# Curtilo

> Curtilo is software for the small developer, land sourcer or self-builder who reads what a plot or a building can become without a planning application in England and Wales: a free permitted development envelope sheet that takes the house type, its width and depth, the curtilage and the existing outbuildings and returns the rear and side extension the house may gain and the outbuilding area still available; a free class Q barn conversion sheet that takes the agricultural building's floorspace, the dwellings proposed and the rear wall and returns the floorspace per dwelling, the headroom under the caps and the extension the class allows, both with no account; and Curtilo Pro, which keeps the site file as the record: every plot with its address, its curtilage, its use, the rights read on it, its constraints, its appraisal and the offer made. It covers the reading of the plot only. It publishes no constraints map, no rule text as law, no builder listing, no valuation of a named plot and no legal opinion.

## What this is for

- The small developer, land sourcer or self-builder in England and Wales who reads a plot before making an offer, with a barn, a wide side return or a field edge in front of them and a spreadsheet of sites to keep,Not the applicant running an application through the authority, not a homeowner with a project question and no site, not an ecologist, not a resident after a council service, not a landlord after a yield, and not anyone looking for a legal opinion or a valuation of a named plot

## Tools

- [Side extension permitted development: the envelope sheet](https://curtilo.com/tools/side-extension-permitted-development-envelope-sheet/): Put in whether the house is detached, its width and depth, the curtilage around it, the outbuildings already on it and whether it sits on designated land, and see the rear depth, the side width, the outbuilding room and the ground floor area the plot may gain without an application.
- [Class Q permitted development: the barn conversion sheet](https://curtilo.com/tools/class-q-permitted-development-barn-conversion-sheet/): Put in the agricultural building's floorspace, the dwellings proposed, the rear wall an extension could run along and what the holding has already converted, and see the floorspace per dwelling, the headroom under the caps, the dwellings left and the extension the class allows.

## Guides

- [Land sourcing](https://curtilo.com/land-sourcing/): the guides explain what class Q and class R allow, what the extension envelopes are, what the curtilage is, what a conservation area, a tree preservation order, green belt and grey belt do to a site, what brownfield land is and how development land is valued, never what a particular authority will decide on a particular plot

## Answers

- [curtilage](https://curtilo.com/answers/curtilage/)
- [class q barn conversion rules](https://curtilo.com/answers/class-q-barn-conversion/)
- [class r permitted development](https://curtilo.com/answers/class-r-permitted-development/)
- [agricultural permitted development](https://curtilo.com/answers/agricultural-permitted-development/)
- [permitted development rear extension](https://curtilo.com/answers/rear-extension-permitted-development/)
- [side extension](https://curtilo.com/answers/side-extension/)
- [permitted development for extensions](https://curtilo.com/answers/permitted-development-for-extensions/)
- [outbuildings](https://curtilo.com/answers/outbuildings-permitted-development/)
- [do you need planning permission to convert a garage](https://curtilo.com/answers/garage-conversion-permitted-development/)
- [porch permitted development](https://curtilo.com/answers/porch-permitted-development/)
- [permitted development in conservation area](https://curtilo.com/answers/permitted-development-in-conservation-area/)
- [tree preservation order map](https://curtilo.com/answers/tree-preservation-order-map/)
- [grey belt](https://curtilo.com/answers/grey-belt/)
- [bng exemptions](https://curtilo.com/answers/bng-exemptions/)
- [section 278](https://curtilo.com/answers/section-278/)
- [brownfield vs greenfield](https://curtilo.com/answers/brownfield-vs-greenfield/)
- [valuation of development land](https://curtilo.com/answers/valuation-of-development-land/)
- [development site](https://curtilo.com/answers/development-site/)

## Pricing

- Free to use. No account, no card, no sign-up.
- Curtilo Pro is £49 per month for your whole team, billed monthly.

## Citation

Cite as: "Curtilo tools", https://curtilo.com/tools/ (updated 2026-10-23).

## About

- Operated by Curtilo. Contact: hello@curtilo.com
- By submitting you agree Curtilo may contact you about your enquiry. We never pass your details to a builder, an agent or a lead buyer.