Module 2
Module 2

Define the project before pricing it

Every number you will ever get for this project, from a contractor's guess on a napkin to a lender's appraisal, is a price for whatever you described. Describe a wish and you get a price for a wish, which is to say a number that will change. This module teaches you to write a project brief: goals, constraints, scope, exclusions, priorities and unknowns, in enough detail that a stranger could price it. It is the most boring hour of the whole course and the one that prevents the most expensive kind of surprise.

1. Why define before pricing Understand

Contractors price uncertainty. When a description is vague, a careful bidder adds money to cover what might be meant, and a careless bidder leaves it out and sends a change order later. Either way you pay for the vagueness; you just pay at different times. Designers work the same way: an architect given a wish list spends your fee discovering what you actually want, and an architect given a brief spends it designing.

A project brief (architects may call it a program) is a short written document, usually two to four pages, that describes what the project is for, what it must respect, what it includes, what it leaves out, what matters most, and what is not yet known. It is written by you, before drawings exist, and it is the document every later document is measured against: the drawings should satisfy it, the proposals should price it, the contract should cover it, and every change should be a visible departure from it.

It is also the document that protects you from yourself. A great deal of scope creep is not a contractor's doing; it is the owner, standing in the opened wall, saying "while we're at it." A brief with a "not now" list gives that impulse somewhere to go other than the budget.

The six parts of a project brief and the test they must pass Six boxes in a row, left to right: Goals, Constraints, Scope and exclusions, Priorities, Unknowns register, then an arrow to a final box labelled "Can a stranger price it?" with a loop back to Scope if the answer is no. Goalswhy Constraintsmust respect Scope andexclusionswhat, and what not Prioritiesmust / should / could Unknownswhat you cannot say yet Can a stranger price it?no: back to scope. yes: ready for design and estimates "no": revise
The brief in six parts. Goals and constraints come first because they decide what belongs in scope. The unknowns register feeds the test: a brief with many unknowns may still be priceable if each unknown is named and given an allowance or an alternate.

2. Goals versus features

A goal is what the project is for. A feature is one way of achieving it. People write briefs full of features and no goals, which leaves everyone downstream guessing at the reasons and unable to offer a better feature when the first one turns out to be expensive.

Feature (how)Goal behind it (why)What knowing the goal lets a designer or contractor do
"A 14 by 16 bedroom with an ensuite on the ground floor""My mother is moving in next year and cannot manage stairs; she needs privacy and a bathroom she can use safely"Propose a smaller room with a wider door and a curbless shower; question the size; check whether the existing den converts for less
"Open the kitchen to the dining room""We cook together and the person at the stove is cut off from everyone"Offer a wide pass-through if the wall turns out to be bearing and the beam is costly
"A detached studio with a bathroom""One of us works from home and needs a space that is not the bedroom, and we may rent it later"Raise the rental question early, because a rentable unit can have different permit, utility and zoning requirements than a studio
"Replace all the windows""The house is cold and the bills are high"Ask whether an energy assessment would show the attic insulation matters more than the glass

Write three to five goals, each as a sentence a stranger would understand. Then list the features you have in mind underneath them, labelled as features. When money gets tight, and it will, the goals tell you which features to defend.

3. Constraints

A constraint is something the project must respect whether you like it or not. Constraints are not wishes and not goals; they are the walls of the room the design has to fit inside. Many briefs forget some of them, and a forgotten constraint is often a redesign later.

