Turning a garage into a bedroom, office or kitchen-diner is often free of planning permission but almost never free of building regulations. This page sets out when permission is needed, which parts of the building regulations the conversion triggers, and the drawing set that covers both.
(£515 if you supply measured drawings)
Garage conversion
Fixed in writing after a free assessment of your property. Council planning fees are separate.
Every price is the total you pay. Checked 24 October 2026.
Most attached or integral garage conversions need no planning application, and the exceptions turn on conditions, designations and use. This is the short table, and our garage conversion planning permission guide sets out each case.
| Situation | Application usually needed? | What decides it |
|---|---|---|
| Integral or attached garage becomes a room of the same house, internal work only | Usually not | Section 55(2)(a) of the 1990 Act: works that affect only the interior, or do not materially affect the external appearance, are not development |
| Garage door replaced with a wall and window (integral or attached garage) | Usually not, on a house | Section 55(2)(a) covers works that affect only the interior or do not materially affect the external appearance. Otherwise Class A can permit an alteration to a house if the materials are of a similar appearance (A.3(a)), unless rights have been removed or the building is a flat |
| The house's permission carries a condition that keeps the garage for parking | Yes: an application to vary or remove the condition | The condition itself: converting against it is a breach, and the remedy is an application. Article 3(4) of the GPDO also stops permitted development rights being used contrary to a planning condition |
| Permitted development rights removed by an Article 4 direction or a condition | Only for external changes that depend on those rights | The Planning Portal advises contacting the council, especially on new housing developments and in conservation areas |
| Garage becomes a separate home or a let annexe | Planning permission may be needed whatever the work | The Planning Portal says so for a separate house, regardless of who will occupy it |
| Garage in a conservation area | Check the external alterations | Class A paragraph A.2(a) does not permit cladding in stone, artificial stone, pebble dash, render, timber, plastic or tiles on article 2(3) land |
| Flat, maisonette or listed building | Ask the council | The Planning Portal guidance covers houses only. A listed building may need listed building consent |
Sources: Planning Portal, garage conversion, TCPA 1990 s.55, GPDO 2015 article 3(4) and Class A, read 14 and 15 October 2026. The decision notice for your house on the council's planning register is the document to read.
The Planning Portal says that converting a garage, or part of a garage, into habitable space will normally need building regulations approval. In our classification the conversion normally engages Part L (energy), Part F (ventilation), Part C (moisture) and Part A (structure), and Part B (fire) where part of the garage remains. The figures below come from the Approved Documents and the Planning Portal.
| Part | What it asks of a garage conversion | Figure to design to | Source |
|---|---|---|---|
| Part L, energy | A garage that joins the heated house is a change to energy status. Retained walls, floor and roof that are poor should be upgraded, and new elements must meet the new-element standards | Retained elements above the threshold are upgraded: wall 0.70 to 0.55 (cavity insulation) or 0.30 (internal or external insulation), floor 0.70 to 0.25, roof 0.35 to 0.16. New wall 0.18, floor 0.18, roof 0.15, window 1.4. Existing windows and doors above 3.30 are replaced (para 11.7) | Approved Document L volume 1: paras 4.12 and 11.6, Tables 4.2 and 4.3, and regulation 22 |
| Part B, fire | If part of the garage stays as a garage, it is separated from the house by fire-resisting construction, and a door between them has to meet para 5.7 | REI 30 separation, and either a garage floor that falls away from the door or a door opening at least 100 mm above the garage floor | Approved Document B volume 1: paras 5.6 and 5.7 |
| Part F, ventilation | Both background and purge ventilation are normally required for a habitable room, and alternatives may be agreed with building control | Background 8,000 mm2 in a multi-storey building (10,000 mm2 single storey); purge opening 1/10 of floor area (opening 15 to 30 degrees) or 1/20 (over 30 degrees) | Planning Portal, ventilation page |
| Part C, moisture | The existing floor may need upgrading: a new damp proof membrane, and thermal insulation that may be required | Screed in the order of 75 mm with mesh on a solid floor; 150 mm minimum void under a timber floor | Planning Portal, flooring page |
| Part A, structure | The infill wall may need a new foundation, because a garage slab is probably shallow, and clay and trees can make it deeper | Deeper than the typical 0.75 m of moisture-driven soil movement; good practice is to dig to the neighbouring foundation depth, and drains within the 45 degree load spread matter | Planning Portal, in-fill garage door page |
Sources: Approved Document L volume 1, 2021 edition incorporating 2023 amendments; Approved Document B volume 1; Planning Portal building regulations, in-fill door, flooring and ventilation, all read 14 and 15 October 2026. Where upgrading to the improved value is not technically or functionally feasible, or does not pay back within 15 years, para 4.13 asks for the lowest U-value that is, generally no worse than 0.7. A 2026 edition of Approved Document L takes effect on 24 March 2027 for most building work, and Circular Letter 01/2026 sets transitional arrangements that turn on both the date of the application or notice and when work starts, so check which edition applies to you. The Part F and Part C labels are our classification of the Planning Portal pages.
