How do I build shuttered concrete walls?
Shuttering or formwork is the mould into which you pour concrete. Concrete floor slab shuttering is not difficult for the average do-it-yourselfer to set up and can be made from custom forms or wooden planks.
Vertical concrete walls require more experience and large projects are be best left to professional installers. If your project is not too large or complex, purchase or rent the forms. It is important to understand how to calculate the amount of concrete you will require prior to ordering a truckload or purchasing your raw materials.
Research shuttering manufacturers' websites or use the yellow pages to find construction rental yards or suppliers and determine what kind of shuttering will best help you complete your project. If you're thinking of making a concrete building, insulated concrete forms (ICF) made from polystyrene blocks or panels are a good choice because the polystyrene remains and negates the need for further installation of insulation. It is simple to join the blocks or panels with adhesive. Other options are removable plastic or metal forms which you can either rent or purchase.
Apply for a permit from your local city or county building and zoning department. It will require a plan of the proposed wall and a plot plan to show where it will be on your lot in relation to your house, other structures and your boundaries. If you do not obtain a permit prior to building, you may have to pay a fine or even demolish the structure.
Calculate how much concrete you will require. For the footings, measure the total length of the footings and multiply by the width and depth. Calculate the dimensions of the proposed wall the same way. Work out the total number of cubic metres you will be pouring and order that amount wet. If you are buying bags of cement, ask the shop assistant how many bags are needed per cubic metre. When you place your order for a truck to deliver ready mixed concrete or when you buy bags, add a little to your result.
Measure and mark the footings and dig the hole for them, sizing them according to your local building codes. It is important to make them as even as possible and corners must be at exactly the right angle. Place metal rebar in the hole for reinforcing before pouring the concrete. Use a plank or screed to level the top of the footings. Each city or county and form manufacturer will have its own specifications and you may have to install vertical bars every few inches to prevent the wall from sliding off the footings. For a large wall you will most likely want to order a truck of ready mixed concrete to pour the concrete into the footings. Use a wheelbarrow and shovel to mix and pour bags of concrete. Allow the footings to dry fully.
Erect the forms according to the manufacturer's recommendations. They all have different methods of clamping or bolting together and it is very important to make certain you have joined them securely so the weight of the concrete will not blow them out. You may have to apply oil to the forms prior to erecting them so that the concrete will not stick and you will be able to remove the forms easily. You may be required to install metal reinforcing in the forms to strengthen the concrete.
Call the ready-mix company to schedule a delivery time to pump the concrete into the forms, or mix the concrete yourself and use a wheelbarrow to transport the concrete to the wall location and shovel it in. Tamp the concrete down to make sure you get as many air bubbles out as possible. Leave to dry.
Remove the forms when you are certain the concrete has totally cured and is able to stand up by itself.