Window and Doors London Ontario: Common Mistakes to Avoid During Replacement

Posted on 2026-06-13 08:19:56

Replacing windows and doors seems straightforward until you are halfway through a cold snap with a draft you cannot pin down and a caulk joint already cracking. I have seen projects in London, Ontario that looked fine on install day but leaked the first time a west wind drove rain against the brick. Most of those failures trace back to avoidable decisions. The materials matter, but so does how they are measured, detailed, and fitted into the building envelope. If you are planning window and door replacement in London, this guide walks through the mistakes I see most often and the practical ways to sidestep them.

Start with where you live: London’s climate, housing stock, and codes

London sits in a part of Ontario that gets real winters, plus humid summers and its fair share of driving rain. Heating degree days often fall in the mid to high 3,000s, some years higher. That means air sealing and thermal performance are not luxuries, they pay back in comfort and reduced bills. Many neighborhoods, from mid-century bungalows to the Woodfield Heritage Conservation District, have brick veneer construction and mixed-age windows. Brick-to-brick replacements, steel entry doors, and patio doors are common requests. Any plan should reflect the wall type, sill detailing, and how wind and water move across your façade.

Ontario’s Building Code allows like-for-like window swaps without a permit, but once you touch structure, change egress size in a bedroom, or alter openings, you enter permit territory. Installers in London should be working to Canadian standards for performance and installation, including NAFS ratings with the Canadian supplement and the CSA installation guidance for windows and doors. Ask about those. They are your best proxy for whether a crew sees beyond the trim.

Mistake 1: Measuring the opening as if it were a rectangle on paper

Old houses rarely stay square. I measured a 1960s ranch in northwest London last spring that was out by 12 millimetres top to bottom on a single double-hung unit. The homeowner had supplied a window to the tightest dimension. It fit the narrow point and bound against the frame everywhere else, leaving no room for shims or foam.

Measure every rough opening in three widths and three heights, then check both diagonals. If a unit will be out of square after shimming, consider a custom size within a few millimetres of ideal. Leave allowance for shims, typically 6 to 12 millimetres, and for low-expansion foam. Door slabs demand the same rigor. Thresholds need room for a continuous sill pan, and you must plan for the door sweep and weatherstripping compression. Steel door installation in London, Ontario often fails on this basic point. A tight jamb with no true plane will fight a multi-point lock and let in water at the corner where the sill meets the jamb.

Mistake 2: Treating water management as a bead of caulk

A window or door is a hole in a rain screen. It needs a drainage strategy, not just a sealant line. When I inspect failed units, I usually find one of three things: no sill pan, misapplied flashing tape, or reverse lapping of housewrap and head flashing.

Get the sill right first. A site-built sill pan from durable membrane or a preformed pan creates a back dam and positive slope to the exterior. If you are working with brick veneer, you want that pan to kick water to the face of the brick or through weep paths, not into the stud bay. Flash the sides with properly lapped tape that ties into the weather-resistive barrier. Head flashings should shed water over the face of the cladding with a drip edge. In retrofit situations where the existing head flashing is buried under brick or siding, a low-profile cap flashing may be needed to bridge the gap. Watch the laps. Water always wants the path of least resistance and it does not forgive reverse laps.

I saw a downtown London window where the tape was run straight to the brick with no primer and no pan. It looked tidy, until wind-driven rain rode the mortar joints and found the lower corner. Inside, the trim swelled within months. The remedy cost three times more than doing it right the first time.

Mistake 3: Focusing on glass options without understanding ratings

Buyers get lost in buzzwords: low-e, argon, triple pane. The labels matter, but the performance metrics matter more. In Canada, look for Energy Star certification and check two numbers: U-factor and Energy Rating (ER). U-factor tells you how readily heat flows through the window. Lower is better. ER balances U-factor, solar gain, and air leakage to give a single value. In London, a low U-factor helps in winter, but so can thoughtful solar gain on south-facing elevations if you have shading under control.

Not every window needs triple glazing. A quiet street with a sheltered elevation may do well with a high quality double pane low-e unit with warm-edge spacers. North elevations or bedrooms near traffic often benefit from triple pane for both comfort and acoustics. The trade-off is weight and cost. A large casement with triple glazing puts more load on hinges and operators. If you want the benefits without hardware strain, split that opening into smaller operable units or choose a fixed unit flanked by operables.

