When it comes to buying a flat, all the tips for buying a house also apply but there are some particular things to consider with a flat too.
One of these is parking: how far away is the parking from the flat you are looking at, and will you be guaranteed a parking space, or does a garage cost extra: often a flat does not come automatically with parking so you need to look into that. Also consider how you will get to your flat: if not ground floor, are there lifts or purely stairs? If only stairs, consider if you are happy to walk up potentially several flights each time you want to leave - and also what you'd do if you broke your leg.
If the building has lifts, then see how long it takes on average for them to come: visit a few times and go to a couple of floors and time how long it takes the lift to come, ideally do this when there is high demand such as when people come back from work in the evening, this will give you a fair idea of how long it will take you to leave your home when you go to work and come back, which is of course when lots of people are out and about.
Another consideration that can be more important that with a house is noise, because of course you are surrounded with people. Now it is very hard to assess this for sure until you move in, but you should arrange visits at a few times of day to see what the noise is like, and particularly from the flat above if you're not on the top floor, as it is the flat above that usually causes most of the noise grief due to thud-thud on the floor or thud-thud of bass. Consider even coming late in the evening so you can get an idea if the person above plays loud music or not!
With flats it is even worth knocking on some adjoining doors and explain you are thinking of moving in and asking if they have any problems with noise or similar - most people are quite willing to share their experiences with you, and it could save you a lot of hassle from a noisy neighbour up above!
Assuming that everything seems OK with the flat and you want to go ahead and make an offer, the key is to feel that you've done as much research as you reasonably can, because living in a flat and enjoying it is as much about the trip to your room and then the noises from other people as much as how nice the flat itself is.
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