  • Money. A ceiling (the most you can spend, all-in), its status (tentative or established), and what it includes: design fees, permits, contingency, furniture, the temporary kitchen. Module 6 builds the budget; the brief states the ceiling and what it covers.
  • Time. A preferred start, a hoped-for finish, and any hard constraint (a lease ending, a loan commitment expiring, a baby, a school year) with its reason. Write "none" if there is none; it is useful information.
  • Site. Lot lines and setbacks (as you understand them; the survey and the building department confirm), access for trucks and dumpsters, storage, slope and drainage, trees you want kept, septic or well, flood zone, easements, utilities and where they enter.
  • Rules and reviews. HOA covenants, historic district or design review, condo board approval, rental restrictions. You do not need to know what the rules say yet; you need to know that a review exists, because it can add weeks and sometimes a veto.
  • People. Who lives there during the work, children and pets, working-from-home hours, neighbors with shared walls, noise and working-hours limits, a family member who cannot be around dust.
  • The existing building. Its age, structure, systems and condition, covered in section 7.

If your setup profile lists constraints, the "Your project" box below will turn them into brief lines. The rule is simple: every constraint gets one sentence, and the sentence says what it affects.

4. Scope, wish list, exclusions and priorities

The wish list

A wish list is everything you would like, in the words you would use to a friend. "A big bright bedroom, a spa bathroom, a walk-in closet, maybe a deck." Write it down; it is the raw material. It is not a scope, and anyone who prices it is guessing.

The scope

A scope describes the work: where it happens, what is built, removed or changed, to what standard, and who supplies what. It is organized by space (room by room) or by trade (demolition, structure, exterior, plumbing, electrical, finishes), and for a residential brief, room by room is easier to write and easier for a contractor to walk through. A scope line looks like this:

Primary bathroom (new, approx. 9 by 11 ft): curbless shower approx. 4 by 5 ft with linear drain, tile floor and walls to ceiling (tile allowance $14/sq ft material, owner selects); double vanity 60 in., owner-supplied, contractor installs; one wall-hung toilet (allowance $900 installed); exhaust fan ducted to exterior; heated floor (electric mat) under tile; paint, mid-sheen; door 32 in. clear, pocket type.

Notice what that line does. It locates the work, states sizes where you know them, names every element, gives a finish level or an allowance for things not yet chosen, and says who supplies what. A stranger could price it, and two strangers would be pricing the same thing, even if their prices differ.

Finish levels

"Nice" is not a finish level. Undefined finish levels are one of the most common reasons two proposals for the same drawings differ by tens of thousands of dollars. For every finish you have not selected, write one of three things: a specific product; an allowance (a placeholder dollar amount, with what it covers: material only, or installed, with or without tax and delivery); or a level in plain words a contractor can translate, such as "stock cabinets, painted, soft-close, no custom sizes" or "standard builder-grade interior doors, hollow core, painted." Module 6 explains how to size allowances; the brief's job is to make sure none is missing.

Exclusions

An exclusion is something a reader might assume is included and is not. Exclusions are as important as inclusions because an unmentioned item is unconfirmed, and unconfirmed items have a way of becoming either a surprise cost or an argument. Common ones: appliances; furniture and window coverings; landscaping and repair of the lawn after the excavator leaves; painting outside the work zone; the driveway the dumpster cracks; work you intend to do yourself; items a different contractor will do. Write them as a list with the heading "Not included," and keep the list even if some items move into scope later.

Priorities

Sort every scope item and every feature into four bins:

BinMeaningWhat happens to it when the estimates come in high
MustWithout it, the project does not meet its goalsStays. If musts alone exceed the ceiling, the project is redefined, not trimmed.
ShouldStrongly wanted; the project is worse without itDefended; cut only after every "could" is gone
CouldNice if the money is thereFirst to go; often priced as an alternate so the decision is explicit
Not nowWanted, but deliberately out of this projectWritten down so it stops reappearing; sometimes designed for (a capped pipe, a conduit) at small cost

The "not now" bin is the one people skip and the one that pays. It is where "while we're at it" goes to live until it has a budget of its own.

5. The unknowns register

An unknowns register is a list of the things you cannot yet say about the project, each with a note on how and when it will be resolved. It is not a confession; it is the most useful page in the brief for a designer or a bidder, because it tells them exactly where to be careful and where you have already decided to accept risk.

