Shingle / Underlayment Calculator
Estimate roofing scope and budget in minutes.
Shingle Summary
Planning a reroof starts with numbers: how many shingles, how much underlayment, and what to budget for the parts most homeowners forget. A shingle underlayment calculator gives you a fast starting point, so calls and bids stay focused on the same scope.
You can use the free Shingle/Underlayment Calculator on our Shingle/Underlayment Calculator page to estimate quantities in minutes. This guide explains the inputs that matter, the add-ons the calculator can’t see, and the questions that lead to a clean, written estimate.
TL;DR: Use the calculator for a ballpark takeoff, then verify roof geometry, penetrations, and flashing details before you buy materials. Add a realistic waste factor and plan for underlayment overlap. When you’re ready for pricing, ask for an itemized written estimate.
Quick Checklist (Before You Price Anything):
- Confirm roof type (gable, hip, complex) and pitch.
- Gather roof area (sq ft) plus ridge and hip length.
- Count valleys, skylights, chimneys, and pipe penetrations.
- Choose shingle style (3‑tab or architectural) and ridge cap plan.
- Pick underlayment type and note roll coverage and overlaps.
- Set a waste factor and list accessories (flashing, drip edge, vents, disposal, permits).
Signs It’s Time For Shingle/Underlayment Calculator For Shingle Underlayment Calculator
| Decision | Why it matters | Quick check |
|---|---|---|
| Material system | Affects lifespan, cost, and appearance. | Confirm shingle/tile type, underlayment, and warranty. |
| Flashing & penetrations | Most leaks start at edges and penetrations. | Specify flashing at chimneys, vents, and valleys. |
| Ventilation | Controls heat/moisture and protects decking. | Confirm intake/exhaust balance and vent types. |
| Tear-off & decking | Hidden damage can change cost and timeline. | Include an allowance and photo documentation. |
If shingles are curling, cracking, blowing off in wind, or dropping granules into gutters, it’s time to price a full scope instead of chasing repairs. Also, Running a shingle underlayment calculator early helps you decide whether you’re looking at a small patch, a partial replacement, or a full reroof with new underlayment.
Situations Where A Quick Takeoff Helps
- You’re comparing 3‑tab shingles vs architectural shingles.
- You’re deciding between felt and synthetic underlayment.
- You’re adding skylights, also new vents, or roof mounts and want to budget flashing.
- You suspect more than one shingle layer and need to plan tear‑off and disposal.
- You want to sanity‑check bundle and roll counts before ordering.
What The Calculator Won’t Catch
The math is useful, but real roofs have details that move both cost and schedule.
- Hidden decking damage that shows up after tear‑off.
- Step flashing and counterflashing at chimneys, walls, and roof-to-wall transitions.
- Drip edge, starter strips, ridge vent parts, and specialty caps.
- Valley and eave protection requirements tied to roof design and product specs.
- Access constraints (steep pitch, tight staging) that affect labor and safety setup.
Hypothetical Before/After Snapshot (Anonymized Example)
Hypothetical example: A homeowner starts with repeated patch repairs after a minor leak, but brittle shingles keep cracking and the underlayment tears during spot fixes. For example, After running a takeoff, it’s clear the roof is small enough that a full replacement may be more practical than ongoing repairs.
After the upgrade, the scope includes new underlayment, refreshed flashing at penetrations, and correct ridge cap coverage—items that often get missed when homeowners only price bundles. For this reason, The bigger win is clarity: the work is documented and easier to maintain because every critical detail is addressed up front.
Small Roof Sections And Add-Ons
Small roof areas (porches, detached garages, patio covers, dormers) are where material estimates get distorted. In addition, Even a small plane can require extra overlap, starter, and edge metal.
- Expect higher waste on small, cut-up sections.
- Check transitions between steep and low-slope areas; they often need different materials.
- Don’t assume leftover bundles from a main roof fit a smaller add-on (color lots and product lines change).
If you’re budgeting multiple roof sections, price them as separate takeoffs first, then consolidate only after you confirm the materials match.
Common Upgrade Paths (What Changes Most) For Shingle Underlayment Calculator
Most reroofs aren’t just “new shingles.” Homeowners usually decide between a basic replacement and a longer-life system that upgrades underlayment, flashing, and ventilation at the same time.
Upgrade Choices That Change Performance
- Shingle profile: 3‑tab vs architectural shingles can change bundle counts, ridge cap needs, and overall appearance.
- Underlayment type: felt vs synthetic affects tear resistance, walkability, and how the roof handles short weather exposures during install.
- Valley approach: added membrane protection in valleys can reduce leak risk where water concentrates.
