Prepare a penetration schedule
List each hole with an identifier, diameter, location, orientation and purpose. Attach a drawing or annotated photograph rather than relying on a verbal description such as beside the column. Ask the plumber, electrician or equipment installer to confirm the finished-clear opening and any sleeve, firestopping or clearance requirements that determine its size.
For several penetrations, identify which locations are final and which are provisional. A change after drilling is a new opening, not an adjustment to the old one. Keep the approval chain clear so the drilling crew does not receive conflicting marks from different trades on the day of work.
Establish thickness and access on both sides
Tell the bidder what is known about the wall or slab and what is merely assumed. Available drawings can help, but the contractor should explain whether further measurement or investigation is needed. Ask how unknown thickness, concealed layers or unexpected reinforcement would change the proposal.
Describe access to the drilling face and to the opposite side. A ceiling below, occupied room, equipment enclosure or difficult exterior elevation can require coordination beyond the drill itself. Identify who supplies lifts, platforms, safe access and protection. The fact that a hole can be reached from one side does not settle how the core and water will be managed on the other.
Separate locating from permission to drill
Ask how the proposed locations will be checked for reinforcement, tendons, conduits and other embedded features. Concrete scanning may be a separate service. Request a marked record that distinguishes inspected areas from areas that could not be assessed, and name the person who interprets findings for the project.
A locator’s marks do not replace the structural designer’s approval where that approval is needed. If a hole conflicts with a marked feature, have the appropriate trade or engineer select the revised position before drilling. Moving a penetration a few inches may solve one conflict while creating another for pipe slope, equipment fit or reinforcement.
Discuss the drilling method and work environment
Ask the contractor how it will secure and operate its equipment in the particular location. Finished surfaces, narrow rooms, vertical walls and overhead work present different constraints. The proposal should explain any anchoring marks or additional holes that remain after the operation and who repairs them.
OSHA’s construction silica guidance addresses exposure controls for drilling and similar tasks. Ask the contractor to describe its dust or water-control approach and how nearby workers or occupants are protected. Avoid prescribing equipment settings yourself. Your role is to require a credible site plan and clear responsibility, not to direct the drilling operation.
Make slurry and core capture explicit
A drilling quote should state who collects water and slurry, protects the area below, and removes the extracted core. Ask how the crew prevents debris or liquid reaching occupied spaces, electrical equipment, drains or finished interiors. Where access below is impossible, have the contractor explain the proposed solution before accepting the job.
Confirm whether cleanup includes the entire affected area or only the immediate drill location. If the building has specific waste-handling or housekeeping requirements, provide them with the bid request. These practical constraints can distinguish a complete price from a low quote that leaves the general contractor to solve the difficult parts.
Compare mobilization and hole pricing
Small drilling jobs may be dominated by setup and travel rather than drilling length alone. Ask whether the quote contains a minimum callout, a per-hole charge, a depth allowance or separate prices for different diameters. For a larger schedule, clarify what happens when some holes are not ready or approved at the booked time.
Compare bids using the same schedule and access assumptions. Identify scanning, lifts, water supply, slurry removal, cores, patching and return visits as included or excluded. If the contractor offers a discount for grouping work, make sure the receiving trades can actually release all the locations together rather than forcing repeated mobilizations.
Coordinate the work that follows the hole
Coring does not automatically include installing a sleeve, connecting a pipe, sealing against water, restoring a fire-rated assembly or finishing the exposed edge. Ask the relevant designer or installer to specify those requirements and identify the party completing them. An unused penetration should not be left as an unassigned task.
For walls and floors exposed to weather or water, ask how the opening will be protected between drilling and permanent installation. Where the building remains occupied, agree temporary barriers and access controls with management. A handover plan prevents the last contractor on site from being assumed responsible for every unfinished detail.
Document the actual penetrations
At completion, match each hole to the schedule and record any approved relocation or size change. Have the receiving trade inspect locations and clear dimensions before the drilling crew leaves where practical. Check adjacent finishes and the cleanup area, including the opposite side of the slab or wall.
Retain photographs, scan records and the revised drawing with the invoice. If a penetration was abandoned because of a conflict, keep that information too. Future work benefits from knowing which marks became holes, which were rejected and what remained uncertain. An accurate record is particularly useful when finishes later conceal the drilled surface.
Sources and scope
Official sources support the regulatory and technical points identified below. General comparison advice is editorial guidance. Local examples apply only to their stated jurisdiction; a site assessment determines which conditions apply to your property.
- Occupational Safety and Health Administration ↗
Construction silica guidance includes exposure controls relevant to drilling; task-specific employer assessment remains necessary.