When people call in a foundation contractor or engineer, it is typically because they are already noticing signs of stress. It is important to remember that the signs of stress are less of a problem in and of themselves. Rather, they are clues to help us understand the types of movement and their meaning during the damage survey process.
In the Damage Survey Process, Where Do the Signs of Stress Occur?
Noticing where the signs of stress occur will help determine where the problem lies. Every area must be checked for certain conditions in order to indicate where the damage originated. Below are examples of areas to check in the damage survey process and what the visible signs of damage may be telling us.
Damage in High VS Low Areas
The first thing we have to ask is, generally, where do the signs of stress occur? Near the high areas or the low areas? High areas support upward movement in that area, vs. the low areas that indicate downward movement. A high-low area will have hinge points at the epicenter of movement, not always necessarily at the lowest or highest point.
Interior VS Perimeter Damage
The second thing that we need to observe is if the damage is on the perimeter walls (both the inside of the wall and the exterior of the same wall) or the interior only walls that don’t sit on footings.
The outside walls are supported by footings and carry the roof load. Movement there most likely means settlement has occurred. This is because they are small, deeper, and more heavily loaded. Although, on occasion, the area can have heave.
Damage of interior walls can usually indicate heave because these walls do not have footings or bear any roof loads. This is because these walls are up higher than the footings, have a large area of contact with the soil, and are lightly loaded. Again, on rare occasions we have seen settlement in these areas.
During the Damage Survey Process, Don’t Forget the Doors
Along with checking interior walls, check if any interior doors are out of square (pinched on one side, or a gap on the other). However, the same logic does not automatically apply to exterior doors. This is due to the pour out strips that go underneath the door frame.
These pour out strips (diagram above) are commonly added so that horizontal joints between the stem wall and interior floor slab do not run directly under the door threshold. You can see this easily by looking on the stem wall below the door and noticing a cold joint running down each side under the door frame.
When there is floor slab heave, you can see distress at this cold joint because the stem wall does not move together with the floor slab.
Most pour out strips don’t protrude like the one to the side. It is pictured here because it illustrates the distress from the slab movement.
Since the door frame sits on top of the pour out strip and is part of the floor slab, an outside door that is out of square, or pinched, could be a result of either footing movement or slab movement.
The Windows Should Be Checked Too
On the other hand, windows out of square, almost always indicate footing movement, since they rarely sit on top of the interior slab.
It’s worth noting that walls can be patched, and doors shaved off, but usually windows are not replaced for being out of square. As a result, windows are a more consistent sign of footing movement.
Other Common Signs of Stress to Look for During the Damage Survey Process
Above I discussed how to interpret signs of stress from settlement or heave, particularly in walls, doors, and windows. Continuing that line of thinking, I would like to highlight a few more common signs of stress to watch out for during the damage survey process.
Cupping of Trusses
Above is a picture of where a ceiling intersects with an interior wall. The pattern seen is referred to as cupping. It usually happens when the interior wall is pushed up into the ceiling, where above it, the bottom of the trusses are suspended. Drywall pushes up more easily where it only meets drywall from the ceiling rather than meeting the bottom of trusses which resist the pressure.
Alternatively, cupping could also, albeit rarely, be caused by downward movement of a perimeter wall. Although, this typically would be accompanied with distress in that wall.
In the Damage Survey Process Also Look for Gaps Where Center Walls Meet Ceiling
The opposite of cupping results in a gap between the top of the wall and the ceiling. This can happen particularly in the center areas of the home. Gaps are usually present in bowl-shaped foundation/slabs where the edges are higher than the middle. We commonly see this in newer post-tensioned foundation systems that often have heave on the edges. Occasionally, it could be the result of settlement in the center areas, but that is not very common.
Interior Corner Cracks that are Wider at the Bottom
We regularly see cracks in the corners where interior walls meet the perimeter walls. These are usually wider at the bottom than the top. This is caused when interior walls move differently than perimeter walls. See the illustration above.
This is usually caused by upward movement of interior walls in the middle areas. As that wall holds its rectangular shape and moves up and away, it starts to pull away at the bottom where it meets the perimeter wall.
Alternatively and more rarely, if the outside wall footing settles, it can pull away perpendicular from the wall, while also moving down. It’s important to notice all of these details during the damage survey process.
Baseboards Gaps and Cramming
Another important clue to pay attention to during the damage survey process is the condition of the baseboard trim along the bottom of the wall. For instance, check if the floor slab is floating separate from the stem wall or crawl space foundation.
These gaps under the baseboard will indicate that the floor is either settling more than the stem wall or the footing is heaving more than the slab. Another baseboard condition to watch for is cramming. This is when the floor moves up or the stem wall moves down. Usually cramming is an indication of heave. In these cases, the baseboard trim can be wavy or misshapen.
Translating Clues in the Damage Survey Process: A Summary
It can be difficult to create a mental picture from these signs of stress that makes sense. Sometimes, during the damage survey process, you may discover signs of stress that are not consistent with each other. Thus, why I say it requires a holistic approach. All these signs of stress must be examined in conjunction with all of the other seventeen items to include during the foundation repair process. There are no silver bullets!
- Cupping of trusses usually means heaving of interior walls, (hence heaving of the floor slabs)
- Corner cracks between interior and perimeter walls usually means heaving of interior walls and floors
- Cramming of baseboards usually means floor heaving
- Perimeter damage usually means settlement
- An important exception is exterior door frame movement, which can equally signal footing settlement or floor slab heave.
- Interior only damage usually indicates heave
- Damage in high areas usually means heave (up to or near the hinge point)
- Damage in low areas usually means settlement (up to or near the hinge point)
Some Final Tips
It is super helpful to create a damage map with appropriate symbols on the floor plan of the house. This helps the human brain put everything together, try out several hypotheses, and see which ones are consistent with each other and all the other data. A good analogy is to compare this to a road map. By having all the relevant data on the map you can plan out your trip better than just reading a narrative. I find it helpful to overlay the signs of stress on top of the 2D topo map as shown below. Sometimes, all together it can look a little cluttered and having a clean damage map is helpful.
It is also helpful to have commonly accepted iconography so that everyone intuitively understands the signs of stress without having to convert things in their heads.
Thanks for the comment. I agree that damage maps are not enough. I firmly believe that no 1 thing can be a smoking gun. i feel that all 17 things need to be considered carefully before conclusions can be reached. I have a future blog being posted to talk about this more.