AAC or Drywall?

[Mrdjc]

Hi guys,

I'm a student, currently living in Slovakia and I've agreed to help renovate a property here.

I've been doing some research and can't really decide what method to go for, hopefully someone will be able to give some valuable input.

The property in question is a 60-70 year old bungalow, without any insulation currently, I'm proposing to gut the whole lot and insulate it, re-wire it, re-plumb etc.

The walls are made of Mortar/rubble/mud/whatever they could find.

I'm proposing to knock the render off on the inside as there is a bit of a damp problem and breathing issues (Don't worry, new floors will be fitted as well, as well as a Heat recovery ventilation system)

Now the thing I am stuck on, I wish to build a new internal wall inside each room, for insulation properties, as well as being able to run cables and the likes inside it or inside the surface.

Now do I go for:

Plasterboard (Drywall) with a Wooden or Metal studwork, damp proof membrane, and 50mm of Mineral wool insulation.

OR

"Ytong" AAC (Aerated Autoenclaved concrete)

I've been looking at the K / R values of both materials, as well as the costs, and I think the costs will both end up roughly similar, with the AAC being slightly more expensive.

The AAC has less thermal resistance than the mineral wool, but it seems to do away with any risk of damp forming, and is far more "sturdy" than drywall.

Does the AAC still require a damp proof coursing behind it, and a air gap?

I'm a bit worried about creating a cold bridge if I end up using metal or wooden studwork.

Any opinions? I don't mind it being slightly more expensive if the overall quality will be better, I also don't mind if its slightly more work to finish, as long as the finish is good.

Regards,
Daniel.

 

[Mrdjc]

Thanks for the overwhelming response!

99% decided on AAC (Ytong) now...

Calculated I need approx 200M[sup]2[/sup] of wall, at approx €9,- per M[sup]2[/sup]

The wood alone will cost near enough €1300,- Then you need Plasterboard, Insulation, damp proof membrane etc etc.

Did the following on calculations:

Material K value Thickness (mm) Thermal Resistance

Plasterboard 0.16 W/mK 12.5 0.078125 M² K/W
Mineral Wool 0.03 W/mK 50 1.666666667 M² K/W
Air 0.024 W/mK 20 0.833333333 M² K/W
Mortar/Concrete Wall 1.3 W/mK 400 0.307692308 M² K/W
Polystyrene 0.03 W/mK 50 1.666666667 M² K/W
Total 4.552483974 M² K/W

Thermal Transmittance (U) 0.219660301 W/M²K

Versus:

AAC 0.15 W/mK 50 0.333333333 M² K/W
Air 0.024 W/mK 50 2.083333333 M² K/W
Mortar/Concrete Wall 1.3 W/mK 400 0.307692308 M² K/W
Polystyrene 0.03 W/mK 50 1.666666667 M² K/W
Total 4.391025641 M² K/W

Thermal Transmittance (U) 0.227737226 W/M²K

The K value's have been picked off internet, Ytong boasts 0.09 but other sites say its 0.10-0.20 so I went for 0.15
The wall itself is rather complicated, its a mix of Mortar, Concrete, stone, bricks, clay/mud etc etc, So ranges from 1 to 2 so I thought 1.3 was realistic enough.

The building code says NEW buildings should have a U value of around 0.25, currently walls alone have a U value of 3.25, so whatever is done, its a vast improvement.

The 50 mm polystyrene is for the outside, and will be done some time at the end of the summer, and will bring it from 0.36 down to 0.23 ish. (provided all the values are correct)

I'm going to see how thick the render is on the inside of the house to see how much further I can go back "into" the wall, I'd ideally like to use 75mm AAC, and a 50mm airgap, but might very well end up only being a 25mm air gap, we'll see once I start prodding around in there.