Insulation Help

Orkatec

Hi
I have just had a timber frame extension built.
I am doing the internal work myself.
The drawings specify 140mm mineral wool between the stud work,I have some rolls KNUF earth wool lofttherm insulation is it OK for the walls.
I also have some rolls of KNUF frametherm and it looks identical but is only 50 mm thick.

James

System

What's the uvalue required? You can use alternative insulation as long as you can achieve the same values...

Orkatec

I only have a value for the completed walls.
0.19W/m2K using mineral wool.
I will check the KNUF web site for values and take it from there.
Loft insulation is much cheaper at the moment, maybe it is subsidised in some way and not wall insulation even if it is the same just a different name.

James

Johnandabby

Orkatec wrote: »

I only have a value for the completed walls.
0.19W/m2K using mineral wool.
I will check the KNUF web site for values and take it from there.
Loft insulation is much cheaper at the moment, maybe it is subsidised in some way and not wall insulation even if it is the same just a different name.

James

50mm won't be enough to achieve a u-value of 0.19 w/m2. Even 140mm by itself wouldn't be enough - probably 200mm if using mineral wool. You would normally use a rigid insulation board with lower conductivity.

You'll need to think about condensation issues, as there can be issues with mould growth on mineral wool in timber walk constructions.

Orkatec

Apologies I should have posted this the first time


4.0 WALLS
4.1 RENDERED BLOCKWORK WALLS
U-Value 0.19W/m2K
20mm Dry dash or polymer render (White)
100mm Dense concrete block
50mm cavity – with proprietary insulated cavity closures at first floor and wall head levels & with integral dpc to all window sill, soffits and jams
Breather membrane – Glidevale Protect TF200
Treated sw studs to eng spec with 9/10mm OSB sheathing to external face
140mm Mineral wool insulation between studs – Crown FrameTherm 32
Vapour barrier – Glidevale Protect VC Foil – Fully lapped and taped
20mm batten cavity
12.5mm plasterboard with skim finish (moisture resistant pb to kitchen, utility & bathroom areas) 125x19mm profiled painted SW skirtings.

What I need to find out is there any difference between frame insulation and loft insulation if both have the same thickness and U value.

withabix

Frame Therm 32 will be 0.032 W/mK thermal conductivity.

Be careful using loft insulation, which only provides the 'advertised' thermal conductivity when uncompressed.

Frame Therm panels are designed to friction fit between studwork at 600mm c/c rather than fall out or slump over time.

Furts

Roof insulation looses its effectiveness with time. It compacts under its own weight in a roof and will tend to slump in a timber frame.

Orkatec

Thanks I have noticed that KNUF insulation is semi pre cut for friction fitting.
As with all things building lots to think about.