Understanding Thermal Properties of plasterboard.

[JKami84]

Hi, 

In my garage conversion , I will be having plasterboard on ceilings and wall. 

I assume current quote from builder includes 'standard' 12.5mm plasterboard.

 

I was considering 'upgrading' to sound proofed plasterboard. 

 

However, it seems the thermal values of soundproof plasterboard is worse (0.25 W/mK) than standard plasterboard (0.19 W/mK). but at 12.5mm is this a major difference?

 

For the thermal values (W/mK) I understand lower is better... is that right? But also when weigh it up with the thickness, is this a considerable difference?

 

I feel like I need to weigh up whether I want better sound properties or better thermal properties?

 

The R value (worked out using thickness divided by thermal values above) then works out to 0.066 for cheaper standard plasterboard or 0.05 for acoustic one.

 

Products I am looking at were just on travis perkins websites - 

 

https://www.travisperkins.co.uk/standard-plasterboard/british-gypsum-gyproc-wallboard-tapered-edge-2400mm-x-1200mm-x-12-5mm/p/760084?gclid=CjwKCAiAvaGRBhBlEiwAiY-yMPTWF6cOpsSYmiAi_DKmXVHNbeTUVUxqbttEX0S_hhvgRq3MGyGYMBoCSmMQAvD_BwE&gclsrc=aw.ds

 

https://www.travisperkins.co.uk/specialist-plasterboard/british-gypsum-gyproc-soundbloc-tapered-edge-2400mm-x-1200mm-x-12-5mm/p/865328

 

 

Edited March 9, 2022 by JKami84

[Russell griffiths]

Your insulation value should be geared around the insulation, not the plasterboard, get the insulation levels right and it hardly matters what board you use. 

[SteamyTea]

You also have different air film values for ceilings and walls that affect the overall R-Value.

But as @Russell griffiths says, let the proper insulation do the real work. It is what it is made for.

[JKami84]

Hi both, Yes, the walls will be insulated, ceilings will be "stuffed" with what ever type of insulation they call it, and the walls will be celotex either 50mm or 25mm depending on whether they exterior walls or adjoins neighbours.

 

But I am just choosing a plasterboard product here, and I wouldn't mind spending more on acoustic properties , but not at expense of thermal properties. 

 

Does this help answer my question whether acoustic plasterboard impacts thermal properties given that standard plasterboard seems to have better thermal properties.

[JKami84]

i see you point. I've just done a calculation, bear with me lol. 

50mm Celotex with thermal conductivity of 0.022 means R value is 0.05 / 0.022 = 2.27

 

so whether you add onto that R value of soundproof plasterboard (0.05) to total 2.32 

 

Or you had R value of standard plasterboard (0.066) to total 2.336

 

I guess now it hardly makes a difference right?

[MikeGrahamT21]

You'll never notice the difference, its just because its denser than standard plasterboard.

[saveasteading]

1 hour ago, JKami84 said:

I wouldn't mind spending more on acoustic properties

What acoustic property are you seeking?

Noise in or out of the new space? Or reverberation within?

What sort of noise?

[Andysmith]

With regards to soundproofing and cost two layers of 12.5mm plasterboard is better than one layer of acoustic plasterboard 

[joe90]

2 minutes ago, Andysmith said:

With regards to soundproofing and cost two layers of 12.5mm plasterboard is better than one layer of acoustic plasterboard 

I agree and they are easier to handle 👍.

[JKami84]

2 hours ago, saveasteading said:

What acoustic property are you seeking?

Noise in or out of the new space? Or reverberation within?

What sort of noise?

Mostly noise out.. i.e. I want to use this space for parties and games room. I want to not allow it to disturb neighbours so much even though they only use their garage as a gym occasionally. 

[saveasteading]

2 hours ago, JKami84 said:

Mostly noise out.

You therefore need both the density of the plasterboard and the softness of the insulation, and had best use mineral wool.

Outside structure brick?

Remember that sound escapes through small weaknesses in the structure. for example through windows and doors. 

Don't forget the ceiling.

 

A nice hard and rectangular surface internally will increase the internal reverberation noise and so may persuade you to keep your sound levels down

[JohnMo]

In the grand scheme of things it would make the about 0.01 change in the wall U value, so really not worth a discussion.  To put this into perspective.

 

10m2 of wall with a 25 deg temperature difference between inside and outside.  Worst material would loose an additional Watts of

 

10 X 25 X 0.01 = 2.5W so worst day wall heat loss, would increase by 2.5W.

 

U value is the inverse of the R value.  The higher the R value the better.  So the lower the U value the better.

 

1/R = U.

 

Also PIR adds nothing to sound proofing, so not the best if you want to block noise.