It is not legally required for you to have a survey done when buying a house, however, it is advised that you have one to avoid unexpected costs or other surprises.
If you are applying for a mortgage on the property, then your mortgage lender will do a valuation on the property which may also include a survey. This is because they want to ensure that the property is structurally sound and that they are not taking a risk by lending you money.
The mortgage lender may not lend money for the property if they find that there is a structural problem. Similarly, they may ask that further checks are carried out on the property before they give you a mortgage.
You can do your own independent survey when buying by instructing a separate surveyor. They will advise you of any issues with the property including with the roof, the timbers, the walls etc.
There are a few reasons why you should do your own survey when buying a property. Above all, a survey gives you peace of mind and makes you aware of all of the potential and existing issues with the property. Because buying a home is a significant purchase, you want to make sure that you know what you are buying and that you are not putting lots of money into something that will lose you money later down the line.