Hy-Lite Glass Block Window 5x4: Pre-Assembled Privacy Without the Mortar Mess

This pre-assembled glass block window weighs 96 pounds and eliminates traditional mortar installation while providing 50% weight reduction compared to standard 4-inch glass blocks. For contractors handling bathroom and basement window installations in Montana’s demanding climate, that weight reduction translates directly to faster installation and fewer backs thrown out on the job.

The Hy-Lite 5x4 configuration features 20 blocks total in a 41-1/4” x 33-1/2” rough opening. Real safety-tempered glass blocks come factory assembled and watertight — no mixing mortar, no leveling individual blocks, no waiting for cure times.

Installation Efficiency That Actually Matters

Contractors find the pre-assembled units much faster to install than site-built block windows. The 96-pound weight requires two people for safe installation, but that’s still manageable compared to hauling and mortaring dozens of individual blocks.

Multiple frame options with 7/8” or 1-3/8” nail fin offset accommodate various wall types including wood frame, masonry/brick (with appropriate anchors), and vinyl siding. The flexibility matters when retrofitting existing openings or dealing with Montana’s mix of construction styles.

Installation follows standard window procedure: verify rough opening matches 41-1/4” x 33-1/2”, apply flashing tape to sill and jambs, set window in opening and level using shims, secure via nailing fin or through-frame fasteners, and seal exterior with high-quality silicone caulk.

Specification	Value
Rough Opening	41-1/4” x 33-1/2”
Actual Size	40-3/4” x 33”
Block Configuration	5 x 4 (20 blocks total)
Block Thickness	2 inches
Weight	96 lbs
Nail Fin Offset Options	7/8” or 1-3/8”

Thermal Performance for Montana’s Climate

The numbers tell the truth about energy efficiency: U-factor of 0.51 and R-value of 1.96. Not Energy Star qualified — and that matters in Montana’s Climate Zone 6 where code demands better thermal performance for primary windows.

The 2-inch block thickness provides less insulation than standard 4-inch blocks. For non-egress basement windows where privacy trumps view, these specs work. For heated living spaces demanding maximum efficiency, contractors need to manage customer expectations about thermal performance.

Structural testing to DP-50 or higher (model dependent) handles Montana’s wind loads without issue. The frame material options include vinyl and thermally broken aluminum in white, tan, bronze, and driftwood colors.

Glass patterns affect both privacy and light transmission: Wave, Ice, Glacier, and Cross Rib patterns available. Each pattern diffuses light differently — Wave provides the most light transmission while Cross Rib offers maximum privacy.

The 10-year limited warranty covers manufacturing defects in frame and glass assembly. Standard coverage for this product category.

Frequently Asked Questions

What’s the real installation time savings compared to traditional mortared blocks? Contractors praise the pre-assembled units as much faster to install than site-built block windows. Figure 2-3 hours for a typical installation versus a full day or more for mortaring individual blocks.

Can one person handle the installation? No. The 96-pound weight requires two people for safe installation. Plan accordingly when bidding labor.

Does it meet egress requirements? This is designed for basement window replacements (non-egress). The fixed design and limited opening size make it unsuitable for bedroom egress windows.

How does the caulk line appearance compare to real mortar? The easy-to-clean caulk line resembles mortar but requires no mixing. It provides the traditional look without the installation hassle.

What wall types can accommodate this window? Compatible with wood frame, masonry/brick (with appropriate anchors), and vinyl siding. The dual nail fin offset options provide flexibility for different wall thicknesses.