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Invisible Studio reveals woodland compost loo

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Piers Taylor’s practice Invisible Studio has completed this composting toilet serving his woodland studio


The tiny 2m2 project, which has been entered into the 2017 AJ Small Projects Award, is made entirely from scavenged material and cost nothing to build.

The toilet was designed around available material including timber battens, polycarbonate sheeting and fibre cement cladding – much of which had been left over from other projects.

See a selection of other entries into this year’s awards in the AJ Buildings Library 

Long Drop by Invisible Studio

Long Drop by Invisible Studio

Architect’s view

The principle of the toilet is that solids and urine are separated just below the seat. The urine is captured at ground level via a drainpipe, and will be used as fertilizer, as it contains nitrogen, phosphorus and potassium. The solids are captured via a series of stacked (donated) wheelie bins, and will be used as fertilizer once left for 12 months.

The toilet was designed around available material. The studwork, battens and sheet material were all left over from other projects, and are of varying sizes. The poles were cut on site, and braced with offcuts from the steel black bar bracing used on out studio. The flashing piece at the ridge was left over from when we built ‘Moonshine’ close by, and the polycarbonate for the door and the black fibre cement tiles were scavenged from skips.

Project data

Location near Bath
Type of project toilet
Architect Invisible Studio
Client Invisible Studio
Start on site November 2016
Completed December 2016
Floor area 2m2
Procurement self-build
Budget £0

Long Drop by Invisible Studio

Long Drop by Invisible Studio

Ajsp 2017 twitter silver 1

Ajsp 2017 twitter silver 1

How to enter the AJ Small Projects Awards

1. Head to the AJ Small Projects Awards website, register and pay your entry fee.

2. An email will then be sent to you with log in details for the AJ Buildings Library. 

3. Upload your project to the AJ Buildings Library. You will need to provide: 

  • A 150-300 word text describing your project
  • At least eight photographs, five drawings and one working detail to illustrate your project. Images should be copyright free and high resolution.
  • Project details including name of practice, name of project, date of completion, total cost, gross internal floor area, client, structural engineer, services engineer, quantity surveyor, main contractor, and other subcontractors and suppliers


  • Entries must have been completed between 1 January 2015 and 31 December 2016
  • All entries must have a maximum total contract value of £250,000
  • Projects must not have had significant coverage in the architectural press (if your project has been covered elsewhere, please declare where)
  • Projects must be located in the UK or built by a UK-based practice abroad
  • All entries will be displayed in the AJ Buildings Library

Deadline 20 January 2017 

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