Written Investing in a kitchen in a cupboard could help to generate extra income for homeowners who rent out spare rooms to lodgers, one expert has said.A growing number of professionals are letting rooms in private homes to be close to work during the week.To make the most out of an arrangement like this, homeowners should consider how kitchen space will be shared, said Judy Niner, founder of professional renting service Mondaytofriday.comSpeaking to the Independent, she said If its a long-term let and you want the lodger to be more independent, then provide the basics of a kettle and toaster.However, Richard Rogan from Spacesavers, suggested that landlords can opt for a mini-kitchen.For around 400 you can choose a range of small appliances or, for a little over 2,000, you can buy a kitchen in a cupboard (it needs to be about 1m deep), he explained to the newspaper. This will include a mini dishwasher, microwave and fridge. It takes about a day to install and that price should include any extra plumbing and wiring necessary.The National Association of Estate Agents recently revealed that the current housing market has opened the rental market up to a new audience. Britons who may never have traditionally considered renting are now looking to the lettings market.