The bathroom might be the smallest room in your tiny house, but it handles big jobs. You need space for a toilet, a way to shower, and ideally a sink with some storage. Making all that work in 20 to 40 square feet takes thoughtful design.
Tiny House Bathroom Design: Layouts, Showers & Toilets (2026 Guide)
Plan your tiny house bathroom with our 2026 guide. Covers wet vs dry baths, shower sizes, composting and flush toilets, ventilation, and storage solutions for small spaces.
TLDR: Tiny Bathroom Design
Plan for 20 to 40 square feet of bathroom space depending on layout
Wet baths save space by combining shower and bathroom into one waterproof room
Dry baths separate the shower with a door or curtain for more comfort
Composting toilets eliminate the need for black water tanks and septic
Ventilation is critical to prevent mold and humidity damage
A 30x30 inch shower is the minimum comfortable size for most adults
Key Decision
Wet vs Dry Bath
Wet baths save 5 to 10 square feet but require full waterproofing.
Bathroom requirements vary by local codes. Check regulations for minimum fixture requirements.
Designing a Functional Tiny Bathroom
Many tiny house owners worry about sacrificing bathroom comfort. The good news is that a well designed tiny bathroom feels perfectly comfortable for daily use. Some tiny house bathrooms are nicer than those in full size apartments because owners put extra thought into every detail.
This guide covers everything from basic layout decisions to specific fixture choices. We will look at wet baths versus dry baths, toilet options, shower sizing, ventilation needs, and storage solutions. By the end, you will know how to design a bathroom that works for your lifestyle.
Bathroom Layout Options
Your bathroom layout depends on available space, your tiny house width, and whether you choose a wet bath or dry bath design. Most tiny house bathrooms fit in one of a few standard configurations.
Minimum Size
16 sq ft
Wet bath only
Comfortable Size
25-30 sq ft
Most common
Spacious Size
35-40 sq ft
Room for tub
Shower Minimum
30x30 in
Comfortable
| Layout Type | Space Needed | Can Include | Best For |
|---|---|---|---|
| Wet Bath | 16-25 sq ft | Toilet, sink, shower in one | Smallest builds, RV style |
| Linear Dry Bath | 25-35 sq ft | Separate shower, toilet, sink | Most tiny houses |
| L-Shaped | 30-40 sq ft | Corner shower, more storage | End of house placement |
| Split Bath | 30-40 sq ft | Toilet room separate from shower | Couples, privacy needs |
Placement in Your Tiny House
Bathroom Placement Tips
- •Place bathroom near the trailer hitch end for easier plumbing drainage
- •Keep bathroom close to kitchen to minimize pipe runs and water heater distance
- •Consider placing under or adjacent to sleeping loft to use vertical space
- •An exterior wall makes venting and drainage simpler
Wet Bath vs Dry Bath
The wet bath versus dry bath decision is one of the first you need to make. Each has clear advantages and drawbacks. Your choice affects construction, daily comfort, and maintenance.
Wet Bath
Entire room is waterproof
Saves 5 to 10 square feet of floor space
Simpler construction, fewer walls
Easy to clean with hose down
Everything gets wet when showering
Toilet paper needs covered storage
Common in RVs and boats
Best For: Very small builds under 150 sq ft
Dry Bath
Shower separated by door or curtain
More comfortable daily experience
Toilet stays dry during showers
Can have regular bathroom storage
Takes more floor space
More construction complexity
Standard in most tiny houses
Best For: Daily comfort, long-term living
Hybrid Approach
Some tiny house owners use a hybrid design. They waterproof the entire bathroom floor and lower walls but install a shower curtain to keep the toilet area mostly dry. This gives you wet bath durability with some dry bath convenience. The curtain can push aside when not showering for a more open feel.
Toilet Options
Your toilet choice affects your entire water and waste system. Composting toilets have become popular in tiny houses because they eliminate the need for black water tanks and septic connections. Flush toilets remain an option when you have proper hookups available.
Composting Toilet
Cost$900-$2,000
Water UseZero
MaintenanceEmpty every 2-8 weeks
Best ForOff grid living
RV Flush Toilet
Cost$150-$400
Water Use0.5-1.5 gal/flush
MaintenanceEmpty black tank
Best ForRV park living
Standard Flush
Cost$100-$500
Water Use1.28-1.6 gal/flush
MaintenanceSeptic or sewer
Best ForPermanent hookups
Composting Toilet Details
Composting toilets separate liquid and solid waste. The solid waste composts with peat moss or coconut coir. The liquid drains to a separate container or outdoor drain. Most models have a small fan that vents odors outside. When properly maintained, composting toilets have no smell.
- 1.Self-Contained Units: The entire system fits in the toilet. Empty the solids bin every 4 to 8 weeks depending on use. Popular brands include Nature's Head and Separett.
