# silicone vs mortar glass block



## carterarce

Hey guys, I do 3-4 bathrooms a year. I sub out the glass block windows. Most of the older homes in my area have a 28x48 DBL hung in the tub area and I love putting in a glass block window as a replacement and tiling them in.
About half the subs I have met use silicone and half use mortar. None do both 
I like silicone because there is no mortar joint and it has a clean look. I like Mortar because it's old school and it is a time tested method. The last guy I got a price from swore up and down how great silicone is. I can understand it's faster to put together with silicone but I have heard if the silicone fails, there can be major problems.
Silicone has it's place and one of those is on smooth surfaces like glass so it makes sense.
What's your opinion? What's your experience?
I read in the glass block 411 post guys think silicone is weak. Makes sense for a freestanding wall but a window is a different application. My personal opinion is that they both probably work if done well.


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## Tom Struble

how about a hyliter acrylic block window you could open?


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## jarvis design

I have done probably 20 jobs over the years where we removed a window and installed glass block (in tub area).
I used to install the block in place but about 7-8 years ago, I pre-built the panel in the shop and installed in on site. Obviously it depends on how big the window is, but I think I have done up to about 36x36. I used fibreglass mesh - interwoven and wrapped around the entire panel (embedded in mortar) with great success.

I know the thread wasn't exactly about pre-building and I apologize, but I thought I would throw it out there.

P.S. I have never tried silicone - always done mortar


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## carterarce

hyliter acrylic block? I will look that up. Thanks.

I have built them in place but having a block guy drop one off on site or install it for me seems to save me a lot of headaches.

The company I was using just switched vendors and they have a terrible selection of privacy block. 
The guy before that quit doing the installs himself and his employees thought it was a good idea to use their finger to tool the silicone. 
The guy before that went out of business. He was great.


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## Mike Finley

We've installed dozen of Hyliters, love em. Would never install glass block in a window again.


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## carterarce

It looks like they install from the exterior. Are they light? Do they look cheap or is it hard to tell the difference between them and glass?


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## platinumLLC

I've installed a couple of them and they look good and the biggest thing is you can open them if you choose. I have done glass block walls with mortar, and tried one with silicone and ended up tearing it down and re doing with mortar for strength reasons. For windows the silicone will work good but I find it easier to just order the Hyliter window and install it.


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## red_cedar

We have a couple glass block windows in our master bathroom. They leaked bad everytime we had blowing rain due to the moisture being transfered from the outside to the inside via the mortar joints. I have had to seal up the joints with silicone. No more problems.
I personaly like glass block with mortar. I recently modified our glass block shower that I built with ' white silicone' interior side apx 3/4 to 1 inch of the joints the first couple of courses where the moisture hits most.

Once you waterproof the side that gets the moisture they are good to go. I would never silicone the whole thing, just to "amateur like" type of work"


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## carterarce

*thanks*

Thanks for that. I agree on the "amateur-like" aspect but these guys that like the silicone have been at it a long time. 
I would think a guy would offer both styles.


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## Mike Finley

I only offer what I'm comfortable with be it for warranty reasons or many others.

Silicone isn't forever, silicone has a rather short lifespan before it starts to look like sh*t.


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## carterarce

*silicone*

True, Especially if it isn't tooled properly. I use it in all my inside corners of tiled walls and around the toilet, etc. I use a lot of tape and spit and a little denatured alcohol if needed.

I think it's great for smooth surfaces and using it as a "suction" adhesive under a corian shelf or some other flat smooth surface. It beats water based caulks any day.

What's your take on muriatic acid for cleaning grout joints?


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## red_cedar

I just wanted qiuckly explain the silicone of the glass block windows . 
When I caulked the outside joints it wasnt some big bead straight out of the gun. The silkicone bead was very small and then tooled smooth with my finger. Just enough silicone to spread very thin and just cover the joint . You cant realy tell its there actualy.
Didnt want you guys thinking im leaving some big ole string of silicone on the windows. :no:
I hardly ever used silicone until I started in our bathroom. If you have good adhesion then its okay. I did use it to adhere the curtain rod between the shower opening. Its still up and looks good after 5-6 years

I have used muriatic acid after I have rebuilt chimneys, to clean them. It seems to 'brighten' everthing up.
I cannot offer how it works with grout. I would imagine it would work well if you control the strength.


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## silvertree

I used silicone glass with a vent (code in Minnesota), and I use the plastic (acrylic) in my bath remodels.
When I did my own place I went with glass and silicone for the window.
All good in my opinion.
I had a 5X5 acrylic in my shop, I thought it was great there. You could bounce a piece of wood off it when the saw kicked back and all you had to do was duck for the rebound.


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## Mike Finley

I'm not referring to tooling of silicone joints looking bad, I said a short life span before it starts to look like sh*t. Silicone get dirty and ugly looking over time. Silicone isn't forever. I've never seen a silicone anything, be it a tub joint a regular window joint or a glass block joint that didn't look nasty if it was 5 years old or more.


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## carterarce

*true*

Yup. Maintenance, maintenance, maintenance.


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## jarvis design

carterarce said:


> What's your take on muriatic acid for cleaning grout joints?


 
Just a quick note on the above - I would strongly recommend against using muriatic acid. It can etch the tile (and if enamel) the tub. 

A good grout cleaner (sorry, no specific types) would probably be a lot safer


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## Brock

silvertree said:


> I used silicone glass with a vent (code in Minnesota), and I use the plastic (acrylic) in my bath remodels.
> When I did my own place I went with glass and silicone for the window.
> All good in my opinion.
> I had a 5X5 acrylic in my shop, I thought it was great there. You could bounce a piece of wood off it when the saw kicked back and all you had to do was duck for the rebound.


i just subbed out a 14' x 8' wall of glass block. The sub used the silicone and did not clean as he went. It looks horrible. I'm not sure if they will ever be able to clean them. Needless to say they haven't got a penny yet from me.


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## carterarce

*muriatic acid*

Have you had it etch tile before?


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## carterarce

*silicone*

Denatured alcohol will clean that up. My plumber carries a 5 gallon pail of the stuff


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## simplejack

*Rememer who's the boss...wotta a great show.*

What does the Client prefer? I'd explain the difference between the two, discuss pros and cons and ask the client whether they want a grout line or not.


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## Kevin.

*silicone vs mortar glass block windows*

There are many advantages of silicone over mortar when used for basement windows. The effect of the light blocking mortar vs the translucency of clear silicone is a major reason I use silicone for basement windows. I am able to build with or without mortar for joints - I choose silicone for its clean, sharp look. Also, it adheres so well that it is used in the aviation and aerospace industries.

Take a look at silicone uses on the website for Silicones Environmental, Health and Safety Council of North America (SEHSC). This website is particularly useful when clients ask for more information.

I use mortar in other applications, but for basement windows silicone is king.


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## tyler durden

*I hate to say it but....*

Why not just put in a nice fixed glass DP window. Like rain glass or a bamboo design.

You can have an exact fit and install takes like an hour.

In my opinion glass block is dated and is a DIYer material.


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## perrydon

*Silicone vs. mortar*

I,m surprised to see that nobody has mentioned the fact that mold will grow on or in silicone.
For that reason I'd say not a good idea for the shower


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## Keeyter

perrydon said:


> I,m surprised to see that nobody has mentioned the fact that mold will grow on or in silicone.
> For that reason I'd say not a good idea for the shower


I have put in at least 50 of the Silicone Bonded Glass Block Windows going back 7+ years and have not had one with Mold Growth. I guess if Homeowners don't clean their shower Mold would grow on anything, but again I have never had an issue or complaint


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