Comparison

Span Calc vs RedX Decks

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Span Calc

Calculate maximum horizontal spans for wood joists and rafters using various lumber species and grades. Compares multiple options for common loading conditions based on NDS® standards.

Highlights
  • Calculates joist and rafter spans
  • Supports all softwood and hardwood lumber
  • Uses 2021 NDS® for Wood Construction
  • Compares multiple species and grades
  • Handles common loading conditions
Features
Read full description

The American Wood Council (AWC) Span Calculator for Wood Joists and Rafters (Span Calc) performs calculations for all species and grades of commercially available softwood and hardwood lumber as found in the 2021 National Design Specification® (NDS®) for Wood Construction. Joists and rafter spans for common loading conditions can be determined. A span options calculator allows selection of multiple species and grades for comparison purposes. Supported by the Softwood Lumber Board. Maximum horizontal spans for joists and rafters are calculated based on the following assumptions and conditions: · Joists and rafters are oriented to support vertical loads applied to the narrow (1.5 in. thick) face of the member, resulting in strong-axis bending. · At least three joists or rafters are installed parallel to one another and spaced not more than 24 inches on-center, with properly designed sheathing attached on the top (compression) edge of each joist or rafter. · Joists and rafters are single-span with adequate structural support at each end. The Span Calculator does not address cantilevered joists and rafters, multiple-span joists and rafters, or spliced joists and rafters. · For joists and rafters, most building codes specify a minimum bearing length of 1.5 inches on wood or metal and not less than 3 inches on masonry or concrete. These minimum bearing lengths are to be used in the absence of calculated bearing lengths. Consult the local building code for specific requirements. · Joists and rafters carry only combinations of dead load plus live load (D + L), dead load plus snow load (D + S), or dead load plus roof live load (D + Lr). The Span Calculator does not address wind load or seismic load. · Buildings in regions with ground snow loads greater than 70 psf should not use the prescriptive provisions of the governing building code without approval of the authority having jurisdiction. Buildings in these high snow zones should be designed in accordance with accepted engineering practice. While every effort has been made to insure the accuracy of the information presented, and special effort has been made to assure that the information reflects the state-of-the-art, neither the American Wood Council nor its members assume any responsibility for any particular design prepared from this Span Calculator application. Those using this Span Calculator assume all liability from its use.

About

RedX Decks

Design and visualize complex deck structures, including roofs and stairs, with automatic framing and structural calculations. Generate professional, permit-ready blueprints and detailed material lists for efficient construction.

Highlights
  • 3D deck and roof design
  • Automatic framing layouts
  • Structural calculations
  • Permit-ready blueprints
  • Material and cut lists
  • 3D visualization and renders
Features
Read full description

Design decks. Add roofs. Generate permit ready blueprints. RedX Decks is powerful deck design software for contractors, designers, and serious DIY builders. Create structurally sound decks, add roof-over-deck systems with beams and posts, and generate professional construction drawings in minutes. Build straight, wraparound, gazebo, L-shaped, U-shaped, freestanding, multi-level, or fully custom decks with automatic framing layouts and structural calculations. Decks With Roof Structures Design: • Roof over deck systems • Post and beam covered decks • Gazebo roofs • Decks with integrated stairs and railings • Multi-level structural framing Create complete deck and roof framing plans including beams, joists, posts, and railing systems. Permit Ready Blueprints Generate professional PDF construction drawings: • Joist and beam layout plans • Elevation blueprints • Framing layouts • Post and railing layouts • Stair stringer plans • Structural load calculations • Detailed material and cut lists Perfect for permit applications, contractor submissions, inspections, and client presentations. Automatic Structural & Framing Layout RedX automatically calculates: • Deck tributary areas • Beam sizing logic • Joist and beam placement • Load distribution • Structural checks Automatically generate: • Beam layouts • Joist layouts • Divider boards • Joist blocking • Post spacing • Stair framing Adjust spacing, deck load, materials, and wood species to match your project requirements. 3D Visualization & High-Quality Renders View your deck and roof structure in realistic 3D. Rotate, zoom, and inspect every component before building. Export high-resolution render images for client presentations, marketing, social media, or permit documentation. Complete Material & Cut Lists Get accurate: • Lumber quantities • Cut lists • Fastener estimates • Material summaries Reduce waste and build with confidence. Built for decks attached to a house or fully freestanding structures — from simple backyard builds to covered roof-over-deck systems. Download RedX Decks and start creating permit ready deck and roof blueprints today. Terms of Use (EULA) https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ RedX Apps Terms of Service https://www.redxapps.com/terms-of-service In-App Purchases Available Premium Monthly and Yearly subscriptions unlock advanced features. Payment is charged to your iTunes account and renews automatically unless turned off at least 24 hours before the end of the current period. Manage subscriptions in your App Store settings. Current pricing starts at $6.99 USD/month or $59.99 USD/year. Prices may vary by region and are subject to change. Active subscriptions cannot be canceled during the billing period.

