When Drawings and Specs Disagree: The Order of Precedence

Why this matters

Every set of construction documents disagrees with itself somewhere. The schedule says one size and the spec says another, the dimension string says one thing and the scale says another, the plan shows a part the detail leaves out. A crew that resolves each of those by habit, or by picking whichever reading is cheaper to build, is making a contract decision with the shop's money. Sometimes the habit happens to match the contract and nothing comes of it. Sometimes the shop builds the cheaper version, the engineer points to the clause that said otherwise, and the shop does the work twice.

This card is about paper disagreeing with paper. When the documents agree and the building in front of you does not, that is a different problem with its own card (see related: When the Drawing and the Installation Disagree).

The habits everyone repeats, and why each exists

These rules circulate on every job site. Each is commonly written into contracts, and each has a reason behind it, which is what lets you spot when it does not apply.

• Written over graphic. A note or a spec paragraph beats what a picture seems to show. Words are deliberate; a line on a drawing may be a drafting convenience.
• Figured dimensions over scaled ones. A dimension written on the drawing beats a measurement taken off it with a scale. Prints get reduced, enlarged and reproduced, so a scaled measurement carries every copying error the sheet ever went through (see related: How to Scale a Dimension Off a Print).
• Large-scale over small-scale. An enlarged plan or a detail at 1-1/2 in to the foot was drawn to show exactly that condition; the 1/8 in plan behind it was drawn to show the whole floor and simplifies.
• Specifications for quality, drawings for quantity and location. A common shorthand for what each document is good at, and in some contracts close to what the clause says. In others the clause simply puts specifications above drawings, or the reverse.
• Complementary, read together. The documents are one contract, so something shown on the drawings and not mentioned in the specs, or the reverse, is still required.

That last one is the habit people forget, and it is the one most contracts actually state.

Why the contract's own clause decides, not the habit

The habits are tendencies. The contract is the rule, and contracts differ:

• The AIA family of forms, where a contract uses them, states in A201 Article 1 that the contract documents are complementary and what one requires is as binding as if all required it. A201 itself does not rank the documents. Parties who want a ranked order add one, usually in the supplementary conditions or the agreement.
• Federal construction contracts that include FAR 52.236-21 say that where drawings and specifications differ, the specifications govern, and that anything shown in one and not the other is of like effect as if shown in both. The same clause has the contractor submit a discrepancy in figures to the contracting officer for a written determination, and says an adjustment made without one is at the contractor's own risk and expense.
• Many private contracts carry a ranked list, and many add a tiebreaker: where documents conflict on quantity or quality, the greater quantity or the higher quality governs. That tiebreaker can point the opposite way from the ranked list on the same item.
• Small residential work often has no specifications at all, and the drawings plus a proposal are the contract; whatever the proposal says it includes is what the precedence question is asked of.

So before applying any habit, find the clause. It is usually in the general or supplementary conditions, sometimes in Division 01, occasionally on the cover sheet. Who wins a dispute about what the clause means is a legal question for the shop's own attorney, and this is not legal advice; what the shop can always do is find the clause before it builds.

Here is the kind of clause you are looking for, in illustrative wording:

1.4 ORDER OF PRECEDENCE (SUPPLEMENTARY CONDITIONS)
A. In case of conflict, documents govern in this order:
   1. Agreement and Modifications
   2. Supplementary Conditions
   3. General Conditions
   4. Specifications
   5. Drawings
B. Within the Drawings: large-scale details govern
   small-scale plans; figured dimensions govern scaled.
C. Where documents conflict on quantity or quality,
   the greater quantity or higher quality governs.
D. Report any conflict to the Architect before
   proceeding with the affected work.

Notice that paragraphs A and C can disagree about one item, and paragraph D tells you what to do when they do.

The worked example: three conflicts on one fit-out

A plumbing and HVAC shop is building out a small office suite under the clause above. Reading its own scope before ordering, the project lead finds three disagreements.

Conflict one: the water heater. The plumbing equipment schedule on P-601 lists WH-1 as a 40 gallon electric unit. Specification section 22 33 00, Part 2, calls for 50 gallons. Under paragraph A, specifications rank above drawings, so 50 governs. Under paragraph C, greater quantity governs, so 50 again. Both rules agree. The lead still checks one thing before ordering: the enlarged plan shows WH-1 in a closet, and a 50 gallon tank is taller and wider than a 40. A clause cannot make a tank fit a closet, so the lead checks the closet dimensions against the 50 gallon unit's data sheet. It fits with the access the manufacturer calls for, and the order goes in at 50 gallons with a note in the job file citing 1.4.A and 1.4.C.

