Stucco Calculator
Stucco is a cementitious plaster applied in layers over metal lath on wood-framed walls, or directly to CMU block and masonry. A traditional three-coat system — scratch coat (~3/8"), brown coat (~3/8"), finish coat (~1/8") — totals 7/8" thick and is the most durable exterior finish. The one-coat system uses a single reinforced coat at 3/8" and is faster and less expensive. Each 80lb bag of stucco base coat covers approximately 40 sq ft on metal lath (rougher surface) and 50 sq ft on masonry (smoother surface). Metal lath is sold in 2.5×8 ft sheets (20 sq ft each) and is needed for all wood-framed walls. The calculator shows scratch coat bags, brown coat bags (3-coat only), finish coat bags, and lath sheet count based on your substrate selection.
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Top PickStucco Base Coat 80lb — Home Depot~$14.98/bag* Affiliate links — we may earn a commission at no cost to you.
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How to Use This Calculator
- 1Enter your measurements in the fields above. Use the units shown next to each field (ft, in, etc.).
- 2Click Calculate to get your material estimate instantly.
- 3Review the highlighted result — it shows the key quantity you need to order.
- 4Use Copy Results to save your estimate, or bookmark the URL — your inputs are encoded in the link.
Pro tip: Always add 10% to your material order to account for waste, cuts, and defects.
Frequently Asked Questions
How many bags of stucco do I need for 400 sq ft?
For a 3-coat stucco system on metal lath: scratch coat = 11 bags, brown coat = 11 bags, finish coat = 7 bags = 29 bags total (80lb each). For one-coat: scratch + finish = 18 bags.
What is the difference between one-coat and three-coat stucco?
Three-coat stucco (scratch, brown, finish) totals 7/8" thick and is the traditional exterior system — very durable and weather-resistant. One-coat stucco applies a single 3/8" reinforced coat and is faster, less expensive, but thinner. Both are code-compliant for residential exteriors.
Can I apply stucco over existing stucco?
Yes — a rescore (scratch coat) and new finish coat can be applied over existing sound stucco. The existing stucco must be firmly bonded (no hollow spots), clean, and free of oil or paint. Spray lightly with water before applying new stucco to prevent the old surface from drawing moisture out of the new coat too quickly.
How long does stucco last?
Properly installed stucco on a wood-framed house lasts 50–80 years with minimal maintenance. Cracks should be sealed promptly with an elastomeric stucco patching compound to prevent water intrusion. In freeze-thaw climates, hairline cracks are normal and should be addressed every 5–10 years.