Inline Fiberglass

• ▸Founded: 1994
• ▸HQ: Ontario, Canada
• ▸Market position: Premium fibreglass windows for Passive House and high-performance residential
• ▸Primary material: Pultruded fibreglass
• ▸Thermal coefficient: Fibreglass expands at the same rate as glass - minimal seal stress through temperature cycling
• ▸Climate context: Ontario - freeze-thaw cycling, extreme cold, hot humid summers
• ▸Certifications: ENERGY STAR, Passive House PHI certification, CSA
• ▸Website: inlinefiberglass.com

• ▸Pultruded Fibreglass Casement Windows
• ▸Fibreglass Awning Windows
• ▸Fibreglass Fixed Windows
• ▸Fibreglass Doors

Pultruded fibreglass has a thermal expansion coefficient almost identical to float glass - approximately 9 x 10-6 per degree Celsius for both materials. This means the frame and the glass unit expand and contract together, dramatically reducing stress on the edge seal through freeze-thaw cycling. Because fibreglass and glass move together, the perimeter seal on Inline windows is under less cumulative fatigue than the same seal on a uPVC or aluminium window in the same climate. However, the seal still needs inspection - it is not immune to failure. Fibreglass profiles are paintable and often left in factory colours - white, grey, bronze, and black are common. The factory finish on fibreglass is applied differently from powder-coat on aluminium and responds differently to cleaners. Passive House windows are extremely airtight. The frame-to-wall interface is carefully detailed with membranes and tapes that are part of the building airtightness layer. Window cleaning should never involve pressure washing or water application at the frame perimeter - protecting the airtightness membrane is a professional obligation on these buildings.

This is how I clean Inline Fiberglass windows. The tools and technique below come from 25 years of daily professional work on the glass. Every step has been tested on real installations and adapted specifically for Inline Fiberglass systems.

• ✕Do not use razor blades on glass without confirming no inner-face Low-E or solar control coatings are present - Passive House glazing almost always has multi-layer coatings
• ✕Do not use solvent-based cleaners on painted fibreglass frames
• ✕Do not pressure-wash the frame perimeter - Passive House airtightness membranes at the frame-to-wall junction must not be disturbed
• ✕Do not use abrasive pads on fibreglass frame surfaces - the factory finish coat is not indestructible
• ✕Do not apply water at the frame-to-wall junction on Passive House installations

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