Sizing

[zingo]

I know there is a lot written about how to dimension roof trusses, beams, and joists when building small houses and decks.

I want to construct a "building," read "barn," which I can't see falling under either small house or deck. It will not be insulated and will only have a tongue-and-groove roof with shingles or at most roof sheets.

And then I wonder if you really need to dimension in the same way as when building small houses.
For example, could it suffice with wall studs of 45 x 95, beams of 45 x 145, and roof trusses of 45 x 170?

I live in South Sweden where snow load is negligible.

 

[Oldboy]

Dimensions of the house? (span, etc.)
Roof design? (flat, gable, or low-slope)
Foundation? (wall, post or slab)

I wouldn't call snow weight negligible even in the southernmost part of Skåne. It doesn't fall very often, but when it does, it can come a lot, with drifts of 50-200cm where there is some shelter.

A barn can mean a variety of things in how it is used and the possible loads it may encounter. If it is supposed to be a simple unheated building, it will be exposed to wood-boring insects. If you want to build a robust building that will last >100 years, you should consider moisture and wood-borers that can weaken the structure, as well as the wind in frequent storms. In that case, the older style of more square timber with a lot of heartwood is considerably more suitable.

 

[zingo]

Dimensions of the house? (span etc.) Roof design? (flat, gable or low slope) Foundation? (wall, pillar or slab)

I wouldn't call the snow load negligible even in the southernmost part of Skåne. It might not fall very often, but when it does, it can come a lot, and with drifts of 50-200cm where it's a bit sheltered.

A barn can mean both one thing and another in terms of how it is used and thus what potential loads may occur. If it is then to be just a simple unheated building, it will be exposed to wood borers. If you want to build a robust building that will stand for >100 years, you should account for moisture and wood borers that weaken the structure, as well as the wind in frequent storms. Then the more square timber from the old days with lots of heartwood is considerably more purposeful.

Thank you. There's certainly a lot I haven't thought about. Especially not the wood borers.

Dimensions: 9.6 x 6.6 m Gable roof with approximately a 27-degree slope. The foundation should not be a slab. Preferably pillars but possibly will be a wall. Snow zone: 2.0

 

[Oldboy]

Dimensions: 9.6 x 6.6 m

I assume 9.6 is the length and 6.6 is the width?

Are you planning to have posts or load-bearing walls inside, or should it be a single large space?

Free-spanning truss rafters have no problem with the span.

Wall studs at 45 x 95, (with lateral bracing such as noggings), support beams at 45 x 145, (do you mean standing on edge as reinforcement for the wall plate?), and rafters at 45 x 170, (do you mean this as the dimension of the truss rafter's upright?) sounds a bit more reasonable.
However, I'm not a structural engineer, so I can't say for sure what is structurally sound and/or meets building regulations.

Lateral bracing against wind loads is essential. Like diagonal braces. A typical example is the timber frame of half-timbered houses with angled braces in the corners. Needed in the roof as well.

Will there be openings in the walls wider than about 120 cm?
(Especially on the long sides where the rafters load at 120 cm centers.)
Depending on the width, 145x45 may not be sufficient.

 

[TorpAnders]

Not much to save on, stick to standard measures for a trouble-free build.
Here is what you need to know to avoid guessing.
https://www.traguiden.se/konstrukti...akstol-taklutning-12-27/?previousState=010100

 

[zingo]

Not much to save on, stick to standard measurements for a trouble-free build. Here is what you need to know to avoid guessing. [link]

Thanks. I've studied that page and understand how the roof trusses should be dimensioned.

What I'm most wondering about is how the standing wall studs should be dimensioned. The suggestion is 45 x 145. Length: 9.6 and width 6.6. One large space. No opening larger than 120, but there is one.

 

[TorpAnders]

Thank you. I have studied that page and understand how the trusses should be dimensioned.

What I am mostly wondering about is how the vertical wall studs should be dimensioned. The suggestion is therefore 45 x 145. Length: 9.6 and width 6.6. A single large space. No opening bigger than 120, though there is one.

You haven't mentioned how the walls will be constructed, paneling, rough boarding, other. That is, how will the studs be stabilized in all directions? A 45 mm stud is very weak in "lateral" if not stabilized by the rest of the construction.

Anyway, here comes my 5 cents...

Your roof in zone 2 can be subjected to about 12 tons in snow load or 120 kN.

If you have 38 evenly distributed wall studs, maybe you could say 3 kN/stud? Then there's the roof's own weight and "common sense" margins... I would probably guess that at least 6 kN/stud is reasonable to start with.

So about 600 kg per pillar/stud 45x120 can theoretically support 3.2 tons if the stud is stabilized correctly by other materials in the walls. But only modern 45 mm lumber can quickly make it a short-lived story.

If you use double 45 x 95 C 24 lumber and glue-screw the posts (95x95) it should work. Of course, classic four-squares 145x145 with a core are to be preferred, at least in the corners and a few per wall.

Note I am not a structural designer or calculation engineer so take it for what it is.

 

[fribygg]

If you use double 45 x 95 C 24 timber and glue-screw the posts (95x95), it should work.
Of course, classic four-sided posts 145x145 with a core are preferable, at least in the corners and a couple per wall.

What strange dimensions you suggest @torparanders. If I cut a four-sided post, it gets the traditional size of 6"x6" and if you buy it at Beijer, it's 150x150mm. If I glue-screw a couple of 45x95 to a post, it becomes 90X95.

To TS: 45x95 as a wall stud is probably sufficient if you have panel material on the frame or install diagonal braces of wood or perforated tape.

 

[zingo]

You haven't mentioned how the walls will be constructed, paneling, tongue and groove boards, or other. In other words, how will the studs be stabilized in all directions?

Vertical paneling on the outside, with cover strips
Inside: nothing, except diagonal studs for stability

 

[TorpAnders]

What strange measurements you suggest @torparanders. If I cut a fyrskäring, it gets the traditional measurement of 6"x6", and if you buy it at Beijer, it's 150x150mm. If I glue screw a couple of 45x95 to a post, it becomes 90x95.

To A, I answer that when I cut it, it becomes 145x145 if the remaining planks are to be 45x145, which TS might have wanted
To B, I answer typo

 

[zingo]

You haven't mentioned how the walls will be constructed: cladding, rough boards, other. In other words, how will the studs be stabilized in all directions? A 45 mm stud is very weak "sideways" if it is not stabilized in the rest of the construction.

Vertical paneling on the outside, with cover strips
Inside: nothing, except diagonal studs for stability