Brick homes stand out for their strength and character. Yet replacing windows in these solid structures brings its own set of technical challenges. Unlike wood or vinyl siding, brick walls rely on steel lintels for support, and after decades of settling, their window openings are rarely perfectly square. Failing to account for these details can lead to leaks, drafts, and costly damage.
This guide explains how to approach retrofitting windows in brick homes, what to watch for with steel lintels, and how to install a new, square window in an uneven masonry opening.
Understanding Window Retrofits in Brick Construction
A retrofit, often called an insert replacement, involves fitting a new custom window inside the existing frame. It is different from a full-frame replacement, where all components are removed down to the rough opening.
The two major factors that define retrofit work in brick houses are:
- Steel lintels: The row of bricks above each window rests on a horizontal steel angle that carries the load. It must stay in place and be protected during installation. According to the Wikipedia article on shelf angles, these steel supports are critical elements in masonry veneer construction, designed to transfer loads safely around window openings. It must stay in place and be protected during installation.
- Out-of-square openings: As brick homes age, foundations settle. The result is openings that lean, slope, or have corners that are not perfect 90-degree angles.
Understanding these structural features is the first step to a durable installation.
Why These Details Matter
Dealing correctly with lintels and crooked openings is not just cosmetic. It determines whether the wall stays watertight and stable.
- Structural soundness: Rusted or weakened lintels can cause cracks and sagging brickwork. Inspecting and repairing them before installing a new window is essential. The University of New Mexico’s Historic Preservation Committee highlights that early detection of rust and proper priming of steel lintels are crucial steps when restoring or retrofitting older masonry windows.
- Water protection: The junction between the lintel and the window frame is a common entry point for water. Proper flashing must redirect rain away from the wall cavity.
- Energy performance: A square, well-shimmed window seals evenly. Forcing a new frame into a twisted opening can break glass seals, create gaps, and undo all the benefits of energy-efficient glass.
Comparing Replacement Options
| Parameter | Insert Replacement (Retrofit) | Full-Frame Replacement |
| Cost | Lower | Higher |
| Installation Time | 2-4 hours | 4-8+ hours |
| Disruption | Minimal | High (removes all trim) |
| Lintel Exposure | Limited (flashing critical) | Full (lintel visible) |
| Adjusting Crooked Openings | More difficult | Easier (can re-frame) |
| Skill Level | Moderate to high | Very high |
Working with Steel Lintels
You cannot remove or replace a lintel casually, but you can inspect and protect it during installation. As outlined by the National Building Code of Canada, steel lintels over masonry openings must meet specific bearing and corrosion protection standards to maintain structural integrity.
- Inspection: Once the old window is out, check the lintel for deep rust or flaking. If the metal has lost more than about 10 percent of its thickness, call a professional to assess replacement.
- Cleaning and protection: For light surface rust, use a wire brush to clean the metal, then apply a rust-inhibiting primer and an exterior-grade paint.
- Flashing: Proper flashing is the most important step. Flexible self-adhesive flashing tape should extend up the wall sheathing, across the top of the lintel, and down its face. The top edge of the new window trim or flange should sit beneath this flashing to shed water outward.
Fitting a Window into an Uneven Opening
In older masonry homes, no two openings are perfectly aligned. The installer’s goal is to make the window square, not to follow the shape of the brick.
- Measure accurately: Measure width in three spots (top, middle, bottom) and height in three (left, center, right). Use the smallest measurements to size your new window. Check diagonals to see how far the opening is out of square.
- Shim for alignment: Set the window on shims until the sill is level, then adjust the sides until plumb. The window itself must be square, even if the wall is not.
- Seal the perimeter: Secure the window through the shims, then fill the remaining gaps with low-expansion spray foam designed for windows and doors.
- Cover uneven edges: Inside gaps can be finished with wood stop trim. Outside, aluminum or vinyl capping hides small irregularities and creates a clean look.
Mistakes That Lead to Problems
- Skipping lintel repairs: Painting over severe rust traps moisture and accelerates decay.
- Poor flashing: Simply caulking the top of a window does not stop water migration. Flashing must overlap correctly.
- Over-shimming or over-tightening: Too much pressure can warp a vinyl frame and break the glass seal.
- Wrong spray foam: Standard high-expansion foam can bow a frame outward. Always use the low-expansion type labeled for windows and doors.
DIY or Professional Job?
While many homeowners can handle basic insert replacements in wood-framed walls, brick retrofits demand higher skill. Steel components, irregular openings, and complex flashing make this an advanced project.
A trained installer can inspect structural steel, ensure proper drainage, and deliver a neat finish that protects your home for decades. For most homeowners, hiring a professional is the safer and more cost-effective choice.
Frequently Asked Questions (FAQ)
1. What should I consider when retrofitting windows in a brick home?
Your primary considerations must be the structural condition of the steel lintel, the quality of the new flashing installation, and your plan for dealing with an out-of-square opening.
2. How do I choose the best replacement window for a brick opening?
An “insert” or “retrofit” window is the most common choice as it is custom-sized to fit the existing frame, minimizing disruption to the brick and interior walls. Choose a high-quality window with a welded frame that will resist warping.
3. What are the advantages and disadvantages of retrofitting in brick?
- Advantages: You can significantly boost energy efficiency and home comfort without having to remove or alter the exterior brick, preserving the home’s character.
- Disadvantages: It is a very technical installation. There is a high risk of hidden water damage from old, failed flashing, and structural issues from rusted lintels.
Conclusion
Replacing windows in a brick house is not about speed but accuracy. Success comes from inspecting and protecting the steel lintel, installing the new window perfectly square, and sealing every edge to prevent moisture intrusion.Whether you tackle the project yourself or hire an expert, attention to these details ensures your new windows will last for decades while maintaining the beauty and integrity of your brick home. The International Energy Agency notes that upgrading windows in existing masonry homes plays a significant role in improving global residential energy performance, particularly in older, heat-retaining brick structures.