Adding Value to your Home
Extending your own home through an increase in your mortgage or funded from savings can be much more cost effective than moving to a larger house ( especially once removal fees, agents fees, and stamp duty are taken into account) and can increase the overall value of your property.
Before you commit to your project, you may want to check this aspect with a local Estate Agent. Adding a double bedroom will typically increase the property value, but there is often a maximum ceiling on the house prices in your area, no matter how many improvements you make.
It might be that a garage or loft conversion doesn't actually add a penny to your property value, but it could provide you with invaluable additional living space that you couldn't afford if you moved house. It can also make your house first to sell compared to another house with a similar price but without the extra space.
It can be helpful to view each decision you make from three different perspectives, 'wearing a different hat' so to speak, as follows:
i) Homeowner perspective: Adding perceived value and enjoyment for you personally, like the quality of fittings and finishes
ii) Estate Agent perspective: Adding actual value, or just improved saleability/kerb appeal, to the property
iii) Developer perspective: Maximising available value from a minimum financial outlay
Estate Agents normally give free valuations and if you feel cheeky asking for a valuation, you can justify it by the fact that if you can't extend, you may need to move house instead!