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iGUIDE Measurements and Drafting Standards

Updated

Overview

iGUIDE ensures square footage measurement accuracy by following industry-recognized standards including Alberta's Residential Measurement Standard (RMS) and ANSI Z765. These standards support consistent, reliable data reporting and provide a defensible basis for comparing iGUIDE measurements against other sources.

This article explains how iGUIDE achieves measurement accuracy, how to interpret discrepancies between sources, what falls outside the iGUIDE Drafting Standard and important notes about how rooms and totals are calculated.

In This Article

Measurement Accuracy in iGUIDE 

Measurement accuracy in iGUIDE refers to the high level of precision used when calculating square footage and other dimensions of a property. iGUIDE follows the Alberta Residential Measurement Standard (RMS), adapted from the ANSI Z765-2013 standard — among the most comprehensive measurement protocols in North America.

iGUIDE's laser-based camera system delivers a low margin of error — about 1% for square footage — comfortably meeting or exceeding the 2% uncertainty allowed by both RMS and ANSI standards. All measurements are standardized and legally defensible, making iGUIDE data a trusted source in real estate transactions.

Download our full Drafting Standard & Policy here. 

Disputes about square footage

iGUIDE square footage is sometimes compared to numbers from other sources, raising questions about reliability. Several factors should be considered before drawing conclusions.

Different measurement methodologies produce different totals. Methods primarily differ in which spaces are excluded from the reported square footage and how features such as sloped attic ceilings or shared demising walls are handled. The iGUIDE method follows the Alberta RMS, which is currently the most comprehensive standard in North America. Alberta RMS is based on ANSI Z765-2013 for single-family houses and extends it to condos and apartments in multi-family residential buildings. It was created because municipal tax record values are produced without a prescribed standard, making cross-property comparisons unreliable.

Every real measurement also has an associated uncertainty. The iGUIDE camera measures wall distances to within 1 cm of uncertainty. For a typical house, this can mean up to 5 cm of uncertainty across the whole house when several rooms are stacked, or about 0.5% for distance measurements at that floor size. The resulting square footage uncertainty is about 1% (double the distance uncertainty). When comparing measurements:

  1. Differences smaller than 1% (about 25 sq ft for a 2,500 sq ft house) are below measurement noise and should be ignored
  2. If the difference exceeds 1%, the second number's uncertainty must be examined and combined with iGUIDE's
  3. Combined uncertainty is calculated as the square root of the sum of squared uncertainties — for example, 1% and 3% combine to 3.16%
  4. If no uncertainty is available for the second source, iGUIDE should be presumed to be the most accurate measurement

Both Alberta RMS and ANSI call for a maximum allowed measurement uncertainty of 2% — iGUIDE technology meets and exceeds these requirements.

Reviewing iGUIDE Numbers for Accuracy

The Drafting Team follows a Quality Assurance process that thoroughly checks every iGUIDE before it is uploaded to the Portal, ensuring all floors are drafted correctly. If you suspect a discrepancy:

  1. Provide specific details about where you believe a discrepancy may lie so the team can investigate
  2. Use the on-screen measuring tool in the iGUIDE to measure anywhere on the floor plan
  3. Refer to the arrows in PDF floor plans, which indicate the dimensions of each room and where measurements start and end
  4. Use the colour coding — coloured areas are included in the total square footage, while white space is excluded

Why iGUIDE Differs from Tax Records

Tax record square footage is not considered an accurate total unless the numbers have been independently verified. The measurements are calculated from an estimation of the outside of the structure. The estimator often has not entered the building and may not be aware of areas that should be excluded from interior square footage — such as areas open to below, cold rooms, or differences between the first and second floor footprints.
 

Why iGUIDE Differs from a Builder's Floor Plan

A builder's floor plan describes what the builder intended to build (build-as). Changes occur during construction for many reasons, and the resulting floor plans may differ from the original blueprints. iGUIDE floor plans describe what was actually built (as-built) and what a real estate agent is selling.

After construction is complete, it is recommended that an independent company verify room dimensions and total square footage, as they may differ significantly from the original builder's plans. Builders use floor plans to sell unbuilt homes and typically include disclaimers for potential deviations in the sales contract.

