Need an outdoor cooking facility to match your house and outdoor entertaining area? Why not use up left over bricks from a house build (or someone else's house build) and a few bags of instant concrete for a cost effective BBQ setup? Once the concrete is polished and sealed it becomes very non-porous and food/grease just wipes right off.This makes it a healthy cooking surface and is extremely durable over time.
- A BBQ or two (or three)
- Bricks. Either source the type/colour you want or just scrounge up free leftovers that can be painted.
- Circa 3 x 20kg bags instant concrete plus aggregate (can add some river pebble or colour on the top of the mix if that floats your boat)
- Screws, a sheet of plywood for the form, plus a whole bunch of timber scraps for sides and supports. Kitchen melamine is best for the sides of the form as it is smooth and peels off the hardened concrete best
- rebar and mesh. Since the quantities are small, chances are you can find something suitable for free that people are throwing at when pouring driveways etc. Right angled ones for corners are beneficial
- Diamond tipped concrete grinding cup (can hire someone to grind the top which won't break the bank)
- Can of sealant
- BBQ(s) of your choice
Step 1: Plan
Fail to plan, plan to fail.
Spend some time working up concept drawings to ensure your finished product will be fit for purpose. Decide a budget, and what type of BBQs you want and need (gas, charcoal, wood, smoker etc). Once concepts are complete, do some more details plans on paper.
Decide on the types of BBQs you intend to use and put some research in to the makes/models. Cheap BBQs will only be guaranteed for a year or two and will show signs of rust in about the same period of time. An outdoor BBQ will be exposed to the elements so it is advisable to source one with a 10 year stainless guarantee if you want one that will last (maybe difficult to find a replacement BBQ to fit the gaps 5 years down the track).If you are going to use a round BBQ like a Kamado or kettle, then work a gap beneath the bench in to the design for easy access to the ash pan. Buy the BBQs BEFORE you start the build, so you know the exact sizes for the cutouts. Other things you may need to do is get an electrician to install an outdoor power point or two, for rotisserie units, and other appliances you may want to run like electric knives, electric frypans (I use these to cook mussel fritters), dehydrators, etc. And consider outdoor lighting so you can cook in the dark (I already had a 30w LED floodlight installed to light up the entire cooking area)
Step 2: Lay the Bricks
Decide on size and placement of your BBQ bench, you can never have too much bench space when preparing food so don't skimp on the size. Mine is almost around 1.2m deep (almost the full width of a plywood sheet) in order for my Kamado lid to open fully. For me it was convenient to make the overall length the same as a section of my fence (for aesthetic purposes); it also worked out to be the same length of a sheet of plywood (2.4m). Lay out the bricks on a solid base leaving 10mm gaps for mortar) and decide if the proportions are suitable before making the permanent structure. Either lay the bricks yourself if you can do this straight and tidy, or pay a bricklayer a cashie to do it; it wont take him/her long. Ensure you leave weep holes for water to drain from beneath of necessary. And leave a decent size access gap to get in underneath for storage, getting to the gas bottle and power points, and for hosing out. When choosing the height of the bench, measure your kitchen bench height if it works well enough for you, and add another row of bricks for good measure.
Build some supports for the back corners of any gas BBQs to take the weight of it. I made brick pillars for mine however this was time consuming and finicky. If I was repeating this project I would just use 2 x wooden posts and paint them to match.
Step 3: Build the Concrete Form for the Bench Top
Lay the plywood out on top of the bricks (once the mortar has set).
Use a jig saw to cut the hole for any circular BBQ and place a bucket in the hole with a few heavy objects in it so it doesnt move when the conrete goes in.
Use a saw to cut any straight cuts for gas BBQs (or other types)
Build the sides of form, suggested depth of 40mm to 50mm similar to kitchen benches. Use a grinder to cut up rebar and mesh, and place it around the form to strengthen the bench. Concentrate of thinner areas of concrete (ie the sides) which are more susceptible to breaking, and get these reinforced as much as possible.
Step 4: Mix the Concrete and Pour the Bench
Take a shovel and mix the concrete according to the instruction on the cement packet. Some cement comes with aggregate and some does not. You must have aggregate in the mix or it wont set properly. I found a large flexi bucket easier to mix, and in smaller quantities than a wheelbarrow. The mix could easily be lifted and poured straight in. lift the rebar up a centimetre or two from the plywood base, so that it is roughly in the centre of the bench. make sure the mix is a wee bit runnier than a dough consistency so that he concrete all settles downward with gravity. You can bang the side with a hammer to do this, but a wetter mixture is even better and working out air pockets. Smooth the top out with a trow so that its flat (and tapers out to the side so rain drains off but this can be done during the grinding process).
Let it set over about a two week period assuming the weather is warm
Step 5: Take the Form Apart and Admire What You Built
unscrew the form, crack a beer and admire what you built (optional)
Step 6: Add Some Concrete Strips Below the BBQs (optional Step)
If you planned to add strips of concrete for looks like I did, then build some forms, mix up the same type concrete as the bench, and pour. I waited for this step so that I could get the exact height needed for the gas BBQ to fit perfectly (otherwise you can do this when pouring the bench)
Step 7: Grind, Polish and Seal the Concrete. Paint the Brick If Desired
After about two weeks the concrete will have hardened enough to grind. It is advisable to practice this first as I left obvious waves of grind marks that were quite visible when I first tried it. I was worried the gouge marks may not polish out easily. Within 20 mins you should be able to easily grind a few millimeters off the top to expose the aggregate and give you a desired looks. Then give it a gentler, more delicate grind to try making it smooth as possible. Then you can either use proper wet/dry polishing pads starting at about 500 grit right through to 5000 grit wo smooth the surface right out (mine kept cracking and breaking after a few mins of use when the plastic discs broke up) or an electric sander does the job also. I gave mine a tinkle with an orbital sander for half an hour and a couple of different grits and it came out great..
Sweep up the concrete and keep it in a container before throwing it away. This dust can be remixed in to a paste and used to cover the holes/gaps on the sides of bench and concrete strips below where the forms had been ripped off. Just mix a paste and apply like putty, smoothing it out with a clean scraper. Let this dry for a few days and sand or polish it smooth. I wouldn't take a grinder to it on the sides.
Hose down the concrete surfaces to get rid of all the dust and when it's dry, use a paint brush or roller to apply a thin coat of concrete sealer.After just one coat is applied you will be amazed at the difference. pour on a little water and it just forms beads instead of leaching in to the concrete like it would have before the sealer, Apply a second coat and store the leftover in a dry shed and reapply every few years as porousness of the bench top declines.
Paint the bricks with a few coats of paint (I had done this earlier on as I was already painting some seating at the same time)
Step 8: Install the BBQs
Install the BBSq, connect up the gas and any additional components like rotisseries. Test lids open and close properly. Clean and tidy your work area so that food can begin being prepared
Step 9: Cook and Enjoy
Find a huge roll of steak and carve off some doorstop slices. Fire up your BBQs for the first time to christen it.
Take all of the accolades from you wife graciously as she puts photos on social media telling everyone how wonderful her husband is. Bank the brownie points to get you of the dog box in coming months.