Double board or layer of OSB?

[Dreadnaught]

2 hours ago, Alex C said:

Resilient bar is a good call and not expensive. for our 150m2 ground floor it was about £400 in materials and 2 man days to fit it.

 

Out of interest where did you choose to install resilient bar on your ground floor? Everywhere or selectively?

[Visti]

On 14/11/2019 at 10:50, Moonshine said:

 

If you are only looking to get an equivalent level of acoustic performance from the OSB, then look at getting a similar surface density from the liner board, below is a link to the surface density of many plasterboard sheets.

 

If you are using standard 12.5mm Gyproc wallboard thats 8.0 kg/m², the OSB / ply thickness should be matched to this surface density. 

 

OSB has a density of around 640 kg/m3, you will need min 13mm boards to give you a surface density of 8.3 kg/m2

 

 

@Moonshine - doing a review on the £/kg and it looks like the no brainer if going for acoustic performance is bog standard wallboard at 4.52 kg per £

 

I may as well double up on standard board which will give me a surface density of 16 kg/m2 at £3.53 per m2.

 

That is a full pound pound cheaper per m2 than the most economical soundboard GTEC dB check, and gives an extra 3kg/m2 to boot.

 

Why have soundboard at all? Is it a question of labour?

 

 

@Nickfromwales - 100% correct on ply... a very expensive approach. I'll be doing it strategically as recommended

Edited November 17, 2019 by Visti
spelling

[Dreadnaught]

A very clear presentation, @Visti! Very helpful.

1. Is your logic correct: does a board of a given density provide the same acoustic attenuation as double the amount of board of half the density? In other words, is kg/m² linearly proportional to acoustic attenuation, and across all wavelengths?
2. As your research continues, I would be interested to know your view on using resilience bars?
3. If you choose to use standard board, will you therefore be wet skimming with plaster too?

 

[Russell griffiths]

Double boarding will cost you double in labour. 

 

[Moonshine]

1 hour ago, Visti said:

 

@Moonshine - doing a review on the £/kg and it looks like the no brainer if going for acoustic performance is bog standard wallboard at 4.52 kg per £

 

I may as well double up on standard board which will give me a surface density of 16 kg/m2 at £3.53 per m2.

 

That is a full pound pound cheaper per m2 than the most economical soundboard GTEC dB check, and gives an extra 3kg/m2 to boot.

 

Why have soundboard at all? Is it a question of labour?

 

 

@Nickfromwales - 100% correct on ply... a very expensive approach. I'll be doing it strategically as recommended

 

Interesting graphs, and I agree that the 'acoustic' in a name does give a up lift in cost when it's the density you are really getting.

 

High density boards are needed as they offer the higher acoustic ratings needed in some situations (e.g. trying to meet ADE conversation requirements on a timber floor with limited floor to ceiling space).

 

Also as you say labour, people will start looking at you funny if you start asking for triple boarding, when you could do it in a double layer of SoundBloc.

 

@Dreadnaught in simple terms a single skin partition with double the density will increase the sound insulation by 6 dB In the mass control 

region, but maybe more like 4-5 dB when considered throughout the whole frequency range. See below

 

 

 

Edited November 17, 2019 by Moonshine

[Visti]

So I did the number crunching, and it looks like there is actually a good case for Fermacell if you can find a good supplier (found at £6.47/m2, making it £2.22/kg. only slightly worse than standard soundboards in my last chart).

 

1. Label every wall...

 

 

 

2. Take all the measurements...

 

 

 

3. Calculate labor and materials cost per m2...

 

 

 

I've got quotes coming in at 25-33k (Double Plasterboard) - so not far off!

Using only standard board I'd save ~£2k in materials.

 

 

4. Get a decent quote for Fermacell materials from here ... 

 

This is for a single layer of fermacell, equivalent density as doubled up gyproc wallboard.

The labour is also an additional £1/m2 for installing these boards. The contractor also quoted more for applying the Fine Surface Treatment than skimming.

 

 

5. But what if I did just a single layer of standard wall board...

 

This is half the density of the above except at the ground floor ceiling, and limits fixings to just areas with planned noggins or plywood backing.