Requests Outside the iGUIDE Drafting Standard

The Drafting Team drafts every property according to the iGUIDE Drafting Standard. Photographers can leave the team a note in the uploaded data indicating a special request, and requests can also be made after an iGUIDE is completed.

If a special request that goes against the iGUIDE Drafting Standard is fulfilled, the requester assumes responsibility if the measurements are later brought into question. Charges may apply depending on the request.

Use Cases for iGUIDE Measurements

iGUIDE measurements support a range of professional use cases:

  1. Accurate residential measurements — real estate professionals in Alberta rely on iGUIDE to comply with RMS, ensuring consistent measurements across complex properties such as condos and multi-family units
  2. Visual identification of GLA — iGUIDE floor plans use colour for finished (included) spaces and white for unfinished or excluded areas, making it easy to determine what counts toward Gross Living Area
  3. GLA reporting based on ANSI Z765 — GLA is equivalent to Finished Above Grade area and can be clearly viewed in imperial PDF floor plans

Custom RMS Compliance Tools

iGUIDE users can customise reports for RMS compliance using the following tools.

Append Measurement Diagrams to PDFs:

  1. In iGUIDE Defaults — go to User Settings > iGUIDE Defaults > iGUIDE Viewer > Other Options > Append Measurement Diagrams to PDF (Alberta) > Save
  2. In a specific iGUIDE — go to Search My iGUIDEs > Edit > Options > Append Measurement Diagrams to PDF (Alberta) > Save

Add Custom Text to PDF reports (such as surveyor confirmations or area instructions):

  1. In iGUIDE Defaults — go to User Settings > iGUIDE Defaults > iGUIDE Viewer > Default PDF Custom Text > Save
  2. In a specific iGUIDE — go to Search My iGUIDEs > Edit > Custom Text for PDF > Save

Insert Additional Notes to clarify total areas and measurement responsibilities:

  1. In iGUIDE Defaults — go to User Settings > iGUIDE Defaults > iGUIDE Report > Default Report Notes > Save
  2. In a specific iGUIDE — go to Search My iGUIDEs > iGUIDE Report > Additional Notes > Send

Important Notes

Keep these points in mind when reviewing iGUIDE measurements:

  1. Uncertainty exists across all measurements — differences in square footage below 1% are considered insignificant, and larger discrepancies require knowledge of the comparison method's margin of error
  2. Varying standards lead to misleading comparisons — municipal tax records or alternative measurements may not follow a consistent or recognised standard, while iGUIDE's adherence to ANSI/RMS ensures consistency
  3. Room height rules apply — finished rooms must have a minimum floor-to-ceiling height of 7 ft (2.1 m), and rooms with sloped ceilings are only included if the ceiling exceeds 7 ft in at least one spot, measured from 5 ft (1.5 m)
  4. Perimeter wall thickness is measured once, usually at the main entrance, and is not adjusted for variations around the property
  5. The sum of listed room areas will not add up to the total square footage — the property details section shows dimensions for major rooms only, measured paint-to-paint, while total floor area includes all floor plans except non-habitable or excluded spaces; rounding may cause about a 1 sq ft difference
  6. Multiplying room width by length will only give an accurate floor area for perfectly rectangular rooms — most rooms have more complex shapes, so iGUIDE uses precise measurements rather than length × width

Frequently Asked Questions

Q: Why is my square footage different from another source?
A: Differences often stem from the use of different measurement standards or unknown uncertainty margins. iGUIDE’s 1% margin of error is exceptionally low and should be the benchmark for reliability.

Q: Why are some rooms shown in white on the floor plan?
A: White indicates excluded or non-reported areas. This could be due to unfinished space, insufficient ceiling height, or space being open to below.

Q: Why weren’t room dimensions included for all rooms?
A: Only major rooms have dimensions shown. Minor rooms (e.g., foyers, closets) are hidden to maintain clarity, but this data is available on the Portal.

Q: Can iGUIDE accommodate varying wall thicknesses?
A: Wall thickness is measured once and applied uniformly. It does not adjust dynamically for variations.

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