Minimum sizing roof beams for "bike shed"

[krbj]

Hello!

I'm planning to build a simple screen roof with slatted walls to store bikes under. I've searched and checked Träguiden but I'm not quite sure.

The rear beam will be attached directly to the existing garage wall, the front one on 3 posts 70x70. The width is 2400, so about 1200 between posts. Is 45x120 suitable for the beams or can I go up or down a notch?

I plan to put a regular metal roof on top. The span of the joists will be 2 meters, c/c 60. However, I need to save as much as possible on the roof height to avoid hitting my head on the outer edge. How small can I go with the joist dimensioning? 45x95? Glued 45x70? I'll add battens on top with suitable c/c spacing depending on the type of roof.

Is it possible to save on the slope? I was thinking 1:10 but if it can be reduced further, you'd save a few cm there as well. We can accept a bit of leakage during the worst rainstorms, as well as some deflection if, against all odds, we get a few dm of snow. Snow zone 2.

What do you think?

 

[nimhed]

I would easily take a chance on 45x95.

You could compensate a bit for that by reducing the cc measurement between the roof trusses.

 

[krbj]

I would easily dare to take a chance on 45x95.

You could compensate for that a bit by reducing the cc-distance between the trusses.

Thanks for the answer. Feels reassuring 👍Yes, can go down to 400 between the beams instead, so it evens out.

 

[BSOD]

Our outbuildings have 95 x 45, around a 3m span. Snow zone 1.5. I wasn't the one who designed them, I think it's a bit too flimsy. I've shoveled the roof once in 15 years, and the roof is asbestos cement, so it's apparently worked all these years.

Maybe the previous owner installed supports under the beams to the slab below, or shoveled. Or just got lucky.

If you're aware you have flimsy roof trusses, you can plan to shovel the roof.

I wouldn't go below 14 in roof pitch with metal in normal cases, but if it's just for storing bikes, I guess it wouldn't have such big consequences if it gets a little wet under the roof?

 

[krbj]

Our outbuildings have 95 x 45, around 3m span. Snow zone 1.5. I didn't dimension them, I think it's a bit too flimsy. I've shoveled the roof once in 15 years, and the roof is eternit, so it apparently has worked all these years.

Possibly, previous owners put in supports under the beams towards the slab underneath, or shoveled. Or just been lucky.

Being aware that you have flimsy rafters, you can plan to shovel the roof.

I wouldn't go below 14 in roof angle with metal in normal cases, but if it's just for storing bikes, I guess it doesn't have big consequences if it gets a little wet under the roof?

Sounds good!

Regarding the roof pitch, I'm mostly wondering if there are more risks than just some leakage now and then? Two sides will still be open, so rain and storm will blow in occasionally regardless. I've seen that there are metal sheets that should handle more low-sloped roofs (7-8°/1:8) and that seem quite easy to lay. Should work fairly well and also handle a bit more snow load if I also reduce the space between the beams as nimhed suggested.

 

[BSOD]

Some debris tends to get stuck on the roof if it has a slight slope. Moss can usually form over time. The snow doesn't slide off as easily, hence it's a bit more important to shovel off the snow if the rafters are weak and there's a lot of snow.

No major problems as I see it in this case.

 

[stugfar]

Perhaps debris can collect on the roof against the garage wall, which could cause it to deteriorate. Especially if you have a low roof pitch. It also depends on the surroundings with trees, etc.

 

[Thomas_Blekinge]

You can save a few cm by notching the beams where they rest on the support beam or out on the posts. Next to the notch, use a carriage bolt from top to bottom to bind them together.

 

[krbj]

You can save a few cm if you notch the beams where they lie on the bearing beam or out on the posts. Beside the notch, run a carriage bolt from the top down to bind together.

I'm not quite following. I don't have a current picture, but this is what the garage looks like. The idea is to attach an inner bearing beam under the eave (remove the molding that is there now) and then attach the beams with joist hangers, plus possibly support with vertical posts against the wall if needed. Then we thought to push the outer roof as far as possible under the eave and mount a fascia board behind the bottom panel board in the garage roof (the one that is removed in the picture). How do you think that would work? The garage's eave is about 25 cm.