how do you build a concrete base for a shed

A step-by-step guide to laying a concrete shed base

Full Answer

How to build a concrete shed Foundation?

Build the shed foundation framework and make sure it is level and squared off properly. You need to tamp the soil and gravel for a firm base. Purchase the right amount of concrete according to the square area and depth of your foundation. Mix it properly and pour it slowly while using a 2×4 to screed the concrete to make it level and smooth.

How to build a wooden shed?

Prepare the ground for your shed by digging the foundation to the proper depth. Build the shed foundation framework and make sure it is level and squared off properly. You need to tamp the soil and gravel for a firm base. Purchase the right amount of concrete according to the square area and depth of your foundation.

Should I put a shed on a concrete slab?

But a slab has two main drawbacks you should consider before you make a final decision. The cost: A concrete slab could easily cost 3 to 10 times the amount of a wood floor. Your shed is no longer portable.

What are the advantages of a concrete shed base?

Four Advantages of a concrete shed base 1. Most durable form of foundation A concrete slab is without a doubt the most durable form of shed foundation. Dense well compacted concrete provides a level stable base that is resistant to frost and localised ground movement.

How do you construct a concrete base for a shed?

A step-by-step guide to laying a concrete shed baseStep 1: Measure up and mark out. ... Step 2: Dig out the base area. ... Step 3: Lay the sub-base. ... Step 4: Frame the slab area with the formwork. ... Step 5: Add your damp-proof membrane (DPM) ... Step 6: Order the concrete and mixer. ... Step 7: Mix, pour and spread the concrete.More items...•

How thick does a concrete slab need to be for a shed?

The best concrete thickness for a shed tends to be 4 inches which is the standard size used for most residential concrete patios, walkways and sidewalks. You can pour 6-8 inches if your storing something heavier but it's rare. Concrete slabs are typically poured over 4-8 inches of compacted gravel and earth.

What is the best base to put under a shed?

A gravel pad (crushed stone) with a lumber perimeter is the best shed foundation option in most cases. We recommend gravel shed foundations because they provide a stable base for your shed to rest on and do a great job of draining water away from the bottom of your shed.

Should you put a concrete slab under a shed?

Concrete shed foundation If you're getting a shed without a built-in floor you're going to need a concrete pad. The walls of your shed will actually get anchored to the concrete pad and that will provide a lot of stability that you would have otherwise gotten with a built-in floor.

What is the cheapest way to build a shed base?

Hi, The best way would be a concrete slab base and the cheapest way if the ground your putting the shed onto is reasonably level would be to lay pressure treated bearers across the joists of the shed base.

What is the cheapest way to pour a concrete slab?

One of the least expensive ways to get concrete is to mix your own. You can buy bags of the mix from a home improvement store. Typically, you only have to add water for it to be ready to pour. However, it is important to get the ratio right and to mix the concrete thoroughly.

Do you need gravel under concrete?

You do need gravel under a concrete slab, footing, or patio. Gravel provides a solid foundation for your concrete as it can be compacted. It also improves drainage, preventing water from pooling beneath the concrete.

How high should a shed be off the ground?

If you're planning to use your shed as a woodworking shop, the ceiling should be at least 9 ft. tall for dealing with sheet goods. If you're adding an overhead door, the ceiling should be at least 16 in. above the opening.

How deep should a shed base be?

75mmThe concrete base should be at least 75mm thick, with a similar layer of sub base, so you will need to excavate to the required depth and ensure that all plants, stones and debris are removed before compacting the ground with a roller or tamper.

How do you pour concrete under a shed?

Step 1: Mark the Location of the Shed. ... Step 2: Dig Out the Foundation. ... Step 3: Build the Concrete Form. ... Step 4: Set the Form in Place and Level. ... Step 5: Install Gravel to Achieve Uniform 4″ Depth. ... Step 6: Install Reinforcing Bar. ... Step 7: Mist the Gravel and Rebar with Water. ... Step 8: Mix and Pour Concrete.More items...•

Do I need rebar in shed slab?

Concrete makes a permanent slab on which to build or place your shed, but it is brittle. It needs reinforcement to give it added tensile strength and to prevent cracking. You can use steel rebar, or steel mesh, or opt for having synthetic fiber added to the concrete before pouring.

How thick should a concrete slab be?

Standard concrete floor slab thickness in residential construction is 4 inches. Five to six inches is recommended if the concrete will receive occasional heavy loads, such as motor homes or garbage trucks. To prepare the base, cut the ground level to the proper depth to allow for the slab thickness.

