How to Make Concrete Countertops

hey there and welcome to DIY projects with Pete 
in today's episode we'll be building concrete   countertops we'll go through the processes of 
building the molds pouring the concrete finishing   it and installing them if you liked this video 
please give it a thumbs up and subscribe to the   channel and let's go ahead and get started with 
today's project I started by removing the old   laminate counters these were attached with screws 
from the underside so I simply removed the screws   and pulled them out I found a big duel basin under 
mount sink at the store and unboxed it so I could   find the sink template now this sink had a nice 
cardboard template which will help with making the   sink knock out for the mold will be building in a 
later step I measure the cabinet area to determine   the layout for the concrete counters I'll keep 
the slabs manageable by creating one seam in   the concrete to the right of the sink today's 
project will be a total of three pieces the long   slab with the sink knock out the l-shaped corner 
and the small slab to the right of the stove you   can measure the areas to determine placement and 
sizing or you can build a template now building   a template is definitely helpful to make sure 
you get the measurements correct especially for   really complex counters or if the walls aren't 
exactly square it's not 100% necessary but it   can help make it easier to get the perfect layout 
since we'll be using the reverse cast technique   in building these counters so we'll actually have 
to build the molds mirrored to how they'll be when   they're flipped right-side up I cut a few strips 
of quarter inch thick plywood to about one and   a half inches and width to help with building 
the templates then I piece the wood together   to get them the exact size that I want the actual 
counters I went with a 3/4 inch overhang over the   actual cabinet doors typically this would be about 
one and a half inches from the cabinet's face   frame since the doors are another 3/4 inches thick 
you know typically I usually use a hot glue gun to   quickly make the templates but I ran out of glue 
sticks so I used a fast setting super glue that   was laying around the house I labeled the template 
so I knew the front back left and right sides as   well as a seam side and where the sink would 
be the next big step is to build the molds that   are going to hold the concrete I transferred the 
measurements to a sheet of melamine now melamine   is basically a particle board with a smooth white 
and waterproof coating on each side it's going to   help you get a smooth finish since the concrete 
will form against it you can use the template to   double-check everything and to make sure the 
layout is correct just remember to flip the   template upside down if you're using the reverse 
cast technique like I'm doing in this video I used   a circular saw to make quite a few of the cuts 
a table saw is another option if you have one   and I finished off a few of the cuts with a jig 
saw here's a look at the piece that will be the   base of the mold for the smallest slab the next 
step is to build the side walls of the mold it's   best to use a table saw for this portion of the 
project we'll cut the strips to 2 and 3/4 inches   in width to form our 2-inch thick counter tops 
that extra three quarters of an inch accommodates   for the three quarters of an inch thickness of the 
base of the mold since it's going to be attached   from the side find a flat surface to assemble 
your molds on cut the sidewalls down in length   on a miter saw then pre-drill and secure the side 
walls in place with one and 5/8 inch long drywall   screws I typically space the screws about every 
six to eight inches or so pre-drill through the   side wall and into the base piece and make sure to 
hold the drill as level as possible to help insure   the screw goes into the center of the base piece 
I cut 45-degree angles where there were inside   corners this way I didn't have any particle board 
facing inside the mold double-check the sink is   in the proper location and trace around the mold 
if you haven't already I had four inches of room   toward the wall behind the sink and three inches 
in front of the sink this is about as narrow as   I'd recommend having the pieces between the front 
and back of the sink the next step is to build the   sink knockout I used two inch thick foam for this 
process you'll want to trace around the template   onto the foam and then cut it out I find that 
cutting all four sides with the table saw seems to   do a good job a scroll saw or a bandsaw would work 
well too especially with sinks with more curves to   them the corners for my sink only needed a slight 
round over a belt sander or a roundover bid on a   router will do this process there are a number 
of ways to create sink knockout molds so feel   free to use your method of choice now once this 
is cut you can lightly sand out any rough areas   I use the drywall sander with us next you'll want 