Tinted or heavy low-e coatings that crush solar gain can make a sunny room feel dim year-round. I once replaced west-facing patio sliders in Byron where the homeowner complained of a cave-like living room after a previous replacement. The installer had used a very low solar heat gain low-e glass that made sense for south Texas, not southwestern Ontario. We re-specified glass that balanced glare control with a modest solar gain. The room warmed naturally in the shoulder seasons, and they ran the furnace less.

Mistake 4: Treating a structural change as an afterthought

Expanding a window to a patio door, converting a solid door to a door with sidelites, or lowering a sill line are structural moves. Altering the width or height loads the header and changes shear paths. In brick veneer, a lintel sits over the opening to carry the brick. I have seen people torch-cut lintels to gain another 50 millimetres of glass. It works for a month and then the brick begins to settle and crack.

For any change in opening size, especially in older London homes with mixed framing practices, consult a designer or engineer and pull a permit. The City of London’s process is straightforward for residential alterations, and inspectors are reasonable when you show drawings and proper lintel or header sizing. The costs are modest compared to repairing stepped cracks and stuck doors.

Mistake 5: Using the wrong foam and skipping air sealing details

The orange can of expanding foam from a big box is not a one-size solution. Around windows and doors you want low-expansion, window and door rated foam that will not bow jambs. Start with a backer rod or compressible tape where gaps allow, then foam conservatively in lifts. Over-foaming creates pressure points that tweak operation and ruin reveals.

Air sealing is a system, not a single pass. Think interior and exterior. On the exterior, use vapor-permeable sealants or tapes that allow drying to the outside. On the interior, a higher vapor-resistance sealant or tape closes the air path. The combination lets the assembly dry one way and keeps moist interior air from riding into the cavity in winter. I have torn out new work in London where installers only caulked the exterior. The interior trim looked tight, but the winter air found the gap and condensed behind the casing, feeding mold on the drywall paper.

Mistake 6: Assuming every swap is permit-free

If you stay within the existing opening and do a like-for-like window, you usually do not need a building permit. The moment you increase size in a bedroom where egress rules apply, or you cut structure for a wider patio door, the rules change. For doors, changing from a standard slab to a door with operable sidelites can affect both structure and exits. London’s zoning and building departments can confirm quickly. Calling first saves the unpleasant surprise of a stop-work order or, worse, a home sale held up later by undisclosed alterations.

Safety glass is another code point. Any glass within a certain distance from the floor, stairs, or tubs often needs to be tempered or laminated. That includes sidelites next to entry doors and low patio door glass. Skipping safety glazing to shave costs is a false economy. Tempered units cost more, but the liability of a non-tempered panel shattering into shards is not worth it.

Mistake 7: Forgetting how doors actually live day to day

Entry doors in London take hits: wet boots, salt, kids hanging on levers, and winter heave pushing thresholds. A good steel door installation in London, Ontario respects that reality. The insulated core should be properly bonded to the skin to prevent oil canning in the sun. Jambs should be plumb in both planes so weatherstripping compresses uniformly. If you feel a cold stripe at one corner in February, odds are the reveal is not even and the sweep is not meeting the sill.

Multi-point locks shine in our climate, especially on tall doors that would otherwise bow slightly with humidity cycles. They pull the slab tight at multiple points for a consistent seal. Pair that with composite bottom rails and rot-resistant jamb materials at the base, where splash and meltwater accumulate. For the sill, adjustable thresholds let you tune compression as weatherstripping compresses over time.

One winter on a new build, the homeowner called about light at the corner of a beautiful fiberglass door. The installer had driven fasteners hard through the hinge-side shims, twisting the jamb. Backing off a few screws, re-shimming, and re-tuning the threshold fixed the problem. No amount of caulking would have.

Mistake 8: Ignoring heritage character and neighborhood context

London has several heritage conservation districts, with Woodfield being the best known. You do not need to own a Victorian to care about context. Trim profiles, grille patterns, and brickmold scales all change how a replacement reads on a façade. Dropping a flat, modern vinyl unit into a façade with deep casings and divided lights can cheapen the look.

If your property sits inside a designated district, approvals may be required for visible changes. Even outside those zones, take cues from neighboring homes. I once advised a client in Old North to keep simulated divided lites on the street-facing windows but use simpler, high-performance units at the rear. The front kept its rhythm, the back gained larger, cleaner glass, and the budget stayed tame. With doors, sticking to a panel style that echoes the original can make a steel or fiberglass unit feel at home.

