We are adding on a lean-to, 14X16, to a shop. Are 2X4's good enough rafters, placed 24"?

1 good solid plate,use collar ties, use 2x6. unless ure going to support the roof in the middle.

I would use color ties for stability. also 2x4's will work but 2x6's are much better if you get a lot of snow in the winter. Also use treated lumber. It's a little more expensive but you won't have to keep replacing rotted board. I would also make the space between the rafters 16" not 24". have fun and good luck

Here in Maine I would use at least a 2 x 6 with a 16 on center spacing for a 16 foot or less span, because we get a lot of snow. If you pick up a 14 or 16 foot 2 x 4, it is pretty wobbly. If you are set on 24oc, then my suggestion would be to go with 2 x 8's. Collar ties will help hold the addition to the existing, and provide a ceiling. I would secure them to the existing with joist hangers. Two top plates are necessary in framing to tie the corners together by over-lapping the joints....I would do this for sure.

Is it good enough? I would say go with every one here's recommendations, 2X6's on 16 inch centers with a 3/4 ply roof and a single top plate should suffice if you use lag bolts to the shop walls, and collar ties, overkill is always better.

Too bad you didn't add location detail as opposed to stating type of construction.

Certainly if it's not meant to be occupied, or hold anything of real value, or sentiment, 2 x 4's might be adequate.

I'd liklely use a double ledger at the high point, pre made ties, birds mouth cuts at the outside wall, and 3/4 ply for the roof.

Not knowing,,,again,,, the conditions in winter, you might consider 2 x 6,,,however you might also have permit and code issues?

Rev. Steven

When you need 3 X 5

If you dont intend on going up on the roof to repair it at any time sure. If you are going to need access to that roof to reshingle or repair I personally would use 2x6 instead and put in a couple of off-set lat boards to sturdy your rafters if you run them 24" on center.

Tis better to add 10% to the material cost than it is to redo everything. wet snow is the demon.