How I bought an airport with my pension Sipp providers will allow commercial property investments only if they are persuaded that there is a sound business case for proceeding, and investors are always advised not to tie up all their assets in a single enterprise. Isle of Wight Sandown airport Martin Tilley, director of technical services at Dentons Pensions Management, the provider that runs Mr Fowler's Sipp, said: "We find lots of people want to invest in things they really understand and have a connection with. If you have an area of expertise, why not make it work for you in your pension as well as in your career? Investors have been able to invest in commercial property through Sipps for years, and can also borrow up to 50pc of the value of the Sipp to fund property purchases. We have a client who is in the music business who has invested in a music studio in Costa Rica. One investor has bought a fishery lake; another has converted a chapel into a bar and a police station into office space. Commercial property investment through Sipps is about creative use of the assets available to you," said Mr Tilley. When your own business is the tenant of your Sipp's commercial property, you know it is a tenant you can trust. For small businesses starved of capital, the Sipp fund can work out a cheaper and easier way of accessing capital," he added. [Get the best of Telegraph Money once a week. Enter your email] Suffolk Life, another provider, has one client whose Sipp owns a single parking space in Kensington and another who has bought a cave with their Sipp. Some investors have put lucrative French yacht perths in a pension Greg Kingston, head of marketing at Suffolk Life, said: "The investor came along and asked if they could put a local tourist attraction, Mother Shipton's Cave in North Yorkshire, into their Sipp. That was no problem as it stacked up as an investment proposition. The investor's Sipp now owns the cave and the business that runs the tourist attraction on the site pays its rent. Commercial property investments have yet to come anywhere near pre-credit-crisis valuations. A commercial property worth £100,000 in June 2007 had fallen to just over £55,000 by June 2009, and had only recovered to £63,000 by September this year, according to the IPD UK commercial property index. But the Royal Institution of Chartered Surveyors commercial property market report for the second quarter of the year said capital values were expected to increase. Mr Kingston said: "Most of the commercial properties held within Sipps are connected to the investor in some way. But there appear to be indications that the commercial property sector could be turning a corner. Any commercial property investment carries risks, but if you have got excess cash tied up in your pension and a business idea you've always dreamed of, a Sipp could hold the key. Sipps to suit you: How the plans work There are two main types of Sipp - "full Sipps" and "online Sipps." The main difference between the two is the range of investments you can hold. Another key difference is that full Sipps are almost always taken through a financial adviser, in light of the complex types of investments they allow. Full Sipps are offered by specialist Sipp providers and life insurance companies. They give access to nearly all of the investments on HM Revenue & Customs' long list of permitted investments. These include commercial property, traded endowment policies, structured products and unlisted shares, which only a few Sipp providers will accept. Borrowing of up to 50pc of the Sipp's value is permitted to fund commercial property purchases. The wrappers tends to be more expensive than with online Sipps. Online Sipps are low-cost online pension investment plans that give around-the-clock access to thousands of funds, shares, bonds, gilts, ETFs and investment trusts. They are the fund supermarket-type investments that will be very familiar to Isa investors. They can be direct, or taken through a financial adviser. How to get rich slowly: sign up to our newsletter for tips