This example is arithmetic, not a real job, and the dimensions are assumed. A single integral garage measures 2.6 m by 5.0 m inside, so the floor area is 13 m2. The house is two storeys, so it is a multi-storey building for the ventilation table.
Background ventilation would be 8,000 mm2 equivalent area, normally a trickle vent in the new window. For purge ventilation, the opening part of a window that opens between 15 and 30 degrees must be at least one tenth of the floor area, 1.3 m2. A window that opens past 30 degrees needs one twentieth, 0.65 m2. The window dimensions on the front elevation come straight from that sum.
For energy, the existing floor is solid concrete with no insulation, so its U-value is likely to be above the 0.70 threshold in Table 4.3 (the figure depends on the floor's shape, and a lesser standard can apply where levels are a problem). As a retained element in a conversion that joins the heated house, it should be upgraded to 0.25 W/m2K, or to the best feasible value under paragraph 4.13. The new infill wall in the door opening is a new element, so it needs 0.18, and the new window 1.4. These figures all go on the section and the specification sheet.
A garage conversion set serves two readers: the council's planning team, if an application or certificate is needed, and building control. The scales are our working practice, and your council's validation list may add to them.
| Sheet | Typical scale | What it shows for a garage conversion | Why it is asked for |
|---|---|---|---|
| Location plan | 1:1250 | Site edged red, north point, two named roads | Identifies the land. The Planning Portal describes a standard metric scale, typically 1:1250 or 1:2500 |
| Block plan | 1:200 or 1:500 | House, garage, drive, any parking spaces left, crossover and boundaries | Councils check what parking remains, and any parking condition on the house |
| Existing floor plan and front elevation | 1:50 or 1:100 | Garage dimensions, floor level against the house, door opening, services and the street front | The baseline for what changes, and for the front elevation the council compares |
| Proposed floor plan | 1:50 or 1:100 | New room use, any step or ramp up to house level, door and window positions, route to the hall | Shows the use and the escape route |
| Proposed front elevation | 1:50 or 1:100 | Infill wall and window in matching materials, lintel line and openings that line up with the house | Tests the effect on the external appearance and, on a permitted development change, materials of similar appearance (A.3(a)) |
| Section through the floor and the infill | 1:20 or 1:50 | Floor build-up with membrane and insulation, infill foundation depth, wall build-up, ceiling height | Building control checks Parts C, L and A from this sheet |
| Building regulations details and specification | 1:20 and notes | Ventilation, fire separation where part of the garage remains, electrics, drainage | Part of the full plans application, which building control must decide within five weeks or a longer period agreed in writing (regulation 14A(6)) |
Sources: Planning Portal, plans and drawings, read 14 October 2026; GPDO Class A, condition A.3(a); Building Regulations 2010 regulation 14A. See planning application drawings for each borough's checklist and building regulations drawings for the construction set.
Two things can change the route. A planning condition on the house that keeps the garage for parking means the conversion breaches the condition, and the remedy is an application to vary or remove it. The condition appears on the decision notice for the house on the council's register, not on site. An Article 4 direction removes named permitted development rights across an area, and a condition can do the same for one house. The interior of the garage is still not development under section 55(2)(a), but the external changes may need the rights that were taken away.
