What a contractor needs to bid a bathroom remodel
Most bathroom bids go wrong before anyone picks up a tile. The homeowner says "redo the bathroom", the contractor walks the room for twenty minutes, and the number on the bid rests on a few tape measurements and a guess about what is behind the walls. When the scope shifts later, so does the price, and both sides feel burned. A tight bid needs a short list of inputs. This post is that list, written for small remodelers who want to price faster and for homeowners who want to hand over a package that gets comparable bids.
Updated 2026-10-10. Rules and prices quoted here are published figures we read on that date. Your city and your trades may differ, so treat this as a checklist, not a code reference.
1. An accurate existing floor plan
Start with what is there today. The plan should show:
- Room dimensions, wall to wall, and wall thicknesses where you can get them.
- Ceiling height, and any soffits or slopes.
- Door and window positions and sizes, including swing direction.
- Every fixture: toilet, vanity, tub or shower, with centerlines.
- Where the room sits in the house: what is below it (crawlspace, slab, finished ceiling) and what is above it.
This matters for permits too. The City of San Diego's remodel bulletin, for example, asks for a floor plan identifying "room uses, dimensions, windows, doors, plumbing fixtures, heating equipment, and exhaust fans" (San Diego IB 140, read 2026-10-10). If you draw it once, accurately, the same plan serves the bid and the permit.
If you are measuring yourself, our guide on how to measure a room covers the order that avoids most mistakes.
2. A proposed layout, even a rough one
"Same layout, new finishes" and "move the toilet, swap the tub for a walk-in shower" are different jobs. The second moves drain lines, may change venting, and can open the floor. A contractor cannot price that from a verbal description.
The proposed plan should mark each fixture as existing to remain, replace in place or relocate. Relocations are where bids diverge most, so they deserve to be on paper.
For the clearances a plan reviewer checks around toilets, showers and lavatories, see Bathroom remodel drawings: what the permit office wants to see.
3. A fixture and finish schedule
Bids drift when every bidder assumes a different product. A one-page schedule fixes that:
- Toilet, vanity, faucet, shower valve and trim, tub or shower base, with model numbers or an allowance in dollars.
- Tile: floor, wall, shower floor, niche. Size, and the height wall tile runs to.
- Glass: frameless, framed or curtain.
- Accessories, mirror, lighting fixtures, exhaust fan.
If the owner has not chosen yet, write an allowance per line. Allowances let three bidders price the same thing.
4. Quantities
This is where an accurate plan pays for itself. From the dimensions you can calculate:
- Floor tile area, plus a waste factor for cuts and pattern.
- Wall tile area for the shower and any wainscot, minus openings.
- Cement board or waterproofing area in wet zones.
- Drywall and paint area for the dry walls and ceiling.
- Linear feet of trim and baseboard.
Our free takeoff calculator turns room dimensions into drywall, flooring and paint quantities you can price. For a worked example on one bathroom, read Bathroom material takeoff example. Waste factors vary by tile size and layout, so set them from your own past jobs rather than a generic number.
5. Electrical, plumbing and ventilation scope
Even on a cosmetic job, write down what changes:
- New or moved circuits, outlets, switches and lights.
- Ground fault protected outlets near water, which most current codes require; check your local adopted code for the exact rule.
- Exhaust fan: new, replaced or upgraded, and where it vents.
- Water heater capacity if the client wants a bigger tub or a rain head.
- Any plumbing relocation, and whether the floor structure allows it.
If your city requires a permit for this work, the plan reviewer will ask for the same items, so collecting them once saves a second round.
6. Photos and the unknowns
Photos of every wall, the ceiling, under the vanity, the access panel and the floor below (basement or crawlspace) let you price from the office and spot problems early. Then list the unknowns in writing: possible rot around the toilet flange, old galvanized supply lines, a floor that is out of level. Price them as clearly labeled contingencies or exclusions, so the client sees them before work starts, not after.
7. Permit scope
Decide who pulls the permit and what it covers. Many cities publish a bathroom remodel checklist. San Diego's bulletin also says plans must be "drawn to scale and be of sufficient clarity to indicate the location and extent of the proposed work" (San Diego IB 140, read 2026-10-10). Check your own city's list; requirements vary by jurisdiction and by scope. Build the permit fee and the drawing cost into the bid, or list them as owner costs.
Putting the package together
A complete bid package for a bathroom fits in a short PDF:
- Existing floor plan, to scale.
- Proposed floor plan with fixture status.
- Fixture and finish schedule with allowances.
- Quantity list.
- Electrical, plumbing and ventilation notes.
- Photos and a list of unknowns.
With that in hand, three contractors can bid the same job and the numbers become comparable. Contractors also save site visits: the walk-through confirms the package instead of creating it.
Where RemodelSet fits
We produce the measured plan, the proposed layout and the material takeoff as one builder set, priced by floor area with a minimum and quoted before you pay. If you only need quantities from a plan you already have, there is a takeoff-only option. To see a full set before you order, read our sample project, a demonstration on a made-up house. Current prices and what each tier includes are on our pricing page. We do not stamp drawings or replace your engineer or your building department's review.
--- Sources, read 2026-10-10 (UTC): City of San Diego Development Services, Information Bulletin 140 (Residential Addition/Remodel). Checklist items beyond that bulletin are general trade practice, not code citations; confirm with your local building department.