Fiberglass Windows Built for Long-Term Performance
Inline Fiberglass manufactures fiberglass windows for homeowners, architects, builders, commercial projects, and high-performance building needs.
Our window systems are designed for projects where comfort, energy efficiency, durability, clean sightlines, and design flexibility all matter
Whether you need tilt and turn windows, casement windows, fixed windows, sliders, single hung windows, double hung windows, or high-performance window options, Inline helps you choose the right fiberglass window series for your project.
Fiberglass Is Not an Add-On Product Line for Inline
Fiberglass is the material Inline is built around.
That focus helps our team support stronger product knowledge, clearer guidance, and window systems designed around the strengths of fiberglass: stability, strength, thermal performance, durability, and clean design.
Inline fiberglass windows are used across:
- Residential window replacement projects
- Custom homes and renovations
- Architect-led projects
- Builder and contractor projects
- Commercial and institutional buildings
- Passive House and high-performance building needs
- Dealer-supported projects across select markets
Why Homeowners, Builders, and Architects Choose Inline
Inline combines fiberglass specialization, manufacturing control, technical support, and product flexibility to support a wide range of residential and commercial projects.
Fiberglass Manufacturing Specialization
Inline focuses exclusively on fiberglass windows and doors, delivering specialized expertise, product consistency, and long-term performance across every series.
Canadian Manufacturing & Showroom
Visit Inline’s Toronto / Etobicoke showroom and benefit from local manufacturing, product support, and project consultation services.
Residential & Commercial Experience
Inline products are used across custom homes, renovations, commercial buildings, and high-performance projects throughout multiple markets.
Technical Resources & Product Support
Access product specifications, technical documents, drawings, and support resources to assist with planning and product selection.
Certified Performance & Testing Standards
Product-specific certification details are available where applicable, including PHIUS, PHI, NFRC, AAMA, Energy Star, and IGMAC.
Flexible Design & Performance Options
Choose from glazing, colours, hardware, grilles, and configuration options tailored to specific product series and project requirements.
Compare Inline Fiberglass
Window Series
Explore the full Inline fiberglass window lineup and compare operating styles, design applications, and performance-focused features.
300 Series Tilt & Turn Windows
Best for: Ventilation, easy cleaning, modern homes, high-performance projects
The 300 Series Tilt & Turn window offers two ways to open. Tilt the sash inward from the top for controlled ventilation, or turn the handle to open the window inward like a door for wider airflow and easier cleaning.
This is a strong option for projects that need clean design, practical ventilation, and a high-performance window feel.
Best-fit uses:
- Bedrooms and Living spaces
- Multi-storey homes
- Modern custom homes
- High-Performance homes
- Inward-Opening Spaces
400 Series Strip / Fixed Windows
Best for: Large glass, modern design, minimal sightlines, wide openings
The 400 Series is a contemporary fixed fiberglass window system designed for larger glass areas and clean sightlines. It can help create dramatic walls of glass while still allowing operable windows to be incorporated where needed.
This is a strong fit for projects that need more daylight, larger views, and a modern architectural look.
Best-fit uses:
- Large fixed openings
- Modern homes
- Commercial spaces
- Feature walls and view-focused rooms
- Projects needing minimal sightlines
700 Series Casement / Hopper Windows
Best for: Ventilation, cleaning access, European-style operation
The 700 Series is an operable fiberglass window series with casement, hopper, and fixed window options. It is designed for projects that need strong ventilation, practical operation, and flexible window configurations.
This series is ideal for projects that require operable windows with strong performance and clean sightlines.
Best-fit uses:
- Bedrooms
- Kitchens
- Bathrooms
- Basements
- Multi-unit projects
- Architect-led residential projects
325 Series Fixed Windows
Best for: Natural light, unobstructed views, fixed openings
The 325 Fixed window option is designed for projects that prioritize larger glass areas, uninterrupted views, and strong energy performance within a streamlined fixed window configuration.
Choose this path when ventilation is not required and the priority is daylight, comfort, and clean design.
Best-fit uses:
- Picture windows
- Living rooms
- Bathrooms
- Stairwells and feature openings
- High and low profile fixed windows
- Where view and light matter most
325 Series Casement Windows
Best for: Everyday ventilation, airflow, unobstructed views
The 325 Casement window is a practical operable fiberglass window option for rooms that need fresh air, clear views, and a clean window profile.
