How to Extend a Concrete Slab

Posted by

Concrete slabs Melbourne are key structural elements in buildings. Extending your current slab is an affordable renovation option that does not require professional architect or engineer consultation.

To extend a concrete slab, it will require careful planning, excavating the area, building a frame and pouring fresh concrete. This article will explain all these steps step-by-step.

Plan Out Your Slab Extension Area

An extension to your concrete slab can be an intimidating undertaking, yet can become a valuable renovation that increases value and utility in your home. Planning the entire project ahead will only make the task simpler.

Prepare the ground by clearing away organic materials and compacting its subgrade using a mechanical mixer. Backfill the excavated area with stone as soon as possible for best results.

Calculate how much concrete you will require by calculating its volume in cubic yards. You can do this by multiplying the length (in feet) by width and depth of your slab extension extension project.

Mark the Area with Spray Paint or Stakes

Mark the area using spray paint or stakes so you can keep track of where the new concrete slab extension will go and avoid pouring it over existing pipes or tree roots by accident. This will also ensure a successful pour.

Also, building the frame will ensure the concrete you pour goes exactly where it should go. Once complete, you can fill your newly crafted foundation with concrete – or hire professionals who know exactly how to fill in these holes faster and more accurately than most homeowners can manage; plus they’ll install rebar for increased strength and stability.

Create a Frame

If your slab extension will be curved, a frame must be made. This could consist of several 2x4s nailed together.

Once your frame is assembled, it can be secured with nails to ensure that it stays level while pouring the concrete – this process is known as “squaring”.

Your new concrete slab requires adding rebar and welded wire mesh for reinforcement, either free-floating or secured with wire lashings. Control joints 3X the thickness should be added at least 12 feet apart, for optimal results.

Prep the Slab

Concrete is very strong when subjected to compression forces, yet can crack when subjected to torsional forces. Therefore, adding rebar to slabs helps increase their strength while decreasing the likelihood of large cracks appearing in them.

Before pouring a concrete slab, it’s advisable to layer gravel or compacted hardcore over the ground surface. This helps keep your slab above the water table and protects your structure from moisture intrusion.

Before adding concrete mix, it’s a good idea to “screed” the surface of your extension with lumber by running it back and forth across top of forms.

Pour the Concrete

Concrete must be prepared properly, which starts with installing concrete forms. Drive stakes into each corner of your slab extension area before using a level to set an appropriate form slope.

Concrete has an exceptional compressive strength but is susceptible to tensile forces, so for maximum crack prevention it should be reinforced with steel rebars or polyester anchor grout. You will also require polyester anchor grout between new slab and old one.

Before mixing concrete, determine how much will be required by multiplying length, width, and depth of your new slab extension and then dividing by 27 to get an approximate figure for how many cubic yards of material will be necessary.

Cure the Concrete

Concrete must be properly cured before it can support weight. Improper curing can result in weak and dusty surfaces with low resistance to abrasion, making the finished product unfit for use.

Crack control is also essential, since concrete shrinks when it sets and can create tension that leads to cracking. Luckily, using control joints can prevent this issue.

Planned cuts into concrete create intentional weak points which will be the first to crack when your slab experiences settlement. For more information on this subject, consult with a concrete contractor.

Leave a Reply

Your email address will not be published. Required fields are marked *