when I see tie-ins like this in modern construction, it's to support the roof, not the other way around.

 

[MadScientist3019]

The piece of missing data is the ceiling joist span, but span tables (assuming the span is within length) have 2x6 at 24" OC being within spec for an attic space with storage load. I doubt that 200 lbs spread out is going to bother it much. How much load depends on the span and grade of lumber.. Older lumber is probably better in this case.

Tie it in like that and you're transferring load to the roof, which again, may be OK... Worried about it, I'd just put anything "heavy" as close to a wall as possible. I wouldn't tie it in over 200 lbs.

You are sorta building your own "truss" here. Usually when I see tie-ins like this in modern construction, it's to support the roof, not the other way around.

Be careful as it's only a truss if you run the additions between the top chord and bottom cord such that when in compression it is pressing on the wood grain and not relying on fastener shear strength. Again this is a non-issue in my opinion (mathematician and aerospace engineer that's engineered trusses for myself in the past) but it does depend on the span of the bottom chord or ceiling joists. If it's 40 ft your spanning it's not gonna work very well but if it's I'd say 15 ft or less you're just fine doing nothing.

 

[mountainmaverick90]

What's the span of the rafter tie (ceiling joists)? I can't imagine that putting what little you're talking about will affect it at all if you put a few boards up to go over the top spreading the load to a few of the joists. I mean it'll probably be fine with you walking up there on the joists and the amount you quoted, about 200 lbs, isn't much.

Not home at the moment but it's a 2-car garage so I believe it to be approximately 18'.

 

[dcg9381]

Not home at the moment but it's a 2-car garage so I believe it to be approximately 18'.

Now I'm a little worried...

 

[firebirdparts]

Those would indeed make the ceiling joists hold more, at the expense of the rafters hold less. If you live where it doesn't snow I think you're good.

 

[mountainmaverick90]

Now I'm a little worried...

Right, I've read through span calculators and that's why I'm asking about the additional pieces to install. Up until the mid 2000s there were but (3) 2x4 rafter ties spanning these with some thin plywood being used for storage (don't ask me how/why it was like that). I've since replaced with 2x6s. I know it's not optimal it would've been impossible to add any thicker 2x's... I've seen a lot worse. Just looking for whether it's better to leave it for now or add the extra noted lumber.

Those would indeed make the ceiling joists hold more, at the expense of the rafters hold less. If you live where it doesn't snow I think you're good.

Coastal northern California - no snow ever...

 

[billconner]

The once customary solution to support rater ties was a vertical 2x4 or 1x6 from rafter tight to ridge board to rafter tie.

 

[mountainmaverick90]

Here's what it looks like now

 

[Innovate1]

If you are worried about it I would run a vertical 2 x 4 from the ridge to the center of the rafter ties. Overlap the existing rafter/ties or use a plywood gusset.

I think you are fine with what you describe putting there but often people keep adding a bit at a time and loose track of how much.

 

[CraigStu]

I am in the don't worry about it camp. Put your stuff as close to the walls as possible. Think if you and 3 friends at say 180# each went up there and laid down on the rafter ties out near the walls. Two of you head to toe on each side. Would you expect a problem? That is 720# total but spread out over maybe 6 rafter ties. You could make it even more spread out by starting your stash on each side at opposite ends of the garage. Now you might be spreading the weight over even more rafter ties and only on one end of each. If you want to hedge your bet, I'd use 1x4s for your additional supports glued and screwed in place.

 

[Bert_]

This doesn't really add anything meaningful. You need to get the weight transfered to the ridge.

A 2x4 from the ridge down to the rafter ties would be much more effective. It would make it into a king post truss.