If you have read our broader custom vs standard sliding windows guide, you have the decision framework. This is the math for standard sliding windows vs custom fabrication: the numbers and the lead times you actually need to put a project budget together.
Quick caveat. Ranges below are illustrative for a typical Jamaican residential install in 2026 and will move with size, glass spec, hardware, and location. Custom fabrication has also gotten more competitive over the last few years, so the gap is smaller now than it was even five years ago.
Standard sliding windows vs custom fabrication: the cost premium
The general industry pattern for standard vs custom sliding windows in residential aluminum:
- Custom-sized units cost roughly 30 to 50 percent more than the equivalent stock size for the same glass spec and finish.
- Custom finish (non-standard RAL colour or anodised) adds 10 to 20 percent on top of that.
- Custom glass spec (laminated, hurricane-rated, specific tints not in the supplier’s standard runs) adds another 20 to 40 percent depending on what you’re asking for.
Stacked together, a fully custom window (custom size, custom finish, custom glass) lands at 60 to 100 percent more than the equivalent stock unit.
On a single window, the dollar difference is modest. On a project of 12 windows, it adds up. A house that would come in at a notional 12 budget units in pure stock might land at 18 to 20 in pure custom.
So the answer for most projects is some mix. Stock where it works. Custom on the openings where the result actually changes once installed.
The lead time math
Lead times are where the gap is biggest in absolute terms.
- Stock units: typically ship from supplier inventory within 5 to 10 business days of order confirmation.
- Custom-sized standard finish: 3 to 5 weeks of fabrication after order confirmation.
- Fully custom (size + finish + glass spec): 5 to 8 weeks.
- Imported specialty systems (European slim-profile, fiberglass): 8 to 12 weeks or more.
The install itself takes the same time regardless. Stock units don’t install any faster than custom ones once they’re on site.
For a renovation with a hard deadline (rental turnaround, sale closing, family event), the lead time gap often matters more than the cost gap. A six-week custom build that pushes install past your move-in date can cost more in lost rental income than you saved by not going stock.
When the custom premium actually pays back
A few scenarios where the math works in favour of custom:
- The opening is non-standard enough that a stock unit would need frame extensions, packers, or visible trim to hide the gap. That work adds labour cost up front and shortens the lifespan of the install.
- The design intent specifically wants dimensions that stock cannot provide: a feature opening, a wall-of-glass run, a heritage proportion.
- The home is a long-term hold (15+ years), so the custom premium spreads across more years of use.
- The glass spec the project needs (hurricane-rated, very low SHGC, sound-attenuating laminated) is not in the stock catalogue.
If none of those apply, the custom premium does not pay back. Stock is the right answer.
A worked example for a real Jamaican project
A typical 3-bedroom home with 12 sliding windows tends to break down like this:
- 8 bedrooms, bathrooms, and kitchen openings all within stock-size range. Stock units, 1/4 inch tempered, white powder coat. About 1 budget unit each.
- 2 standard openings that are slightly oversize because of existing house quirks. Could be stock plus trim, or custom for a cleaner fit. Going custom adds about 30 percent on those 2.
- 1 living room slider, 8 feet wide. Custom for the dimensions, 5/16 inch tempered for the panel size. About 50 percent more than the equivalent stock would have been.
- 1 feature opening (corner slider, master bedroom). Fully custom in slim profile. 80 to 100 percent more than equivalent stock.
The total project lands at about 25 to 30 percent above pure-stock cost. Lead time is set by the slowest custom unit on the order, so 5 to 6 weeks from order to install-ready instead of 1 to 2 weeks for an all-stock job.
Pure stock saves the most money but compromises on the openings that matter. Pure custom is the cleanest fit but costs noticeably more on openings where the difference doesn’t show. Mixed is almost always the better value.
Related reading
- Custom vs standard sliding windows: which fits your home?
- How long does a sliding window install actually take?
Frequently asked questions
How much more do custom sliding windows cost than stock?
A fully custom window (custom size, custom finish, custom glass spec) lands at 60 to 100 percent more than the equivalent stock unit. Custom-sized only adds about 30 to 50 percent. The premium compounds across a multi-window project, which is why most projects mix stock and custom.
Does custom fabrication really take longer?
Yes, meaningfully. Stock units ship in 5 to 10 business days from supplier inventory. Custom-sized takes 3 to 5 weeks. Fully custom is 5 to 8 weeks. Imported specialty systems can run 8 to 12 weeks or more. The install itself takes the same time once units are on site.
When does the cost premium for custom sliding windows pay back?
When stock would require visible trim or packers to disguise a poor fit, when the design specifically needs dimensions stock cannot provide, when the home is held long enough for the premium to spread across many years, or when premium glass spec is required that stock catalogues don’t carry.
What’s the cost difference between stock and custom for a whole house?
A typical 12-window residential project mixed with stock and a few custom feature openings lands at about 25 to 30 percent above pure-stock cost. Pure custom across all 12 openings would be 50 to 60 percent above. The mixed approach is almost always the best value.
How do I know if I need custom sliding windows?
If your existing openings are within 2 to 4 inches of a standard stock size and the spec you want is conventional, stock works. If the openings are non-standard, the spec is unusual, or the design intent specifically requires exact dimensions, custom is the right call.
The next step
If you want this math run for your specific project, the quote request form takes the opening list and the priorities. We come back with a quote that breaks out stock vs custom per opening so the difference is visible at the line-item level.
The sliding windows service page covers what we install. The contact page is for questions before the formal quote.
Mixed is the answer for most projects. The exercise at quote stage is just figuring out which openings are which.