UnknownWhy it mattersHow it gets resolvedBy when
Is the wall between kitchen and dining bearing?Beam, posts, footing, engineer's fee, two weeks of designEngineer's site visitBefore design development
Does the panel have capacity for the new circuits?Panel or service upgrade; utility lead timeElectrician's assessment; utility if a service changeBefore bids go out
Is there asbestos in the floor tile or pipe insulation?Regulated handling if disturbed; cost and scheduleQualified testing firm samples itBefore demolition is priced
Will the HOA approve the roofline?Veto or redesign; weeksPreliminary submission to the review committeeBefore construction drawings
Tile selectionRough-in positions, allowance accuracyOwner decidesDecision date tied to the plumbing rough-in

Some unknowns become allowances (tile). Some become alternates, a separately priced option so the decision can be made with a number in hand (the panel upgrade). Some become verification questions for Module 4 (the HOA). None of them should be invisible.

6. The test: can a stranger price it?

Here is the whole distinction between a wish list and a sufficiently developed scope. Hand the document to a competent contractor who has never met you and never seen the house. Could they, with a site visit, produce a price that would survive the first week of work without a change order for something you "obviously meant"? If not, it is a wish list with ambitions.

The test has seven parts. A brief passes when it answers all seven for every part of the project.

QuestionPasses whenFails when
Where?Every room or area of work is named, and the boundary of the work zone is stated"The back of the house"
What?Every element to be built, removed or changed is named"Update the bathroom"
How much?Sizes, counts and quantities where you know them; "approximately" is fine"Some recessed lights"
To what standard?Each finish has a product, an allowance with a definition, or a level in plain words"Nice tile," "good quality fixtures"
What not?An exclusions list exists and covers the things a reader might assumeNo exclusions list, or "everything else as needed"
Under what conditions?Existing conditions, occupancy, access, storage, working hours and known hazards are statedThe contractor learns at the walk-through that you live there with a newborn
Who supplies what?Every owner-supplied item is listed; every unknown has an allowance, an alternate or a resolution date"We'll figure out the lights later"

A brief that passes is not a set of drawings and not a specification. Those come later, from professionals, and they will be far more detailed. The brief is the document that helps make those later documents cheaper and more accurate, because the professionals start from your decisions instead of guessing at them.

7. Existing conditions

For any project that touches an existing building, the building itself is the biggest source of unknowns, and the brief should say what you know about it and what you do not. This is documentation, not diagnosis: you are recording facts and listing questions, not judging the structure or the systems.

  • Year built, and the years of any major changes you know of. Age suggests which materials may be present (lead paint, asbestos products, galvanized or polybutylene pipe, aluminum wiring, undersized panels) and what an inspector may want to see when the walls open.
  • Prior permits. Your building department keeps permit records; ask how to see the history for your address (some put it online, some require a records request). Unpermitted past work is a common and expensive discovery, and knowing in advance changes the scope. Keep whatever you find with the brief.
  • Drawings and surveys you already have. The plat or survey from your purchase, any old drawings, the septic as-built, the well log. Note which exist and where they are.
  • Structure and systems as you observe them, in plain words: "two-by-six rafters, no ridge beam visible," "100-amp panel, no open slots," "gas water heater, 2015 label," "cast iron drain under the slab, we think." Photographs help. You are not drawing conclusions; you are telling the designer where to look.
  • Hazardous materials: a question for qualified testers, not a DIY claim. If the house was built before 1978, lead paint is possible. The United States Environmental Protection Agency (EPA) explains its Renovation, Repair and Painting rule on its page Renovation, Repair and Painting Program: Do-It-Yourselfers; the page states that the rule requires lead-safe certified firms for renovation work in pre-1978 housing and child-occupied facilities, explains the cases in which a homeowner's own work is and is not covered (for example when part of the home is rented), recommends hiring certified firms, and lists the practices it advises for anyone who proceeds. Asbestos appears in many products from the same era (floor tile, pipe and duct insulation, some ceiling and wall textures, siding); whether a survey is required before demolition, and who may remove what, is set by state and local rules that vary. The brief's job is to write down: the year built, whether anything has been tested, by whom, and the results; and if nothing has, to list testing as an unknown with a qualified testing firm as the way to resolve it. Do not write "no asbestos" or "no lead" unless a qualified tester has told you so in writing.
  • Utilities and private systems. Where the water, sewer or septic, gas and electric enter; whether the septic has capacity for another bedroom (often a health-department question); whether the well has been tested.
  • The outside of the work zone. The rooms adjoining the work, the hall the dumpster path crosses, the lawn the excavator drives over, the neighbor's fence, the driveway. Say what condition they are in now, with photographs, so that "it was like that before" has a date on it.
Boundary

