I think you need to take the following into account - first, what is your current interest rate and type of mortgage? If you have a competitive tracker rate now, I would think very very seriously about selling and rentingm because you are not likely to get a cheap mortgage again any time soon. Any new mortgage is likely to be at a relatively high interest rate (that is, in comparison to the types of rates we saw during the boom). Second, stamp duty. What % fall in house prices would make it worth your while having to pay stamp duty again and what % of the total cost of the mortage will it represent? I would base my decision on the answers to those questions. We were thinking of doing exactly what you are planning but we have a very competitive mortgage (ECB plus 0.5%) and worked out that if we put the sum it would cost us in stamp duty to move to a bigger house/better area into improving our current house, we could make it much nicer and more suitable for our needs, so that is what we have decided to do. (Of course, that is also a gamble, my mother thinks I am mad to put money into doing up a house that is falling rapidly in value and which we will 'never' get back when we sell!). Having said that, our next door neighbours have 4 kids and made the opposite choice six months ago and are paying reasonable rent for an enormous house in a smarter part of the same general area and are delighted with themselves! Good luck with your family whatever you choose to do.