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Stud walls 600c/c vs 400 c/c


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I'm going to be annoying here and not entirely answer your question, but instead pick up on something slightly different 😉 I notice you have acoustic insulation shown in your drawing. If you're looking for decent sound insulation within this staggered wall, I'd recommend you use a continuous roll of insulation which zig-zags behind the staggered studs. 25mm acoustic insulation isn't going to do much and with the current design you only have 8mm between staggered stud and plasterboard so too narrow to do anything. In that sense, depending on the noise levels you want to achieve, you might be better using 38 x 89 studs which are installed on 38 x 140 studs at top and bottom. You can of course go for 38 x 63 and increase the gap behind each stud using 50mm insulation but I'm not sure how quiet the wall will be.

 

Remember though that your stud spacing will be 600c/c at each side of the staggered wall so in effect 300c/c (Just noticed PeterW already said this)

 

Most places will supply C16 cls in my experience.

Edited by SimonD
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3 minutes ago, SimonD said:

a continuous roll of insulation which zig-zags behind the staggered studs

Yes, this is important. Would 50mm studs work and allow more insulation to run past without over compression?

50mm insulation roll wiggled through the length of the wall.

 

Also: the noggin shown is linking the 2 faces , so defeating the object of the two separate surfaces. You have shown a slight gap which is clever, but  if you bang on one side then the noise will still reverberate through the noggin to the other face. (I have done this myself recently without full thought, so thanks for bringing it up.

 

It is a a compromise but I suggest using a 50mm noggin on one side, ie not touching the other face of board, or with your idea  but leaving a bigger gap on both sides.

 

What are noggins for anyway?

This is not a structural wall so they are only to keep the studs vertical, and perhaps could be removed once a face of board is in place, or use osb one side before the plasterboard..

 

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3 minutes ago, WWilts said:

2.3m floor to ceiling height

Not saying I could prove it structurally, but I have used CLS placed the other way (wide face to the room) and it worked really well.)

Used it as a sports hall liner 2.1m high with no noggins and one face of MDF. It moved very slightly when our 15 stone tester  shouldered it.. So it should work in a house without noggins.

It also makes the board fixing very easy with such a wide surface.

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12 minutes ago, saveasteading said:

when our 15 stone tester  shouldered it

I should add that it withstands 5 -a side football in real life. 

The stud doesn't have the same strength when sideways on, but plenty, (the plasterboard will fail before the timber) you won't need noggins, and you have room to Z the insulation through. 

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52 minutes ago, saveasteading said:

Would 50mm studs work and allow more insulation to run past without over compression?

50mm insulation roll wiggled through the length of the wall.

 

My concern with that would be the absorption co-efficient of the insulation. Knauf and Rockwool kindly sent me their test data a while ago and if you look at the performance of 50mm versus 75mm it's pretty significant, especially at lower frequencies (obvious caveat that the acoustic performance depends on total buildup of course). Files uploaded for reference below.

Knauf Insulation Acoustic Roll - Absorption Co-efficients .pdf Absorption Coefficients of ROCKWOOL Slabs - v2 2019.pdf

Edited by SimonD
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1 minute ago, SimonD said:

50mm insulation roll wiggled through the length of the wall.

So 75mm quilt, squeezed to 50 (or as final detail) at the studs?

Otherwise it becomes a very thick wall, which may not be an issue if the rooms are big.

 

Attention to detail is important, as sound leaks through gaps significantly. 

Sound 'pours' through any significant gaps, so the quilt needs to be tight to all interfaces.

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2 hours ago, WWilts said:

Sketchup (available in a free version which is highly capable)

The last time I tried it I found that I was not highly capable though. 

Perhaps Sketchup is now more intuitive.... (had no instructions, it just assumed we learned as we went....I didn't, and didn't need to either).

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28 minutes ago, saveasteading said:

(had no instructions, it just assumed we learned as we went.

Yes, roughly true.
Difficult to look back now and recall the challenges. After a while it seems easy. Does 3D too

I find LiveHome more intuitive

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I have found it is handy to select the timber in person so you can weed out the twisted and banana shaped ones.  Some batches can be dreadful.

 

The drawing needs twice as many studs.

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46 minutes ago, Mr Punter said:

weed out the twisted and banana shaped ones.

A good point. And big knots and shakes too.

One of the plus points of Wickes, as long as someone hasn't already taken the good bits. There is often more out the back.

 

I once went into Travis to do exactly that, and the supervisor complained that we were taking all the best bits.

In fact we took it nearly all, including a 2x2 that rotated 90 degrees in its 3.6 length. Then he complained that he had no saleable wood left if anyone wanted any.

Straight wood is good. It grows straightest in very cold places like Siberia and Finland. Siberia is a no-no of course.

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Thanks to all posts. This has been an issue I struggled with . The sketch software are. Very useful and the pdf on sound blankets are instructive. From my reading you need putty pads on sockets and down lighters and mass vinyl sheets help . My needs are a room off the open plan kitchen /diner and a bedroom floor .

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On 31/03/2022 at 19:42, saveasteading said:

A good point. And big knots and shakes too.

One of the plus points of Wickes, as long as someone hasn't already taken the good bits. There is often more out the back.

 

I once went into Travis to do exactly that, and the supervisor complained that we were taking all the best bits.

In fact we took it nearly all, including a 2x2 that rotated 90 degrees in its 3.6 length. Then he complained that he had no saleable wood left if anyone wanted any.

Straight wood is good. It grows straightest in very cold places like Siberia and Finland. Siberia is a no-no of course.

Lol. When i was younger working in a builders yard it was standard practice to send out all the crap twisted timber stock on deliveries, as no one would come in to the yard and buy those pieces.

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  • 1 month later...
On 31/03/2022 at 21:01, WWilts said:

True.

 

Architect is ok with this version (pic). 

 

 

stud wall detail plan view Acoustic insulation 50mm - Copy.jpg

 

I'd be worried about having the 63x38 CLS studs that way round. The deflection under the same load is 2.7 times as much in that orientation and thickness in the line of the load force is king for keeping deflection down. 600mm centres compounds it further and makes it 4 times floppier than 400mm c/c with 63x38 CLS in the correct orientation.

 

You'd probably be better without staggered studs and using resilient channel or think about using Metal C-studs (also Acoustic studs are an option there).

 

Second Moment of Area: (63*38^3)/12 = 0.29E6  vs (38*63^3) / 12 = 0.79E6  ->  0.79E6 / 0.29E6 = 2.7

Beam deflection is inversely proportional to Second Moment of Area.

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