Tag: concrete countertop

Blog entry

Concrete Prep / Kitchen and Utility

Round 2 of our concrete countertop work.  For the kitchen and utility room countertops, since we did not create integral sinks, our formwork was generally simpler.  We created cutouts for the sinks and cooktop, and we also formed a 3/4" drop-down lip for the kitchen pieces.  In pouring, we had to be particularly careful to place the large remesh and rebar spans in the middle of the 1.5" counter thickness.  We again rented a concrete mixer but vibrated and finished the pours by hand.


We covered the pieces with plastic tarps in order to retain moisture as the concrete cured (this has been a very, very dry summer in Austin).  After 5 days, we released all of the pieces and finished them with several rounds of sanding.  We again filled air holes in the surface with Rockite, though in comparison to the bathroom pieces we spent more time sanding to a finer level of polish.

Blog entry

Concrete Install / Master Bath

Installing the beast: the 500+ lb master bathroom countertop with integral sink.  Our plan involved building a platform on top of a dolly, and then getting some strong men together to maneuver the sink on and off the dolly into place.

Once inside the master bedroom, we raised the countertop on 2x4s so that it could be slid onto the supporting studs nailed to the master bathroom walls.  Then we could knock away the supporting pieces and let the sink hang.

All went surprisingly smoothly.  No cracks so far!

Blog entry

Concrete Install / Small Baths

For the bathroom countertops, we were interested in preserving as much of the raw concrete look as possible.  We did minimal sanding with an orbital and 60/120-grit paper--enough to smooth the top surface and sink and expose a tiny amount of aggregate.  We filled air holes in the top surface with Rockite, but left the sides exactly as they were poured--we like that the open air pocket texture really emphasizes the materiality of these pieces.

The Rockite fill is substantially lighter than the Quikrete, so we also rubbed a diluted white stain over the surfaces.  This didn't change the overall color noticeably, but it did even out some of the texture by filling in tiny imperfections in the surface with white.

Then, after we caulked the vanity surfaces, two fellas lifted these pieces into place (the vanities below them will be painted white).

Overall, we're pleased with the results.  We love the look of these big block of concrete, and since we weren't aiming for a completely polished look, the imperfections (many of which are at corners and edges) add great character.  When we make the kitchen and utility countertop pieces, we'll potentially test out more aggressive sanding methods and staining the fill color to achieve different effects.

Blog entry

Concrete Released / Master Bath

After the small countertops were done we started on the big one.  The smaller countertops are 3 feet long and about 2.5 bags of Quikrete each (about 230 lbs in total with the water weight).  This guy took almost 6 bags, and is probably 550 lbs.

No problem for these strapping young men to flip over.  Same process as before to release all of the remaining melamine.

I like the underside texture (this piece was wetter on that surface when we poured than the others).  And here is the raw product.

Blog entry

Concrete Released / Small Baths

Five days after we poured, we released our new countertops & sinks.

To start with, we unscrewed all of the perimeter melamine pieces.  They pulled off fairly easily.

We used packing tape to seal the edges of the bottom-side formwork.  The concrete picked up every detail--all the lines and the shine.

The countertop was poured upside down, so we placed white foam to help soften the edges when we turned it over.  Once flipped, we had to drill/dig into the sink area to pry off the top.

Then we knocked out the faucet piece, and carefully pried out the sink pieces.  Hello concrete vanity with sink!

Blog entry

Concrete Formwork / Bathrooms

We have been extremely busy over at the Garden Street site.  We're in the final month of construction, which for us means a lot of hands-on custom work building cabinetry, shelving, and other Lowdo details.  We love it but we have a lot of retroactive blogging to do...

One of the biggest projects we took on was pouring concrete countertops with integral sinks for all three bathrooms.  These were a beast to make, but we can't wait to see the results.

In the master bath, the concrete countertop and sink will hang from these 2x8s.  We'll have rebar in the front edge of the counter, which we are making 7" deep so that it will serve as a "beam" to span across the 6-foot space.  The two smaller bathroom counters (3' across) will simply rest on the cabinets below.

We first built the forms for smaller bathroom countertops.  The forms are upside-down--the bottom surface will be the top of the counter when the concrete is poured in, and the asymmetrical box will be the inside of the sink.  We used melamine for the formwork, which has a slick surface that concrete won't stick to.  The corners are all caulked, and PVC pipe wrapped in tape serves to make holes for the faucets and drains.

We put remesh in the countertops to strengthen them against cracking or breaking.  On top goes another, secondary melamine form that will shape the deeper parts of the countertops.

The master bath formwork.  Ryan is tying in the rebar that will strengthen the front edge of the counter.  A second piece will be tied in to run along the bottom of the beam.

And then...with the much appreciated help of Ryan's dad...we poured!  We were all working quickly with the wet concrete, so no pictures of the pour in action.  More to come in a few days when we release the mold.

Blog entry

Concrete Counter Test Pours

We exposed the aggregate by performing a throw test: We threw the block of concrete up in the air.  We did this three times.  The first two it landed on natural ground/debris and stayed intact.  The third time it landed on the sidewalk and broke.  Conclusion: no throwing concrete at our countertops.






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