Property valuation is difficult as what you are hoping to achieve is an estimate of the value that will be realised. No matter if you are buying or selling, you will need to have some idea of the actual value and possibly what might affect a properties value.
You need to have undertaken prior analysis of the market place to ensure that the price you market you property reflects its value. Likewise, if you are buying, then you need to know if your offer is realistic and competive.
When selling you may decide that the local estate agents opinion as to the value of the property will be enough. By relying on this opinion is no substitute for an actual independant property valuation. The consumer group 'Which' pointed out that there may be a conflict of interest with estate agents. It has been known for estate agents to increase the value of a property in order to obtain the instruction. By contrast, if the estate agent has potential buyer, they may give an under-valuation for a quick sale.
Back in the early 2000's, property prices were rising so fast in parts of Scotland that valuations became outdated in just a few months. However, the boom in rising prices has now steadied, although they are still rising faster in some parts. Experience has showed that by looking at similar properties in the same area will give you a feel for a valuation, although, you must take into account the condition of the property.
If the house is new, then you should have no problems and maybe even have the balance of a house builders guarantee. When house get a bit older, say 50 years, then you might start to question when the heating system was put in, which might be okay 10 years old, but you might like to consider replacing. When the house is around 100 years old, you may like to examin the wiring, damp proofing and of course the timbers and roof.
Of course, comparing two properties is not going to be easy, as no two properties are the same. Alterations, decor and extensions will all play their part to the valuation.
A professional valuation may give you a better insight.