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We just bought a house in Minnesota. The front steps are concrete I believe and they are built with what seems to be small glass block windows or tiles in the top that leads into the basement, letting light into a storage space (which is not necessary as there is a light inside).

The top block broke this winter. Right now we have a large piece of plywood covering it for safety and to keep the elements out, but we need to get it fixed ASAP. We prefer to try to do it ourselves because of costs. Not sure if we can fill the hole or if we have to replace the tiles. We just want the safest and most inexpensive way to fix it on our own.

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  • Can you provide a picture from underneath the step/glass block, showing what it looks like from there? You'll have to put some sort of framing there to hold up the concrete patch, so knowing what's there will help people guide you. – FreeMan May 5 at 16:46
  • Natural light to the space below is a good thing when the power goes out in daylight, but do what you like. I've seen many that have lasted many decades, even in busy city sidewalks, so it's not like they can't be durable, but if you'd rather plug it with concrete, you can do that. – Ecnerwal May 5 at 17:24
  • Are you sure there aren't more such blocks there that should also be removed? – isherwood May 5 at 18:03
  • This picture was the closest I could get to the underside. – Curtrice Gavin May 5 at 18:14
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Remove (bust out) the glass block, install permanent support underneath (plywood patch supported either by blocking between joists, or fastened directly to the underside of the slab with concrete screws), notch the edges 1.5" wide by 1.5" deep, pour a cement mix patch with standard aggregate, make sure you get out air bubbles as you go (no voids), finish as you please... you might look at a product line called Top-Cast for matching the aging on the existing, as far as that tan sanded concrete coating goes, maybe it's Rollerrock?... Hopefully you have a leftover can that the sellers left you.

You might should embed a tight grid wire mesh in there in the top 1.5 inch portion to help with any deflection.

If you do what others have commented, where you just fill the existing block with concrete, that will chip out. Concrete needs a minimum 1.5" thickness or it with break apart.

Also, it is essential to prevent any exposure to the elements with a cold joint. Water will penetrate and both leak into living space and freeze and break the concrete apart. If this is the case, you may want to pour the concrete with a removable 1/2" band between old and new to later fill with self-leveling waterproofing concrete sealant. You would use something like polystyrene (xps or eps) foam board that won't damage the concrete edges when you remove it.

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  • I'm curious where you've seen others comment about "filling the existing block with concrete". – FreeMan May 5 at 18:23
  • Freeman, Ecnerwal's comment... as a general rule in life, the world is a better place when we try helping ourselves before asking other people to put effort forward. ... remember when you gave me this little tidbit? "now that you've taken the tour, you'll know to click the up arrow (if you haven't already) to say "thanks" for any answer that you find useful and helpful, and (give it 24- to 48-hours to see if anyone else is interested in chiming in), click the check mark on the answer that helps you the most." so why don't you take your own advice and click the up arrow on this comment? :) – The Ghost of Jon May 6 at 4:25
  • @Jon "as a general rule in life, the world is a better place when we try helping ourselves before asking other people to put effort forward" comes off as quite rude and makes no sense. Ecnerwal's comment doesn't appear to have any encouragement of improper patching, so FreeMan was asking what you were referring to. There are also only 7 people who contributed more than FreeMan this year by site metrics (0.69% per capita) so obviously he has a huge focus on helping others. You make it sound like you were irritated he informed you how the site worked. – K H May 6 at 7:17
  • Not everyone will have the knowledge necessary to correctly upvote (either it helped you or you are verifying it. If it didn't help you and you can't verify, many people will avoid upvoting.) or downvote (dispute the veracity.). For me, I would prefer you add mention of stripping or chipping any paint or adhesives and using concrete primer before pouring new concrete. – K H May 6 at 7:20
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    Ah... "plug it with concrete" I believe is the phrase that caught your attention. To my untrained eye, that's exactly what you're suggesting, except that you're being more explicit that the glass block should be removed, then a form made to hold the concrete in place. Good on you for being explicit (as one would expect in an answer, not so much a comment) - I inferred that from Ecnerwal's comment, but not everyone would. You have my +1 – FreeMan May 6 at 11:38

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