Eek, my garage rocks in the wind.

[Zebedeewesty]

We've had some pretty strong winds gusting to 60-70mpg today and my garage rocks slightly. Maybe 2" side to side measured at the top of the 7ft walls.

Theres no roofing sheets and no doors on it yet so i'm wondering if once they are installed if it'll be a little more structurally sound.
It looks like this at the moment.


If not then i need to figure out how to stop it rocking.
The way these things are conctructed they aren't connected to the concrete slab at all just relying on the weight (3+ tons) to hold it in place.

Maybe a few steel plates attaching the floor to the walls would work?

 

[KELLHAMMER]

Roof sheathing will help but probably will not eliminate it. The horizontal connection of the walls to roof framing may need additional work. But it's tough to get the required connection to brace the long side from wind loading just by the way your building is currently constructed. Having the large opening on the one end it has little shear resistance. But that's typical of most garages. Think of a rectangular cardboard box with no top or bottom with only three sides. In your case the missing side is on the short end. If you had more wall before the door started things would be much stiffer. Lately, we are designing our garages with moment frames to combat what your describing and keep the building stiff of the soft elevation. Essentially, a upside u shaped steel frame around the garage door opening. Either in a square or rectangular steel tube. This is complex part that is welded together and may not be in your budget. But it will stiffen the walls on either side significantly. The other way is to diagonally brace the walls to the roof. But this interferes with the interior space.

 

[Zebedeewesty]

To be honest its a pretty **** design.
The steel trusses are only held to the walls by two M8 bolts on each side and the supports only extend 5" down the walls anyway.

This is how the trusses are fitted:


I wondered about adding an additional diagonal support in the same 40mm x 40mm steel angle that the trusses are made of but it'd still only be 5" down the wall like this so i'm not sure how effective it would be:

 

[rburke65]

Well I would have to think that some anchor bolts into the concrete, add the hussars as posted above and some roofing and it should make a big difference. Good luck!

 

[Bondo]

Ayuh,.... Put the diagonals from the wall to the truss, not from the truss to the truss,....

 

[jgorm]

The truss connection looks really weak. Have you tried adding a full length X brace on the back wall?

 

[Alan Douglas]

2" of play doesn't seem possible. The trusses can't be bending that much. Are the walls flexing? If they are, perhaps some vertical stiffeners at the top would help.

 

[PassnThru]

Two questions -
1. Are your walls concrete?
2. Where did you measure the deflection - the front or rear of the garage?

I'll go ahead and add - the front opening is the weakest point of your structure and I'll bet that's where you measured the deflection also. You don't currently have anything tying the front of the building together except for one truss. A header not only carries the load above it but it also helps to tie the walls together without relying on the roof structure. You have no header thus two vertical walls have virtually no side support. I'm betting that you have more deflection in the front than you have on the back wall.

 

[Notgrownup]

Cross brace it in the back at least.

 

[n8n]

that's my thought too, a diagonal upper left to lower right corner or vice versa on the interior of each wall to keep everything square and not a parallellogram... not sure how to address the door opening though. But maybe three walls of bracing would be enough.

 

[SweetD]

So you're saying the walls are not connected at all to the concrete slab floor...just sitting on it? That doesn't seem very safe?

 

[MagnumForce]

You must not be in a storm prone area. The first Midwest Thunderstorm that rolled through with a 50 mph gust and that thing would be down. Go rent a hammer drill, get some 1/2 by 3 1/2 tapcoms and anchor that puppy down.

 

[JACDes]

nice ! but in the states we call that a tool shed.

Is this a attempt at humor or just a shelter for the micro?

if those walls have sill plates they should be anchored to the slab..

3 tons is nothing... wind can move sail boats across the water that weigh much more.

 

[theoldwizard1]

that's my thought too, a diagonal upper left to lower right corner or vice versa on the interior of each wall to keep everything square and not a parallellogram... not sure how to address the door opening though. But maybe three walls of bracing would be enough.

+1 !

I don't know what you plan on doing for a door, but hopefully the hinges and latches will be mounted well enough to add the same type of bracing to the front.

 

[why worry]

OP a header over the door opening would be best to stiffen the opening up. Preferably one welded in. You can also use the post to carry your door tracks or hinges. As far as the diagonals go the lower down the wall the better and try for a 45 degree brace. By this I mean 2 feet down 2 feet out. Also as others have said anchor the walls to the slab.
Why Worry

 

[railfancwb]

Don't know how much space you have outside the walls, but it might be worthwhile to run screw anchors (such as used for guy wires on utility poles) into the ground a foot (two if possible) out from the base of each post then run guy wires with turnbuckles from the anchors to the tops of the posts.

 

[Coolabah]

We've had some pretty strong winds gusting to 60-70mpg today and my garage rocks slightly. Maybe 2" side to side measured at the top of the 7ft walls.

Theres no roofing sheets and no doors on it yet so i'm wondering if once they are installed if it'll be a little more structurally sound.
It looks like this at the moment.

If not then i need to figure out how to stop it rocking.
The way these things are conctructed they aren't connected to the concrete slab at all just relying on the weight (3+ tons) to hold it in place.

Maybe a few steel plates attaching the floor to the walls would work?

I'm building a much larger garage at the moment ( but proportionally my garage door is the same size ie not much structure at the entrance that is NOT door ) , and although I am not an engineer here is what I gleaned from what my engineer told me :

The back wall will provide strength ( you do not have a back wall yet from what I can see ???) and in my case I had to add an inverted "U" shape of steel girders at the front to provide flex resistance. The roof when properly braced will also provide support ( your incomplete roof trusses at the moment barely do anything ! )
my 2 cents....

 

[Lippyp]

You need to frame in the door opening, my old one had a flat roof rather than a pitched on (sloped from front to back) but the door opening was framed in with decent sized timber and it didn't flex at all. Mine also wasn't attached to the slab but it did have a fillet of mortar run along the bottom inside and outside. The roof sheeting will also stiffen it up enormously.

 

[Zebedeewesty]

Coolabah, the back wall (and all the other walls) are up to roof height. I just used that piccy to show how the trusses connect to the posts.
Its also got the purlins fitted tying the trusses to one another. I may add some diagonal bracing too.

Its appears only the front 2 posts around the door opening are moving. I've added some bracing and the sheeting on the two gable ends and its virtually stopped the movement. Looks like the wind is getting in and eddying around inside. With the roofing sheets attached and the doors on its should stiffen it up a bit more too.

ielengsabi, doesn't everyone in the states have acres of land attached to their properties? Sorry for the social stereotyping.
In the UK most gardens are small and space for a garage is limited.
Mines still bigger than most UK singles as i can actually fit a car in it.

Thanks for the helpful comment though.

 

[Alan Douglas]

X bracing between the first two trusses should keep the front one from moving independently.

 

[Zebedeewesty]

Thats what i'm now planning on doing. It'll also give me somewhere to attach strip light to.

 

[vintagespeed1956]

you probably might want to replace that header that runs across the top of the doorway. appears to have been cut off at the walls.

edit: and, ha first post!