Clear the Physical Space Around the Crack
The first thing to understand is that the crew will not move your stuff. Some of them might help you push a bookshelf a couple of feet, but they are not there to empty a basement. If your finished basement has furniture against the wall being injected, or if your unfinished basement has stacks of storage bins along that wall, you are the one moving it. The clock starts when they arrive whether you are ready or not.
Give yourself at least a four foot working corridor along every wall that has cracks being repaired. Six feet is better if you can spare the room. The crew needs space to run drop cloths, set up an injection pump if they are using one, and step back to check their spacing. A cramped work area produces a rushed job.
What Actually Needs to Move
Anything within reaching distance of the crack has to move. That means the shelving unit even if you cannot imagine how they could hit it. It means the freezer even if it is technically far enough away. Vibration from drilling injection ports travels farther than you expect, and a chest freezer that gets bumped during the repair is your problem, not the crew's. Move it, or push it out of the room entirely.
Storage bins in front of the crack should come out completely. Do not try to slide them a foot to the side and consider that done. Epoxy and polyurethane both have a habit of running or dripping in small amounts during the injection process. Anything you leave in the vicinity should be considered potentially at risk.
Protecting What You Cannot Move
If you have built-in shelving or an HVAC unit near the work area, protect it with drop cloths or plastic sheeting the night before. The crew will bring their own drop cloths for the immediate work area, but they typically do not cover the whole basement. I use painter's plastic sheeting from any hardware store, a couple of dollars a roll, and just drape anything I do not want overspray or dust to touch.
Clean the Crack Line
This is the step homeowners skip most often, and it is also the one that has the biggest impact on repair quality. Epoxy and polyurethane injections rely on chemical adhesion to bare concrete. Any coating on the concrete surface, whether it is paint, dust, mold film, or crystalline efflorescence, weakens that bond. A crew doing a fast job will inject on top of whatever is there. A crew doing a careful job will pause to clean the surface, and that adds time to your bill.
Doing the cleaning yourself 48 hours ahead of time solves this. It gives the surface time to fully dry, it removes the labor cost from the invoice, and it ensures the concrete around your crack is actually prepped rather than half prepped.
The Actual Cleaning Steps
Start with a stiff nylon brush, not a wire brush. Wire brushes leave metal fragments in the crack that can interfere with injection. Scrub the crack line and about six inches to either side. You are trying to remove loose paint, dust, cobwebs, and any powdery efflorescence deposits that have built up over the years. If the paint is flaking, keep going until you are down to sound paint or bare concrete.
Then vacuum the whole area with a shop vac. A regular household vacuum will clog and struggle with concrete dust. If you do not own a shop vac, borrow one from a neighbor for the evening. Vacuum the crack itself by holding the nozzle right against it. You will pull out surprising amounts of dust from inside the crack, which is exactly what you want.
Finish with a damp rag wipe down of the surrounding area, then let it dry completely before the crew arrives. Do not use household cleaners or degreasers. Plain water on a rag is fine. Chemical residues can interfere with epoxy cure just like dust can.
Manage the Basement Environment
Temperature and humidity affect how the injection material behaves. Most epoxy formulations want to be applied to concrete at temperatures between roughly 50 and 90 degrees Fahrenheit. If your basement runs cold in winter, that matters. If it runs hot and humid in summer, that also matters. Ask your contractor what their material's temperature range is when you schedule the appointment, and plan accordingly.
For most homeowners the practical takeaway is simple. If your basement is unheated and it is January, plug in a space heater the night before to bring the wall surface temperature up to at least 55 degrees. If your basement is a swampy 80 percent humidity in July, run the dehumidifier hard until 24 hours before the appointment, then turn it off. The wall needs to be at whatever its stable state is when the crew arrives, not actively drying or actively absorbing moisture.
The Dehumidifier Timing Matters
Running a dehumidifier right up to the moment the crew arrives sounds like a good idea but is actually counterproductive. What you want is for the concrete surface to be at equilibrium with the room air. When a dehumidifier is running hard, it is pulling moisture out of the air faster than the concrete releases it, which means water can wick to the surface of the concrete during injection and interfere with adhesion. Turn the unit off the day before, let the room stabilize, and you will get a better bond.
Public technical resources from the American Concrete Institute discuss surface moisture as a common failure point for concrete repair adhesion. Their published guidelines are worth a look if you want to understand why this step matters more than most homeowners realize.
Have the Paperwork Ready
Pull out any documents related to your foundation problem and stack them on a table where the lead technician will see them. This includes the original inspection report, any engineer's assessment, previous quotes from other contractors, photos you have been taking of the crack over time, and the current contract you signed with the injection company. The reason this matters is that experienced technicians often catch things during the actual work that were not visible during the initial sales visit.
Twice now I have watched a lead injector notice a secondary crack, a bowing wall section, or evidence of active water intrusion that changes the scope of the day's work. If you have your engineer report right there, you can compare what they are seeing against what the engineer said and make a fast decision. If your paperwork is in a filing cabinet upstairs, you are making decisions from memory and that goes badly.
Ventilation and What Happens After the Crew Leaves
Polyurethane injection especially produces strong odors during the cure phase. It is not toxic at typical residential exposure levels but it is noticeable and can be unpleasant for hours after the crew is gone. Epoxy has less odor but can still off-gas mildly. Plan for ventilation.
If your basement has a window well, open the window during the work and leave it open for at least four hours after. If you have a basement dehumidifier, wait to restart it until the odor is mostly gone, which is typically evening if the crew was there in the morning. Do not put fans directly blowing on the injection sites during cure. That can create dust movement or slightly speed cure on the surface while the interior is still curing, which is not what you want.
First 48 Hours After Injection
Keep basement humidity moderate for the first two days. Not bone dry, not dripping wet. Aim for roughly 40 to 60 percent relative humidity if you have a way to measure it. Restart your normal dehumidifier schedule after the odor dissipates, usually within 12 to 24 hours depending on formulation and ventilation.
Do not paint over the injection area for at least seven days, and preferably longer. Ask the contractor for their specific recommendation because paint compatibility varies. Same goes for waterproofing coatings. Give the injection material time to fully cure before adding anything on top of it.
Documenting the Work
Take photos of every injection port location before the crew leaves. Get a clear shot showing spacing, port count, and the injection line coating that is typical after this kind of work. If problems develop later or if you sell the house, you want documentation of what was done and where. Ask for the warranty paperwork before payment is due, not after. Contractors are more responsive to paperwork requests when the check is still on the counter.
A Short Prep Checklist
Two days before: Clean the crack line with a nylon brush. Vacuum thoroughly. Move furniture and storage to create a working corridor. Cover anything that cannot move.
One day before: Turn off dehumidifiers. Bring basement to a stable temperature if needed. Pull all paperwork and stack it on a visible surface.
Morning of: Open the window well window if possible. Have coffee or water available for the crew, which is a small courtesy that occasionally gets you a more thorough job. Be present for the first fifteen minutes and the last fifteen minutes, but let them work in between.
After they leave: Ventilate for four to six hours. Photograph everything. File the warranty. Restart normal humidity control after odor dissipates.