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Roof Insulation R Value Calculator
Calculate total roof R-value from insulation thickness.
layers Free Online Tool
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📊 Clear Comparison
🔒 100% Free Tool
Total R-value
Compare Your Options And Get Clear Answers
Calculate total roof R-value from insulation thickness.
Roof Insulation R Value Estimator
Enter your numbers below for an instant estimate.
0
💡 Tip: Typical loft target is 270 mm of mineral wool.
How It Works
Key concepts behind this calculator
1
Enter Values
Fill in each field with your own numbers.
2
Calculate
Results update as you change the inputs.
3
Review
Read the breakdown and the explanation.
4
Adjust
Change values to compare scenarios.
Quick Reference Guide
Roof Quick Guide
Typical values for reference.
| Thickness | k | Total R | U |
|---|---|---|---|
| 100 | 0.04 | 2.80 | 0.357 |
| 200 | 0.04 | 5.30 | 0.189 |
| 270 | 0.04 | 7.05 | 0.142 |
| 300 | 0.035 | 8.87 | 0.113 |
| Rule of Thumb | Check inputs | Use as a guide | Round sensibly |
Common Questions
Roof Insulation R Calculator FAQ
Answers to common questions about this calculator.
Thermal resistance.
It gives a quick estimate of roof insulation r value from the values you enter.
No. It is a planning estimate, so check important figures with a professional or official source.
Yes. Edit any field and the result updates when you calculate.