When the children at Chisenhale Primary School in east London come rushing outside to play, they know exactly where they are going. They make a beeline for the elevated play structure on one side of their playground, running up either side of a mound, assisted by ropes or handholds, or using a climbing net. When they get to the top there is another area of net, a deliberately quiet space and also access to two slides, one of normal width and the other large enough to accommodate six abreast.

This simple, elegant timber-clad structure is a far cry from the off-the-shelf play equipment that head teacher Helen James believed she needed to address the problems of her largely dull and very small playground. ‘I said that I just wanted it to be bigger,’ she said. In the manner of good head teachers, she called on the expertise of her parents, in this case architect Asif Khan who has two children at the school.

He soon persuaded her that a bespoke structure could be better and they set about developing a design and raising money. The result is a surprisingly ‘adult’ looking piece of architecture, a rectilinear box where the only colour comes from the warm tones of the heat-treated timber. It is marvellously flexible, a place where the children can play in their own way, rather than following prescribed activities. And this was something, said James, that the children understood immediately, knowing instinctively how they wanted to use the space.

This is a tribute to the detailed briefing process that Asif Khan undertook. From Helen James he learnt not only about her lack of space but about the fact that the playground was boring and the result was a certain amount of rowdiness and bickering. One part of the space was already devoted to a very successful vegetable garden and a dedicated area had to be left for ball games. Lifting up the play space therefore effectively created more room – as well as the potential for excitement.

But James was not the only client who Asif Khan consulted. He held regular meetings with the school council and every child at the school was encouraged to express, in words and drawings, their aspirations for their new playground. Some were brilliantly impractical – giant slides issuing from top-floor windows – and others uncannily like the end result. One of the lessons that Khan learnt was that, as well as wanting play and adventure, the children wanted some quiet space and privacy.

All this fed into his design, with the space between the structure and the building being good for quiet activities, as well as the ‘chill-out’ area in the actual play space. Nothing is signalled and there are no signs – the architecture simply caters for the children’s needs, both rumbustious and reflective. It is the work of a very good architect, a reflection of the fact that Asif Khan is not ‘merely’ a parent who happens to be an architect, but a highly talented and up-and-coming member of his profession. His projects include the ‘Mega Faces’ pavilion at the 2014 Sochi Winter Olympics, and the Coca-Cola Beatbox at the 2012 Olympics in London. Most recently he has been commissioned to design a summerhouse to sit alongside BIG’s Serpentine summer pavilion.

The structure is of galvanised steel, clad in slats of heat-treated tulip wood and with beams and flooring in heat-treated ash. Asif Khan was keen to use timber, because of its visual warmth, a contrast with the hard playground and the brick of the school building and surrounding housing. ‘I was keen to introduce a natural material that would age and grow with time,’ he said.

He had seen the American Hardwood Export Council’s (AHEC’s) use of heat-treated timber in a project for the London Design Festival, in particular a contemplative shed that was designed for use by fashion designer Paul Smith.  ‘When we decided that we wanted to work with wood,’ Khan said, ‘I felt that they would know technically what would work outside.’ 

Both he and Helen James are great fans of the tulipwood because it is so smooth to the touch – an important factor when considering how often small hands are going to be gripping it. The heat treatment, as well as changing the colour to make it darker, makes timbers that would not otherwise be durable for use outside stable and long-lived. AHEC is particularly keen on the use of tulipwood because it is one of the most abundant timbers in US hardwood forests, so there is a strong environmental argument for its use – the resource is increasing much faster than it is being harvested. Ash is also one of the most abundant and fastest growing timbers. Both are lighter in weight than traditional durable hardwoods such as oak, allowing the entire structure to be more lightweight. And oak, while it has many advantages, would not offer such a smooth finish. 

The slats create a sense of enclosure for the children, while still allowing teachers to see into all parts of the structure – important as they want to keep an eye on behaviour. Another crucial factor is that the slatted panels allow plenty of light to pass through which, since the structure stands close to first-floor windows, was a prime consideration. 

Carpentry company Aldworth James & Bond had not worked with heat-treated timber before but found it easy and a pleasure to use. It worked out a method of using a CNC (computer numerically controlled) machine to cut all the individual elements, making allowance for example for the rebates where the slats fitted to the steel frame. In this way it could make the panels relatively rapidly and simply.

This degree of precision was used throughout the project. So, for example, Asif Khan gave the driver of the digger that was constructing the mound a three-dimensional model to follow to achieve the perfect conical shape. The mound is made from demolition rubble, and topped with a surface made from recycled tyres.

For Helen James and Asif Khan this is an important first step in rethinking the school and its grounds, with the aim of making it more flexible and enhancing the facilities for the children. The play space is modular and has been designed so that it could extend, possibly to the roof of a nearby outbuilding, where an additional classroom could be built for specialist activities.

It is exciting to see this scale of ambition and imaginative thinking, driven by the head teacher, the school council and the architect. Even if these further ideas do not come off, the school is benefitting from an innovative and beautifully designed play space. Observers will admire it and anybody with any appreciation of architecture will grasp the sophistication of thinking that has gone into its design. And the children? They will just continue to enjoy playing in it, not noticing how much exercise they are getting or the physical confidence that they are acquiring. And that is exactly as it should be.