Conflict two: the mop sink. On the 1/4 in enlarged plan, the mop sink's centerline is dimensioned 2'-0" from the east wall. Scaled, it reads closer to 3'-0". Paragraph B says figured governs scaled, and nothing else on the sheet conflicts with 2'-0": the door swing clears it and the floor drain is on its own dimension. The crew lays out at 2'-0". No RFI is needed, because the rule resolves it cleanly and the resolution does not collide with anything physical. What the lead does write down is that the sheet scales wrong, because if the sheet is a reduced print, every other scaled reading on it is suspect too.

Conflict three: exhaust fan EF-1. The mechanical schedule on M-601 says EF-1 is belt drive, 450 cfm. Specification section 23 34 00, Part 2, says exhaust fans shall be direct drive with electronically commutated motors. The floor plan tag beside the fan reads 400 cfm. Now the rules stop agreeing:

• Paragraph A says the spec governs the drive type, so direct drive.
• Paragraph C says higher quality governs, and whether a direct-drive EC motor is higher quality than a belt drive at this size is an opinion, not a fact the lead can settle.
• On airflow, both 450 and 400 are on drawings, at the same rank. Paragraph B does not help, because a schedule is not a large-scale detail.

The cheaper reading is visible from where the lead sits: a belt-drive fan is the item already quoted by the supplier. Building to it on the theory that "the schedule is the schedule" is exactly the move the clause's paragraph D forbids. The lead writes one RFI covering both questions: "M-601 schedules EF-1 belt drive at 450 cfm; 23 34 00 2.1.B requires direct drive EC; plan tag on M-101 reads 400 cfm. Please confirm drive type and design airflow." The fan is not ordered until the answer comes back.

The tally. Three conflicts, three different outcomes: one built under the clause after a physical check, one built to the rule with a note about the sheet, one held for an RFI. The point is not that the RFI was the safe answer every time. The point is that each was decided by the clause, read in full, rather than by a habit.

Why the safe move on a real conflict is an RFI

Three reasons, and the third is the one owners underrate.

The engineer may know something the paper does not. The 400 cfm tag might be the corrected value from a revised calculation that never reached the schedule. Picking either number without asking is a coin toss that only one party can see.

Most general conditions put a reporting duty on the contractor. A201, where used, has the contractor report errors, inconsistencies or omissions it discovers in the documents. A shop that saw the conflict and built through it has given up the argument that it did not know.

The cheaper reading is the one that gets reversed. When an engineer resolves a conflict after the fact, the resolution tends toward whatever the design intended, which is rarely the cheaper option. The shop that ordered the belt-drive fan to save a few hours of supplier calls now owns a fan it cannot use and a lead time it cannot recover.

Timing changes the instrument but not the principle. A conflict found before bids are due goes to the designer as a bidder's question, usually by a deadline the instructions to bidders set, so the answer comes back as an addendum that binds every bidder equally (see related: How to Check an Addendum Against Your Bid). A conflict found after award goes on an RFI (see related: How to Write an RFI That Gets a Usable Answer).

What changes the answer

• Code is above all of it. A drawing and a spec that agree with each other and conflict with the adopted code are both wrong, and no precedence clause makes the code-violating version buildable. That goes to an RFI with the code section named.
• A later document beats an earlier one only when it is genuinely a modification: a change order, a construction change directive, an addendum issued before bid. A revised sheet with a newer date in its revision block supersedes the old sheet (see related: The Revision Block and Why It Decides Everything). A sketch attached to an RFI answer may or may not be a modification, depending on how it was issued (see related: The Paper That Changes a Job: RFI to Change Order).
• Design-build and delegated design flip the question. Where the shop is the designer of record for its own scope, an internal conflict is the shop's own error to fix, not an owner's to resolve.

References

• AIA Document A201, General Conditions of the Contract for Construction, where the contract uses it (Article 1 on complementary documents; Article 3 on the contractor's review and reporting of errors).
• FAR 52.236-21, Specifications and Drawings for Construction, on federal contracts that include the clause.
• See related: When the Drawing and the Installation Disagree
• See related: The Paper That Changes a Job: RFI to Change Order; How to Write an RFI That Gets a Usable Answer
• See related: Reading Construction Plans + Specifications