Waste, material costs, and pitch

Three settings - waste, material pricing, and (for roof/loft work) pitch - decide how the app turns a plan measurement into a quantity you can actually order. Set them on each component once and every quote stays consistent.

Waste

Insulation almost always has some waste:

• Batts and rolls - 5-10% covers offcuts at edges, around penetrations, and between irregular joists. 7% is a sensible default.
• Blown / loose-fill - 5-8% to allow for settling and slight overfill in tight corners.
• Vapour barrier / membrane - 8-12% because of overlaps and tears at junctions.
• Edge tape / sealing bead - either a small percentage or a fixed allowance per quote.

Set waste against each component so it applies automatically every time you use that component.

Material price and pack sizing

How a product is sold determines how the app converts measurement to order quantity. Get this right and you stop over- or under-ordering.

• Pack by area - e.g. a roll covers 6.84 m². The app divides plan-adjusted area (after waste and pitch) by 6.84 and rounds up.
• Pack by length - a roll is x metres long. Useful for vapour barrier sold by linear metre at a fixed width.
• Pack by count - x bags per pallet for blown insulation, or x batts per pack.
• Single unit - per-bag or per-pack price where one unit equals one pack.

Use realistic pack sizes from your supplier - it's the single biggest driver of accurate material cost.

Pitch calculation (roof / loft)

When you measure a loft or roof space from a floor plan, you're seeing the plan area, not the actual slope area where the insulation sits between or over rafters. Turning on the pitch multiplier corrects for that.

Only rafter pitch is supported. Valley and hip pitches are not used for insulation - they don't apply to the way batts and rolls are laid.

When to use it:

• Loft roll between rafters on a sloped roof.
• Insulation laid over rafters in a vaulted ceiling.
• Any roof-space insulation where the material follows the slope.

When to leave it off:

• Flat ceiling insulation laid on joists (the plan area is the actual area).
• Floor insulation.
• Wall insulation (use wall length × height instead).

A worked example

Loft roll 200mm laid between rafters on a 25° pitch roof:

• Plan loft area: 80 m²
• Rafter pitch multiplier (25°): ×1.103 → 88.2 m² actual slope area
• Waste at 8%: 88.2 × 1.08 = 95.3 m²
• Roll coverage: 6.84 m² per roll
• Order quantity: 95.3 ÷ 6.84 = 13.9 → 14 rolls

Same loft without the pitch multiplier turned on would have ordered 13 rolls and come up short.

Related

• Plan vs Actual
• Creating a component