Wheelchairs come in a range of sizes and with different mobility potentials. Their dimensions depend on the needs of their users. Some people will have rigid legs which cannot be straightened. This will increase the operational length of their wheelchair and reduce their ability to turn sharp corners.

Designs should assume that disabled people will want their own, independent access, without needing to rely on assistance. Handles, surfaces and controls need to allow for a wheelchair user in a sitting position and with limited reach.

Counters and work tops for disabled people should be high enough for them to get their legs underneath so that they can get close enough to use the surface. This height needs to allow for electric wheelchairs having controls, such as joy sticks.

Gradients take extra energy to get up and can make speed control difficult when going down. A steep incline can put the chair in danger of tipping backwards or forwards. Many users cannot lean forward or adjust their balance to allow for a gradient.

A cross fall can similarly put a wheelchair user at risk and may also affect the steering, particularly on a manually propelled chair.

Gradients of 1 in 20 or less are counted as virtually level. Gradients up to 1 in 15 can be negotiated with a little difficulty. Between 1 in 15 and 1 in 12 it is getting noticably harder, particularly if the incline is long. Above 1 in 12 there is a very real potential for tipping over and such gradients are outside the recommendations of Part M of the Building Regulations. Part M:2004 gives the maximum lengths of slope between level resting landings for gradients between 1 in 12 and 1 in 20. Level landings should be at least 1500mm long.

At 1 in 12, slopes should not be longer than 2000mm. At 1 in 15, slopes should not be longer than 5000mm. At 1 in 20, slopes should not be longer than 10,000mm. Distances can be interpolated between these values for other gradients.

Rough surfaces make steering difficult, particularly on slopes. They will also be uncomfortable for the wheelchair user. This can be severe, particularly for people with spinal conditions. The tactile paving necessary for people with visual impairments can cause discomfort and difficulties for wheelchair users. The early designs of textured paving had to be redesigned with more rounded textures to make them easier for wheelchair users.