Core drilling for MEP trades

On renovation and build-out projects, the mechanical, electrical, and plumbing trades generate nearly all the core drilling — and nearly all the re-drills. The holes themselves are the easy part. The order of operations around them is where projects win or bleed. This guide is the order of operations.

The penetration schedule is the product

A penetration schedule — every required hole with size, location, level, and owning trade — is the single document that turns coring from a string of service calls into one priced, sequenced package. It doesn’t need to be beautiful: a spreadsheet or a marked plan works. What it must do:

• Consolidate all trades. Plumbing, HVAC, and electrical penetrations drilled in one mobilization amortize setup and scanning across every hole — the pricing math is in the cost guide.
• State sizes as core diameters, not pipe sizes. The core = contents + insulation + sleeve/annular clearance. A “4 inch pipe” needs a 5–6 in core depending on the sleeve detail. Whoever writes the schedule owns this conversion — or explicitly hands it to the estimator by listing contents instead.
• Carry tolerance. Locations marked ±2–3 in where the design allows give the crew room to shift off tendons and bars found in the scan — which converts conflicts into non-events.

The sequence that avoids re-drills

1. Coordinate before drilling. The classic failure: plumbing drills its holes, then HVAC discovers a duct wants the same corridor inches away, then the electrician needs the cluster moved. Penetrations coordinate in design (BIM on big jobs, a markup meeting on small ones) before the first core.
2. Scan once, mark everything. GPR the full penetration zone in one pass rather than location-by-location across weeks. Marks on the deck serve every trade.
3. Drill to a frozen layout. Layout marks placed by the trade that owns the fit-up (or by the crew from drawings — decide which, in writing), then drilled in production runs.
4. Sleeve, seal, firestop — by the trades. The coring scope ends at a clean, correctly sized hole. Sleeves, insulation, and listed firestop systems belong to the trade installing the service. What coring can do: drill to the exact diameter the firestop system specifies — if the schedule says so.

The mistakes that generate change orders

• Drilling before coordination — see above; the most expensive version involves patching abandoned holes in a PT deck.
• Pipe-size cores. A core sized to the pipe OD with no sleeve clearance is a re-drill wearing a hard hat.
• Unstated below-deck conditions. Slurry through a fresh core into an occupied suite is a project-relations event no schedule recovers gracefully.
• Serial mobilizations. Five visits for five trades on the same floor pays the mobilization minimum five times.
• Skipping the scan to save a line item. One tendon repair funds years of scanning. The PT guide does the arithmetic.

What to send

The schedule (any format), the level(s) and building type, GPR status, what’s below the work, and the window — day or night. The request form takes the files directly, and a consolidated MEP package comes back priced as one scope of work.