Casement windows are often a good fit when homeowners want strong ventilation without moving to a tilt and turn system.
Best-fit uses:
- Bedrooms
- Kitchens
- Living rooms
- Home offices
- Renovations
- Custom homes
325 Series Awning Windows
Best for: Controlled ventilation, compact openings, weather-conscious airflow
The 325 Awning window is designed for projects that require controlled ventilation, weather protection, and efficient airflow through compact openings.
Choose this path when ventilation, comfort, and energy performance are priorities.
Best-fit uses:
- Bathrooms
- Basements
- Kitchens
- Smaller wall openings
- Areas paired with fixed windows
- Rooms where ventilation matters but space is limited
800 Series Horizontal Slider Windows
Best for: Horizontal openings, simple operation, traditional layouts
The 800 Series Horizontal Slider window opens by sliding left or right. It is designed for full top-to-bottom ventilation on the operable side, while the other side remains fixed.
This is a practical option for projects where a horizontal sliding window is the right fit for the opening and room layout.
Best-fit uses:
- Bedrooms
- Basements
- Renovations
- Wider horizontal openings
- Traditional home layouts
- Spaces where swing-style operation is not ideal
850 Series Single Hung Windows
Best for: Traditional homes, simple vertical operation, replacement projects
The 850 Series Single Hung window provides a classic vertical window style. The lower sash operates while the upper sash remains fixed.
This series is a good fit for projects that need a familiar window style with the strength and performance benefits of fiberglass.
Best-fit uses:
- Traditional homes
- Replacement projects
- Bedrooms
- Front-facing windows
- Multi-window elevations
- Projects needing a classic look
900 Series Double Hung Windows
Best for: Traditional design, flexible ventilation, classic window styling
The 900 Series Double Hung window includes two operating sashes that move up and down. This allows ventilation from the top, bottom, or both.
This is a strong fit for homeowners who want traditional window styling with more ventilation flexibility than a single hung window.
Best-fit uses:
- Traditional homes
- Renovations
- Bedrooms
- Living rooms
- Front elevations
- Projects where classic appearance matters
Which Fiberglass Window Series Is Right for Your Project?
Not every window series is designed for the same use. The right choice depends on the opening, style, ventilation needs, glass size, performance goals, and project type.
Best for Ventilation
Choose a window series with strong operable function.
Good options include:
- 300 Series Tilt & Turn
- 700 Series Casement / Hopper
- 325 Series Casement
- 325 Series Awning
- 800 Series Horizontal Slider
- 850 Series Single Hung
- 900 Series Double Hung
Best for Large Glass and Views
Choose a fixed or strip window system when the goal is natural light, larger glass, and cleaner sightlines.
Good options include:
- 400 Series Strip / Fixed Windows
- 325 Series Fixed Windows
Best for Modern Design
Choose window systems with clean lines, minimal sightlines, and flexible sizing.
Good options include:
- 400 Series Strip Windows
- 300 Series Tilt & Turn Windows
- 325 Series Fixed Windows
- 700 Series Casement / Hopper Windows
Best for Traditional Homes
Choose window styles that match familiar residential architecture while upgrading the frame material to fiberglass.
Good options include:
- 850 Series Single Hung Windows
- 900 Series Double Hung Windows
- 325 Series Casement Windows
- SDL and flat bar design options where applicable
Best for High-Performance Projects
For Passive House, PHIUS, commercial, or other high-performance projects, product selection should be confirmed by series, glass package, configuration, and documentation.
PHIUS certification applies only to specific products and configurations, including 325 SER CSM/AWN/FXD, 400 SER, and 3000 SER TNT/FXD. PHI certification applies to 3000 SER TNT/FXD.
Inline can help architects, builders, and homeowners identify the right product path and request the correct technical documents.
Inline's Custom Fiberglass Window Options
Inline fiberglass windows can be configured for different project needs. For an accurate recommendation, share your project location, window type, plans, preferred style, and performance goals.
Ask Inline about:
- Double-glazed and triple-glazed options by product series and configuration
- Interior and exterior colour flexibility
- Custom colour needs
- Standard and oversized product options
- SDL and flat bar options where applicable
- Fixed, operable, and combination window layouts
- Product drawings and technical documents
- Performance data by product and configuration
- High-performance and Passive House project suitability by certified product and configuration
See Fiberglass Windows in Real Projects
Explore how Inline fiberglass windows are used across residential, commercial, and high-performance projects throughout a variety of applications.