Documenting existing conditions means recording what you can see and what you have been told. It does not mean deciding whether a wall is bearing, whether a panel has capacity, whether a material is hazardous, or whether past work met code. Those are questions for an engineer, an electrician, a qualified testing firm and the building department respectively. Write the question; do not write the answer.

8. See it: one brief, written twice See it

Fictional example

The Dunmore household, Fennimore Road, their house and every number below are invented for teaching. The wish list is typical of what owners first write; the scope version is what the same owners produced after an afternoon with this module.

The Dunmores own a 1962 single-story ranch and want a primary suite. Here is their first attempt, as sent to an architect by email.

Version 1: the wish list

Hi, we'd like to add a master suite on the side of the house where the screened porch is. Big bedroom, spa bathroom, walk-in closet, lots of light, maybe a small deck off the bedroom.Four features, no sizes, no finish levels, no goal. "Spa bathroom" could be $25,000 or $80,000. While we're at it we might redo the hall bath since the plumber will be here anyway.Unpriced second project hiding inside the first. Needs a bin: could, or not now. Budget is around $200k, hopefully less.Does it include design fees, permits, contingency, the deck, the hall bath? Tentative or firm? We'd love to have it done by Thanksgiving.Which Thanksgiving, and is it a hope or a constraint? No start date. The house is from the 60s, I don't think there's anything weird in it.Year built is useful; the rest is a guess standing in for testing. We both work from home and have a dog.The one genuinely useful constraint in the email, and it is not connected to anything.

The architect would have replied with twenty questions. Instead, the Dunmores worked through sections 2 to 7 and sent this.