Mistake 9: Underestimating lead times and weather windows

Windows and doors are not off-the-shelf most of the time. Custom sizes, color-matched cladding, and specialty glass can push lead times to 6 to 12 weeks, sometimes longer in peak season. Plan installations for days with reasonable temperatures, since many sealants need substrate temperatures above a certain threshold to cure properly. Foam behaves differently below freezing, and caulk can skin over before it bonds in summer heat.

I keep a simple rule: avoid pulling more openings than you can close weather-tight the same day. In London’s shoulder seasons, a surprise squall can drive water into an open wall cavity in minutes. I watched a well-meaning DIY crew pull every window on a Saturday morning. The rain came at noon. They spent the afternoon draping tarps and fighting wind, then spent the next month drying framing.

Mistake 10: Shopping on price without vetting the installer

You can buy a great window and ruin it with a bad install. Conversely, a mid-tier window installed well can outperform a premium unit installed poorly. If you are searching for door installation in London, Ontario or a team for window and door replacement in London, ask about training, standards, and details, not just brands.

Here is a short pre-hire checklist that keeps the conversation honest:

Proof of liability insurance and WSIB coverage, with certificates in your name and address Knowledge of CSA installation practices and NAFS performance ratings relevant to your project Examples of similar projects in London, with references you can call A detailed scope that names materials by brand and model, including flashing, foam, and sealants A workmanship warranty in writing that covers more than the manufacturer’s product warranty

I like to see photos of in-progress work, not just finished shots. Anyone can show a pretty after photo. You want to see how they build sill pans, how they shim, and how they treat the weather barrier. Also, read the contract for exclusions. If rot shows up under the door and window replacement services London sill or a lintel is compromised, how will they handle it?

Mistake 11: Confusing “insert” and “brick-to-brick” replacements

An insert replacement fits a new unit into the existing frame. It preserves interior and exterior trims and can be faster and less invasive. But you lose some glass area, and you cannot always address water and air sealing behind the old frame. A brick-to-brick replacement removes the entire old frame back to the structure, allowing new insulation, flashing, and brickmould. On older London homes with tired frames and failed insulation, brick-to-brick often pays dividends in comfort and lifespan.

For doors, replacing a slab while keeping an old jamb often leaves you with an ill-fitting sweep and weatherstripping that never quite mates. In many steel door installations in London, Ontario, moving to a prehung unit with a new jamb and sill provides a better long-term seal.

Mistake 12: Overlooking condensation risks and interior humidity

In winter, condensation at glass edges points to high indoor humidity or a cold interior surface, or both. Warm-edge spacers help, but air leakage from the interior side is a big culprit. Seal the interior perimeter carefully. Control humidity with ventilation, especially if you have a tight home. Bathroom and kitchen fans that actually exhaust outside, not into an attic, matter. Blinds that trap cold air against the glass can make condensation worse. I have had calls from owners convinced their new windows leaked, when the issue was condensation dripping from the interior pane onto the sill. The fix was a balanced HRV setting and a small tweak to the interior seal.

Mistake 13: Skipping hardware and screen quality

Windows and doors are only as satisfying as they are easy to use. Casements with undersized operators or cheap gearing get old fast. Choose robust hardware, especially on larger sashes or triple-glazed units. Screens should fit snugly and pull out without bending frames. On patio doors, ball-bearing rollers make a world of difference in how a heavy panel glides. A London window and door package that feels light under hand tends to get used, which improves ventilation in summer and overall satisfaction.

Mistake 14: Forgetting exterior finishes and transitions

New work has to meet old finishes. On brick, a properly sized brickmould reduces awkward caulk joints. On siding, add a backer behind the joint and a neat, tooled bead of high-quality sealant designed for the substrates. If you paint after installation, respect cure times for sealants and foams. I have seen topcoats peel because they went on over uncured beads in October chill.

Also, think about head flashings showing against brick or stone. If you prefer a hidden look, discuss recessed flashings early. You cannot hide a flashing that never got installed.

