Cracking Glass Blocks

CLYDE

A friend of mine has glass block wall for his shower, and he has about a half dozen that are cracked. Also his metal tabs are rusting also. what causes this?

MALCO.New.York

A Noob who starts out with "A friend of mine....."

And YES ! I stolded this image!!!

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SLSTech

That image is to good to not use in a situation like this...

Home inspector who doesn't understand that rust is caused by water & metal interacting - I think you may be in the wrong forum

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CLYDE

Wow, you guys are intelligent I guess I should have asked what are "contractors or other S.A's are using to keep the water from infiltrating the mortor. Is there some kind of water repellent being applied or is it just a diff type being used to protect the metal from the moisture?

But the basic and first question was not answered. Has anybody seen cracked glass and what could be the problem. temp,loads..etc?

NOOB is spelled newby, by the way

MALCO.New.York

http://dictionary.reference.com/browse/noob

Care to try again?

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Tscarborough

In a non structural wall, cracked glass block mean physical abuse, i.e. some beat on them with something. Glass block mortar has integral waterproofing.

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concretemasonry

Mortor is actually spelled MORTAR.

There are specific types of mortar that you friend should have used. Also, glass blocks need the proper mortar and cushioning to prevent the concentrated loads that can cause cracks, since they have been brittle for the last 70-80 years of use.

The blocks or mortar does not rust. It is the attachments and any embedded materials.

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Dick

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gallerytungsten

Perhaps the surfaces the blocks are set against wasn't prepared correctly, letting water in.

But I suspect the house settled, the mortar cracked open, water penetrated, etc.

SelfContract

Expansion in joints caused cracks. When water get in join, and temperature make it frozen/iced, the forzen water pockets/volumes will expande, forcing adjacent blocks of joint to crack. Rusty metal also expands joint.

Burby

This is just a "test", yeah I bet that is what he is doing, to see if we know this can happen when improperly built..

And for just 3 easy payments of just $49.99 I can offer a free "fix" for "YOUR" freind..

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Ms. Fix-It

Cracked blocks sounds like settling, which would also explain the mortar being compromised, allowing rust...

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strathd

BB guns

skyhook

I agree, settling could be the culprit since double framing members are required to support glass block. The rest about water in the cracks too. Still don't see how the blocks cracked since they are literally bullet proof.

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WarriorWithWood

Where have I seen that before.....Hmmm.

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EIDOL

someone used sand with iron in it then put way two much portland that made the mortar harder than the glass a home owner i would guess
here in annapolis with lot of old homes the bricks are soft so if you put to much cement it will blow the face off or cause cracking

Darwin

Maybe wackin' off too wildly in the shower caused this, I dunno..

glassman

glass block is installed either with mortar or silicone,older installs used metal strips that acted as spacers that also locked each block to the next.
newer installs,mostly shower enclosures use silicone with mildew inhibitors,and the metal strips were replaced with plastic chairs.
silicone provides a cleaner joint,is easier and less time consuming,provides a more water resistant seal.
as other posters have stated water infiltration has caused the rust problems,also as a metal corrodes or rusts,it will also swell somewhat,causing breakage. settling of the home will also cause breakage as abuse or impacts will too. using mortar or silicone for sealing is fine,the main thing is to leave a specified gap at the top,hidden by molding or trim,thus eliminating stresses from compression,most install prohibit the glass block wall from being a load bearing wall. you can go to the pc glass block website for install instructions.
on a side note glass block has been reduced in depth allowing installs into vinyl window frames,allowing reduced weight for new construction windows for exterior wall applications for privacy in bath locations.

jarvis design

Not to be a b*tch, but, Glass Block mortar is modified (ie. polymers), but is no where near being waterproof.

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skyhook

BS

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naptown CR

That depends on the height of the crack


I agree with this

I do not agree with this mortar is not waterproof silicone may not be also but is markedly more moisture resistant than mortar.

We are talking about glass block not brick.

I recently had a glass block window I took out and replaced with an acrylic block awnng window because several of the blocks were cracked. This also happened to be in a shower. There was double framing at the base and 1/2" of space between the header and the block. the cracked block were in the center of the unit. I know that it takes a lot to crack these things I wonder if it was thermal shock as they are not tempered.