Your Markham home may have been constructed prior to 1990, so there is a high probability that your window frames, seals, and glazing are way beyond their useful lifespan. Among the top contributors to heat loss, increasing energy bills, and moisture issues in GTA houses are older windows, and the freeze-thaw climate of the Markham area only makes such old fashioned windows more expensive to overlook.
You will find all the information you need to know about replacing windows in older Markham homes: when you should change, why older homes pose special structural problems, and how the process of replacing the windows will look like.
Why Older Markham Homes Present Unique Window Replacement Challenges
Markham residential neighbourhoods Unionville and Milliken to Cornell and Cathedraltown are residential areas consisting of thousands of houses constructed between 1960s and 1990s. These are lovely and well-placed properties, but they have certain challenges associated with windows that newer properties do not.
1. Non-Standard Frame Openings
In older houses, standardised window rough openings were not commonly used. Settling, renovation layers, and original custom construction over decades imply that off-the-shelf window sizes will not often fit. Measurements of individual openings have to be accurate before order placement to a professional installer, or you will have expensive gaps, structural loss, and lack of weatherproofing.
2. Deteriorated Wood Framing and Sills
Most Markham homes built before 1990 had wood window bucks and sills. Decades of Ontario moisture, ice damming, and poor caulking bring about rot, mold, and building instability of the wood. In other situations, the framing that surrounds it may need to be repaired or replaced first, and then the new windows can be installed – something that a professional window installer will spot during an in-home inspection.
3. Single-Pane and Early Double-Pane Units
Homes of this period have single-pane glass or early double-pane sealed units that have long since lost their gas fill (argon or krypton). Condensation and fogging between panes, and excessive temperatures on the cold side are all indications that the glazing unit is not functioning any longer – and cannot be fixed.
4. Lead Paint and Asbestos Considerations
Older homes (constructed prior to 1980) have window casings or surrounding trim that could have lead-based paint or asbestos-containing material. These risks will be detected by a qualified window contractor during the assessment and appropriate containment and disposal procedures will be followed. This is a very important reason to go to a licensed and insured installer instead of a handyman.
Pro Tip — Milano Windows & Doors Milano installations start with a free home assessment. We have technicians who check the size of every rough-opening, examine the framing around it, and mark any structural problems prior to a single window being ordered – so there are no surprises on the date of installation. |
Signs Your Older Markham Home Needs Window Replacement
Unsure of whether to make a repair or complete replacement? These are the obvious indicators that a replacement is long overdue:
- Fogging or condensing between the glass panes – the closed unit is dead and cannot be repaired
- Frame drafts – caulking and weatherstripping will not solve structural seal failure
- Increased heating and cooling expenses – particularly when your HVAC is well maintained
- Problems with opening, closing, or locking windows – distorted frames due to water damage
- Rot, peeling paint or water spots on interior or exterior sills that can be seen
- Excessive street noise penetration – older single or early double-pane glass has little sound insulation.
- Windows over 25 years old – in Ontario climate, most sealed units last between 20 and 25 years.
Window Types Best Suited for Older Markham Homes
Whether to use the appropriate style of window on a heritage or old building is a matter of balancing energy efficiency, style and cost. The most popular ones among Markham homeowners are as follows:
Casement Windows
The most energy-efficient standard option. Casement windows have compression seals when closed and therefore they work well during cold winters in Ontario. They fit the sizes of the majority of pre-1990 Markham houses and can be ordered in custom sizes to fit non-standard openings.
Double Hung Windows
One of the traditional styles that can be adapted to traditional Markham neighbourhoods such as Unionville. Double hung windows can be ventilated through the upper or bottom sash and can be easily cleaned on the inside; a convenient option in upper-floor applications.
Picture Windows
To rooms that do not require ventilation and would like the maximum natural light. Picture windows are fixed, highly sealed and one of the most energy efficient in combination with Low-E triple-pane glass.
Awning Windows
Typical of the kitchens and bathrooms of older Markham houses. Awning windows are hinged on the top and open upwards and outwards resulting in the ventilation even on the rainy shoulder seasons that are characteristic of Ontario.
Energy Performance Note
To achieve the highest energy savings in the climate of Markham, it is recommended to find windows with Low-E argon or triple-pane glass, a U-factor of 0.25 or less, and an ENERGY STAR® Canada label. These requirements have the potential to cut the yearly heating and cooling expenses by 30 percent.
The Window Replacement Process for Older Markham Homes
Knowing how to install it will assist you in planning and keeping your expectations realistic. The following is a step-by-step view of a professional window replacement project:
- Step 1 – Free In-Home Consultation: A specialist comes to your house, measures every opening, inspects the framing around the opening and gives you a detailed quote.
- Step 2 – Custom Window Manufacturing: Windows are made to your precise rough opening size. The windows produced by the Canadians are constructed according to the climate in Ontario.
