Final Sub-base Prep and Vapor Barrier
At 0:13 in
So exciting to watch this go up
What happens here
After all underground utilities are installed, trenches backfilled, and the backfill compacted, perform a final, meticulous inspection of the entire sub-base. Re-compact any areas that may have been disturbed during the utility installation to ensure a uniform density across the entire slab footprint. Use a fine-tooth rake and a long straightedge to achieve a perfectly smooth and level surface, ready for concrete. For crucial protection against moisture, lay down a continuous vapor barrier, typically 6-mil polyethylene sheeting, over the entire sub-base. Ensure seams overlap by at least 6 inches and are securely taped with construction tape. This final step prepares the sub-base perfectly for the concrete forms and the subsequent slab pour.
Goal: Ensure a perfectly level and moisture-protected sub-base for concrete.
Tools and materials
- Long Straightedge — Checking for flatness and levelness across the entire sub-base
- Plate Compactor — Performing final compaction of any soft spots or disturbed areas to ensure uniform density
- Rake — Fine-tuning the level and smoothness of the sub-base surface
- Tape Measure — Measuring overlaps for the vapor barrier seams to ensure proper coverage
- Utility Knife — Cutting the vapor barrier (polyethylene sheeting) to the required size and shape
- Construction Tape — Sealing vapor barrier seams and around any penetrations to maintain a continuous moisture barrier
- Polyethylene Sheeting — Acting as a moisture barrier to prevent water vapor from rising from the ground into the concrete slab