# CRSI Rebar Reference vs Duct Construction

The clearest difference is price: CRSI Rebar Reference at Free against Duct Construction's $0.99. CRSI Rebar Reference also leads on rating (3.3 vs 1.0) and review sentiment (33% vs 0%). Duct Construction's advantage is in-app purchases (none vs 3) and chart position (#194 vs unranked). On ads and device support there is nothing between them.

CRSI Rebar Reference is free to download; Duct Construction costs $0.99 up front. CRSI Rebar Reference sells 3 one-off in-app purchases. Duct Construction asks for nothing beyond the download.

CRSI Rebar Reference holds the better App Store score, 3.3 against 1.0. That said, the two scores are not equally well evidenced: CRSI Rebar Reference has 16 ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 33% of CRSI Rebar Reference's written reviews are positive against 0% of Duct Construction's.

CRSI Rebar Reference ships an update every 5 weeks, Duct Construction every 10 months. The most recent releases landed on June 1, 2026 and September 9, 2026 respectively.

## The numbers

| Metric | CRSI Rebar Reference | Duct Construction |
| --- | --- | --- |
| Price | **Free** | $0.99 |
| Rating | **[3.3 (16 ratings)](https://appshunter.io/ios/app/crsi-rebar-reference/id1423271565/reviews)** | [1.0 (1 ratings)](https://appshunter.io/ios/app/duct-construction/id6443518338/reviews) |
| Number of ratings | **16** | 1 |
| Positive reviews | **33.3% of reviews** | 0.0% of reviews |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 5 weeks** | Every 10 months |
| Monetization | **Free** | Paid |
| Best chart rank | — | **#194** |
| Size | 51 MB | 1 MB |
| Requires iOS | **15.1** | 17.6 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 17+ | 4+ |
| Developer | [Concrete Reinforcing Steel Institute](https://appshunter.io/developer/1423271564) | [Wassim Murr](https://appshunter.io/developer/1474939474) |

## What reviewers say

### CRSI Rebar Reference

[App page](https://appshunter.io/ios/app/crsi-rebar-reference/id1423271565)

Access essential data for reinforcing bars (rebar) including specifications, hook details, and marking requirements. This app serves as a quick reference for industry standards and links to online resources.

**Highlights:** ASTM standard reinforcing bar specifications, Standard hook details (90, 135, 180 degrees), Stirrup/tie hook details, ASTM reinforcing bar marking requirements, Minimum yield and tensile requirements, Links to CRSI online resources

**Features:** macOS Compatibility

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| CRSI - Rebar Identifier Module | $2.99 | one-time |
| CRSI Development Length ACI | $4.99 | one-time |
| CRSI Development length AASHTO | $4.99 | one-time |


### Duct Construction

[App page](https://appshunter.io/ios/app/duct-construction/id6443518338)

**Currently charting:** #194 Top Paid · Productivity (US App Store)

This app helps determine duct construction and reinforcement options based on duct size and system pressure class. It provides condensed lists of suitable options, saving time spent on manual calculations and table lookups. Results are based on industry standards for galvanized steel duct sheets.

**Highlights:** Duct size range from 2" to 120", Pressure classes up to 4 in.wg, Calculates duct weights per linear foot, Determines required duct gauge and reinforcement spacing, Clear illustrations for reinforcement types, Simple and effective UI design

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is CRSI Rebar Reference free?

CRSI Rebar Reference is free to download, with in-app purchases available.

### Is Duct Construction free?

Duct Construction costs $0.99, with no in-app purchases.

### Which has better reviews, CRSI Rebar Reference or Duct Construction?

CRSI Rebar Reference is rated higher. CRSI Rebar Reference averages 3.3 out of 5 from 16 ratings, while Duct Construction averages 1.0 from 1 ratings.

### Do CRSI Rebar Reference or Duct Construction have ads?

Neither CRSI Rebar Reference nor Duct Construction shows ads.

### Which is updated more often, CRSI Rebar Reference or Duct Construction?

CRSI Rebar Reference ships an update every 5 weeks, and Duct Construction every 10 months. Most recently, CRSI Rebar Reference was updated on June 1, 2026 and Duct Construction on September 9, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*