The principal reasons are the small size of Islamic banks, and the additional legal transactions involved with Islamic mortgages. In the UK, Muslims are often surprised to find that Shariah compliant Islamic mortgages are noticeably more expensive than conventional ones. A conventional mortgage is a reasonably simple transaction to document legally. Conversely, a residential Islamic mortgage involves both the bank and the new owner occupier purchasing the property jointly. The contracts used are less standardised and there are simply more pieces of legal paperwork involved in an Islamic mortgage. Furthermore, the stand-alone Islamic banks in the UK are very small compared with the very large conventional banks. All these costs must ultimately be borne by the customers and are reflected in the higher prices Islamic banks charge for Islamic mortgages.