to seam the sides of the foam stucco tape works   well for this process other smooth tapes will work 
as well go around the foam and make sure the tape   goes on evenly without any creases the concrete is 
going to form against the tape so any unevenness   or creases will show on the final result the 
tape might not go over the foam completely but   a silicone bead will cover it since the bead will 
be run around this portion to give the sink area   a slight bevel once this was complete I started 
working on the reinforcement for the concrete for   today's project I'm using wire mesh that you can 
buy in four by eight sheets at the hardware store   in the concrete section I started by cutting the 
mesh down to size with a bolt cutter so that it   fits in the mold and has about an inch of room 
between the reinforcement and perimeter of the   mold next I removed reinforcement from the sink 
area and help strengthen the concrete around the   sink area I added some 3/8 inch rebar around 
each side of the sink you can cut it to length   with a cut-off blade on an angle grinder once it's 
cut I attach the rebar to the existing wire mesh   using zip ties now you'd usually use metal wire 
but I've never had any issues with the zip ties   and they make it super easy to attach it make 
sure to cut the zip tie tails and then continue   adding reinforcement to the rest of the molds I 
typically only use rebar if my counters are at   least two inches thick and another option for 
reinforcement is hog wire mesh it's about 1/4   inch diameter and it works really well it's a 
bit harder to find but is generally available   at most farm supply stores I used a speed square 
to make sure all the side walls and corners are   square if anything is slightly out of square you 
can slightly push or pull the side wall to adjust   it then pre-drill and add a screw go ahead and 
give the molds a good cleaning with a shop vac   and some rubbing alcohol if needed then attach 
the foam knockout to the mold with some silicone   next we'll seal each mould with silicone there's 
a number of ways to do this but we're going to use   the taping method in today's example because 
it's pretty foolproof and it makes it so you   don't get silicone all over if you don't have 
much experience applying it you'll want to have   a razor blade scissors and some painters tape 
handy for this part leave about 3/16 of an inch   gap between the tape and the seem go around the 
base of the mold and then do the same thing on   the sidewalls at each corner you'll want to run 
the tape vertically so that it can be sealed with   silicone as well one thing I made a mistake on 
was I accidentally added silicone along the side   where the seam would be for where the large piece 
butts up to the l-shaped corner concrete piece now   you don't want to add silicone where the seam is 
because if you do the seam edges are beveled and   so your seam is going to appear much larger so 
learn from my mistake mark the seam sides and   don't add silicone where any seams will be next 
will make the Knockouts for the faucet and soap   dispenser you may need to reference your sink 
to see if you need to line up holes with any   holes already pre-drilled in the sink I made 
the Knockouts using foam pipe insulation and I   cut it with a razor blade now you may need two 
different sizes of insulation if your counter   is too thick for the faucet stem length so you 
have enough thread to secure the faucet from the   bottom with the nut you can buy premade rubber 
faucet knockouts from Amazon if you prefer and   a lot of people make them out of PVC pipe and 
put a slot in it so it can contract a bit easier   when pulling it out if you use that method I'd 
recommend going around the pipe a couple times   with duct tape to help it come out easier I use 
the pipe insulation because it's easy to cut and   it pulls out super easily do a quick cleaning to 
remove any debris before you apply the silicone   apply a bead of 100% silicone around the perimeter 
of each mold have a cup of water and paper towels   handy for this step next dip your index finger in 
the water and run it over the silicone to bevel   it pull up at each corner and use a paper towel 
to remove the silicone from your finger then dip   your finger in the water again and do another 
side this process goes pretty quickly and if   you accidentally get any silicone on the mold 
just wipe it off go around the sink as well I'd   recommend taping it off or if you're comfortable 
using a roundover tool then go for it once all the   silicone is applied you can go ahead and remove 
the tape I found that I get the best result if   I remove the tape while the silicone still wet 
make sure to have a garbage can nearby for all   the excess tape I used some silicone to attach the 
sink knockouts to the mold and put some tape over   the knockouts to prevent concrete from getting 
in them do a final cleaning of the mold before   the concrete is poured use a razor blade to remove 
any dried silicone and some rubbing alcohol and a   rag to get rid of anything else you'll want to 
