HOW TO LAY ACONCRETE

PAD

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WHAT YOU’LL NEEDTake this into store with you to make sure you get everything in one trip. For this project the following materials and equipment are required:

MATERIALS:

Boxing timber (100 x 25mm rough sawn untreated timber)

Nails

Dazzle

Basecourse

Pegs

Sand

Polythene

Mesh

Aggregate

Cement

TOOLS:

Hammer

Compactor

Rake

Concrete mixer

Gloves

Magnesium (mag) trowel

Steel trowel

Shovel

Straight edge

Level

THE FINISH For the first stage of the finishing process, use a

straight piece of timber to screed the concrete o� . It is best to have a little excess concrete in your slab so you have a little extra to work with which will make for a more uniform � nish.

Next, use a magnesium (mag) trowel. This stops drawing the water up and out of the concrete too soon.

How long you wait for this to dry is entirely weather dependant. You may need to test the concrete a couple of times to ensure it has dried enough for you to hit it with the steel trowel but not so dry that you can’t work with it.

The final stage is with a steel trowel for a nice, smooth � nish. You can repeat this � nal step to create a smoother � nish if that’s the look you want.

CURING A pad this size will need around 48 hours to cure but

keep an eye on it. Concrete that dries too fast can crack and shrink, so in sunny conditions you might want to give the concrete a light mist with your hose to prevent this. Alternatively you can also use wet sacks to retain the moisture.

Mitre 10 Handy Hint:• Using old engine oil on your boxing will help

the timber strip away from the concrete with great ease.

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Limitation of LiabilityThis project planner has been produced to provide basic information and our experienced sta� are available to answer any questions you may have. Because this planner is general in nature, neither your Mitre 10 supplier nor their sta� are responsible for the application of these design principles in any particular case, as the contents of this brochure may need to be modi� ed for the particular site and circumstances.Mitre 10 is not responsible for the quality of work carried out on the goods by the consumer and is not responsible for the design or construction of any structure in which the goods are incorporated.Where applicable consumers should ensure that they comply with The New Zealand Building Code and/or Local Body Bylaws in respect of any such structures.Consumers are advised to call a quali� ed tradesman such as a builder, electrician or plumber where expert services are required.Mitre 10 will not be liable for any consequential loss howsoever arising from the use of goods sold, nor for any loss caused by defective or inadequate structures in which goods are incorporated.

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Mitre 10 Stay Safe Hint:Concrete is safer to work with than most other common materials. There are three main safety points to remember:

1. Be careful lifting and handling, concreting materials are heavy and you could hurt your back.

2. Don’t let freshly mixed concrete or mortar come into direct contact with your skin. Wear protective gloves. If you do get wet concrete on your skin, wash with soap and water within an hour.

3. If cement gets in your eyes wash immediately with clean water and seek medical treatment.

Laying a concrete pad is a handy DIY skill that can be put to use in a variety of ways around your home from driveways and paths to � oors. In this guide we will take you through the process of laying a concrete pad for a 1.8m by 1.5m garden shed.

GETTING STARTEDSelecting and preparing the site

When you are deciding where to place your shed you need to allow enough distance from hedges and fences.

BOXING Boxing is the outer framework that is pegged in place

on the ground that holds your concrete in place.

This can be made out of any old timber you have lying around. If the timber is not straight it can be easily straightened with your pegs. Ensure to use enough pegs to support the boxing so when the weight of the concrete is loaded up against it, it will not ‘blow out’.

Using 100x25mm rough sawn untreated timber, nail the boxing timber together and place on your selected site. Measure the diagonals to make sure they are both the same to ensure your boxing is square. Use your stringlines and dazzle to mark out where the perimeter of your concrete pad is going. Do all necessary soil removal prior to placing your boxing timber and basecourse down.

A concrete pad can be level with the ground or raised above it. For this job we are laying the pad level with ground.

PREPARING THE SITE

This shed requires a total depth of 150mm. This depth can vary depending on the job or terrain. Generally speaking, a � oor slab or a driveway will be 100mm minimum basecourse and sand, and 100mm concrete. Before commencing work, check with your local council as you may require a permit.

Peg the boxing timber in place. Make sure it is level so your shed sits flat, and then fix the pegs to the boxing timber.

Rake and remove any loose dirt.

For this shed we are going to create a rebate. This is a step around the edge of the concrete pad which the shed will sit into. We do this just for the purpose of water tightness.

Attach pieces of 20x25mm timber to the inside of the boxing timber to create the rebate in the pad that the walls of the shed slot onto.

Add 75mm of basecourse and compact it.

Add 10-20mm layer of sand and give it a rake. This is to stop the polythene being punctured by the basecourse.

Place a sheet of polythene over the sand and tuck it in neatly around the edges. This will act as a moisture barrier.

If you are laying mesh, use small concrete blocks or mesh chairs to hold it o� the polythene, so it sits in the middle of the concrete slab.

A concrete pad this size doesn’t require mesh but anything larger or heavier will.

THE MIX Mix your concrete in a mixer according to the

instructions on the pack and then pour it into the boxing timber. Spread it out and then give the boxing timber a tap with your hammer to settle the concrete and get rid of any air bubbles.

Machine mixing - this is better for larger quantities.

Hand mixing - hand mixing is appropriate for small volumes.

1. Measure out the sand and builders mix into a heap on a hard surface or in a wheel barrow.

2. Make a crater in the centre of the heap and add the cement.

3. Mix the materials together thoroughly, aiming for a uniform colour.

4. Make a crater in the mixed heap and add some of the water. Bring the dry material to the water from around the edge of the crater. Keep mixing and adding water until the whole pile is mixed well.

Placement of concrete Start in the corner and work your way along the

edge. Ensure to occasionally lightly tap the side of the boxing timber to remove any air bubbles. For a shed this size, you can place all your concrete in and move straight to the � nishing stage.

Mitre 10 Handy Hint:• Leave the nails sticking out so the boxing timber

is easier to remove at the end of the job.

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