Version 2: the scope

FENNIMORE ROAD PRIMARY SUITE: PROJECT BRIEF (v2, March) GOALS 1. A bedroom and bathroom we can use for the next 25 years, including if one of us has limited mobility.A goal that tells the designer why a curbless shower and a wide door are "musts." 2. Morning light in the bedroom; the current bedroom faces north and is dark. 3. A bathroom that two people can use at once without the second one waiting. 4. Keep the house livable during construction; we both work from home. CONSTRAINTS Money: ceiling $240,000 all-in, including design and engineering fees, permits, a 15% owner's contingency on construction cost, and the deck if it stays in scope. Excludes furniture. Tentative until estimates; financed from savings plus a home-equity line we have been pre-approved for.What the ceiling includes is stated, and so is its status. Time: preferred start after the ground thaws (April next year); hoped-for finish before November next year. No hard constraint. "Thanksgiving" was a hope. Site: the porch sits 8 ft from the side lot line per our survey (attached); we do not know the setback and have asked the building department.Known fact, unknown rule, and who answers it. Driveway access is fine for a dumpster; no storage indoors; one mature maple on that side we want kept if practical. Rules: no HOA. Not a historic district as far as we know (asked the planning office; answer pending). People: both of us work from home 8 to 5; one dog, friendly but must be kept out of the work zone; no children. Working hours 7:30 to 5 are fine; no weekend work preferred. SCOPE (room by room) Demolition: remove the existing 10 by 16 ft screened porch, roof and slab. Protect the adjacent dining room windows and the maple. Addition footprint: approx. 400 sq ft single story, matching existing ridge and eave lines, siding to match existing (painted fiber-cement is acceptable if clapboard match is unavailable). Primary bedroom (approx. 14 by 15 ft): east-facing windows, as much glazing as the energy code and budget allow; one closet pass-through to the walk-in; hardwood floor to match existing oak (sand and finish allowance $9/sq ft installed); two ceiling-mounted reading lights per side, one ceiling fixture, outlets per code plus two floor outlets if feasible; paint.Sizes, counts, finish levels and an allowance. A stranger can price this. Walk-in closet (approx. 6 by 9 ft): rod and shelf, painted wood; one ceiling light; no custom cabinetry. Primary bathroom (approx. 9 by 11 ft): curbless shower approx. 4 by 5 ft with linear drain and glass panel, tile floor and walls to ceiling (tile allowance $14/sq ft material, owner selects); double vanity 60 in., owner-supplied, contractor installs; wall-hung toilet (allowance $900 installed); exhaust fan ducted to exterior; electric heated floor; door 32 in. clear, pocket type; paint. Deck (COULD, priced as an alternate): approx. 8 by 10 ft, composite decking, aluminum rail, one step to grade, off the bedroom. Mechanical: extend existing forced-air system if the HVAC contractor confirms capacity; otherwise ductless head in the bedroom (alternate). Plumbing to new bathroom; water heater capacity to be assessed. Electrical: new circuits for bath, heated floor, bedroom; panel capacity unknown (see unknowns). Connection to the existing house: new doorway from the hall, approx. 36 in.; patch and paint the hall wall. NOT INCLUDED Hall bathroom renovation (NOT NOW; see priorities). Furniture, window coverings, closet systems beyond rod and shelf. Landscaping beyond rough grade and seed where the excavator disturbs the lawn. Painting of any room other than the new suite and the hall patch. Appliances: none in scope.The hall bath has a home now. The lawn and the hall are the outside of the work zone, addressed. PRIORITIES Must: bedroom, bathroom with curbless shower and 32 in. doors, closet, east light, livable house during work. Should: heated bathroom floor; hardwood match; pocket door. Could: deck (alternate price); floor outlets; glass panel vs. curtain. Not now: hall bathroom; replacing the remaining original windows elsewhere in the house (design the new electrical so a later hall-bath exhaust fan circuit is possible if cheap). UNKNOWNS (register) Side setback: asked building department, answer due in two weeks. Affects footprint. Panel capacity: electrician assessment before bids. Affects cost and utility lead time. HVAC capacity: HVAC contractor assessment before bids. Affects the ductless alternate. Hazardous materials: house is 1962; nothing has ever been tested. Qualified testing firm to sample porch ceiling texture and any floor tile under the porch before demolition is priced.Age stated, testing status stated, resolution named. No claim either way. Prior permits: records request filed with the building department for the porch (we believe it was added in the 1980s). Tile, vanity, toilet, fixtures: owner selections; decision dates to be set against the plumbing rough-in in Module 8. Historic district status: planning office, answer pending. EXISTING CONDITIONS 1962 single-story ranch, approx. 1,650 sq ft, slab on grade, forced-air gas furnace (2012 label), 100-amp panel with no visible open slots, gas water heater 40 gal (2016), municipal water and sewer, overhead electric service on the porch side. Survey from 2019 purchase attached. Photographs of the porch, the side yard, the hall and the dining room taken this week, dated, in the binder.

Version 2 is about 800 words and took the Dunmores an afternoon. The architect's first meeting was spent on design. Two things to notice: the budget line answers questions nobody had asked yet, and the hall bath did not disappear; it was moved somewhere it cannot quietly rejoin the scope.