Using only standard board I'd save ~£1k in materials.

 

 

6. and what if no plywood backing at all...

 

Probably the cheapest it'd get unless all the sound board was replaced with the standard board to bring it down to £11.5k.

 

Edited November 21, 2019 by Visti

[Visti]

I think it comes down to value for money.

 

The standard single layer of wallboard is cost effective, but personally it doesn't sit right with me.. neither acoustically and quality wise (I'm big, clumsy and have many holes/dents punched through and patched in my current home). The plywood backing also adds a lot of cost to enable fixings to handpicked areas.

 

If I double up for quality, fermacell is just a far more cost effective way as it doesn't double up on labor. Doubling up also still doesn't address the fixing issue, where as fermacell will allow me to do it anywhere.

 

I might also have found a willing laborer to do it at much more favorable rates too... 

[ProDave]

Don't get sold of "it's easy to hang things on Fermacell"

 

Yes it is strong, but have you ever actually tried fixing anything to it?

 

Well this week I had to fix a consumer unit to it.  I could not find any sort of screw that would just screw into it, even with a small pilot hole drilled.  I ended up drilling a hole, putting a rawl plug in and screwing into that.

[eandg]

52 minutes ago, Visti said:

So I did the number crunching, and it looks like there is actually a good case for Fermacell if you can find a good supplier (found at £6.47/m2, making it £2.22/kg. only slightly worse than standard soundboards in my last chart).

 

1. Label every wall...

 

 

 

2. Take all the measurements...

 

 

 

3. Calculate labor and materials cost per m2...

 

 

 

I've got quotes coming in at 25-33k (Double Plasterboard) - so not far off!

Using only standard board I'd save ~£2k in materials.

 

 

4. Get a decent quote for Fermacell materials from here ... 

 

This is for a single layer of fermacell, equivalent density as doubled up gyproc wallboard.

The labour is also an additional £1/m2 for installing these boards. The contractor also quoted more for applying the Fine Surface Treatment than skimming.

 

 

5. But what if I did just a single layer of standard wall board...

 

This is half the density of the above except at the ground floor ceiling, and limits fixings to just areas with planned noggins or plywood backing.

Using only standard board I'd save ~£1k in materials.

 

 

6. and what if no plywood backing at all...

 

Probably the cheapest it'd get unless all the sound board was replaced with the standard board to bring it down to £11.5k.

 

I can't read any of that from my phone but in any case I'm feeling very inadequate. Replying to compliment your work and for ease of reference if I shame myself into undertaking that level of detail/control. 

[oldkettle]

@Visti, it's a very thorough comparison.

Looking at your original costing (from 2 years ago), it seems the "basic" price comes close to the sum of "ceiling + walls", but of course upgrades are much more expensive. I hope you will get a chance to update your spreadsheet sometime.

[Russdl]

Great research and detail there @Visti. I see that you've specced the Powerpanel H2O in the Fermacell table. Any specific reason for that?

My understanding was that the standard Fermacell board, plus a waterproofing treatment, was suitable for domestic bathrooms/kitchens. Is the waterproofing treatment not required on the Powerpanel and therefore it works out cheaper?

[Visti]

2 hours ago, Russdl said:

Great research and detail there @Visti. I see that you've specced the Powerpanel H2O in the Fermacell table. Any specific reason for that?

My understanding was that the standard Fermacell board, plus a waterproofing treatment, was suitable for domestic bathrooms/kitchens. Is the waterproofing treatment not required on the Powerpanel and therefore it works out cheaper?

I over spec'd I guess. I saw that standard board could be used, so I may do that instead in my next revision.

 

On 21/11/2019 at 22:44, eandg said:

I can't read any of that from my phone but in any case I'm feeling very inadequate. Replying to compliment your work and for ease of reference if I shame myself into undertaking that level of detail/control. 

 

It is more a representation of feeling out of control! I always do this (engineering background) so that I can feel like I am making an informed decision... I am not sure whether the results are improved following a week of evening spreadsheet of

 

good advice @ProDave, I think that is generally the way to go. I may also get a spare box of fermacell screws for other jobs in case.

