Crawl Space Ventilation Calculator
Vent area for a crawl space.
Work It Out And Get Clear Answers
Vent area for a crawl space.
Crawl Space Ventilation Estimator
Enter your numbers below for an instant estimate.
How It Works
Key concepts behind this calculator
Enter Values
Fill in each field with your own numbers.
Calculate
Press Calculate to see the result.
Review
Read the breakdown and the explanation.
Adjust
Change values to compare scenarios.
Crawl Space Ventilation Quick Guide
Typical values for reference.
| Crawl space area (sq ft) | Vapour barrier fitted (1 yes 0 no) | Net free area per vent (sq ft) | Required net free vent area |
|---|---|---|---|
| 1,000 | 0 | 0.5 | 6.67 sq ft |
| 500 | 0 | 0.5 | 3.33 sq ft |
| 2,000 | 0 | 0.5 | 13.33 sq ft |
| Rule of thumb: check your inputs, use the result as a guide and round sensibly. | |||
Crawl Space Ventilation FAQ
Answers to common questions about this calculator.
1 sq ft per 150 sq ft, or per 1,500 sq ft with a vapour barrier.
It uses the default inputs shown and the formula described above. Change any value and press Calculate to see how the result moves.
It is an estimate based on the inputs you enter. Check real quotes, labels, product data or official guidance for important decisions.
Yes. Replace each input with your own figures and press Calculate to update the result.