9. Practice: write your brief Practice

Time: 60 to 90 minutes for a first version; expect to revise it twice. Open the project brief and scope worksheet, which has sections for each part of the brief and a priority column for scope items. Then:

  1. Write the goals first. Three to five sentences, each starting with why. If you cannot say why a feature is there, it is a "could" until you can.
  2. List constraints by category: money (ceiling, what it includes, status), time (preferences, any hard constraint and its reason), site, rules and reviews, people, the existing building. One sentence each, saying what it affects.
  3. Dump the wish list into the scope section without editing. Then rewrite each item as a scope line: where, what, how much, to what standard, who supplies. Use allowances or plain-words levels for anything not selected.
  4. Write the exclusions before you think you are done. Walk the house in your mind from the front door to the work zone and back out to the street, listing everything you pass that the work might touch and that you do not intend to pay for.
  5. Sort every scope item and feature into must, should, could and not now. Argue about it with whoever shares the decision; the argument is the point.
  6. Fill the unknowns register: each unknown, why it matters, who resolves it, by when. Anything resolved by an authority goes to the verification list as well.
  7. Record existing conditions: year built, permit history request, what you observe, testing status, photographs of the outside of the work zone.
  8. Run the stranger test from section 6 against every scope line. Mark the fails and fix them, or move the item to unknowns with a resolution.

If you do not have a project yet and are still exploring, write the brief for a project you might do; the practice is the same and the document will be useful when the real one arrives.

10. Your project Your project

11. Check your work Check your work

Criteria

  • Every goal is a "why" sentence; every feature sits under a goal or in "could."
  • The money constraint states a ceiling, what it includes and excludes, and whether it is tentative.
  • Every scope line passes the seven-part stranger test, or the failing part is listed as an unknown with a resolution.
  • Every finish has a product, a defined allowance or a plain-words level. No "nice," "good," "modern," or "updated."
  • The exclusions list exists and includes the outside of the work zone (adjacent rooms, access routes, the lawn, the driveway).
  • There is a "not now" list with at least one item on it. (A project with nothing deferred has usually deferred nothing honestly.)
  • The unknowns register names who resolves each item and by when, and nothing hazardous is declared absent without a tester's report.
  • The year built and the permit-history request are recorded.

Worked example

Apply the test to one line of the Dunmores' first version and one of their second:

Question"Spa bathroom" (v1)Primary bathroom line (v2)
Where?Fails: no location or sizePasses: new, approx. 9 by 11 ft, within the addition
What?Fails: no elementsPasses: shower, drain, glass, tile, vanity, toilet, fan, heated floor, door, paint
How much?FailsPasses: shower 4 by 5, vanity 60 in., door 32 in. clear
To what standard?Fails: "spa"Passes: tile allowance per sq ft material, toilet allowance installed, curbless, pocket door
What not?Fails: nothing excludedPasses by reference: exclusions list covers closet systems, window coverings, other rooms
Under what conditions?FailsPasses by reference: occupancy, working hours, dog, 1962 house, testing pending
Who supplies what?FailsPasses: vanity owner-supplied, contractor installs; tile owner selects within allowance

Note that v2 still contains unknowns (panel, HVAC, setback, testing). It passes anyway, because each one is named, assigned and dated. A priceable scope is not a scope with no uncertainty; it is one where the uncertainty is visible. What remains open is real: the setback answer could shrink the footprint, the panel and HVAC assessments could add cost the ceiling has not yet seen, and the testing could change the demolition price. The brief passes because those are named and assigned, not because they are settled, and the ceiling is a constraint the estimates have not yet tested.