How strong is a 2 inch concrete slab?

A 2-inch concrete slab can hold 750 psi of weight. The stronger the slab will be, the more concrete is normally put at a thickness of 2 inches or more. A slab's thickness is most commonly four inches. The stronger the slab will be, the more concrete is normally put at a thickness of 2 inches or more.

Do you need rebar for 4 inch slab?

Generally, you do not need rebar for a 4-inch slab. But if one should choose to reinforce their concrete patio, the reinforcement bar they should use should be a size #3, which is 3/8 in diameter. Generally, rebar has an immense impact on concrete.

Does a shed slab need footings?

Does a cement slab need footings for a shed? It depends on what your local building code requirements are. In some cases, a floating concrete pad (4” thick on a base of crushed stone) is sufficient. In other cases, 12” deep footers may be required as part of the concrete pour.

Does a shed slab need reinforcement?

Concrete makes a permanent slab on which to build or place your shed, but it is brittle. It needs reinforcement to give it added tensile strength and to prevent cracking. You can use steel rebar, or steel mesh, or opt for having synthetic fiber added to the concrete before pouring.

2 - Level the site

Ensure the ground is clear and level. The flatter your site is to begin with, the easier the job will be. If your base isn’t level, it won't support your shed properly and may compromise the integrity of the structure over time. The timbers will flex with changes in temperature and humidity - and the doors and windows might not shut properly.

3 - Build a timber frame to contain the concrete

Make sure the inside measurements of your frame are the size you want your base to be.

4 - Mix the concrete and pour it into the frame

Either use ready-mixed concrete, or make your own by mixing sand, cement and water according to the manufacturer’s instructions (usually a cement to sand ratio of 1:5). Add water slowly until you have a workable consistency. If you mix a small amount at a time, use the same amount of water each time. For large quantities, hire a cement mixer.

5 - Install your shed on top of the base

Leave your new concrete base to set for at least three days before removing the frame. If it rains, cover it with plastic sheeting. Don’t allow it to dry out too quickly: in warm weather, prevent cracking spraying it with water and covering with damp cloth.

What is the best base for a shed?

For a sound footing, we would suggest using concrete , slabs or paving stones. Concrete makes the strongest most durable shed base, especially when it is reinforced. It is suitable as a base for all types of garden building; however, it is expensive, time-consuming to lay and permanent, so you need to get it right first time.

How much concrete will I need?

Whether you’re buying ready-mixed concrete or mixing your own with ballast and cement, concrete is typically measured in cubic metres.

How to measure base dimensions?

Accurately measure and mark out your base dimensions with wooden pegs and string. A good way to check your dimensions are even is to measure across diagonally, if they are the same, then your sides are even. Make sure any overhanging trees and bushes are cut back to allow at least a foot around the actual base.

What is the ratio of ballast to cement?

If you’re making your own, the ballast and cement ratio of 5:1 is typically the recommended choice. While mixing the concrete, add the water gradually to the mix until the whole pile is uniform in colour and sufficiently workable to use. Do not make the mix too wet as this will weaken the concrete.

Do you need electricity for a potting shed?

Keep in mind your requirements, if you’re erecting a potting shed, you will want to consider shade and natural light. If you are wanting to install electricity, you’ll need to consider when the mains supply is. Once you’ve chosen your location, roughly mark out the area and remove the turf.

Can you build a shed base vertically?

If you are not confident about tackling it then we recommend employing a reputable builder. A garden building will not stand truly vertical if the base isn’t level.

Do I need a base for my shed?

We are frequently asked this question and the honest answer is that all garden buildings need a high quality, properly constructed base. Otherwise, your new garden shed will be hard to assemble, difficult to align correctly and will inevitably rot and sag due to water penetration.

What is a good shed?

A great shed is also a handsome natural timber addition to your outdoor space, blending beautifully with your lawn, trees, shrubs, flowers and fencing. So, it’s worth taking the trouble to build a shed that’s attractive and sturdy as well as useful — and that has to start with the foundations.

How to compact gravel sub base?

Once your gravel sub-base is in place, thoroughly compact it using an HSS light vibrating wacker plate. Spread a layer of sand on top to prevent the sub-base stones from puncturing the damp-proof membrane.

How long does it take for concrete to go off after mixing?

Once you’re ready to start, speed is of the essence because concrete starts to go off around two hours after mixed. For a slab the size of an average garden shed, you can transport the concrete from the mixer to the site by wheelbarrow — both of which are available to hire from HSS.