In either case, the drawings are the planning application. The block plan shows the parking left, the front elevation shows the infill, and a short statement answers the council's parking test. Our conservation areas and Article 4 guide explains how to find a direction, and the permitted development rights guide covers the wider limits.
These are common errors that delay a garage conversion or leave it without a certificate.
The price panel on this page shows the starting price for garage conversion drawings, covering a measured survey, drawings, parking and Article 4 checks and council submission. It is the total you pay, survey included. Council fees are separate and paid to the council. The pricing page lists building regulations drawings and structural calculations as separate items.
Tell us about your project and get a fixed, no-obligation quote back within one working day. If you don't need planning permission at all, we'll tell you that too — for free.
The same measured survey feeds the planning sheets and the building regulations set, so the floor levels and wall thicknesses on the section are the ones your builder finds on site.
We look for a parking condition on the house's permission, an Article 4 direction, a conservation area or a listing, and tell you whether an application, a certificate or building control alone is the route.
We measure the garage, its floor level against the house, the door opening and the services, because the slab level often decides the design.
We draw the conversion to your brief and show the build-ups, ventilation sums and fire separation that building control checks. A full building regulations set is a separate item.
We submit what the route needs and revise the drawings free until the council decides.
Usually not. The Planning Portal says planning permission is not usually required if the work is internal and does not enlarge the building. You do need to apply if a condition on the house's planning permission keeps the garage for parking, and the Planning Portal says you may need permission if the garage becomes a separate home or loses rights to an Article 4 direction. A listed building may need listed building consent.
Normally yes. The Planning Portal says that converting a garage, or part of one, into habitable space will normally require building regulations approval. It covers the floor, the infilled door opening, ventilation and energy performance, and planning permission does not replace it. A full plans application is decided within five weeks, or a longer period you agree in writing.
Approved Document L treats a previously unheated garage that joins the heated house as a change to energy status. Retained walls, floors and roofs with high U-values should be upgraded, and new elements such as the infill wall and window must meet the new-element standards. Where the full upgrade is not feasible or does not pay back in 15 years, the document asks for the best value that is, generally no worse than 0.7.
In Approved Document L volume 1, 2021 edition, a new wall in an existing dwelling is 0.18, a new floor 0.18 and a new window 1.4 W/m2K. Retained walls and floors above 0.70 are upgraded to 0.30 for an insulated wall and 0.25 for a floor. The document gives exceptions, and a 2026 edition takes effect on 24 March 2027, with transitional arrangements.
Search your council's planning register for the decision notice on the permission that built the house or garage, and read the numbered conditions for wording that keeps the garage for parking. If you cannot find the notice, ask the planning team. A condition usually means a section 73 application to vary or remove it before the conversion.
Usually not, on a house. Section 55(2)(a) of the 1990 Act protects works that do not materially affect the external appearance, and Class A can otherwise permit the alteration if the materials are of a similar appearance. Rights may have been removed by a condition or an Article 4 direction, and flats have no householder (Part 1) rights, so check with your council.
Often, if it is used incidentally to the house, as an office, gym or playroom. Using it as a separate dwelling, or as a self-contained annexe let independently, can need planning permission. The Planning Portal advises discussing a separate house with the council whatever work is involved. A detached garage in a conservation area adds further checks.
The Planning Portal gives background ventilation of 8,000 mm2 equivalent area for a habitable room in a multi-storey building and 10,000 mm2 in a single storey building. Purge ventilation is an opening of one tenth of the floor area if the window opens between 15 and 30 degrees, or one twentieth above 30 degrees.
The Planning Portal says moisture-driven soil movement typically occurs to about 0.75 m, so foundations should go deeper, and it treats digging to the neighbouring foundation depth as good practice. Clay soil and nearby trees can make foundations deeper. A structural engineer or the building control body confirms the figure for your ground.
The price panel on this page gives the starting price, which is the total you pay and covers a measured survey, drawings, parking and Article 4 checks, council submission and free revisions until the council decides. Council fees are paid to the council. Building regulations drawings and structural calculations are separate items on the pricing page.
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