Part 1. How to make a Concrete Coffee Table for the Patio (Concrete Top)

hey there welcome to DIY projects with Pete today we're going to build a concrete coffee table with a wood base that would work great out on the patio this summer and we're going to do it so that it's three inches thick around the entire perimeter but we're going to save on weight so the whole interior portion is only going to be one and a half inches thick thus it's going to be a lot lighter to transport and just to have in your home let's go ahead and get started with today's project the first step is to measure and Mark for the base piece of the melamine mold we'll pour the concrete in for the detailed tutorial and links to the plans head over to DIY Pete comm forward slash patio concrete coffee table use a circular saw to cut out the base piece I made the concrete top in this project four feet by three feet but feel free to modify the size to best fit your space next we'll cut the strips for the side walls of the mold use a table saw or a circular saw for this process and we'll cut the strips to three and 3/4 inches to give us a finished piece with a three-inch thick apron the extra 3/4 of an inch accommodates for the 3/4 inch thick base piece of the mold cut the lengths of each board down to size two of the boards will be the exact same length of the base and the other two end pieces will be cut an inch and a half longer to overlap the side pieces and to form a box we'll attach the side strip to the base piece using screws always pre-drill to ensure the wood doesn't split make sure the bit and screw our levels so they go in straight and don't create a bulge in the base piece continue around each side of the mold and use a screw about every six to eight inches once the side strips are attached check to make sure they're square the outer strips on mine were a bit off so I used a screw to fasten them to the perpendicular sidewall which helped pull in the boards and square up the mold next we'll create the foam knockout for the mold this is going to allow us to have a thick looking three-inch concrete top without the additional weight and materials cost the foam came in two foot by four foot pieces so I cut it down to size and then used packaging tape to connect the pieces to get just the right size you want to run packaging tape around the entire perimeter of the mold as well which is going to help seal the sides of the foam so it removes cleanly from the concrete the outer perimeter will have a channel without foam where concrete will flow into during the pouring process and the one and a half inch thick foam will fill up the inner part of the mold allowing only one and a half inches of concrete to flow into the center portion since we're using the reverse cast technique for this project the foam will need to be suspended by connecting it to the boards that will hold it off the base of the mold Center the foam to ensure you have an even 1 and 1/4 inch gap which will form the apron around the concrete table and attach wood strips to the foam using silicone to hold them in place spaced the strip's evenly mark them so they'll line up with the side walls of the mold and will fasten the strips to the mold using screws later in the pouring process next we'll cut the reinforcement down to size using a bolt cutter it should be slightly smaller than the size of the mold and have about an inch of room between the perimeter of the reinforcement and the mold sidewalls then the metal if needed to get it to lay as flat as possible before sealing the mold with silicone flip the mold upside down to remove sawdust and other debris then use rubbing alcohol to wipe down the melamine next we'll apply silicone to the seams of the mold this will help create a slightly beveled edge for your concrete top and the corners run a bead of silicone and then use a beveling tool or your index finger to round over the bead have plenty of paper towels around for this process and make sure to wipe up any excess silicone let the silicone dry completely before starting the concrete pour I'm going to be using a 5000 psi concrete bag mix that you can pick up at your local hardware store for about $5 a big pour the concrete into a tub and then add water as recommended by the manufacturer you'll notice the water I'm using looks black and that's because I added a little bit of charcoal concrete coloring to give the concrete a slightly darker gray color but it's not necessary mix the concrete until it's about an oatmeal consistency and I mix the concrete up with just a tad more water than I usually do to help it flow underneath the knock out easier use a bucket to transport the concrete to the work surface area and begin placing the concrete into the mold always wear rubber gloves and continue filling the mold until it is just over three-quarters of an inch full which is half the thickness of the majority of the concrete top which is one and a half inches thick you can check by using your finger to get a good idea of how much concrete is in the mold then vibrate the concrete by lifting the table or by hitting the underside of the work surface and the sidewalls this is going to help remove air voids and it's going to help level out the concrete next add the steel reinforcement and do your best to make it lay as flat as possible then continue to fill the mold until there is an inch and a half of concrete this will be the thickness of the majority of your table vibrate the table again and then put the knockout in place and secure it to the top of the side walls by pre drilling and using screws my camera ran out of disk space while attaching the knockout but it is a pretty straightforward process next fill the gap or apron around the foam and between the side walls with concrete use your fingers to help push it in and blend it into the rest of the