Georgia Residential Contractor Practice Exam

What type of material must be placed over the aggregate before backfilling?

1. Plastic sheeting

2. Building paper, straw, or similar approved material

3. Concrete mesh

4. Metal grill

The correct answer is: Building paper, straw, or similar approved material

The requirement for placing a material such as building paper, straw, or a similar approved material over aggregate before backfilling is rooted in the principles of construction and soil stability. This layer serves several important functions: it acts as a moisture barrier that helps maintain the integrity of the aggregate, protects the aggregate from contamination from soil and debris, and reduces the potential for the aggregate to mix with surrounding soils. This layer also aids in preventing erosion during the backfilling process and contributes to the long-term stability of the structure being built. In contrast, options like plastic sheeting, while they could potentially offer some moisture barrier benefits, do not provide the necessary drainage characteristics that a more permeable material offers. Concrete mesh and metal grills are primarily utilized for reinforcement and do not serve the purpose of acting as a protective layer over the aggregate. Therefore, materials like building paper or straw, which are specifically designed for such applications, are ideal for ensuring the best possible conditions for backfilling and support of the structural components above.