A buddy of mine went to refinish his basement in his 1960s home and once the walls were removed, he realized that there were many horizontal, vertical, and stair step cracking in his CMU foundation from hydrostatic pressure and frost heaving due to poor grading and bad backfill. Note that this is near Conneat, Ohio. Surprisingly, there was not much water penetration where he would have noticed this before, but the CMU had efflorescence on the impacted walls. He had a structural engineer out that recommended fixing the exterior issues and also 3 primary approaches to reinforce the walls with no solid recommendation on which one to go with so he asked my opinion, which is why I am here. None of the walls are at the point of failure thankfully either. I believe the report said a max of 1/8" crack with no seepage and a max of a 5/8” inward lean.
The three recommended approaches for reinforcement by his structural engineer were:
Cutting into the CMU to install rebar and filling with cement
Steel I-beams every every 4 feet
Carbon fiber straps epoxied to the wall every 4 feet.
I’ve read various threads here that the carbon fiber strap approach is basically snake oil and the interior drainage solutions are also, so those ones are out of the recommendation. He got 2 bids from contractors for the other approaches.
Both contractors want to excavate the exterior, install new PVC drainage, seal exterior and interior cracks, exterior waterproofing, and backfill with gravel with the last 12" topsoil. However, the first one is an older school guy that wants to notch into the CMU to install 1/2" diameter rebar in the center of the hollow cores and fill with 3500 PSI cement every 16 inches. Note these would not be tied to the footer. He then wants to backfill with washed #57 limestone gravel. The second guy wants to jackhammer into the slab to create a beam pocket to install steel i-beams every 4 feet and seal with 4500 PSI cement and tie the top into the existing joists. He then wants to backfill with river rock. His structural engineer is rather shit and basically just said both would work without giving a solid opinion on which is better, which is why I’m here.
So few of questions. Do you all notice anything glaringly off here? Which approach is better in general to reinforce a foundation (i.e., rod and grout or the steel i-beams jackhammered into the slab)? Lastly, which material is better for backfilling? Limestone, river rock, or something else entirely? Any info that I could pass along would be greatly appreciated. Thanks!
Edit: fixed the info above on the crack width and inward lean. I can see if he can send me photos also.
Brandon, IMO it’s best to tackle the source of the problem first, which is the external pressure. Determine if it’s a poor soil problem, grading problem, high water table, etc. If you can’t reduce the external pressure to an acceptable level then reinforcing the wall is the next best option. You have to start by identifying the condition of the wall, such as the amount and type of visible cracks, and any measurable bowing, leaning or shoving. If the wall contains some reinforcement you have to determine if it’s under reinforced. If so adding reinforcement is an option up to a point. Adding rebar and grout in empty cells or applying carbon fiber to the interior surface can be an option if the wall is bowing. These two methods will not help for walls tilting or shoving at the base, the steel wall braces tied into the floor slab and into the floor joist would be a better solution. Your last option if the wall is too damaged or weak from age, then wall replacement is you final option. None of the strengthening methods will help with a water intrusion problem. Excavating and waterproofing the outside combined with reducing the water content in the soil has to be included when determining where to spend your money.
Ease up on the engineer, lol. He said both would work. Simple statement which should have been received with its intended meaning. i.e. Both will work. Have you ever heard the saying “there is more than one way to skin a cat”?