How to make a tray for a sub base?

Lay heavy-duty plastic sheeting over the entire sub-base with the edges turned up inside the formwork to form a tray. If there are any joints, make sure to overlap and tape them. This DPM serves two purposes:

How many wheelbarrows are needed to move concrete?

Bear in mind that working with concrete is a two-person job, as it’s essential to keep everything moving. A square metre of concrete is around 40 wheelbarrow loads!

How to calculate the volume of concrete needed?

Multiply the length by the breadth by the depth of the slab, and you have the total volume of concrete required.

What is the best way to protect yourself from cement?

Cement is caustic and can do severe damage to your skin and eyes. Therefore, your highest priority should be working safely. Wear long sleeves and trous ers, a hat, gloves, rubber boots and safety goggles at all times.

How Deep Should Concrete Piers Be for a Shed?

Basically, your piers should go below the frost line to prevent frost heave, or the piers moving with the freezing and thawing of the soil. Plan to dig your holes at least a foot below this frost line. Your building authority should have information on the depth of the frost line in your area.

How Many Concrete Piers Do I Need for My Shed?

This depends on the size of your shed. Common spacing distance is about eight to ten feet apart. An 8 x 12 ft. shed typically has six piers, one on each corner and another in the middle of the long sides. You also need to also take into consideration what you plan to put in your shed.

What Size Sonotube Do I Need?

SonoTubes and other such tubes made for pouring round concrete posts and piers come in many sizes. They are made from moisture-resistant cardboard or paper and may be waxed inside. They are usually available at any home improvement store or lumberyard.

Can I Make the Form from Wood?

Most forms for concrete slabs are made from wood planks, which are later removed once the slab has fully dried. However, with piers, you are not pouring a slab. You can make square piers with forms made from scrap lumber, but wooden forms are usually utilized for much shallower pours.

Do I Need to Put Rebar Inside the Concrete Pier?

This is a matter of some discussion. Some people urge inserting rebar into the concrete while others don’t think it necessary. Basically, it comes down to soil and weather conditions. If your soil is unstable, you may want to use rebar in the piers to prevent the concrete cracking.

Do I Need a Base for the Concrete Pier?

You don’t need a base per se, but you should put four to six inches of gravel into the base of each hole and tamp it down before pouring the concrete. This will help with drainage and help keep underground water from pooling around the bottom of the pier as well as providing a firm foundation for the pier.

What Will It Cost for Concrete Piers?

The approximate cost is $3 to $7 per square foot, but this is the cost if you pay someone to build them for you. If you are putting these piers in yourself, it basically comes down to the cost of the concrete mix, or cement, sand and aggregate if you are mixing your own from scratch.

How does cement bond with sand?

Through a process called hydration the water activates the cement to bond the aggregate (sand and gravel) together . Some concrete mixtures have polymers added to allow for quicker times for curing and resist cracking.

What is concrete mix?

Concrete is a mix of gravel, sand, cement and water. You can purchase this with the gravel, sand and cement already premixed, such as with Quikrete or Sakrete . Other options are to buy the mixture separate and mix it entirely by yourself. However, the premix is perfect and easy for sheds.

How to make concrete nonslip?

Immediately after this use a stiff bristle broom and drag across the concrete to make a nonslip surface. Always drag the broom in the same direction for the entire foundation slab.

What are the key technical details for a concrete shed base?

Once you have decided that a concrete slab is what is required for your situation then you will need to enter the 'planning phase' for your slab.

What are the advantages of a concrete shed base?

Four Advantages of a concrete shed base. 1. Most durable form of foundation. A concrete slab is without a doubt the most durable form of shed foundation. Dense well compacted concrete provides a level stable base that is resistant to frost and localised ground movement.

What is a good base for a timber subfloor?

A level concrete slab is a good base on which to construct a timber sub-floor. Damp from the ground is minimised by using a PVC damp proof membrane beneath the slab.

What is the strongest shed base?

A concrete shed base is without a doubt the strongest and most durable form of shed foundation. It is also the most costly and labour intensive.

What is the strongest foundation for a shed?

A concrete shed base is the strongest type of shed foundation. It is at the heavier end of the work you will do to build your shed. This article will help you to decide if you really need such a heavy duty solution or if something a bit lighter and simpler to install would work just as well.

What does concrete floor mean in a shed?

If you have wheeled equipment that you need to get in and out of the shed, having a concrete floor means that the level of the floor can be close to ground level.

