How Many Satchels for a Stone Roof?

If you’re planning a stone-coated or stone-chip roof, one of the first questions is how many satchels for a stone roof you’ll need. Order too few and you’ll lose time (and often money) waiting for more; order too many and you’ll have waste and extra cost. The good news: with a few measurements and the coverage information on the product bag, you can calculate the right amount quickly.

What Exactly is a “Satchel”?

A satchel is simply the bag or package that the manufacturer sells the stone chips, granules, or ballast in. There is no universal amount of satchel, as it depends on the product and manufacturer. That is why the simplest method of calculation involves the actual coverage contained in the bag. 

How To Calculate: Step by Step

1. Measure your roof area (plan view).
   Walk the roof or use plans to get the total flat (plan) area in square metres or square feet.
2. Adjust for roof pitch.
   If the roof is sloped, multiply the plan area by a pitch factor (or add ~5–15% for typical pitches) to get the actual surface area.
3. Find coverage per satchel.
   Check the bag label or technical data sheet; it should list coverage in m² or ft² per satchel.
4. Do the math:
   • Base satchels = (Actual roof surface area) ÷ (Coverage per satchel)
   • Add waste allowance (use 5–10% for simple roofs; 10–15% for complex roofs with valleys, hips, or many cut pieces).
5. Round up to the nearest whole satchel; manufacturers don’t sell fractions.

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Example (Practical)

Let’s say your roof’s actual surface is 50 m² (after pitch adjustment). Here are three hypothetical coverage examples to illustrate:

• If one satchel covers 0.5 m²:
  • Base =
    50 ÷ 0.5 = 100 satchels
  • Add 10% waste =
    100 × 1.10 = 110 satchels (round up = 110)
• If one satchel covers 1.0 m²:
  • Base =
    50 ÷ 1.0 = 50 satchels
  • Add 10% waste =
    50 × 1.10 = 55 satchels
• If one satchel covers 2.0 m²:
  • Base =
    50 ÷ 2.0 = 25 satchels
  • Add 10% waste =
    25 × 1.10 = 27.5 → round up → 28 satchels

These are some of the reasons why you should apply the cover figure provided by the manufacturer; it would make the total very different. 

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Quick Checklist & Tips

• Read the bag label carefully and follow instructions. 
• Take into consideration roof pitch and intricacy (valleys, hips, dormers). 
• Order slightly more of the same batch/lot so that there will be no color or texture difference on subsequent deliveries. 
• Store receipts and unused satchels as an eventuality of repairs or similar requirements.

Final Thoughts

Asking how many satchels for a stone roof is smart, but the only reliable answer uses your roof area and the satchel’s stated coverage. Use the simple formula above, add a sensible waste allowance, and round up. If you’d like help measuring, checking product coverage, or getting a professional estimate, the team at ONLY Roofing can help! Contact us for a site visit or a quote!