- Edge details: drip edge and starter strips help with wind resistance and clean roof edges.
- Flashing refresh: new pipe boots and correct wall/chimney flashing prevent the “new roof, old leak” problem.
- Ventilation: balancing intake and exhaust (ridge vent or other options) helps control heat and moisture in the attic.
- Decking allowances: a clear plan for replacing damaged sheathing avoids vague “we’ll see” pricing.
Roof Layout Planning For Accurate Takeoffs
Roof “layout” matters as much as square footage. As a result, A simple gable roof wastes less material than a hip roof with multiple dormers, even if both measure the same area.
- Map roof planes and note gable vs hip sections, dormers, and cut-up areas.
- Measure roof area (or calculate it from footprint and pitch) and convert to squares (100 sq ft).
- Record ridge and hip length; ridge cap and hip/ridge products are separate line items.
- Count valleys; valleys increase cuts, waste, and underlayment protection needs.
- Count penetrations (vents, pipes, skylights) so flashing is priced correctly.
- Set a waste factor that matches your roof complexity, not an “average” roof.
Bundle counts also vary by product, so confirm the packaging for your exact shingle line before you order.
Common Takeoff Mistakes That Skew Totals
- Using footprint area instead of actual roof area (pitch changes everything).
- Forgetting starter strip and ridge/hip cap quantities.
- Assuming every underlayment roll covers the same area.
- Underestimating waste on roofs with multiple valleys and dormers.
- Skipping accessories in the budget (flashing, vents, fasteners, edge metal, disposal).
- Treating a material-only estimate as an installed price.
Budget Ranges And Timeline (Typical)
US Construction & Remodeling Corp. Meanwhile, helps homeowners turn calculator totals into a buildable roofing scope: we confirm measurements on the roof, review shingle and underlayment options, and spell out the accessories that affect price. For this reason, Because we’re based in Sacramento and work throughout California, we keep permit and inspection steps on the radar from day one.
Request a written estimate and send any photos you have of the roof, attic access, and problem areas. Additionally, Include your address, the shingle style you’re considering, and whether you want options (good/better/best) in writing. Prefer a quick call first? For example, Reach us at +1 (916) 234-6696.
What To Prepare
- Any takeoff results you already have (squares, bundles, rolls).
- Roof type and complexity notes (dormers, multiple planes, steep areas).
- Known issues (active leaks, soft spots, prior repairs).
- Penetrations and features (chimney, skylights, solar mounts, vent type).
- Access constraints for staging and disposal (gates, parking, tight driveways).
Budget Ranges & Timeline (Typical)
- Budget: Installed reroofs in California vary widely; many single-family homes land roughly in the $10,000–$30,000+ range depending on size, pitch, layers, and repairs.
- Material-only vs installed: calculator totals still need add-ons like starter, ridge cap, flashing, vents, fasteners, disposal, and delivery.
- On-site time: many straightforward tear‑off-and-replace jobs take 1–3 working days; permitting, inspections, and material lead times can add calendar time.
- Big cost drivers: complex geometry, multiple layers, or decking replacement can extend both schedule and budget, so ask how those items are handled in writing.
| Decision / input | What to verify | What it changes |
|---|---|---|
| Roof shape | Gable vs hip, dormers, valleys | Waste factor, ridge/hip cap quantities |
| Pitch | Steep sections and access | Labor, staging, safety setup, waste |
| Shingle type | 3‑tab vs architectural, ridge cap type | Bundle counts, accessory line items |
| Underlayment choice | Felt vs synthetic, roll coverage | Roll quantity, overlap assumptions |
| Valley / edge protection | Membrane needs at valleys/eaves | Extra material, install steps, schedule |
Resale And ROI Priorities
A new roof can support resale value, but buyers and inspectors usually care about details more than the shingle label. Overall, Focus on what’s easy to verify and hard to fake.
- Itemized scope that lists underlayment type, flashing replacement, and ventilation plan.
- Permit and inspection sign-off paperwork when required for your jurisdiction.
- Photos of key details (valleys, penetrations, drip edge) before the job is closed out.
- Clear warranty terms for both materials and workmanship (no vague promises).
Maintenance Tips After Installation
- Clean gutters and downspouts so water doesn’t back up under the edge.
- Trim tree limbs that scrape shingles or drop heavy debris onto valleys.
- Check flashing after storms; most roof leaks start at penetrations and transitions.
- Keep attic ventilation clear; blocked intake vents can trap heat and moisture.
- Address small issues quickly (a loose pipe boot is cheaper than deck repairs).
