Glass Block Window Repair: What Can Be Fixed

Glass Block Window Repair: What Can Be Fixed

Glass block fails differently than a regular window. There's no sash to bind, no hardware to wear out, and no seal between panes to fog up.

When something does go wrong, it's almost always one of three things. Two are repairs. One usually isn't.

Legacy Glass Block & Window Co. has installed and repaired glass block across Will, Cook, and DuPage counties since 1986.

A Cracked or Broken Block

A single damaged block can be cut out and replaced without rebuilding the panel.

It happens — a stray rock from a mower, a hard impact, settling that puts stress on one block. The block comes out, the opening is cleaned, and a matching block is set and mortared in.

This isn't a DIY job. Broken glass block is genuinely dangerous to handle, and cutting one out without cracking its neighbors takes the right tools. It's also easy to end up with a panel that looks patched if the replacement block isn't matched properly.

Failed Mortar Joints

Mortar is the part of a glass block panel that ages.

Over twenty or thirty years, joints can develop hairline cracks, and the perimeter sealant where the panel meets the masonry eventually gives up. That's where air and water start getting through.

Repointing the joints and resealing the perimeter restores the panel without replacing it. On a panel that's otherwise sound, this is the cheapest fix available and it buys years.

Worth catching early. Once water has been working through a joint for a few seasons, the masonry around the opening starts to suffer — and then you're fixing more than mortar.

A Panel That's Come Loose

This one usually isn't a repair.

If the panel is moving in the opening, or there's a visible gap between the panel and the masonry, the problem is the opening rather than the block. Foundation movement, deteriorated brick, or an original installation that never keyed properly into the masonry.

Repointing a panel that isn't held by anything just delays it. These get rebuilt.

What Glass Block Doesn't Get

A few things people ask about that don't apply here.

Fogging between panes. Glass block isn't an insulated glass unit. Each block has a sealed air pocket formed when the two halves are fused at manufacture, so there's nothing to reseal. If a block ever clouds internally, that block gets replaced.

Weatherstripping and hardware. A solid panel has neither. If you have a vented panel, the vent unit itself can be serviced or replaced without touching the block around it.

Painting. Glass block doesn't need it, and painting it usually causes problems. If yours has already been painted, removal is its own project.

Repair or Replace?

The line is straightforward.

Repair when the panel is sound and the problem is localized — one or two blocks, or mortar and sealant.

Replace when the panel has moved, when several blocks are cracked, or when the masonry around the opening has failed.

If you're not sure which one you're looking at, that's what an on-site look is for. We'll tell you honestly — a repair we can do in an afternoon is better for both of us than a rebuild you didn't need.

Get Your Glass Block Looked At

We repair glass block as well as install it. Cracked blocks, failed mortar joints, resealing, and vent units.

Family-owned, serving Will, Cook, and DuPage counties since 1986. Our own crews do the work — no subcontractors — and every installation is backed for as long as you own your home.

Call (708) 247-2044 or see our Glass Block Windows page.