How to secure timber board?

Place the timber board in position and then secure it in place with either steel pins or 2x2 timber pegs. The steel pins are easiest to drive in place as 1 12 mm bar will go 200mm into the ground quite easily with a 4lb lump hammer. Timber pegs are harder to drive in but are easier to fix the side forms to as nails can be used to hold the wood in place.

How big should a concrete base be for a shed?from diy.com

We recommend making a concrete base the same size as the base of your building or 25mm smaller on all sides than the base of the shed. This creates an overhang and prevents water accumulating around the timber floor and runners.

What should be the starting point for a shed?from diy.com

A firm, level base should be the starting point for any shed or garden building. Without this the structure is likely to be assembled improperly - screw holes will not line up correctly, doors may not fit their doorways and the quality and service life of your shed could be greatly reduced.

What is an interlocking shed base?from diy.com

An interlocking plastic shed base is the perfect option for a quick and easy installation. This type of base is made from 100% recycled plastic and the plastic tiles (or grid) fits and locks together to form the base. The grids are free-draining and self-ventilating, ensuring the floor of the shed stays dry.

What is a portabase?from diy.com

A timber shed base , or portabase, is made from pressure-treated timber and comes with metal spikes which are hammered into the ground to keep the shed base in place. These can be installed on a level lawn or the frame can be placed onto a patio using the metal L-shaped legs (supplied with the kit) to help keep it level.

How to make sure the corners are square?from diy.com

Use a square to make sure the corners are square before you start excavating. As a final check, measure the diagonals to make sure they are the same.

How deep should a concrete slab be?from diy.com

This will be about 12cm deep to allow for the sub-base, mortar and paving slabs.

What type of feet are required for a concrete floor?from diy.com

If the base is located on a hard floor (level paving or concrete), only the L-shaped feet are required.

What is the best way to build a foundation for a shed?

A layer of compacted gravel under your shed’s concrete is a very important step in building a long lasting foundation.

How thick should concrete be for a shed?

Concrete Thickness For A Shed. Concrete is a great foundation and flooring material. The best concrete thickness for a shed tends to be 4 inches which is the standard size used for most residential concrete patios, walkways and sidewalks. You can pour 6-8 inches if your storing something heavier but it’s rare.

What is the base of a concrete slab?

A Solid Base. The base under a concrete slab is very important. Sometimes even more so than the thickness of the slab. Concrete should be poured on a base of compacted gravel over compacted soil. The depth of the gravel base, and the type of gravel used, can vary by location.

What causes cracks in concrete?

Cracking: If concrete is poured directly on earth, the soil can shift or sink which creates voids under the concrete. These voids can cause cracks in the concrete floor or footing. Compaction and gravel create a sturdy base for your concrete which eliminates voids and protects against cracks.

What is the best foundation material?

It lasts for a long time and is very strong. When it comes to foundation materials, concrete is the most common and probably the best. Almost every home and building built these days uses concrete somewhere in it’s construction. Because concrete is both a flooring and footing material, one pour does both jobs.

What is the best way to reinforce concrete slabs?

Fiber. Adding fibers into your concrete mix is a cheap and easy way to reinforce the slab without adding any thickness.

How many measurements are needed for a concrete shed?

Keep in mind that concrete calculations are all figured in cubic calculations not square footage. This is because a shed has 3 measurements, length, width and depth.

How thick should a concrete slab be?

Make your slab 4 inch thick and it will hold all the weight you can put on it. Any thicker is a waste of concrete and money.

Why hang siding over slab?

This way the siding will be able to hang over the side of the slab an inch to prevent water from seeping under the bottom plate and into your shed. If you want to put an apron in front make sure it slopes away from the shed or is a little lower than the floor.

How to make a bolt into a good anchor?

Put the nut and washer on the bolt and drive it into the hole, then tighten it up with a wrench. This will expand the bottom of the bolt and turn it into a good anchor.

Can a shed floor rot?

But on the plus side is you will have a floor that can carry any kind of weight, will never rot, and your shed will be resistant to almost any source of movement be it water, wind or frost heave.

Can you move a shed?

You can’t move your shed if you need to. And permanent structures are often treated differently by the law. Permanent structures often need building permits regardless of the size. This means you will need to build it to code and have it inspected, both which will cost you additional time and money.

Can you install J bolts in concrete?

You can install “J” bolts in the concrete when it’s wet or you can install expandable head anchor bolts after the walls are in place. If you are building to code check which option they recommend or allow.