Build the ultimate braai

There are many ways to tan a chop, but only one recipe for the ultimate outdoor oven.

It’s a lot more convenient to pop something in the microwave or fry it on the stove, but cooking over fire has a certain sense of occasion to it. Our palaeolithic ancestors were the first to start formalising the braai spot in the camp, and archeological discoveries date this cooking method back almost two million years. Cooking food is like having a stomach outside of your body to process the food and unlock the full nutritional potential. As far as we’re concerned, the braai should be the focal point of outdoor activities, and this is what you’ll need to build a great one that’ll last a long time and keep any smoke from stinking up the place.

OBEY THE LAW

There’s a useful golden ratio when it comes to extracting smoke from your braai area, and understanding that is the first step to grilling nirvana. Ten-to-one is the optimal relationship between braai opening and the flue (the duct inside the chimney). Multiply the height and width of the opening to get the area and then divide by 10 to get the perfect cross-sectional area of the chimney opening.

GET HIGH AND WARM

The taller the chimney, the better the draught. But not always. You want your chimney to create a low-pressure area along its length that will suck the smoke out. A cold chimney is bad for creating this effect, so try and position your fire directly underneath the chimney opening. Moving the fire back in the firebox will also create more distance for the smoke to reach your eyes, encouraging it to take a path of less resistance straight up the chimney.

Placing a cowl on the top of the chimney is a good way to guard against the wind and also create a better draught for the smoke – wind rushing past will create a low-pressure area at the cowl opening.

INSULATE

Normal plaster isn’t going to cut it for longterm durability. No – when the heat is on, it’s best to use boiler plaster. This heat-resistant mix of, primarily, quicklime (calcium oxide, CAO), silicon dioxide (SIO2) and aluminium oxide (AL3O2) sets relatively quickly and is a great barrier for weather, impact and abrasions. The inside of your braai will look pristine for years with a little bit of investment up front.

BUILDING BLOCKS

Do you know why face bricks are the most common braai building material? Because they’re baked at 1 000–1 300˚C to stabilise their structure, and would need heat of that or higher to weaken them. This high thermal mass also makes for great insulation. Go for a cavity wall with brick force and brick ties for optimal strength and insulation.

A standard mortar mix is fine for the outer skin, but go for a 1:5 or even 1:6 mortar mix for the inner skin to allow for better joint movement under heat. This way, you’ll also get fewer cracks.

You don’t really need fire bricks (refractory bricks, fired at 1 600°C) to build your braai, but a little over- engineering never hurt anyone. Go for clay pavers or bricks for the base. Build a frame on top of the cement slab and pack the bricks tightly on a sand bed. You want to leave some room for movement because the base takes the most heat, so don’t cement or grout those base bricks into place.