UK work is metric, and it answers to two separate systems: planning permission, which is about size and appearance, and Building Regulations approval, which is about how it is built. PLOTVA draws in metres and millimetres, names the Building Regulations 2010 and Approved Documents A–Q as its reference set, designs concrete to BS EN 1992 and seismic to BS EN 1998, and produces diagrams, elevations, sections and a native DWG. Offline, from $2.
The single most-searched UK house question is how far back you can build without a planning application. In England, for a house (not a flat or maisonette):
| Type | Permitted development | With prior approval |
|---|---|---|
| Single storey — terraced or semi-detached | 3 m beyond the original rear wall | up to 6 m |
| Single storey — detached | 4 m | up to 8 m |
| Maximum height (single storey) | 4 m, with eaves not above 3 m within 2 m of a boundary | same |
| Two storey | 3 m deep, and at least 7 m from the rear boundary, roof pitch matching the house | not available |
| Conservation area, Article 4 direction, listed building | restricted or removed | the 6 m / 8 m route is not available on Article 2(3) land |
The prior-approval route is the Larger Home Extension / Neighbour Consultation Scheme — it has been a permanent part of permitted development since 30 May 2019, the council consults adjoining neighbours for 21 days, and a fee applies (around £250 in England in 2026, £0 in some circumstances — check your council). Wales and Scotland differ: Wales allows 4 m single storey on any house with no larger prior-approval option.
Whether you may build it at all: size, position, appearance, neighbour amenity. Permitted development removes the need for an application when you stay within the limits above. The local planning authority decides.
How it is built: structure, fire escape, drainage, ventilation, energy, access. Most work needs a Building Regulations application — full plans or a building notice — and the inspector signs it off.
Notice to neighbours when work is within 3 m of their structure, within 6 m and deeper than their foundations, or on a party wall itself. Separate obligation, separate notices, separate timetable.
A drawing set that satisfies one of these does not satisfy the others. The software produces the accurate geometry and the structural numbers; the applications, the notices and the sign-offs are procedural, and they are yours or your professional's to file.
Millimetres on the drawing, square metres in the schedules, and an area table that also reads square feet for the estate-agent conversation.
Concrete to BS EN 1992 and seismic to BS EN 1998, with the parameters and the load combination printed on the sheet so a checking engineer can follow it.
Set the existing rear wall as the datum and the software dimension from it — which is exactly how the 3 m / 4 m test is measured: from the original rear wall, not from a later addition.
30 AIA layers, real units, blocks and dimensions, plus DXF AC1032 — it opens in AutoCAD, BricsCAD, DraftSight and the usual UK practice tools.
In England, permitted development allows 3 m on a terraced or semi-detached house and 4 m on a detached house, up to 4 m high, measured from the original rear wall. The Larger Home Extension route — a prior-approval application with neighbour consultation — extends that to 6 m and 8 m respectively.
No, and both are usually needed. Planning permission is about use, size and appearance; Building Regulations approval is about how it is built — structure, fire escape, drainage, energy, access. The Building Regulations 2010 with Approved Documents A to Q are the reference set this software names.
Yes, metres and millimetres are the default for the UK profile, with areas printed in square metres and square feet.
Usually when work is within 3 m of a neighbour's structure, or within 6 m and deeper than their foundations, or on a party structure itself. It is a notice obligation, separate from planning and Building Regulations.
Send the plot size, the country and the rooms you want. You get a straight answer with the plan that fits, usually the same day. The button opens a ready-written e-mail — just add your details and send.
No phone number and no e-mail address is printed on this page — the contact button opens Gmail with the address already filled in, so it cannot be scraped.