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How to Measure for Window Bars: Step-By-Step with Photos

Rental properties face unique risks: ground-floor and garden-level windows, alley-facing glass, frequent turnovers, and periods when units sit vacant. Window bars are a proven deterrent when used correctly—especially alongside lighting, quality locks, and good visibility. This guide shows landlords how to map risk, decide interior vs exterior placement, pick frame vs wall-mount, and choose quick-release bars for egress windows. We also outline a simple rollout plan across multiple units using SWB’s modular & telescopic system, so you can standardize SKUs, speed installs, and keep costs predictable.

Tools you’ll need

Tape measure (inches)

Pencil/marker & notepad (or phone notes)

Level (optional, helpful for wall-mount)

Camera/phone for quick photos

Step-by-step measuring

Tip: Take three width measurements (top/middle/bottom) and two height measurements (left/right). Record the smallest numbers for sizing.

Step 1 — Measure clear width (W)

Measure inside the opening from left jamb to right jamb (tight points).
Take measurements at top, middle, and bottom; write down the smallest.

Step 2 — Measure clear height (H)

Measure from the sill to the head where the bar will sit.
Measure on the left and right; record the smallest.

Check obstructions

Note crank handles, locks, blinds, shades, security sensors, or trim that project into the opening.
If planning a quick-release (egress), confirm you’ll have a clear swing path.

Step 4 — Identify your mount surface

Frame-mount: into the window frame/jamb.
Wall-mount: into surrounding wall (studs, brick, or block)—best for masonry or out-of-square frames.

Confirm interior vs exterior location

Interior: easier quick-release access; protected from weather.
Exterior: more visible deterrence; plan for weather and proper anchors.

Step 6 — Record everything

Write down: W (in), H (in), mount type (frame/wall), location (interior/exterior), obstructions, and whether this window is egress.

Match telescopic height & plan modular width

A) Pick your telescopic height range

Choose the range that comfortably covers your H (avoid maxing out the adjustment if you can).

B) Plan your width with modules

Start with one core module. Add modules side-by-side until you cover your W (center the assembly on the opening).

Quick module planning (rule of thumb):

48–60″ wide window: Core + 1 module
60–72″ wide window: Core + 1–2 modules
72–79″ wide window: Core + 2–3 modules (typical max span)
Wider than ~79″? Split into two adjacent assemblies or ask us for a layout.

Not sure? Send W × H, a photo, and your mount choice via Buy Direct—we’ll spec the kit.

Frame-mount or wall-mount?

Frame-mount (Model A or B)

Clean look, minimal standoff
Use when jambs are solid, plumb, and square

Wall-mount (Model B recommended)

Ideal for brick/block/stucco or out-of-square frames
Keeps long runs straight (great for sliders).

Do you need a quick-release (egress)?

If the window is a required emergency exit (bedrooms, some basements), choose Emergency-Exit. Plan a clear swing path, install per guide, and test the release after mounting (then monthly).

Sample measurements (worked examples)

Example A — Basement egress, 35″ W × 52″ H (interior, frame-mount)

Telescopic height: choose range covering 52″ H (not fully extended).
Width: Core + 1 module to reach ~35″ W with clean centering.
Model: Emergency-Exit; confirm swing clears blinds/furniture.

Example B — Living room slider, 72″ W × 48″ H (exterior, wall-mount on brick)

Telescopic height: range covering 48″ H.
Width: Core + 2 modules; wall-mount to keep long span level.
Model: Model B, or Emergency-Exit if treated as egress.

Example C — Narrow bath window, 26″ W × 42″ H (interior, frame-mount)

Telescopic height: range covering 42″ H.
Width: Core only or Core + 1 small module for perfect centering.
Model: Model A.

Common measuring mistakes (avoid these)

Measuring trim-to-trim instead of the clear opening
Using the largest numbers instead of the smallest
Forgetting to check handles/blinds that reduce clearance
Over-relying on telescopic height instead of adding a module for width
Ignoring the mount surface (stucco/drywall needs structure behind it)
Ordering fixed bars for an egress window (use quick-release)

Printable checklist

Width (W) at top/middle/bottom → record smallest

Height (H) left/right → record smallest

Obstructions: handles, blinds, sensors, trim

Mount: frame-mount or wall-mount

Location: interior or exterior

Egress? If yes → pick Emergency-Exit and plan swing test

Module plan for width (Core + ___ modules)

Photos attached (front, side, substrate close-ups)

Next steps (order with confidence)

Use your numbers to pick a telescopic height and module count.
Decide frame vs wall-mount (Model A supports both; Model B emphasizes wall-mount).
If egress, select Emergency-Exit and plan a post-install test.
Buy Direct & Save or send measurements & a photo for a same-day recommendation.
When your kit arrives, follow Install Guides for anchors and torque specs.