How much weight will this roof support?

[#1.]

I have a 10 x 20 garage with a flat roof.

The roof is constructed of 2x8's spaced 16 inches and covered with two layers of 5/8 plywood, then a rubber emembrane over that.

Walls are 2x4 framed, 16 inch centers.

How much weight would this support?

The real question....could I stick a Ford T Speedster up there without fear?

 

[IDASHO]

I assume the 2x8's are running the 10' direction? And not lengthwise?\

And how much does the speedster weigh? barely 2-3k?

You shouldnt have any problems, just so long as you have PLENTY of wall shear.

 

[1320stang]

Shoot, probably 1400#-1600# for a speedster.

 

[#1.]

just so long as you have PLENTY of wall shear.

What's "wall shear" and how do I know how much I have?

Yes, 2x8's run the 10 foot length, not the 20.

 

[IDASHO]

It sounds like you have the roof strength, and the wall strength. But you NEED to make sure the walls will not simply fold up lengthwise. To prevent this, you need SHEAR.

Only way to gain this is with sheeting that is rated for shear. Tying a series of studs together with a sheet of plywood or OSB gives that wall shear strength.

 

[kbs2244]

By 'shear" he means the wall folding lengthwise onto its self. Breaking at the place where the studs meet the top and bottom plates.
A sheet of 1/2 plywood nailed to the inside of each wall in each corner will give you what you need to resist that. Space your nails down the studs about 8 inchs apart.

 

[Jack Olsen]

Structural collapse aside, I'm kind of concerned about the risks involved in getting the tub up (and back down) from there -- unless you've got access to a good crane.

Is this for decoration or have you run out of work space?

 

[Torque1st]

It may support the weight but it may also damage the membrane roof.

 

[fireguy976]

Flat roofs are always such a pain,

as others have mentioned, the 2x8's at 16" centers, only 10' long will probably support a fair bit. You can get an idea of what kind of load that will support from building tables, but I would be more concerned with the roof itself. (provided the issues of shear are addressed)

Usually a flat roof has some type of membrane and then a tar mix and layer of gravel. Putting something heavy up there could damage the membrane as just mentioned, or if nothing else cause depressions where you will get standing water. This will then result in a very humid environment around the car as the water evaporates resulting in accelerated rusting.

 

[rburke65]

Yes....it will be ok.