let the silicone in the mold cure for a couple   hours or until it's firm before mixing and pouring 
any concrete now comes the fun part you'll want   to put on some old jeans and a work shirt because 
working with concrete is a pretty messy job now I   usually mix the concrete and a tub by hand but a 
buddy offered to let me borrow an electric mixer   so I gave it a shot for today's project I'm using 
the quick creeks countertop mix it's specifically   formulated for counters and has some additives to 
give you a more flowable mix with less water it   has a few other additives as well now concrete's 
main ingredients are the aggregate which are the   rocks and sand cement which binds them together 
like glue and then water to bring it all together   all mixes are different and there's definitely 
advantages and disadvantages for each type of mix   this mix is $23 per bag and the regular quikrete 
5000 is only about six bucks a bag so I'll go   through a few differences to help you decide 
which is the best for you you'll want to read the   manufacturer's instructions to determine how much 
water to add to the mix you can also add coloring   to the mix and I use some charcoal coloring to 
give them a little darker color the one thing   about color is you have to be somewhat precise 
for everything to match up perfectly which isn't   too hard but I really do like the natural gray 
color concrete as well and not adding color is   one less thing to worry about so that's something 
to think about you want to shoot for somewhat of   a flowable mixture with this mix you don't want 
it too soupy but you also don't want it too dry   you can always add a little more concrete mix if 
it is too soupy while mixing or vice versa you   can add more water if it's too dry I typically try 
to mix about two full bags at a time transfer the   mix to a bucket and then begin filling up the mold 
you'll want to push the concrete into the corners   and throughout the mold use your hands to press 
the concrete around and kind of jab your fingers   to sort of vibrate the concrete a bit you'll want 
to fill each mold a little over half full before   any reinforcement is added one thing I have no 
about this mix is that it starts to set up a   little faster than the normal quikrete 5000 this 
isn't a big deal for smaller projects and slabs   but when you get to larger slabs like this one 
you'll need to hustle a little bit more and it   really helps to have someone helping you take your 
time to get the concrete pushed in and around the   Knockouts corners and sides fill it a little over 
halfway and after it's filled halfway you'll want   to spend a decent amount of time vibrating the 
concrete to get all the air bubbles out the more   time you spend the fewer voids you'll have in the 
finished piece I've found that lifting the table   up and down quickly does a great job getting a lot 
of the air bubbles out you can also tap the sides   with a rubber mallet or use an orbital sander 
or a reciprocating saw without a blade to run   around the outside side walls to help remove voids 
from the sides next we'll put the reinforcements   in place the rebar near the faucet knockouts will 
go behind them and you may need to bend the mesh   a bit to help it lay as flat as possible in 
the concrete it can be a bit tricky so take   your time to get it to sit in the concrete well 
I'd recommend doing the majority of the concrete   vibrating where you're actually shaking the table 
up and down before adding the reinforcements this   is going to prevent any shadowing or ghosting 
that could occur once that's in you can go ahead   and fill the mold completely with concrete make it 
a point to really try and blend the two pores so   the entire slab looks consistent you can poke your 
fingers to blend them together a bit if needed and   to help add additional strength around the sink 
area specifically I mix glass fibers into the   concrete mix I packed this mix around the sink 
area and you only want to mix the glass fibres   into the portion of the counter that will be 
facing down if the glass fibers get into the top   side you'll be able to see them you can find the 
fibres on Amazon or at most local concrete supply   stores once the mold is full use a scrap board 
to screed the concrete move it back and forth in   a saw like motion to level it and to remove excess 
concrete the extra concrete can either be put into   low spots or back into the bucket the high-density 
foam I bought was unfortunately slightly more than   2 inches thick so I had to do my best to level the 
concrete around it after screeding the concrete I   ran a trowel over the slab to work it a bit and 
to start to give what will be the underside a   flat and fairly smooth surface I did the special 
countertop mix might be a little easier to work   with for a beginner and it has a much creamier 
feel to it while traveling it has much smaller   aggregate which is mostly the size of sand and the 
cheaper mix has a larger aggregate about the size   of pea gravel then I mixed up the rest of the 
