Rockwool vs knauf attic roof insulation?

everfor007

I am replace my attic insulation, in wickes noticed knauf insulation cost each around £35 and rockwook is double of cost around £71. Understood rockwool produce better heat comparing to knauf and save the energy bill, Seems energy bills keep increase.. Is it worth spending on rockwool? Kindly advise.

Another question, my builder is removing the old insulation now and lay out of new insulation will take after 4 weeks. Seems summer is starting, is it fine to not having insulation for 4 weeks? will damp increases?

grumbler

everfor007 said:

Understood rockwool produce better heat comparing to knauf and save the energy bill, Seems energy bills keep increase.. Is it worth spending on rockwool? Kindly advise.

Not sure what you mean by 'produce better heat', but for the same slab thickness 100mm I see

Rockwool Thermal Insulation Cavity Slab  - R Value: 2.63 m2K/W

Knauf Insulation DriTherm® Cavity Slab 37- R Value: 2.70 m2K/W

Knauf Insulation DriTherm® Cavity Slab 32 - R Value: 3.10 m2K/W

The higher the R Value, the better thermal insulating properties.

That said, you need as thick slabs as possible, but have to leave about 50mm ventilation gap between the insulation and the membrane under the tiles. Not sure if it's needed if it's felt, not membrane.

Chickereeeee

everfor007 said:

I am replace my attic insulation, in wickes noticed knauf insulation cost each around £35 and rockwook is double of cost around £71. Understood rockwool produce better heat comparing to knauf and save the energy bill, Seems energy bills keep increase.. Is it worth spending on rockwool? Kindly advise.

Another question, my builder is removing the old insulation now and lay out of new insulation will take after 4 weeks. Seems summer is starting, is it fine to not having insulation for 4 weeks? will damp increases?

Knauf and Rockwool LOFT insulation (roll type, which I assume you mean) have same same insulation value for the same thickness. For £71, Rockwool covers 6.6sqm at 100mm depth. Knauf, for £35, covers 5.5sqm at 100mm depth.

Handling is different between the two (Rockwool seems denser, Knauf looser/thinner). I understand Rockwool performs better IF it gets damp. But otherwise, I don't think it matters.

No insulation in the summer will not matter, especially if you have good ventilation.