Need Specs, Drawings, or Certification Details?
Inline can help you access the product information needed to evaluate the right fiberglass window series for your project.
Request support for:
- Product specs
- Technical drawings
- Glass configuration details
- Certification scope by product and configuration
- PHIUS / PHI applicability
- EPD documentation for applicable products
- Commercial project support
- Custom sizing and configuration questions
How to Start Your Fiberglass Window Project
You do not need to know every product detail before reaching out. Tell us about your project, and our team will help you move in the right direction.
01
Tell Us About Your Project
Share your project type, location, timeline, window requirements, and any drawings, plans, photos, specifications, or supporting details available.
02
We Help Identify the Right Window Path
Inline reviews your needs and helps route you toward the right window series, quote path, showroom visit, dealer support, or technical document request.
03
You Get the Right Next Step
Depending on your project, the next step may be a quote, showroom visit, product comparison, or technical consultation.
Common Questions About Fiberglass Windows
Find clear answers to common questions about fiberglass windows, including product options, performance considerations, and how to choose the right solution for your project.
Which Inline fiberglass window series is best?
It depends on your project. For ventilation and easy cleaning, start with the 300 Series Tilt & Turn or 700 Series Casement / Hopper. For large glass and modern fixed openings, review the 400 Series or 325 Fixed options. For traditional residential styling, review the 850 Single Hung or 900 Double Hung series. For a practical everyday casement window, review the 325 Casement series.
Are fiberglass windows energy efficient?
Yes, fiberglass windows are commonly chosen for energy-efficient window projects because fiberglass supports strength, durability, and thermal performance. Final performance depends on the window series, glass package, size, configuration, and installation details.
Should I choose double pane or triple pane fiberglass windows?
Double pane may be suitable for many residential projects. Triple pane may be a better fit when the project needs higher thermal performance, more comfort, or stronger high-performance building goals. Inline can help confirm the right glass package for your project.
Can Inline fiberglass windows be customized?
Inline offers several window styles, series, glass options, and design options. Colour, sizing, SDL, flat bar, and configuration options may vary by series and project requirements. Share your plans or photos so the Inline team can confirm what is available.
Do you offer fiberglass windows in Toronto?
Inline Fiberglass is based in Toronto / Etobicoke, with a showroom at 30 Constellation Crt, Etobicoke, ON M9W 1K1. The showroom is open Monday–Friday, 8:30am–5:00pm, and Saturdays, 10:00am–2:00pm, except holidays. Visitors outside the local area can contact Inline to confirm the right quote, installation, or dealer-supported path.
Do Inline fiberglass windows support Passive House projects?
Select Inline products support Passive House or high-performance building needs. PHIUS certification applies to 325 SER CSM/AWN/FXD, 400 SER, and 3000 SER TNT/FXD. PHI certification applies to 3000 SER TNT/FXD. Certification scope should always be confirmed by product, series, glass package, configuration, and project requirements before specifying.
Does Inline install fiberglass windows?
Yes. Inline has its own installers and offers turnkey replacement service, including removal of existing windows and installation of new products tailored to the project. For projects outside Inline’s direct service area, contact Inline to confirm the right installation, dealer, or contractor-supported path.
Which window is best for large glass openings?
For large glass, fixed openings, and clean sightlines, review the 400 Series Strip / Fixed Windows and 325 Fixed Windows.
Which window is best for ventilation?
For strong ventilation, review the 300 Series Tilt & Turn, 700 Series Casement / Hopper, 325 Casement, 325 Awning, 800 Horizontal Slider, 850 Single Hung, and 900 Double Hung series. The best choice depends on how you want the window to open.
Can I download product specs?
Yes. Architects, builders, and project teams can request product specs, drawings, and technical documents to help evaluate the right fiberglass window system.
How do I get a quote?
Use the Request a Free Quote form and include your project location, window type, timeline, and any plans or photos you have. Inline will review your request and help route you to the right next step.
Ready to Find the right Fiberglass Windows?
Tell us about your project and we’ll help identify the right Inline fiberglass window solution. From custom homes to architectural specifications, our team can provide product guidance, technical support, and next-step recommendations.