After your floor has been treated for termites and the plumbing rough-in has been completed, you’re ready to pour the floor. This is an important step that should be undertaken with great care.
The floor needs to be a minimum of 4” thick and be uniform in thickness. If there are going to be load bearing partitions going over the floor, the foundation crew should have provided additional footing below these walls. If you have steel columns for the first floor that have been set on footers prior to the floor being poured, they should have expansion foam wrapped around the area where the concrete will contact the columns. Any object coming through the concrete (mostly plumbing) should have expansion material wrapped around the area of contact. This gives the floor space and the object space to move.
Once the floor is poured you need to cut-in expansion joints as concrete expands and contracts. These joints should be a minimum of 1/3 of the thickness of the concrete and on a maximum grid of 10’x10’. These should be cut the day after the floor is poured. Backfill of the foundation walls should not occur until the floor is poured and cured, as it will aid in keeping the walls from being pushed in at the bottom.
Depending on the height of the walls and how many offsets you have, you may need to wait until the floor system is placed before backfilling. The floor system will help keep the walls from being pushed in from the top. Remember once concrete cracks… it’s cracked… no going back. Be safe – not sorry. The site contractor needs to be careful when backfilling to not push in large rocks that could damage the walls and create large voids.
Remember, the backfill is loose dirt and small rocks – this will settle over time. This is normal and the only action needed is for additional fill to be placed in these areas. The backfill should ensure positive drainage away from the walls. You don’t want water being pushed towards the walls now or ever. Make sure the daylight drain is open and/or if you are using a sump pump, your plumber needs to hook it up so it will pump out all excess ground water. You want to keep the area under the slab as dry as possible at all times.
You don’t want to encounter flooring problems later on, so be sure to give this job the attention and care it deserves! Following these steps will help you get the job done right.