[redtop]

we keep going round this (wont be needed for a few months yet), and think we will go down the fermacell route and fit ourselves. I couldn't plaster but am confident I could use the fermacell filling compound so labour costs would be zero,

D

[redtop]

as an aside when do you use tapered v square edge board??

[Big Jimbo]

10 minutes ago, redtop said:

as an aside when do you use tapered v square edge board??

Tapered when i am doing dry lining, and square edge when i am doing wet plaster skim.

[Russdl]

2 hours ago, Visti said:

I over spec'd I guess

 

It would seem that way. I've just spoken to Fermacell technical support (I'm going to have him on speed dial). He say's there is no need to use the  Powerpanel in a domestic situation. "You can use our standard panel with our waterproofing product or anyone else's waterproofing product, there all the same" he said.

 

2 hours ago, redtop said:

I couldn't plaster but am confident I could use the fermacell filling compound so labour costs would be zero,

 

He made it sound to be as straight forward as it looks, aimed at us DIY'ers. Jointstick on the factory edges, 5-7mm gap on cut edges and then filled later. FST for any painted finish. 

 

And he confirmed what we all know - it's very heavy.

[Moonshine]

14 minutes ago, Russdl said:

And he confirmed what we all know - it's very heavy.

 

At 14.38kg/m² for 12.5mm its almost double the density of 12.5mm wallboard!

 

41.5kg per 2.4 x 1.2m sheet.

 

I presume its a 2 person job to line a room.

[Russdl]

1 minute ago, Moonshine said:

presume its a 2 person job to line a room.

 

Beyond a doubt I think, but I guess the '1 man boards' can be done by, er, 1 man. The first quote I have for Fermacell is a m2 price and doesn't differentiate between board sizes.

[scottishjohn]

Just now, Russdl said:

 

Beyond a doubt I think, but I guess the '1 man boards' can be done by, er, 1 man. The first quote I have for Fermacell is a m2 price and doesn't differentiate between board sizes.

can you get 6 x3 boards ?

thats what my 74 year old plaster master uses now if he got to do ceilings

[Moonshine]

5 minutes ago, Russdl said:

The first quote I have for Fermacell is a m2 price and doesn't differentiate between board sizes.

 

I hadn't seen they do half boards, be in interesting to knows which size (1500 x 1000 mm or 1200 x 1200 mm) offers the best in terms of wastage.

[Russdl]

1 hour ago, scottishjohn said:

can you get 6 x3 boards ?

 

57 minutes ago, Moonshine said:

I hadn't seen they do half boards,

 

In the 12.5mm they do 1200x1200, 1200x900, 1200x800

[Dreadnaught]

I looked recently at Fermacel prices and prepared a small spreadsheet (see next post). I concluded that 10mm boards were probably the best option from weight and cost. And then I could double-up in locations that required higher sound attenuation. That way I could just buy a single board for use everywhere. 

 

The optimum board size and cost was: 1200 x 800 x 10 at 11 kg per board and £7.23 per m².

A pallet of such boards was: 60 boards at 0.7 tonnes, so I am maybe thinking of getting them on the slab before the frame goes up (!)

 

Interestingly, the one-man boards in 12.5 mm were much more expensive per m² as I assume they are a special order item.

Edited November 25, 2019 by Dreadnaught

[Dreadnaught]

Here are the numbers I prepared:

 

[Visti]

55 minutes ago, Dreadnaught said:

Here are the numbers I prepared:

 

 

Encon.

 

Same size at 12.5mm I am getting quoted £6.48/unit, Inc VAT. That is 6.75 £/m2, nearly 50p cheaper.

 

How many units you ordering? I'm at about 930 so volume may make a big difference.

[Russdl]

29 minutes ago, Visti said:

Same size at 12.5mm

 

@Visti, I presume you’re referring to the highlighted 1200x800 10mm board? Unless I’ve read @Dreadnaught‘s table incorrectly your quote is way way more than 50p cheaper. It’s over £10 cheaper.

 

I’ve had a very similar quote price from Encon for the 12.5mm board, regardless of the size of board.