Screenshots

Span Calc4 screens
RedX Decks4 screens

Verdict

The call

The clearest difference is rating: RedX Decks at 4.3 against Span Calc's 2.9. RedX Decks also leads on ratings volume (528 vs 15). Span Calc's advantage is in-app purchases (none vs 10). On price, review sentiment, update cadence and ads there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. RedX Decks sells 9 in-app purchases, starting at $6.99 per month. Span Calc asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

RedX Decks holds the better App Store score, 4.3 against 2.9. That said, the two scores are not equally well evidenced: RedX Decks has 528 ratings behind it against 15, so its average is the more settled of the two. Written reviews point the same way: 30% of Span Calc's written reviews are positive against 31% of RedX Decks's.

UpkeepUpdate frequency

Both ship on a similar rhythm, roughly every 10 days. The most recent releases landed on October 12, 2026 and October 14, 2026 respectively.

Scorecard4 real differences · 6 level
Span Calc versus RedX Decks: the parameters behind the verdict, then further details
ParameterSpan CalcRedX Decks
PriceFreeFree
Rating2.9 (15 ratings)4.3 (528 ratings) — better
Positive reviews29.6% of reviews30.8% of reviews — better
Number of ratings15528 — better
Update frequencyEvery 10 daysEvery 10 days
AdsNoNo
In-app purchasesNo — betterYes
MonetizationFree — betterFree with in-app purchases
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS14.2 — better15.6
Further details — not scored
Size168 MB177 MB
Age rating17+4+
DeveloperAmerican Wood CouncilRedX Technology Inc

Customer experience

Span Calc

All ratings15 ratings
Positive53.3%
Neutral0.0%
Negative46.7%
Written reviews27 reviews
Positive29.6%
Neutral11.1%
Negative59.3%

RedX Decks

All ratings528 ratings
Positive82.8%
Neutral3.0%
Negative14.2%
Written reviews39 reviews
Positive30.8%
Neutral5.1%
Negative64.1%

In-app purchases

None

Span Calc

No in-app purchases

9 purchases

RedX Decks

Subscriptions6
  • RedX Decks Pro$6.991 Month
  • RedX Apps Pro++ Monthly$9.991 Month
  • RedX Apps Pro++$59.991 Year
Show 3 more
  • RedX Decks Pro7 Days trial$89.991 Year
  • RedX Decks Pro7 Days trial$119.991 Year
  • RedX Apps Bundle1 Year trial2 variants$179.991 Year
One-time3
  • 20 Render Credits$9.99
  • 100 Render Credits$29.99
  • 200 Render Credits$44.99

Questions

Is Span Calc free?
Span Calc is free to download, with no in-app purchases.
Is RedX Decks free?
RedX Decks is free to download, with in-app purchases available.
Which has better reviews, Span Calc or RedX Decks?
RedX Decks is rated higher. Span Calc averages 2.9 out of 5 from 15 ratings, while RedX Decks averages 4.3 from 528 ratings.
Do Span Calc or RedX Decks have ads?
Neither Span Calc nor RedX Decks shows ads.
Which is updated more often, Span Calc or RedX Decks?
Span Calc ships an update every 10 days, and RedX Decks every 10 days. Most recently, Span Calc was updated on October 12, 2026 and RedX Decks on October 14, 2026.

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