Frequently Asked Questions
It’s only as accurate as the measurements and assumptions you feed it. Roof pitch, the number of planes, valleys, and the waste factor can move totals quickly.
- Use it to estimate quantities and compare options.
- Before ordering, confirm ridge/hip length, penetrations, and underlayment roll coverage for your exact products.
- For installed pricing, request an itemized scope that includes flashing, ventilation, disposal, and permit responsibility.
Start with total roof area and roof pitch. After that, the details that usually change totals are ridge/hip length, valleys, and penetrations.
- Total roof area (sq ft) or roofing squares (100 sq ft).
- Pitch (or at least “low / moderate / steep”).
- Ridge length and hip length for cap quantities.
- Number of valleys and major transitions.
- Penetrations: pipes, skylights, chimneys, roof-to-wall lines.
Both can work when installed correctly. Your choice usually comes down to durability, exposure time during install, and how the product pairs with your shingle manufacturer’s requirements.
- Felt: commonly used, familiar install, but can tear more easily.
- Synthetic: typically stronger and more stable underfoot; roll coverage varies by product.
Ask your contractor to specify the underlayment type in writing and confirm it matches the shingle warranty and local requirements.
Waste depends on roof complexity. A simple gable roof wastes less than a hip roof with dormers and multiple valleys.
- Simple roofs: often 10–15% waste.
- Cut-up roofs (dormers/valleys/hips): often 15–20% waste.
Underlayment also needs overlap, so roll quantities can run higher than a straight area calculation.
In many California jurisdictions, removing and replacing a roofing system requires a building permit, but requirements vary by city and county. Confirm rules for your exact address before work starts.
- Ask who pulls the permit and schedules inspections.
- Make sure the estimate states what happens if decking repairs change the scope.
If you’re in Sacramento, permit status is commonly tracked online through the city’s Accela Citizen Access portal.
Look for a scope you can compare line by line, not a single lump-sum number with missing details.
- Tear-off scope, disposal plan, and number of existing layers assumed.
- Shingle type and all accessories (starter, ridge/hip cap, vents).
- Underlayment type and where added membrane protection is included.
- Flashing replacement details at penetrations and transitions.
- Decking repair pricing method (allowance or unit price).
- Permit responsibility, inspection steps, and a realistic schedule window.
Explore the full service overview
If you want the big-picture process, pricing factors, and what to expect, start here: Roofing Remodeling (Landing Page).
Frequently Asked Questions
It’s only as accurate as the measurements and assumptions you feed it. Roof pitch, the number of planes, valleys, and the waste factor can move totals quickly.
- Use it to estimate quantities and compare options.
- Before ordering, confirm ridge/hip length, penetrations, and underlayment roll coverage for your exact products.
- For installed pricing, request an itemized scope that includes flashing, ventilation, disposal, and permit responsibility.
Start with total roof area and roof pitch. After that, the details that usually change totals are ridge/hip length, valleys, and penetrations.
- Total roof area (sq ft) or roofing squares (100 sq ft).
- Pitch (or at least “low / moderate / steep”).
- Ridge length and hip length for cap quantities.
- Number of valleys and major transitions.
- Penetrations: pipes, skylights, chimneys, roof-to-wall lines.
Both can work when installed correctly. Your choice usually comes down to durability, exposure time during install, and how the product pairs with your shingle manufacturer’s requirements.
- Felt: commonly used, familiar install, but can tear more easily.
- Synthetic: typically stronger and more stable underfoot; roll coverage varies by product.
Ask your contractor to specify the underlayment type in writing and confirm it matches the shingle warranty and local requirements.
Waste depends on roof complexity. A simple gable roof wastes less than a hip roof with dormers and multiple valleys.
- Simple roofs: often 10–15% waste.
- Cut-up roofs (dormers/valleys/hips): often 15–20% waste.
Underlayment also needs overlap, so roll quantities can run higher than a straight area calculation.
In many California jurisdictions, removing and replacing a roofing system requires a building permit, but requirements vary by city and county. Confirm rules for your exact address before work starts.
- Ask who pulls the permit and schedules inspections.
- Make sure the estimate states what happens if decking repairs change the scope.
If you’re in Sacramento, permit status is commonly tracked online through the city’s Accela Citizen Access portal.
Look for a scope you can compare line by line, not a single lump-sum number with missing details.
- Tear-off scope, disposal plan, and number of existing layers assumed.
- Shingle type and all accessories (starter, ridge/hip cap, vents).
- Underlayment type and where added membrane protection is included.
- Flashing replacement details at penetrations and transitions.
- Decking repair pricing method (allowance or unit price).
- Permit responsibility, inspection steps, and a realistic schedule window.
