Putting individual glass blocks in an exterior wall assembly. Sometimes the wall is sloped, so waterproofing is critical. From the exterior, the wall is 3″ polyurethane foam and 4″ concrete. The foam is usually coated with an acrylic elastomeric. How would you install and waterproof the glass?
I did some of these with regular glass block mortar, but any lil’ hairline gap wicks water, especially if sloped. Ended up coating joints with DryLock. Anyone have a better way?
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Replies
Urethane caulk? Sticks like snot, cures to tough stuff.
Hi Cloud.
When you say the wall is sloped....are you referring to the window sill portion?
If I'm reading you correctly, the wall is a total of 7 inches thick ( 3 inch poly and 4 inch concrete). If this is so, set your block back onto the concrete portion. If there is a gap between the concrete and the polyurethane, then first install a sill plate that bridges this gap. The sill plate material (7 inch wide) can be either a treated 5/4 deck board or you can form and pour a 1 inch thick concrete sill plate...choice is yours.
I would reccommend purchasing a ready made glass block unit. They can be made in practically any size you need. Have the unit manufactured with silicone instead of mortar between the joints. Place a "bed" of urethane caulk ( NPT-1) down to embedd the bottom of the block and urethane the sides and top too. The urethane caulk will seal out any water, but don't rely on the caulk itself to hold the window in place. Install "feather" shims to hold unit in place and then apply the caulking.
If you don't want to go the prefabbed route, then buy the DIYer materials that Lowes and Home Depot sells for glass block window installations. They sell materials that allow each block to be glued to one another with silicone. After that, installation is still the same.
If you install a treated wood sill plate, you can cover this with aluminum coil stock in any color you desire for a more appealing look.
Good luck.
Davo
The installation is in a setting like this: http://www.monolithicdome.com/gallery/homes/kaslik/pictorialc.html
But for this new case, we're talking about just putting one block here and one there, not a whole assembly. So the prefab frames are too many parts and too much work for single blocks. Same with introducing pt or alum sills. If I can keep away from bringing in a third or fourth material, I lessen the chances of gaps caused by materials expanding/contracting differently, etc.
Also, if I set the block back into the concrete, now I have a 3" depth of foam to angle as a sill for drainage and then waterproof.
I've thought of using a shot of the foam on each of the four sides once the block is secured with shims, etc., but don't know how easy it'll be to waterproof the edge. Plus sanding that smooth without scratching the block will be a barrel of fun.
NP-1 certainly could have a role. I use that stuff by the case.
All ideas welcome...
I've seem glass block done with 100% silicone (vs the standard grout you mentioned). This would allow the expansion/contraction of the block. Movement would be very minimal though since it's only one block.
I'm not sure how well it would adhere to your foam layer though. Might try a sample or two and set it out several months (if you can wait).
Also wonder if you could modify a rubber "T" shaped gasket material. one leg of the "T" goes over the face of the glass block (could even be bed in silicone next to to the glass to make it stick to the block to avoid water infiltrating. The other leg of the "T" angles back into the wall, so that the foam encapsulates it when sprayed. Rubber has a limited lifetime depending on UV exposure.
Just brainstorming here, never tried either of these methods myself. Good luck.
Hey Cloudy, I love the stuff you're dealing with - there's so much room for creative solutions!
Could you come up with a way to secure the block to your rebar grid prior to spraying the conctete? I would think that the shotcrete would adhere to the rough edges of the glass block quite well. With a little carving, you could have it sit a little proud of the outer surface of the concrete, which might aid in coming up with a flashing scheme. Get those Monolithic people to make a little ol' test dome for ya!
did
p.s. DW put up her web site last night, on an honest-to-god Mac-based host; DANG but is Appleshare IP ever sweet!I have
misplaced my pants
didididididdid,
That is the general direction of my thinking, too. If the single block could be secured to the airform and then foamed, it'd be held tight. But the weight of the block could make securing it a bit of a challenge. Or foam the whole dome to half thickness, then secure the block, and then foam the block into place and shotcrete. Capturing the block in some combo of foam/shotcrete would certainly seem secure enough. And that intuitively feels better than what I did on mine based on advice at the time, which is secure a PT buck to the shotcrete and install the block in the buck. Just felt like there's no gain from adding more new materials.
Wondering out loud...could expansion/contraction of the shotcrete/glass ever break the glass? Dunno. The foam would better allow for slight movement. Also, if I had to choose between a recess exterior v interior, I'd rather the recess be interior. Any exterior recesses would make waterproofing more difficult. Interior, you can work the shotcrete edge to a nice quarter-round.
For waterproofing, if there was an inch or half of foam outside of the block, could shape that to shed water. If it were 1/4" or so smaller than the block, then the elastomeric could wrap around and butt into the block. That might make a good bond. Still, wouldn't wanna risk water getting down be/t the foam and the block, so might need to NP-1 where they meet. Hmmmm....
If the installation involves more than one block, then the panel assemblies could well be better than a mortar installation....unless the design goal is to follow the curves of the dome...
>> Just felt like there's no gain from adding more new materials.
Ask yourself this: If adding another material allowed you to replace one difficult interface with two easy interfaces, would that be a gain?
I understand that chrome plating actually consist of a layer of copper(?) followed by a layer of chrome because it's easier to get the copper to adhere to the steel and the chrome to adhere to the copper than it is to get the chrome to adhere directly to the steel.
There's a reason adobe and rammed earth builders use wood window bucks, even when they don't have curved walls or sprayed on foam to deal with.
Is that foam essentialy the same stuff as great stuff ?
If so, why not use great stuff to secure the block to the airform ? You can prop the block up there in just about any fashion the works. Give it a few shots of great stuff. Wait 20 minutes or so, and remove your prop, tape, whatever. Then finish 'gluing' the block to the airform with the great stuff.Quittin' Time
Nah, it's open cell v the closed cell we use. (I think I have that right--I always have a mental block about open v closed cell--same with the spelling of weird, or is it wierd...) The Great Stuff won't shape or finish the same as the polyu.