Common mistakes

  • Scope creep by accretion. Items added one at a time, each small, none priced, none sorted into a bin. The cure is the priorities table: nothing enters scope without a bin and a reason.
  • "While we're at it." The plumber being on site does not make a second bathroom cheap; it makes the first one later. Put it in "not now" with a note on what small preparation (a capped line, a conduit) would make it easier later.
  • Undefined finish levels. A major source of proposal spread and of mid-project arguments. Every finish gets a product, a defined allowance or a plain-words level.
  • Forgetting the outside of the work zone. The hall carpet under the dumpster path, the lawn under the excavator, the dining room next to demolition, the neighbor's side of the fence. If the brief does not say who protects and repairs them, the answer is you.
  • Declaring what you have not tested. "No asbestos" and "nothing weird" are hopes. Write the age, the testing status, and who will test.
  • A budget with no contents. "$200k" without saying whether it includes fees, permits, contingency and the deck is a number that will be wrong by exactly those amounts.

What is still unresolved

  • Everything on the unknowns register, by design. The register is the agenda for Module 4 (authority questions), Module 6 (allowances and contingency) and Module 8 (selection dates).
  • Whether the brief's ceiling is realistic for the scope: that is the first thing estimates will test, and Module 6 prepares you for the answer.
  • Who will turn the brief into drawings, and who will price it (Modules 3 and 7).

12. Knowledge check and scenario

What is the difference between a goal and a feature, and why does a brief need both?
A goal is what the project is for (a bathroom a person with limited mobility can use safely); a feature is one way to achieve it (a curbless shower). The brief needs goals so that, when a feature turns out to be expensive or impossible, the designer and contractor can offer another way to meet the goal instead of guessing at what you cared about.
State the stranger test and its seven parts.
Could a competent contractor who has never met you, with a site visit, price the document and have the price survive the first week without a change order for something you "obviously meant"? The parts: where, what, how much, to what standard, what not, under what conditions, and who supplies what.
Why does the course insist on a "not now" list rather than simply leaving things out?
Items left out silently come back, usually at the worst moment, as "while we're at it." A written "not now" list gives each deferred wish a home, makes the deferral a visible decision shared by everyone who signed off on the brief, and allows cheap preparation (a capped line, a conduit) to be designed in deliberately.
The house was built in 1961. What does the brief say about lead and asbestos?
It records the year built, states whether anything has been tested and by whom, and if nothing has, lists testing by a qualified firm as an unknown with a resolution date before demolition is priced. It does not say "no lead" or "no asbestos" unless a tester has reported that in writing. EPA's rule for pre-1978 housing and state and local asbestos rules are questions for the testers, the contractor and the building department, not conclusions for the owner to write.
Two proposals for the same drawings differ by $30,000. What parts of the brief most often explain that?
Undefined finish levels are the usual first suspect. If the brief says "tile" instead of a product, an allowance with a definition, or a plain-words level, each bidder prices a different bathroom. A missing exclusions list is the other common cause, which lets one bidder include the lawn repair and the other leave it out.
Scenario: your drawings are half finished. Your partner comes home from a friend's renovated house and says, "While the plumber is here for the suite, we should do the hall bathroom too. It would be silly not to." The hall bath is on your "not now" list. What do you do?
"The plumber is already here" is the sentence that scope creep is made of. Adding a second bathroom mid-design typically costs design time, can delay the permit submission, may change the plumbing load calculation, and is priced as a change, not at a discount; the trade being on site saves a mobilization charge and little else. It may still be the right call, but not on this reasoning and not without a price.
This is the course's answer. The brief has a process for exactly this: the "not now" bin exists so that a wish can be promoted deliberately. A scope line makes it priceable; the architect's answer makes the schedule cost visible; an alternate price makes the money visible; a decision date keeps it from drifting; and the priorities table says what gives way if it comes in. Your partner's idea gets a fair hearing with numbers, which is more respect than either a reflexive yes or a reflexive no.
Holding the line has value, and the brief exists partly so that you can. But a flat refusal treats the brief as a wall rather than a tool, and it costs you a conversation you will have again in month four, standing in the opened wall, when the price of changing is higher. Use the process in option B; it may well produce the same "no," and it will produce it with a number attached.

Before you move on

Records your learning only; it is not a qualification.