How many bags do you need for your roof?
You don't need to work out R-values or bag quantities yourself.
The thicker the insulation layer, the better it prevents heat from passing through your ceiling. A thicker installation therefore uses more material per square metre.
A single bag covers approximately 3.8 m² to 5.4 m², depending on the insulation thickness required.
The graph below provides you with a breakdown of the number of bags you require depending on your required R-Value and the area it will cover.
| 1 |
2 |
3 |
4 |
5 |
| Thermal resistance R M2 K/W |
Installed fitted thickness |
Settled thickness |
Min Mass per unit area Kg/M2 |
Max Coverage M2/bag |
Min Bag usage rate bags/100M2 |
| 2.50 |
100mm |
100mm |
2.6 |
5.4 |
18 |
| 2.88 |
115mm |
115mm |
3.1 |
4.5 |
22 |
| 3.13 |
125mm |
125mm |
3.4 |
4.1 |
24 |
| 3.25 |
130mm |
130mm |
3.5 |
4.0 |
25 |
| 3.38 |
135mm |
135mm |
3.7 |
3.8 |
26 |