- 2.Central Systems: Larger capacity with the composting chamber under the floor or outside. Better for families or frequent use. Higher upfront cost.
- 3.DIY Bucket Systems: The most affordable option at under $50. Requires more frequent emptying and manual management. Works well for occasional use.
Learn More About Toilets
Choosing the right toilet involves understanding your water access, waste disposal options, and comfort preferences.
Shower Design and Sizing
Your shower takes up the most bathroom space after the toilet. Getting the size right balances comfort with available square footage. Most adults find 30 by 30 inches usable but prefer 32 to 36 inches when possible.
| Shower Size | Comfort Level | Floor Space Used | Notes |
|---|---|---|---|
| 28x28 inches | Tight | 5.4 sq ft | Minimum functional size |
| 30x30 inches | Adequate | 6.25 sq ft | Common in tiny houses |
| 32x32 inches | Comfortable | 7.1 sq ft | Recommended minimum |
| 36x36 inches | Spacious | 9 sq ft | Room to move freely |
| Neo-angle corner | Good | 7-8 sq ft | Efficient corner use |
Shower Must Haves
- Waterproof walls to ceiling height
- Proper floor slope to drain
- Adequate water pressure and temperature
- Storage for soap and shampoo
- Good lighting for safety
Nice to Have Features
- Rain showerhead for spa feel
- Fold down seat for shaving
- Window for natural light
- Handheld sprayer option
- Heated floor for cold mornings
Shower Pan Options
Prefabricated shower pans come in standard sizes and make waterproofing easier. Custom tile showers look great but require careful waterproofing and add cost. For wet baths, the entire floor acts as the shower pan with a central or corner drain. Fiberglass and acrylic pans are lightweight, which matters for tiny houses on trailers.
Ventilation and Humidity Control
Bathroom ventilation is even more critical in a tiny house than in a regular home. The small volume means humidity builds up fast during showers. Without proper ventilation, you will have mold, mildew, peeling paint, and wood rot within months.
Ventilation Requirements
Install an exhaust fan rated for at least 50 CFM (cubic feet per minute). For bathrooms over 50 square feet, calculate 1 CFM per square foot. The fan must vent to the outside, not into the attic or wall cavity. Run the fan during showers and for 15 to 20 minutes after to remove all moisture.
- •Exhaust fans should vent through the roof or exterior wall, never into enclosed spaces
- •Timer switches help ensure the fan runs long enough after showering
- •Humidity sensing fans turn on automatically when moisture levels rise
- •Windows provide backup ventilation and natural light but should not be your only option
- •Moisture resistant drywall or cement board prevents water damage on walls
- •Leave the bathroom door open when not in use to improve air circulation
Sinks and Storage Solutions
The sink is often overlooked in tiny bathroom planning. You need a sink small enough to fit but large enough to actually use. Pedestal sinks save floor space but eliminate storage underneath. Vanities take more room but provide valuable cabinet space.
Sink Options
| Sink Type | Typical Size | Storage | Cost |
|---|---|---|---|
| Wall Mount | 14-20 in wide | None | $50-$200 |
| Pedestal | 18-24 in wide | None | $75-$300 |
| Small Vanity | 18-24 in wide | Cabinet below | $150-$500 |
| Corner Sink | 15-18 in | Varies | $100-$400 |
| Vessel on Shelf | 12-16 in bowl | Shelf below | $75-$250 |
Storage Ideas
- 1.Medicine Cabinet: Recessed or surface mount mirror with storage behind. Keeps toiletries accessible and hidden.
- 2.Over Toilet Shelving: Use the wall space above the toilet for towels, toilet paper, and decorative storage.
- 3.Hooks and Bars: Towel bars, robe hooks, and mounted baskets use wall space instead of floor space.
- 4.Recessed Niches: Built into the shower wall or above the sink to hold soap and shampoo without shelves sticking out.
Bathroom Cost Summary
Bathroom costs depend heavily on your toilet choice, finishes, and whether you DIY or hire help. Here is a breakdown of typical costs for a complete tiny house bathroom.
Complete Bathroom Costs
Toilet (composting)$900-$2,000
Shower Pan and Walls$300-$1,500
Sink and Vanity$150-$500
Faucets and Fixtures$100-$400
Exhaust Fan$50-$200
Plumbing Rough In$300-$800
Waterproofing Materials$100-$300
Total Range$1,900-$5,700
Budget OptionDIY bucket toilet, $800-$1,500
Save Money on Bathrooms
The toilet is often the biggest bathroom expense. If budget is tight, start with a DIY bucket toilet and upgrade later when funds allow. Prefabricated shower surrounds cost less than custom tile. Used sinks and vanities from salvage stores can save 50 percent or more. Check out the benefits of tiny living to see how others have built affordable tiny homes.