Sure, here is a possible design for a 4-story mews house with a costed bill of materials:

Basement

• Gym: This could be a simple space with a few pieces of exercise equipment, such as a treadmill, elliptical, and weight bench. The cost of the equipment would vary depending on the quality and brand you choose.
• Utility room: This could be a small room with a washer and dryer, as well as storage space for cleaning supplies and other household items. The cost of the washer and dryer would vary depending on the size and features you choose.

Ground floor

• Garage: This could be a large space for parking a car, as well as storing other items such as bicycles and lawn equipment. The cost of the garage would vary depending on the size and materials you choose.
• Utility room: This could be a small room with a washer and dryer, as well as storage space for cleaning supplies and other household items. The cost of the washer and dryer would vary depending on the size and features you choose.

First floor

• Kitchen: This could be a spacious kitchen with stainless steel appliances, granite countertops, and a breakfast nook. The cost of the appliances and countertops would vary depending on the quality and brand you choose.
• Reception: This could be a large open space that could be used for entertaining guests, working from home, or simply relaxing. The cost of the furniture and décor would vary depending on your taste.

Third floor

• Bedrooms: This floor could have three bedrooms, each with its own private bathroom. The size and layout of the bedrooms would vary depending on your needs.
• Bathroom: This could be a large bathroom with a soaking tub, walk-in shower, and double vanity. The cost of the fixtures and finishes would vary depending on the quality and brand you choose.

Fourth floor

• Bedrooms: This floor could have three bedrooms, each with its own private bathroom. The size and layout of the bedrooms would vary depending on your needs.
• Bathrooms: This could be three large bathrooms with soaking tubs, walk-in showers, and double vanities. The cost of the fixtures and finishes would vary depending on the quality and brand you choose.

Costed bill of materials

The cost of materials for this project would vary depending on the quality and brand you choose, as well as the size and layout of the house. However, here is a rough estimate of the costs:

• Foundation: $10,000
• Framing: $20,000
• Exterior: $30,000
• Interior: $40,000
• Mechanical: $10,000
• Electrical: $5,000
• Plumbing: $5,000
• Landscaping: $5,000

Total: $125,000

This is just a rough estimate, and the actual cost of the project could be higher or lower depending on the specific details of your project.

Sure, here is a possible design for a 4-story mews house with a costed bill of materials in UK prices:

Basement

• Gym: This could be a simple space with a few pieces of exercise equipment, such as a treadmill, elliptical, and weight bench. The cost of the equipment would vary depending on the quality and brand you choose.
• Utility room: This could be a small room with a washer and dryer, as well as storage space for cleaning supplies and other household items. The cost of the washer and dryer would vary depending on the size and features you choose.

Ground floor

• Garage: This could be a large space for parking a car, as well as storing other items such as bicycles and lawn equipment. The cost of the garage would vary depending on the size and materials you choose.
• Utility room: This could be a small room with a washer and dryer, as well as storage space for cleaning supplies and other household items. The cost of the washer and dryer would vary depending on the size and features you choose.

First floor

• Kitchen: This could be a spacious kitchen with stainless steel appliances, granite countertops, and a breakfast nook. The cost of the appliances and countertops would vary depending on the quality and brand you choose.
• Reception: This could be a large open space that could be used for entertaining guests, working from home, or simply relaxing. The cost of the furniture and décor would vary depending on your taste.

Third floor

• Bedrooms: This floor could have three bedrooms, each with its own private bathroom. The size and layout of the bedrooms would vary depending on your needs.
• Bathroom: This could be a large bathroom with a soaking tub, walk-in shower, and double vanity. The cost of the fixtures and finishes would vary depending on the quality and brand you choose.

Fourth floor

• Bedrooms: This floor could have three bedrooms, each with its own private bathroom. The size and layout of the bedrooms would vary depending on your needs.
• Bathrooms: This could be three large bathrooms with soaking tubs, walk-in showers, and double vanities. The cost of the fixtures and finishes would vary depending on the quality and brand you choose.

Costed bill of materials

The cost of materials for this project would vary depending on the quality and brand you choose, as well as the size and layout of the house. However, here is a rough estimate of the costs:

• Foundation: £8,000
• Framing: £16,000
• Exterior: £24,000
• Interior: £32,000
• Mechanical: £8,000
• Electrical: £4,000
• Plumbing: £4,000
• Landscaping: £4,000

Total: £100,000

This is just a rough estimate, and the actual cost of the project could be higher or lower depending on the specific details of your project.

Please note that these are just rough estimates and the actual cost of your project may vary. It is important to get quotes from multiple contractors before making a decision.