Product Guides

Guide to Installing a Bay Window

Bay windows add space, natural light, and character to any home. But without proper support, they can sag over time — leading to cracks, drafts, and structural damage.

Installing bay window brackets (also called corbels or support brackets) strengthens the projection and improves the appearance of your home’s exterior.

This guide walks you through how to install bay window brackets safely and correctly, whether you’re upgrading old supports or fitting new ones.

Why Bay Window Brackets Are Important

Bay windows project outward from the main wall, meaning:

• They carry significant structural weight

• They’re exposed to weather

• They rely on proper support underneath

Brackets help:

• Prevent sagging

• Reduce stress on window frames

• Improve insulation performance

• Enhance curb appeal

If your bay window shows signs of dropping or cracking plaster internally, installing support brackets is essential.

Tools & Materials You’ll Need

Tools

• Tape measure

• Spirit level

• Masonry drill & drill bits

• Socket wrench or spanner

• Stud detector (for timber frame properties)

Materials

• heavy-duty bay window brackets

• Heavy-duty anchor bolts or frame fixings

• Exterior-grade sealant

• Weatherproof screws

Step 1: Assess the Bay Window Structure

Before installing brackets:

1. Check if the window has dropped (use a level internally and externally).

2. Inspect for cracks around the bay.

3. Measure the projection depth.

4. Identify fixing points (brickwork or structural timber).

If the window has significantly dropped, you may need professional lifting before bracket installation.

Step 2: Mark Out Bracket Positions

Spacing is critical for even weight distribution.

• Most bays require 2–4 brackets depending on width.

• Position brackets evenly beneath the load-bearing sections.

• Avoid placing them directly under weak trim or decorative fascia.

Mark the drill holes using the bracket as a template.

Step 3: Drill and Install Anchor Fixings

1. Drill pilot holes into brick or masonry.

2. Insert heavy-duty anchor bolts.

3. Position the bracket and loosely secure bolts.

4. Check alignment with a spirit level.

5. Fully tighten fixings once level.

⚠️ Always fix into solid masonry or structural timber — never into mortar joints alone.

Step 4: Seal and Weatherproof

After installation:

• Apply exterior sealant around fixing points.

• Ensure no water can enter behind the bracket.

• Check that drainage paths under the bay remain clear.

Weatherproofing prevents long-term corrosion and damp issues.

Step 5: Final Structural Check

Once installed:

• Re-check internal levels.

• Monitor for movement over the following weeks.

• Inspect annually as part of home maintenance.

Properly installed brackets should provide long-term stability and peace of mind.

Common Installation Mistakes to Avoid

• ❌ Fixing into weak mortar joints

• ❌ Using light-duty screws

• ❌ Uneven bracket spacing

• ❌ Ignoring early signs of structural drop

• ❌ Skipping sealant application

When to Call a Professional

Consider expert help if:

• The bay has dropped more than 10mm

• Brickwork is cracked or unstable

• You’re unsure where structural support is located

• The window is on an upper floor requiring scaffolding

Structural integrity is more important than a quick DIY fix.

Final Thoughts

Installing bay window brackets is one of the most effective ways to:

• Protect your property

• Prevent costly structural repairs

• Improve your home’s exterior finish

With careful measuring, correct fixings, and proper sealing, this project can be completed in a day and will significantly extend the life of your bay window.