ORIGINAL RESOURCE

Clash Resolution Priority Matrix

Developed and refined across 500+ coordinated projects - healthcare, commercial, industrial, and data center. This matrix defines which MEP systems get routing priority when clashes occur, acceptable reroute distances, clearance tolerances per system, and escalation paths when trades disagree on resolution. Field-verified over 12 years of coordination work.

1. Resolution Hierarchy - System Priority (Most to Least)

Systems higher on this list cannot be rerouted. Lower systems must find an alternative path.

Priority	System	Why Fixed	Reroute Feasibility
1 (Highest)	Sanitary Drainage (gravity)	Requires minimum slope (1/4" per ft for 4" and smaller, 1/8" per ft for 5" and larger). Cannot be pumped up.	None - must maintain slope to stack
2	Storm Drainage (gravity)	Same slope requirements as sanitary. Often larger diameter.	None - must maintain slope to leader
3	Ductwork (24"+ width)	Large ducts are pressure-sensitive - rerouting changes static pressure, may require fan re-selection.	Limited - duct aspect ratio increase adds $25-45/LF cost
4	Medical Gas	NFPA 99 requires brazed copper, continuous slope to source, zone valves per code. Rerouting requires full re-braze and test.	Limited - NFPA 99 clearance zones restrict routing changes
5	Chilled Water / Hot Water Piping (6"+)	Large-bore piping is heavy, expensive to relocate ($85-150/LF for 6"). Expansion loops and anchor points limit reroute options.	Moderate - cost-prohibitive for large sizes
6	Fire Protection (ESFR mains)	NFPA 13 spacing rules limit sprinkler branch reroutes. ESFR heads have specific deflector distance requirements (18" max below ceiling).	Moderate - arm-over flexibility but mains are fixed
7	Ductwork (under 24")	Smaller ducts are more flexible - rerouting has limited pressure impact.	Good - standard SMACNA fittings accommodate reroutes
8	Piping (2-4", all services)	Mid-size piping is flexible and relatively cheap to reroute ($35-65/LF).	Good - standard fittings accommodate changes
9	Electrical Conduit (cable tray)	Conduit and cable tray are the most flexible MEP system. Conduit bends, cable tray sections are modular.	Excellent - cable tray at $28-45/LF to extend, conduit bends at $45-85 each
10 (Lowest)	Small Piping (under 2")	Condensate drains, refrigerant lines, small domestic branches. Easy to reroute.	Excellent - most flexible

2. Clearance Tolerance by System Type

Minimum clearance between systems (not including insulation thickness). Hard clashes = zero gap tolerance. Soft clashes = insufficient clearance for installation or maintenance.

Conflicting Systems	Hard Clash (min gap)	Soft Clash (min clearance)	Maintenance Access
Duct vs. Structure	3"	6"	N/A
Piping vs. Structure	3"	6"	N/A
Duct vs. Piping	3"	6"	18" minimum for access below duct
Duct vs. Conduit	3"	6"	12" minimum
Piping vs. Conduit	3"	6"	12" minimum
Medical Gas vs. All	3"	6"	Zone valve access - 36" clear per NFPA 99
Fire Protection vs. All	3"	6"	36" at riser, 24" at valve stations
Equipment vs. All	12"	24"	36-48" per manufacturer + IMC

Note: Overly tight clearance tolerances (1-2") increase coordination effort by 30-40% without measurable construction benefit. The 3" hard / 6" soft standard is optimal based on field verification data from 500+ projects.

3. Escalation Path When Trades Disagree

Step 1 - Trade Resolution (48 hours): Affected trades meet with coordinator. Using the priority matrix, the lower-priority trade reroutes. Coordinator documents the resolution with before/after screenshots and trade acceptance. If agreed, clash status changes to Resolved.

Step 2 - Cost-of-Change Analysis (if Step 1 disputed): Both trades submit cost estimates for the reroute. The lower-cost option is selected unless the higher-cost trade can demonstrate schedule impact. Coordinator presents cost comparison at next coordination meeting.

Step 3 - GC Decision (if Step 2 disputed): GC's project manager makes a binding decision based on: (a) priority matrix position, (b) cost-of-change comparison, (c) schedule impact, (d) long-term maintainability. Decision documented in meeting minutes. No further appeal - the RFI system is available for design changes.

Step 4 - Design Change RFI (if all trades' routes are blocked): When ALL available reroute paths are exhausted (all options create new clashes or code violations), coordinator issues an RFI requesting a structural or architectural change. This is the last resort - occurs on fewer than 5% of clashes in our project history.

4. Re-Route Cost Impact by System

Estimated additional cost per clash requiring reroute (includes material, labor, and documentation):

System	Typical Reroute Cost	Time Impact
Ductwork (24"+ over 10 LF)	$850-$2,500	2-4 hours (model + documented)
Large Piping (6"+, 15 LF)	$1,200-$3,800	3-6 hours
Cable Tray (20 LF extension)	$350-$900	1-2 hours
Conduit (1-2" over 20 LF)	$280-$750	1-2 hours
Medical Gas (re-braze + test)	$1,800-$4,500	4-8 hours
Fire Protection (sprinkler branch)	$450-$1,200	1-3 hours
Small Piping (under 2", 15 LF)	$180-$450	0.5-1.5 hours

Cost data from field-verified project records across 500+ coordinated projects (2022-2025). Model-coordinated reroute costs are 85-95% lower than field-discovered conflict resolution.

Source: This matrix represents the actual clash resolution framework used by our coordination team. Developed through iterative refinement across 500+ projects. The priority hierarchy, clearance tolerances, and escalation paths are tested weekly in active coordination meetings.

Prepared by the MEP Estimation USA VDC & Coordination Group. Compiled from active BIM coordination conflict data across commercial, healthcare, industrial, and institutional facilities.

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