concrete so all the molds could be topped off   make sure your tables are fairly level at this 
point so the concrete doesn't flow to one side   during the curing process and then vibrate the 
sides with a rubber mallet or another concrete   vibrating tool the more time you take for this 
the better results you'll have as the concrete   starts to firm up over the next hour so I like to 
go over the slabs with a trowel yet again just to   give it a little smoother finish not everyone 
will do this but I like to take the extra time   to trowel it next you can put some plastic over 
the concrete to help it cure evenly now it's time   to let the concrete cure and do its thing over 
the next 48 hours or so I had some elk visit for   cocktail hour so I got a little footage of them 
but kick your feet up and take a break after all   your hard work job well done once the concrete 
has had time to cure we'll remove the sidewalls   from the concrete use a drill and remove the 
screws then slowly pull away each sidewall you   can use a screwdriver to help pry the sidewalls 
away but make sure the screwdriver or chisel only   pushes against the wood if you push it against the 
concrete you can easily chip and damage it at this   point since it's still continuing to cure here's 
an up-close look at the sides fresh out of the   mold they still have some moisture which is going 
to continue to dry out but what you're hoping for   is to have smooth sides without too many voids I 
was pretty happy with how they're looking so far   and I like to hydrate the slabs with water as they 
continue to cure because it helps with the process   next I removed the faucet and sink knockouts I 
cut down the center of the sink knockout with   a knife and then slowly pulled out the foam use 
some sandpaper to lightly sand the edges of the   concrete make sure to sand from the corner out and 
not into the corner because you can risk blowing   out a corner sanding the edges will clean them up 
and help prevent any chipping while flipping the   concrete I flipped the smallest slab first you can 
see there are very few voids and that the concrete   is nice and smooth go ahead and hydrate the slabs 
once they're out of the mold next I started to   prepare for the sink portion of the mold you need 
to be extra careful with this one since it has   the big knockout and narrow portions around the 
front and back of the sink if you feel it needs   a little more time to cure before flipping go 
ahead and wait a day or two longer just to play   it safe when ready to flip put a few rags down 
for the concrete to rest on while flipping it I   flipped with the backside against the table that 
way if it chips for any reason it won't matter   since will be against the wall once the concrete 
is vertical move around to the other side and   slowly lower the concrete onto the foam make sure 
the concrete is evenly supported while lowering   it and that the foam will evenly distribute the 
weight of the concrete while it continues to cure you'll see there are very few voids so I was 
pretty happy with it I'd recommend letting it   cure out of the mold for at least another day 
or two before polishing or sanding this way it   will continue to harden to a higher psi which 
will lead to better results while sanding or   polishing I grabbed a tarp to protect the work 
surface and then wield my table outside for   this project I'll be wet polishing the concrete 
wet polishing will give you a very smooth and   professional finish however dry sanding with 
a normal orbital sander is also an option and   I've had great results that way too if you're 
interested in seeing that process please check   out my outdoor kitchen concrete tops video 
which is linked to in the description below   polishing concrete is pretty messy so I like to 
cut a few holes in a garbage bag and wear it to   stay dry rubber boots are also a good thing to 
wear now wet polishers can sometimes be rented   at a local tool rental business but if you 
can't find one there are rental sites online   that will ship one to you or you can purchase 
your own which is in the neighborhood of two   hundred dollars on Amazon I start by doing 
a quick polish of the underside especially   around the perimeter overhang area where someone 
might run their fingers I'll use a two hundred   or a 400 grit polishing pad and then call 
it good I'll also slightly bevel the edge I'll polish each slab and then use a squeegee to 
remove excess water once that's dry I'm applying   sealer to just the underside of the counter this 
way I can minimize how many times I have to flip   the slabs flip the slabs right-side up and start 
polishing them I started out with an 800 grit   pad 400 grit and below will more so grind the 
concrete to expose the aggregate which can be   really cool if you want to see the rocks and sand 
in the concrete it's also what you'd use if you   embed items like crushed glass into the concrete 
anything above 400 grit is more of a polishing pad   and it won't expose the aggregate I wanted to keep 
