How to Extend a Concrete Slab
Pouring a concrete house slabs Melbourne in your yard provides a level surface for anything that sits on it, from an outdoor air-conditioning unit to a hot tub. Expanding or adding new slabs can increase outdoor living space as well as add value to your home.
Framing can help to ensure a proper connection of an extension slab to its original slab, thus avoiding cracks in both instances as demonstrated in this Quikrete video.
Planning
Slabs are an essential component of every home. Not only are they crucial in terms of structure and foundational support, but adding on top of a concrete slab requires careful consideration as an extension project.
Consideration should also be given to the location and slope of the extension, including installing drainage for proper flow away from your house. You should ensure that any new slab will drain into a drain away from it.
Your concrete mix requires a mold. A frame must be constructed of 2x4s that have been nailed together; you can either buy one premade at a construction supply store, or cut your lumber using a circular saw yourself.
Excavation
An extension of a concrete slab requires extensive construction work, but its benefits and utility outweigh its associated expenses.
Excavation is an essential step in any construction project, but especially crucial when expanding a concrete slab. Excavation involves digging trenches for utilities such as water, sewerage, gas and electricity to ensure they’re installed correctly and will continue functioning as intended over the life of the structure.
Before initiating your excavation process, it is essential that you calculate how much concrete will be required for your slab extension project. This volume can be measured in cubic yards (CY). Use an online calculator to ascertain exactly how many cubic yards (CYs) of concrete you require for this specific endeavor.
Forms
Concrete forms can be created using plywood and 2X4 lumber, assembled onsite and secured into place using stakes. Once complete, oil or release agents should be applied so that the forms come off easily when completed.
Once the concrete form framing has been completed, rebar must be added. Half-inch bands of rebar should be tied securely around its perimeter with stakes to complete this step.
Once the rebar has been installed, it is time to brace and level the form boards. Accuracy here is key; an incorrectly leveled board could alter the final shape of your slab; take your time getting them straight! Also be sure to place 2×4 kickers every two feet along your form boards as support to avoid their bowing outward when concrete is poured onto them.
Rebar
Concrete is an extremely strong material, yet can become weak under tension or torsional forces. Steel rebars (reinforcing bars) can help increase structural integrity and decrease chances for large cracks forming in concrete projects – this is particularly crucial when expanding an existing slab.
After installing rebar, it must be secured to an existing concrete slab by chipping away old concrete, drilling holes of sufficient diameter to accommodate its diameter, and injecting polyester anchor grout into each of these holes.
Once the rebar has been secured, it’s time to finish the new concrete slab. This can be accomplished by draggign a piece of lumber across the surface of your forms – known as screeding – which removes excess concrete while showing you where more must be added.
Pouring
Slabs are one of the cornerstones of buildings, bearing most of the load for structural stability. Walls, beams and columns carry less weight compared to slabs; as a result, proper construction and planning of concrete slabs is vital in order for structures to stand and function correctly.
Before beginning to pour the new concrete slab, it’s essential that a frame be created from lumber around the excavation area. This step prevents concrete from moving during its pouring process while simultaneously fixing any pipes or roots that might cause cracking later.
As part of your form construction, don’t forget to include a slope for drainage purposes and score the concrete at least once to increase its strength and durability.