Strength - 90 or 170 timber, vs blocks

[CrawfW]

Evening,

I'm planning a garden studio, and was thinking of timber-framing - until i got worried about how solid it would end up feeling.

Would 170mm carcassing, at 600mm centres, create a much stronger final building than 90mm?

I'm also worried about the sense of strength. For example, if walls made from single skin blocks are a "10" - on my invented tap-test scale - what are 90mm and 170mm timbers like?

Guessing this might not make sense, or that i might get ripped a new one for having such a strange question, but here goes....



Crawf

 

[tony1851]

You're right, it doesn't make sense

 

[Notch7]

Evening,

I'm planning a garden studio, and was thinking of timber-framing - until i got worried about how solid it would end up feeling.

Would 170mm carcassing, at 600mm centres, create a much stronger final building than 90mm?

I'm also worried about the sense of strength. For example, if walls made from single skin blocks are a "10" - on my invented tap-test scale - what are 90mm and 170mm timbers like?

Guessing this might not make sense, or that i might get ripped a new one for having such a strange question, but here goes....



Crawf

We dont know the size and its all relative.

Ive built a 5.4m x 2.7m shed in 95 x 45mm studwork and 145 x 45mm joists. 18mm osb cladding. Its quite solid, for a garden structure.

If you want a rigid garden building you want 145 x 45 walls and a nice big top plate. That would be strong enough for a house extension.

For even more solid walls clad with structural plywood. In and out if you want to really go to town. Double board with plasterboard.

 

[^woody^]

My extension, on the house let alone garden shed, is built from 90 x 38 CLS, plasterboard and timber cladding, and we haven't noticed the pictures on the wall swaying in the summer breeze, or the gin glasses rattling when the cat ambles across the roof.

 

[big-all]

ok my thoughts
carcassing timbers can be off poorer quality less uniform less strong less stable
i would aim for something like 5x2 regularized c16/24 dependent on insulation planned [assume 75-100mm] and whatever timber your timber yard does and at best price

 

[^woody^]

i would aim for something like 5x2 regularized c16/24 dependent

The c ratings for timber are for bending and relate to the strength when used horizontally as individual joists and rafters.

This does not apply to use within a panneled frame with vertical studs, where the strength of the panel comes more from the boards (which can be as thin as 11mm) and the strength of the frame comes from the way the panels are fixed together (which can be as thin as 25mm timber)

Save the trees.

 

[CrawfW]

Hi,

Seems like this divides opinion. On another forum, one chap pointed out that 89mm is all that most New Builds use, and this has suited Woody. Yet Notch7, who might be more similar to me, describes using this size for a garden building as "quite solid".

My aim is to have walls that feel like there are "carved from rock".

(For reference, my comparison is with a cob house, whose walls are over 600mm thick.)

Other points:

1. That amount of structural plywood sounds expensive - how thick would it need to be?

2. I was planning on C16 rated minimum. Is getting treated timber pointless? Assuming untreated is even available at larger sizes!

3. In terms of size, this is going to be a 30m2 internal dimensions permitted development.
​

Further thoughts welcome!

Crawf

 

[CrawfW]

The c ratings for timber are for bending and relate to the strength when used horizontally as individual joists and rafters.

This does not apply to use within a panneled frame with vertical studs, where the strength of the panel comes more from the boards (which can be as thin as 11mm) and the strength of the frame comes from the way the panels are fixed together (which can be as thin as 25mm timber)

Save the trees.

Really helpful stuff. But, i'm not quite clear. Is a "panel" a single wall, and a frame the whole set of walls connected to each other?

 

[endecotp]

My aim is to have walls that feel like there are "carved from rock".

Make it from rock then.

Or maybe bricks.

 

[CrawfW]

Make it from rock then.

Or maybe bricks.

And so, that is the bottom line. Whilst people say they are happy with timber, 89mm or otherwise, the reality is that this is simply never as strong as a brick wall.

Guess we end where we begin - i was originally going to use blocks, then thought surely timber must be fairly strong. Seems it really is only fairly!

 

[^woody^]

the reality is that this is simply never as strong as a brick wall

The reality is that it is.

What are Japanese pagodas made from? How do they perform in earthquakes compared to masonry buildings?

 

[cdbe]

SIP panels. Solid enough on their own but you could further line inside and/or outside with 18mm OSB with staggered joints, 12.5 mm plasterboard inside and clad outside with horizontal timber or cement cladding.

 

[tomfe]

What why how hurrrrrr?
What are you going to in do in your shed that it needs to feel like a bunker?
Surly the practicality of the building should out weigh how it 'feels' unless you are making some statement piece or some art...