What is Slab-on-Grade Installation
Slab-on-Grade is a very simple idea. Instead of digging down and emptying an average of 3 cement trucks to pour a basement foundation footing, floor, and walls; A slab foundation only requires you to level the ground your home will be sitting on and pour the floor of your house. Before starting the construction process, the contract excavates the soil (next to where to construct the foundation) and confirms the ground can support the structure.
This reduces the carbon cost of your home to 1/3rd of a basement foundation, but also saves you a tremendous amount of money compared to a full basement, both with respect to initial investment and the savings on not having to heat/cool your basement.
Also, you can use slab-on-grade foundations in areas with unsolidified grounds. Also, note that these foundations can or may not feature reinforcement in them. However, the reinforcement inclusion depends on the local construction codes and floor loads.
The grade slab should have a thickness of at least four inches. Increase the slab thickness if the soil features porosity. Besides this, to maintain construction safety, a bitumen layer and gravel layer should be positioned on earth before arranging the concrete slab. Through this, you’ll stop moisture content penetration into the grade slab.
Supported slab-on-grade works great when the site already features conventional footings to hold up the columns. Under the supported slab-on-grade, the wall needs to be placed on a conventional footing and grade slab stand on the moisture barrier and gravel layer.
The formwork used on plinth beams works as the slab mold’s batter boards. Also, you have an expansion joint between the wall and the concrete slab to minimize the stress inserted during the high-temperature seasons.
The control joints must be installed in a grid designed with chalk lines. This feature plays a vital role in managing occasional slab cracking.
Note that grade slabs usually stand on the moisture barrier and gravel layers which can resist water penetration into the grade slabs to create surface cracks. Also, the grade slab features a very dense periphery than the remaining surface. This section plays a critical role by working as a mini building footing.
Environmental benefits of slab-on-grade foundations
A popular choice for LEED, BOMA, and Passivhaus building projects, the benefits of slab foundations go beyond just upfront carbon savings. Slab foundations have considerably more thermal mass than basement foundations, storing and releasing heat during the winter; and rejecting it in the summer. Slab foundations are a popular starting-point for passive homes for this reason. While you may not be building to such a high standard, you can still take advantage of the efficiency bonuses of slab-on-grade. In addition to the fact that you don’t have to heat/cool a basement, the passive solar benefits of a slab foundation will substantially reduce the energy requirements to heat and cool your home for as long as your building stands. These foundations work well on garages, barns, and sheds to deliver a beautiful floor without digging deep into your pocket.
If you decide to go with a slab-on-grade foundation, electrical and plumbing works must be positioned inside the building or below grade. This foundation requires the position of all wiring to be within a water-tight conduit. Also, all wiring must respond to replacement whenever there is a need for repairs or upgrades.
Considering slab-on-grade instead of traditional basement foundations confers tremendous environmental benefits, lower upfront-costs, and a passive reduction on utility costs for heating and cooling. Like any building method, slab-on-grade has its pro’s and con’s that make it a better or worse choice depending on the unique circumstances of a build.
With the right design, the detractors of slab foundations can be reduced or done-away-with entirely, and the benefits can be maximized, making slab-on-grade a fantastic choice for home building.