Floor Sinking Causing Gaps Between Floor and Wall

Skills Needed: CMU Piers Construction

Categories: Crawl Space Repair


Mr. and Mrs. M from Hemingway SC contacted CNT Foundations LLC after they noticed a significant gap between the bottom of the wall and the floor between their master bedroom and middle bedroom. Cracks had developed in the drywall on both sides of this wall as well as on the hallway wall outside the rooms. The doors along this hallway were not closing properly and diagonal cracks were seen in the drywall above the doors. When walking down the hall, a slope could be felt in the floor. After talking to Mr. and Mrs. M regarding their major concern, I asked if there were any other areas that they were concerned about. As we started walking around the home, several other smaller diagonal cracks were found above other doorways and entryways. Cracks like these are an indication that the floor structure below the wall is not well supported. The weight of the live and dead loads in the home cause the unsupported floor structure to settle over time resulting in the cracks developing. After our initial walk through, a diagram of the home was made showing where the interior walls were located and where cracks in the drywall had been discovered.


Using the diagram that was created, the crawlspace was entered for evaluation. The placement of the main support girders and double joists is marked on the diagram so we can evaluate if the interior walls are properly supported. Once the diagram is completed while in the crawlspace, the area where the floors are sagging and walls are cracked is measured. CNT then evaluates the condition of the wood floor structure and support columns in that area to determine what deficiencies there are and what repairs are necessary for correction. In this case, Mr. and Mrs. M had significant rot to the girder under the dividing wall that progressed into the hallway area. Joists connecting to the girder were also rotted on the ends. Rot causes weakness in the wood resulting in the wood sagging from the weight above. It was also found that load paths under two entryways were not supported causing the floor to sag and the diagonal cracks to appear.


CNT Foundations was able to remove the existing rotted girder and replace it with new. The joists were sistered and secured to the girder using joist hangers instead of a wood ledger board as is common in older construction. Replacing the rotted wood allowed the floor structure to be lifted back into its original position closing the gap between the floor and wall. The new joists provided the support necessary to raise the hallway floor and prevent further settling of the walls. CMU (Concrete Masonry Unit) piers were constructed under the load paths at the entryways stabilizing the floor structure and preventing any further settling. With these repairs in place, Mr. and Mrs. M could be confident that repairs could be made to the interior walls and a fresh coat of paint could be applied without the worry of further floor settling.