Use of ply in stud wall

[tony1851]

Table 3 is wall thickenesses isn't it?

Anyway no internal wall in any traditionally designed house or low rise building is doing any buttressing .... or needed to do any buttressing. Stabilty comes from the floor/ceiling/roof. That's how it works.

Not so; masonry construction is good in compression but weak in tension. As long, laterally-unsupported walls have a tendency to buckle under loads such as wind load (and buckling induces tension) it is necessary that the laterally-unsupported length is restricted.
The floor, ceilings and roof provide lateral restraint only insofar as they are adequately fixed to the surrounding walls.
Internal buttressing walls are necessary in long lengths of wall; AD A refers to internal buttressing walls at 2C25 and 2C26. Such walls are an essential component in traditional masonry construction.
Structural Masonry Designers' Manual by Curtin, and Structural Masonry by Hendry, amongst many others, make this important point about internal buttressing walls.

 

[^woody^]

Not so; masonry construction is good in compression but weak in tension. As long, laterally-unsupported walls have a tendency to buckle under loads such as wind load (and buckling induces tension) it is necessary that the laterally-unsupported length is restricted.
The floor, ceilings and roof provide lateral restraint only insofar as they are adequately fixed to the surrounding walls.
Internal buttressing walls are necessary in long lengths of wall; AD A refers to internal buttressing walls at 2C25 and 2C26. Such walls are an essential component in traditional masonry construction.
Structural Masonry Designers' Manual by Curtin, and Structural Masonry by Hendry, amongst many others, make this important point about internal buttressing walls.

Alls well in theory and concepts, but we are talking about a small house.

Its a box, a framed box. Stability comes from the floor/ceiling/roof and there is only 2.5(?)m of storey height in any case so again no buttressing needed.

Have you ever needed to design internal buttressing walls to a house?

 

[BBD38]

Just came across this, and with all due respect in case someone comes across this thread again, then Tony1851 couldn't be more correct. Floors, and roof only provide partial fixity (unless concrete in most cases). The below comment couldn't be more wrong and is down right dangerous if that is your thinking.

Anyway no internal wall in any traditionally designed house or low rise building is doing any buttressing

Think of a 2.5m wall along a road and how many piers you see. These are required to provide lateral support to the wall against wind loading. What happens to the un-buttressed walls that the floor and roof aren't sitting perpendicular too? If providing a few straps is your answer, then this will not provide adequate fixity to resist wind loads.

By fixing ply to both sides of a structural stud wall for the purposes of resisting horizontal loads, effectively forms a lattice structure / ply-web. Structural ply should be used, and the thickness required should be calculated in accordance with the relevant codes BS or EC in the UK. The British Standards are not theories, they were developed to be able to adequately design structures, through testing and mathematical theory.

Read more: https://www.diynot.com/diy/threads/use-of-ply-in-stud-wall.501078/#ixzz7LusjGgeu

 

[^woody^]

Think of a 2.5m wall along a road and how many piers you see.

WTF?

How about thinking a of a wall inside a house like in actual context of the thread?

In case anyone comes across this thread again, Tony 1851 could be more correct.

 

[BBD38]

WTF right back at you. Shame you have taken an aggressive approach, but I tried to put it in a very 'simplistic' context for you, so you understand the effects of lateral wind loading.

However, maybe you don't understand what tony has mentioned, or the surveyors comments on the need for internal buttressing walls, with the longest un-buttressed wall being 9m.

I'm not sure why you wrote 'Tony 1851 could be more correct'...are you agreeing with me? It is hard to really determine as your post appears to disagree at 1st.

 

[tony1851]

@woody;
In traditional, low-rise brick domestic structures, internal cross walls provide a buttressing function, supporting the outer walls when under wind load.
You cannot rely just on the floor and roof; these help a little by keeping the structure square, and also provide some beneficial compression in the masonry but the effects are relatively small.
There are many technical books on traditional masonry structures and they all point out the buttressing-effect of internal walls. Yes, some people remove them to gain an open plan, but all they are doing is making the structure that bit more vulnerable to high winds and gusts.

 

[BBD38]

Adding to the above, period property walls were constructed in 9" (sometimes wider if larger properties) so are more robust against wind loads than cavity walls. If removing internal walls, Engineers will sometimes require a portion left in to provide a buttress. Alternatively, wind posts can be installed, Ancon have some particularly good details and guidance, although they have long lead times, so you can use a standard section (Unequal angle or square hollow section). Again, all should be analysed and designed as appropriate (BS6399 to calculate wind load for your region).

 

[phatboy]

Engineers for our extension have included timber sheer walls standing off a 15m long wall....

100x47 C24 timber studs @ 400 crs with timber noggins @ mid-height, provide 9mm OSB sheathing (1 side) fixed with 3.5mm x 50mm LG ring shank nails @ 150mm crs at perimeters to to inner studs.

100 x 47 C16 sole plate fixed to concrete floor with Hilti XU-72 shot fired nails @ 400mm centres

Double 100 x 47 C16 header plates fixed to joists over with Simpson A35 framing anchors.