Thickness of roof timbers to support weight

A shed will have roofing felt applied, so it will need to support the weight of one human to do that. The roof planks are 1.6 metres long, how thick should the be to support (let's say) 90kg of human?

Reply to
Peter Percival
Loading thread data ...

3x2 should be plenty... (depends a bit on how far you have them spaced)
Reply to
John Rumm

Peter Percival scribbled...

You can support the roof when you're working on it with an acro or some lengths of 3x2 wedged with boards under the roof timbers. No point in over building a shed when you're not going up there again.

Reply to
Artic

Until you have to refelt it. But it doesn't take much to support somebody. Of course if you make the roof stronger for that it also makes it stronger for hanging things from :-)

Reply to
Clive George

Wind and snow loadings are the main factor.

Reply to
harryagain

The pitch of the roof will also affect its load bearing capacity. If you are worried it may be too light then increase the purlins in thickness or number and put diagonal bracing in the end bays.

Reply to
fred

I would think if that is the only issue you could get away with a single

2x1.

Of course it isn't the only issue...

Reply to
The Natural Philosopher

Clive George scribbled...

I dread to think what you get up to in your shed.

Reply to
Artic

harryagain scribbled...

Did I miss the part about building this shed in the Artic ?

Reply to
Artic

You obviously missed last Winter here, then.

Reply to
John Williamson

On Thursday 25 July 2013 09:34 The Natural Philosopher wrote in uk.d-i-y:

Indeed. Oversizing the timbers will make screwing a lot easier (remember, crappy flat pack sheds are nailed and stapled together).

A self drilling screw will have no trouble holding and not splitting 2x2,

2x3 or 2x4. 1x2 however would be nightmare to work with IME.
Reply to
Tim Watts

Designing a structure, any structure, to resist wind loading is very import ant even in this country. ISTR snow loading has to be able to account for the dreaded 150 year loading. (i.e.) The worst possible case. I've seen ent ire commercially built chicken sheds take off in high wind and they weren't particularly exposed. Some years back a local bus company while building a bus garage had a wall blown down on them before they could brace it proper ly.

Reply to
fred

obvious seasonal error corrected

Reply to
The Other Mike

that sounds like poor design as the walls should be self supporting, how else will they stay up with the roof adding more loads.

Reply to
dennis

Yes it was bad design or bad building practice. The walls were very tall.

Reply to
fred

Not sure what you mean by roof planks, if you mean the horizontal running planks, length is unimportant, its section & span of rafter underneath is key. Assume you are buying C16 grade timber ...

at 400 c/s a 38x97 will be good for up to 1.92m span that assumes you are having a flat roof (slight slope)

or if you want to do 600 c/s a 44x97 will be good for 1.79m

If it's a pitched roof between 10 and 22 degrees at 400c/s a 38 x97 is good for 2.11m (44 x 100 gives you 2.36m)

or if you want to do 600 c/s a 38x97 will be good 1.94m

Reply to
Rick Hughes

5 degrees maybe.

Reply to
Peter Percival

The roof slopes by about 5 degrees. The distance between the walls is

1.6 metres. The planks will be laid across the walls, with no other support. I have some planks that are 47 mm thick, so I'm wondering if I can use them and buy more of the same thickness. The planks go across the slope not down it.

Excuse my ignorance, but c/s means nothing to me.

Reply to
Peter Percival

Did you mean to call yourself after cold northern climes, or was that a typo?

Andy

Reply to
Vir Campestris

Guess c/s means centre spacing (i.e. distance apart). Shed I built has a roof span of ~3m, pitch 10-20 degrees and I used 2x3s C16s prob about

45-60cm apart. Took my weight when roofing without any issues (I was always supported by boards across multiple rafters though.)

I'm guessing you're proposing completely boarding the roof with the planks. At 2" thick and ~5' span I'd guess you should be just fine assuming you fix the planks down before getting on them. And assuming they aren't rotten!

(The flat-pack shed I bought had an incredibly flimsy roof, and took my very large mate's weight when felting. I wasn't prepared to get up there given how flimsy it was!)

Reply to
Piers

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.