Mistake 15: Assuming rebates will carry the budget

Incentives change. Over the past few years, programs in Ontario evolved, with some grants paused or reconfigured. Do not build a budget that depends on a specific rebate unless you have verified your eligibility and timelines. Check with Enbridge Gas for current efficiency rebates and with the City of London for any municipal programs. Even without rebates, energy savings from tighter, better-performing windows and doors are tangible in a climate like ours. I typically tell homeowners to weigh comfort and condensation control as heavily as projected bill savings. Your nose and fingers will feel the difference on a January morning.

Mistake 16: Treating installation day as a black box

A little preparation keeps the day smooth. You do not need to hover, but you should know the sequence, where crews will stage tools, and how they will protect floors and landscaping. If you work from home, plan around the noise and brief periods without a secure door.

Here are simple steps that help the crew and protect your home:

Clear 1.5 to 2 metres around each opening inside and outside, including removing window treatments Disarm or bypass sensors on windows and doors scheduled for replacement Crate or move pets to a quiet room away from work zones Confirm power access and a path for extension cords that will not trip family members Walk the site with the lead installer in the morning to confirm unit locations, swing directions, and special notes

A five-minute walkthrough at the start prevents errors like a left-hand swing where you expected a right-hand, or a bathroom window with obscure glass installed in a bedroom. It happens.

Mistake 17: Neglecting the small but critical door details

Entry and patio doors leak at the same predictable places: the sill corners, the lockset, and the meeting stile on French units. A quality door installation in London, Ontario solves these details quietly. Sill end dams, properly bedded in sealant, keep those corners dry. Pilot holes for locksets avoid split wood, and careful routing of weatherstripping at the latch prevents the telltale cold streak. On French doors, an astragal that seals positively without dragging on the sill makes all the difference.

I also like to see the installer label which fasteners should never be adjusted by the homeowner. People try to fix a rub by backing off a hinge screw and strip it. Instead, the hinge shims or the adjustable hinges themselves should be tuned. A good installer will show you how to micro-adjust hinges and thresholds before they leave.

Mistake 18: Forgetting maintenance and homeowner responsibilities

New windows and doors are not maintenance-free. They are low maintenance if you know what to do and when. Clean weep holes on vinyl windows each spring so that driving rain has a path out. Lubricate casement operators and patio door rollers annually with the right lubricant, not heavy grease that attracts grit. Touch up small paint dings on aluminum-clad or wood trim before corrosion or rot find them. Keep shrubs trimmed back to allow airflow around frames and to prevent constant moisture against sills.

With steel doors, wipe salt spray in winter from the lower panels and threshold. Adjust the sweep as seasons change so it seals without dragging. If a gasket tears, replace it promptly. Local suppliers in London carry profiles that match most mainstream brands, and a quick swap keeps energy loss and water intrusion at bay.

Mistake 19: Not aligning security and accessibility with design

Security and accessibility can coexist with style. Multipoint locks, laminated glass for sidelites, and solid strike reinforcement provide real protection without bars or awkward add-ons. For accessibility, think lever handles instead of knobs, low-profile thresholds, and clear openings that account for mobility devices. I worked on a bungalow near Masonville where the owners planned to age in place. We installed a fiberglass entry door with a low sill and automatic closer, and widened a rear entry to a gliding patio door with a recessed track. The house looked better, and day-to-day function improved immediately.

Mistake 20: Assuming all “London window and door” companies are interchangeable

Firms vary widely. Some excel at heritage work, others at high-volume replacements, and others at specialty doors. If your project is a mix, do not hesitate to split scopes. Have a window specialist handle the casements and a door-focused team for the entry system if that yields better outcomes. Coordination matters, but so does domain expertise. When you search for window and doors London Ontario, you will find plenty of options. Look beyond the first page. The best match is the one whose portfolio mirrors your house and priorities.

What a well-planned project looks like

A Westmount homeowner called about drafts in a bay window and a tired front door. We walked the house together. The windows were insert replacements from two decades back, poorly foamed and never sealed on the interior. The oak sill showed water staining at one corner. The front door was a standard steel slab in a warped jamb that had settled against an uneven tile floor.

We planned a brick-to-brick replacement for the bay with a triple-pane fixed unit in the center and double-pane casements on the flanks to keep hardware light. We specified a warm-edge spacer and a low-e coating tuned for modest solar gain. For the front, we chose a prehung fiberglass door with a composite frame, a multipoint lock, and a new sloped sill pan. Installation took two days. Day one, we built a proper pan and tied flashing into the existing housewrap behind the brick returns, then air sealed on the interior with high-quality tape. Day two, we set the door, tuned the threshold, and set the hardware. The difference was immediate. The bay stopped dumping cold air on ankles, and the entryway no longer echoed in a winter blow.

