Designing a SEN building: the brief, the spaces and how it is funded

By Grayling Thomas Architects · October 2026

Designing a SEN building starts with the pupils it will serve. The brief sets out how many places are planned, which needs the building must meet and whether pupils are mainly ambulant or non-ambulant, because that one question changes the recommended size of many rooms, the circulation and the site. The Department for Education's area guidance, Building Bulletin 104, turns those answers into recommended ranges for floor area and site area, and lists the specialist spaces a special school should have. The Department's dedicated capital for new SEN places goes to local authorities as the high needs provision capital allocation, funding "to support the provision of new places and improve existing provision". The Condition Improvement Fund (CIF) is mainly a condition fund, which also “supports a small number of expansion projects”.

This article takes the whole-building view, for a trust or local authority planning a new special school or an extension. Room-by-room sizes are covered in our separate guide, BB104 explained: area guidelines for SEND and alternative provision.

What goes into the brief for a SEN building?

A good brief answers a few questions before anyone draws a plan.

Who is the building for? The area guidance treats a special school for ambulant pupils differently from one for non-ambulant pupils. The non-ambulant formulae apply to a special school with a range of specialist physiotherapy, medical and personal care facilities "to meet the needs of pupils with PD and/or PMLD." That choice drives classroom sizes, circulation, hygiene rooms and the site.

How many places? In most cases the area formulae work from the number of places planned rather than the number on roll, because the roll can vary year by year; our guide to the area guidelines explains how.

How will pupils be grouped and supported? Pupils in special schools and AP "need individual teaching, counselling and therapy, requiring a range of small spaces", and visiting professionals such as speech and language therapists "need access to a desk space and storage in addition to the teaching areas." Those spaces belong in the brief from the start, not squeezed in at the end.

How pupils are grouped and supported is knowledge the SENCO holds, and our guide to what a SENCO should bring to a SEN building brief sets out what to ask for.

How firm are the numbers? The guidelines are ranges to be applied flexibly, not fixed rules.

For mainstream schools adding provision, the brief often starts with an inclusion base rather than a separate building. The Department's Inclusion bases in schools guidance says bases "typically require a dedicated space in the setting, which might be separate classes, specialist facilities, or a base where professionals with particular expertise are located." Our guide to inclusion base design covers briefing and sizing a base in detail.

Which specialist spaces does a special school need?

Beyond classrooms, the area guidance lists spaces every special school should have and others that depend on pupils' needs. The core list includes:

• at least one small group room for every three classrooms (one per classroom for severe autism);

• at least one therapy space for visiting therapists, 12m2 for ambulant pupils, 15m2 for non-ambulant;

• at least one sensory room.

Then come the spaces that follow from the pupils:

• for all special schools with ambulant pupils, one quiet/calming room per key stage;

• for all special schools with primary-age pupils, a soft play room for movement therapy on padded surfaces (size will depend on the type of equipment but typically 20-25m2);

• for all special schools with non-ambulant pupils, a physiotherapy room (25-30m2) and a hydrotherapy pool (85m2). The guidance's room schedule lists this as "Hydrotherapy room (ambulant/ non-ambulant) 85m2 (24m2 pool)", with the associated changing and plant areas counted separately as non-net area. A typical suite has "a pool of 24m2 with a surround of 2-2.5m wide (to ensure safe movement) and a hoist". "If there is a pool close by to which pupils can be taken", this provision can be omitted and the area reduced to match.

Additional spaces may include a life-skills kitchen, a soft play room in secondary provision and therapy rooms for occupational or speech therapists or nursing staff. Our guide to SEN classrooms covers class bases and room layout; what follows is the part no room schedule shows: the site, adaptability and funding.

The whole building: storeys, circulation and the site

Some decisions shape everything else. The first is height. "Special schools should ideally be single storey to make circulation easier for pupils using mobility aids, or for those who need assistance or close supervision from staff."

The second is the site, and height affects it too. The area guidance's minimum gross site area formulae "allow for a single storey building, which is generally preferable for a special school." A site area below the minimum "is possible on a constrained site if a two storey building is acceptable, given pupils’ needs." The guidance divides the site into net site area (outdoor PE, informal and social areas, and habitat areas); non-net site area (building footprints, access and parking); and supplementary site area "for community or support functions", which "will either need to be funded from other funding streams or, on an existing site, left as additional to the site area needed for the special school or AP." Outdoor needs vary widely: "For some schools horticultural activities are an important part of the curriculum, for others outdoor PE is the most important activity."