- Step 3 – Framing Inspection and Repair: During the day of installation, the installer takes off the old windows and evaluates the frame. Rottenness or structural problems of any kind will be repaired and new units will then be installed.
- Step 4 – Window Installation: New windows are installed, levelled, shimmed and attached. Foam insulation is used to seal the frame around and seal any gaps.
- Step 5 – Sealing and Finishing: Interior and exterior caulking is done. Interior trim is re-fit or refitted. The area of work is thoroughly cleaned and checked.
- Step 6 – Final Walkthrough: The installer takes you through every new window, shows you how it works and verifies the warranty paperwork.
Average window replacement is 1-2 hours per window. An entire home retrofit of 10-15 windows in an average Markham semi or detached house can be undertaken over a 1-2 day period.
Ontario Government Rebates and Grants — What Markham Homeowners Qualify For
Markham homeowners need to know several things in 2026, one of them being that there are government financial incentives to assist in the offset cost of energy efficient window upgrades.
- Canada Greener Homes Grant: Rebates on ENERGY STAR-certified window replacements are available to eligible homeowners.
- Ontario Home Efficiency Rebate Program: Upgrade incentives based on qualifying energy audits.
- Interest-Free Home Renovation Loans: Various programs provide up to $40,000 in interest-free funds to install qualifying energy upgrades such as windows and doors.
Eligibility is based on the current energy rating of your home, the products installed and audit requirements. Ask your installer of the windows if they can assist you with the rebate application process – or refer you to a qualified energy auditor.
How Much Does Window Replacement Cost in Markham?
Prices depend on the size of the window, the type, package of glass, and the requirement to repair the structure or not. As an overall guideline to the Markham homeowners in the year 2026:
- Single window replacement: $600 – $1,200+ (supply and installation)
- Full home replacement (10–15 windows): $8,000 – $20,000+
- Upgrade to triple-pane glass: Increases the cost of base windows by about 15-25%
- Frame or sill repairs: Costs by window depending on extent of damage
Always demand three itemised quotes of licensed GTA window companies. Wary of prices that are way under-market- these are usually signals of low-quality product, inadequate installation, or uncertified labour.
Ready to Replace the Windows in Your Older Markham Home?
Markham homes of old should have windows that fit the climate of Ontario, not off-the-shelf, one-fits-all. The right window replacement partner will evaluate your individual opening, prescribe the appropriate package of glasses, option on any structural work, and back up the work with a real warranty.
Milano Windows and Doors has a history of operating in the Markham and the GTA market and has worked over the last 20 years to install Canadian-made, ENERGY STAR certified windows in homes of all ages and designs. Book a free in-home consultation today and receive a clear, itemised quote that will not push or include any hidden costs.
Frequently Asked Questions – Window Replacement in Older Markham Homes
Q1. Can I replace windows in my older Markham home in winter?
Yes. Professional window installers work year-round in the GTA. It can and is safe when installed in winter, so long as it is done properly – installers install foam insulation and use methods like weatherproof seals to make sure that no heat is lost in the process. Wintertime scheduling usually implies quicker lead times.
Q2. Do I need a permit to replace windows in Markham?
Markham permit requirements are dependent on the extent of work. Replacement of windows of similar size (similar location) usually does not need a permit. But, when enlarging a window opening or altering a structural component, you are obliged to obtain a permit of the City of Markham. A contractor should always make sure that the work starts.
Q3. How do I know if my older home has non-standard window sizes?
Your rough opening size can only be verified by a professional in-home measure. Many pre-1990 Markham homes have window openings that do not conform to today’s standard sizes. All openings will be measured by a competent installer who will then order the windows to fit perfectly.
Q4. What is the best window frame material for older Markham homes?
Vinyl (uPVC) is the most common in older GTA homes – does not rot, has low maintenance requirements and it has great thermal performance. A high-quality alternative is fiberglass that has better structural strength in larger openings. Heritage properties can be framed with wood, although this type of construction needs frequent attention to work in the Ontario climate.
Q5. How long do replacement windows last in Markham's climate?
Professionally installed quality Canadian-made vinyl windows with Low-E argon glass usually survive 25-40 years in Ontario conditions. Typical effective life span of the sealed glass unit is 20-25 years before the performance of the unit is decreased by the permeation of the argon gas. Both product and installation defects are supported by lifetime warranties with reputable companies.
Q6. Will new windows increase my Markham home's resale value?
Yes. Energy efficient windows are always rated as one of the best home additions with high returns. These enhance the curb appeal, minimize the buyer anxiety on energy expenses and show that the home has been well-managed, all of which are positively impacting the resale value in the competitive Markham real estate market.
Q7. Do I need to be home during the window installation?
During installation, it is advisable to be present or to have a trusted adult present, especially in old houses where the installer can find out during the process that there is a structural problem, and decisions need to be made on the spot. On simple replacements, a few homeowners allow access and exit at the end of the project – make sure your installer agrees on the method.