concrete periodically vibrate the table and side walls to help the concrete flow into all the areas of the mold and to help remove air pockets continue to fill the gap until it is flush with the foam and the top of the side wall then you can use a trowel or putty knife to help smooth out the surface now it's hard to get the concrete underneath the knock out boards so I'd recommend allowing the concrete to set up a couple hours and once you know the foam will not move you can remove the strips and then smooth out and work a little additional concrete into the areas where the boards were cover the concrete with plastic to help it tear evenly and allow it to cure for at least 48 to 72 hours before D molding depending on the temperature humidity and other variables once the concrete has cured it's time to de mold the concrete top which is my favorite part move the screws from each board and then use a hammer and chisel to lightly pry each side wall away make sure to always pry between the side wall and the base of the mold never pry against the concrete because it is still green and can easily be damaged slowly pull each board away and examine the concrete to see how it turned out the fewer voids the better but they can be filled with the slurry paste to help blend them in some people even like a few voids as they say it kind of has an organic type look but you know this can be okay for the sides but I'd highly recommend filling in voids on the top surface next we'll remove the foam knock out from the concrete use a flat pry bar to gently push the foam out of the concrete it takes a little work to get it started so take your time but then it should pop out fairly easily once out I like to ease over the edges of the apron using a hand sander remember to always work the sander from the corner outward because working the sander into the edge or into the corner could blow out that corner of the concrete you can see I slightly under filled the mold which is why the underside doesn't look perfectly smooth but it was a flat overall surface and work just fine flip the concrete right side up I'd recommend finding a friend to help with this process as it is about 220 pounds of concrete place old rags or leftover foam under the concrete to prevent it from chipping then slowly remove the last part of the mold it should release fairly easily and now you'll get your first glimpse of how the surface of your new table looks remember it's still a diamond in the rough and we can fill voids and rough edges as needed so don't sweat it if it doesn't look as great as you thought it would be right away let the concrete cure an additional day once it's out of the mold then move it outside and start the sanding process wear a mask whenever working around concrete dust and doing this outside is best because it can be quite a mess use 120 grit sandpaper to smooth out the underside of the apron and to slightly round over the edges and corners then flip the table again I'd recommend having some help with this and then do the initial sanding of the top and side surfaces the initial sanding will smooth the surface and it will expose a few more air voids I used 120 follow by 220 grit sandpaper to fill in the voids and fix any rough edges you'll want to create a slurry paste mix a little Portland cement with either acrylic for two fire or water mix it until it's about a toothpaste consistency then spread it around in a circular motion to push it into the voids this takes a bit of time so don't be in a rush I cover the entire surface to make sure small pinholes are filled as best as possible work the paste into the sides as well to smooth rough edges and corners you can use the V between your thumb and index finger to push slurry into the voids and to bevel or round over the edges you can then use a plastic putty knife to remove excess that you can reuse and you'll most likely need to repeat the process of filling in voids a couple times to ensure all the voids are filled and I typically let the paste cure at least a couple hours prior to sanding once all the voids are filled use an orbital sander with 220 grit sandpaper to smooth the concrete and to remove the excess slurry mixture go over the top edges and sides once complete fill in additional voids if needed and repeat the process I didn't have many additional voids and the weather started turning on me pretty quickly so I called it good and went inside to prepare to seal the table next I use a blue scotch pad to remove excess slurry I may have missed while sanding the water makes it easy to see what you've missed and it's important to remove it all because the sealer will lock it in and you will notice any excess slurry in the finished product if it's not removed then wipe the surface with a clean rag prior to sealing I like to lightly saturate the surface with a little bit of water this helps the sealer go on more evenly I'll then start the sealing process by applying a couple coats of sealer at about a 1 part water to one part sealer mixture I'll do a total of about six coats and I'll make each coat stronger so by the last coat the sealer is not diluted with any water the water based sealers dry pretty quickly but wait for each coat to dry before adding another after the last coat of sealer you can add wax for an extra layer of protection I used a food grade safe sealer and a wax and have had really good results with it if you do add a wax apply it similar to how you'd whack Sekar and then buff using a microfiber rag or a polisher alright thanks so much for watching please subscribe and give this video a thumbs up if you found it helpful and check out part two if you're interested in building the base and the patio projects playlist for more DIY inspiration thanks again for watching and Cheers from Montana you

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