Arrival and departure need planning early, because at a special school they can take up to 40% of the net site area; our area guidelines article covers the site figures.

The recommended non-net site area, for buildings, access and parking, applies to any special school, but a school for non-ambulant pupils in a single storey school building with more than around 150 pupil places "is likely to be at the top of the range."

Designing a SEN building that adapts to changing needs

Pupil needs change over the life of a building, and the guidance builds that in. Where a special school caters for a broad range of needs, it may have classrooms of different sizes, but "providing too much variation in room size can limit the school’s flexibility to accommodate changing needs." In a special school for non-ambulant pupils with PMLD, the area needed for medical and therapy rooms and for toilet and hygiene facilities will be "significantly higher than in other settings", and "There should be enough flexibility to allow some increase in pupils with these needs."

Undersized classrooms work against this. Below the standard size where there are non-ambulant pupils, a room will "reduce the school or Unit’s flexibility to increase its intake of non-ambulant pupils in the future." Designing the main teaching spaces to the standard size keeps that option open.

How are new SEN places funded?

The high needs provision capital allocation (HNPCA) is paid to local authorities, so a project for new SEN places starts with the local authority. The high needs provision capital allocations guidance states: "This £860 million in capital funding for 2026 to 2027 is essential to increasing the capacity of mainstream schools to meet a wider range of needs." Special school places need a case: "Local authorities who plan to use their allocation to increase special school or AP places will need to demonstrate in their local SEND reform plans an evidence-based rationale for why need cannot be met in mainstream settings."

Where the Condition Improvement Fund fits for a SEN building

The Condition Improvement Fund is a bidding round for eligible academies, sixth-form colleges and voluntary aided (VA) schools. Larger trusts and local authorities with maintained schools receive School Condition Allocation (SCA) instead, so a special school maintained by the local authority generally looks to the local authority rather than to CIF. Our guide to CIF, SCA and urgent capital support sets out who is eligible, including how pupil numbers are counted for special schools.

For a special school whose block is failing, the condition with expansion category may be relevant. Where a block is replaced because of its condition, the Department will accept a new block "where the GIFA of the new block is up to 10% larger than the existing GIFA that is being replaced, if you provide clear evidence that there is no other alternative to meeting area standards as defined by Building Bulletin 103 or 104." The evidence must focus on the condition need; our guide to condition surveys for special schools explains what a CIF bid for a special school needs, including accessibility works. Expansion in its own right is a separate category, and "Only a very small proportion of CIF will be allocated to address expansion issues across high performing applicants and will be restricted to academies, sixth form colleges, and VA schools with fewer than 2,000 pupils."

The DfE's Condition Improvement Fund guidance is the official page for the fund's rules, and our earlier guide to using CIF for school expansion and growth projects looks at expansion bids.

For the 2027 to 2028 round, our article on CIF 2027 to 2028 key dates sets out the deadlines and what to prepare.

Related guides

• SEN classrooms: size, layout and what makes them work

• Inclusion Base Design: Briefing, Sizing and Delivering a Mainstream SEN Base

• BB104 explained: area guidelines for SEND and alternative provision

• School building grants in England: the capital funding routes for new facilities

How Grayling Thomas Architects designs SEN buildings

Grayling Thomas Architects, incorporated in 2010, is a RIBA Chartered Practice that designs and delivers large school buildings, with SEN and education architecture among its services. We work as lead consultant and architect, preparing the evidence, the design and costed options with the school, trust or local authority, from the first brief through to completion.

If you are choosing a design team, our guide to choosing an architect for a school capital project sets out what to check before you appoint.

Grayling Thomas Architects was CIF bid writer, lead consultant and architect for Dorothy Goodman School in Hinckley, a new building for an existing special school, funded through the Condition Improvement Fund. The building was completed in September 2018. It was the winner of Large Non-Residential Scheme of the Year 2019 (Procon Leicestershire). It was also recognised at the RICS East Midlands Social Impact Awards 2020.

You can read more about our approach on the SEN school architecture page.

If you are planning new SEN places, a special school extension or an inclusion base, contact Grayling Thomas Architects to talk through your brief, your site and how it could be funded.