the natural gray look and so I lightly polished   each slab with the 800 polishing will expose new 
voids which we'll fill in later with a mixture of   Portland cement and acrylic fortifier or water 
that I'll refer to as a slurry mix I also like   to use the 800 grit pad to lightly round over 
the top edges and corners the next step is to   fill the voids with a slurry mixture I typically 
use Portland cement and I mix it with an acrylic   fortifier which will help it bond a little better 
than just water I'll mix in a little color if I'm   trying to match the color of the concrete slab 
and I'll use my hands to rub the slurry mixture   into the holes and have a plastic putty knife 
as well the putty knife works great for removing   excess and then do your best to fill in as many 
voids as you can take your time to remove a lot   of the excess so you don't have to polish through 
a bunch of it later once complete let the slurry   mixture dry for at least a few hours then go ahead 
and do the final polishing I used a 1500 grit pad   to remove the slurry and to give the concrete a 
nice Sheen make sure all the excess slurry has   been polished away to polish the sink area I'll 
use a normal polishing pad where I can and then   I'll get the corners and hard-to-reach areas with 
either hand polishing pad or a blue scotch pad   I've actually found that the blue Scotch pad 
works really well after polishing I'll remove   the water with a squeegee to see if there's 
any spots I may have missed with the polisher the next step was to seal the counters I wiped 
each slab down with a clean rag and then applied   a food-safe water-based acrylic sealer apply 
the sealer according to the manufacturer's   instructions this one took a few coats I've been 
using Chang's and tough duck water-based concrete   sealers for years and they work pretty well 
in combination with wax concrete counters can   still stay in through these sealers though and 
I haven't yet found the perfect sealer however   I recently heard a lot of good things about 
the Omega sealer from the concrete countertop   Institute so I'm really looking forward to testing 
that out in future projects I wanted to beef up   the cabinet's a bit for these heavy concrete 
counters I simply strengthen them by adding a   few 3/4 inch thick pieces of plywood in each box 
this also gives the concrete more surface area so   the weight is evenly distributed I used pocket 
holes and screws to secure the extra boards in   place I prepared to mount the sink by framing 
in the cabinet with additional boards around the   perimeter for the lip of the sink to rest on the 
plywood strips are set about 1/8 of an inch lower   than the cabinet so the metal lip of the sink 
will rest flush with the top of the cabinet's   I prefer this method over using Clips because 
I don't really like to drill into the concrete   next we started moving in the concrete I recruited 
my buddy Rick to help install the tops he was in   town to do some fly-fishing so of course I had to 
put him to work after he got back from the river I   applied 100% silicone to the tops of the cabinets 
to secure the concrete in place and prevent it   from shifting here's a look at the area we've 
prepared for the sink I applied clear silicone   to hold the sink in place the sink fit in like a 
glove and is nice and secure I made a few small   adjustments to make sure it would be centered 
for the concrete and then I double-checked that   everything was level the sink I purchased only 
had a hole for the faucet so I had to add an extra   hole for the soap dispenser a step bit is what 
I'd normally use and would recommend using but   I didn't have one so I grabbed the plasma cutter 
and made a quick cut silicone was added to the   cabinet tops and then the final slab was put in 
place make sure the concrete countertop is level   and then it's lined up with the sink I picked up 
a pulldown faucet from Kohler and a soap dispenser   they're really easy to and I mentioned that I made 
a little mistake and beveled the top edges of the   counters where the seam is and so it's definitely 
more noticeable but honestly it doesn't bother me   one bit I push the slabs together as close as 
possible taped each side of the seam mixed up   some silicon with grey pigment and then used a 
putty knife to apply a smooth line next I used   clear silicone to seal the space between the 
counter and the sink I taped on each side of   the seam ran a bead and then smoothed it over with 
my index finger lastly I pulled off the tape wax   the counters and called it good all right thanks 
so much for tuning in I hope you enjoyed today's   episode and that it helps and inspires you with 
whatever concrete project you're working on if you   found the video helpful please give it a thumbs 
up and subscribe to the channel and if you're   interested in more concrete projects I have a ton 
of different ones in my concrete projects playlist   which you can find in the description below 
thanks again for watching and Cheers from Montana

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