Roofing calculator

Ice and water shield

Self-adhered ice-and-water roll count from eave length, coverage up the roof and valley length.

Reviewed formula · v1.0.0

Project inputs

Enter field measurements. Imperial lengths take feet and inches. Unit conversion happens before the reviewed formula is applied.

Eave lengthft + inTotal eave run that needs ice-and-waterftinCoverage up the roofft + inHow far the membrane runs up from the eave. 3 ft is a common cold-climate planning figure — confirm local codeftinValley lengthft + inTotal valley run also covered at the same width. Enter 0 if noneftinRoll coverageft²Net coverage of one roll after laps. A common 2-square roll is 200 ft²Waste factor%Allowance for laps, starter and cuts

All values can be refined when you edit the estimate. This tool does not replace field verification or local requirements.

Calculated result

2rolls

Rolls to order

FormulaROOF-IWS-001

(eave + valley) × coverage up the roof × (1 + waste) ÷ roll coverage

252 ft²

Membrane area

277.2 ft²

Area including waste

Transparent cost view

Planning rates only. Pick a currency — badges, inputs, and totals follow. Material is a rate. Labour is hours × a planning hourly rate. Equipment and delivery are this-job amounts.

Material ratePlanning · per calculated unit · USDEquipmentPlanning · this job · USDDeliveryPlanning · this job · USDLabour hoursPlanning · this jobLabour ratePlanning · per hour · USDOverhead %%Contingency %%Markup %%Tax %%

Planning defaults are office figures, not a bid. US ready-mix in 2026 often lands around $125–165 per cubic yard delivered; place-and-finish commonly $2–4 per square foot. Replace every rate with a supplier or crew quote before you send the letter.

Indicative FX as of Aug 2026. Planning conversion, not a live bank rate.

Material costUSD 170

Labour (8 h)USD 280

Direct costUSD 560

Overhead + contingencyUSD 56.00

Markup + taxUSD 73.92

Estimated project totalUSD 690

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<iframe src="https://construclytic.com/embed/ice-and-water" title="Ice and water shield" width="100%" height="820" loading="lazy" referrerpolicy="strict-origin-when-cross-origin" style="border:1px solid #d7e0da;border-radius:16px;background:#fff;"></iframe>

Paste on a contractor site or blog. The iframe is a planning takeoff, not a bid.

How this calculator works

A transparent ice and water shield takeoff.

Multiply eave length by how far the membrane runs up the roof, add valley length at the same width, then divide by net roll coverage after a visible lap allowance.

Worked example. Example: 60 ft of eave with 3 ft of coverage plus 24 ft of valley is 252 ft². A 200 ft² roll with 10% waste rounds to 2 rolls.

1. Measure every eave that needs the membrane, including porches if they are in the spec.
2. Enter how far up the roof the product must run. That is a code and climate input, not a default you should leave blind.
3. Add valleys, around skylights and at wall intersections as extra length.

Need the broader workflow? Read the roofing planning guide.

Questions

Questions about ice and water shield

Is 3 ft the code width?

No. It is a common cold-climate planning figure. Local code may want 24 in inside the wall line, or from eave to a stated distance. Confirm before you order.

Is this underlayment?

Ice-and-water is a self-adhered membrane at eaves and valleys. Field underlayment is a different roll — use the underlayment calculator for the rest of the roof.

What is the formula ID?

This calculator publishes formula ROOF-IWS-001, version 1.0.0. The ID stays on the result and on the estimate line.

Is this engineering advice?

No. Construclytic is a planning website, not a registered engineering or contracting firm. Field checks, codes and product data still sit with you.

Does Construclytic fetch live supplier prices?

No. Costs use the rate you enter. Construclytic does not fetch live supplier prices.