Hi. Lots of people are having loft conversions these days because it's cheaper and more convenient than moving. A loft conversion should start at around �15k upwards. I think it is worth it, especially if you were to put a bathroom in (or shower/toilet/sink). If you can add a room and a bathroom you will be adding plenty of value, even with another room you'll be adding value. You can expect to get your money back and more. Make sure it's not top heavy though. Are you thinking of using any equity - you mentioned that the value of your house is about �150k. Make sure you don't overspend, do some calculations to check you will be able to pay your mortgage, bear in mind interest rates as well. It's probably best to do a worst case scenario in terms of what you can afford then take it from there. You will need planning permission as well. Good luck.