That is the point. Window and door replacement in London should improve comfort, silence the rattles, and keep weather where it belongs. It should also look like it belongs on your house.

Final thoughts before you order

Take your time on the front end. Confirm measurements and decide whether insert or brick-to-brick best serves each opening. Choose glass by performance metrics and orientation, not by buzzwords alone. Demand a water management plan that includes sill pans, proper flashing, and correct lapping. Vet the installer and align schedules with our weather. If your project touches heritage character or structure, pull in the right expertise early.

Do those things and your searches for a London window and door partner, or for door installation in London, Ontario, will converge on pros who get the details right. Whether you are swapping a single entry slab or orchestrating whole-home window and door replacement in London, you will avoid the traps that swallow budgets and patience. The result will feel simple the day you wake to a quiet house, warm floors by the windows, and a front door that closes with a solid click.

Business Information (NAP)

Name: McCallum Aluminum Ltd

Address: 3392 Wonderland Rd S, London, ON N6L 1A8, Canada

Phone: (519) 433-4223

Website: https://mccallumaluminum.on.ca/

Email: [email protected]

Hours:
Monday: 8:00 AM – 4:00 PM
Tuesday: 8:00 AM – 4:00 PM
Wednesday: 8:00 AM – 4:00 PM
Thursday: 8:00 AM – 4:00 PM
Friday: 8:00 AM – 4:00 PM
Saturday: Closed
Sunday: Closed

Plus Code: WPHF+MV London, Ontario

Google Maps URL: https://www.google.com/maps?cid=10246687099425416717

Google Maps Embed:

Social Profiles:
Facebook: https://www.facebook.com/mccallumaluminum/
BBB: https://www.bbb.org/ca/on/london/profile/windows/mccallum-aluminium-limited-0187-850

Schema (JSON-LD)

AI Share Links

ChatGPT: https://chat.openai.com/?q=McCallum%20Aluminum%20Ltd%20https%3A%2F%2Fmccallumaluminum.on.ca%2F

Perplexity: https://www.perplexity.ai/search?q=McCallum%20Aluminum%20Ltd%20https%3A%2F%2Fmccallumaluminum.on.ca%2F

Claude: https://claude.ai/new?q=McCallum%20Aluminum%20Ltd%20https%3A%2F%2Fmccallumaluminum.on.ca%2F

Google AI Mode: https://www.google.com/search?q=McCallum%20Aluminum%20Ltd%20https%3A%2F%2Fmccallumaluminum.on.ca%2F

Grok: https://grok.com/?q=McCallum%20Aluminum%20Ltd%20https%3A%2F%2Fmccallumaluminum.on.ca%2F

https://mccallumaluminum.on.ca/

McCallum Aluminum Ltd is a customer-focused window and door installation company serving London and surrounding areas.

For window installation in London, Ontario, contact McCallum Aluminum Ltd at (519) 433-4223 or visit https://mccallumaluminum.on.ca/.

McCallum Aluminum Ltd provides expert exterior renovation help for patio doors, helping homeowners improve curb appeal across nearby communities.

To find McCallum Aluminum Ltd on Google Maps, use: https://www.google.com/maps?cid=10246687099425416717.

Looking for a trusted installer near you? Call (519) 433-4223 and learn more at https://mccallumaluminum.on.ca/.

Landmarks Near London, Ontario

1) Victoria Park — Visiting downtown? Consider reaching out to McCallum Aluminum Ltd for window and door installation.

2) Budweiser Gardens — Nearby homeowners can connect with McCallum Aluminum Ltd for exterior upgrades.

3) Covent Garden Market — In the core? Ask about window and door replacement options.

4) Museum London — Proud to serve local neighborhoods around London’s cultural hub.

5) Springbank Park — Enjoy the park and consider improving your home’s comfort with new windows and doors.

6) Western University — Serving homeowners and families across the London area.

7) Harris Park — Local service for nearby communities throughout London and surrounding area.

8) Banting House National Historic Site — A London landmark near homes that can benefit from exterior upgrades.

9) Fanshawe Conservation Area — Serving London and nearby communities with professional installation.

10) Masonville Place — In North London? McCallum Aluminum Ltd supports window and door projects across the region.