Removing walls on the top floor

[Mrs-P]

When removing walls in the top storey of a house (i.e. only the loft space above) can you remove entire walls without weakening the structure, or do you need to go the whole hog with RSJs etc?

Don't worry, we're not about to knock our house down, just investigating whether it's worth getting a builder in to give us some quotes.

[Hawkwalk]

walls upstairs may still be load bearing. Get it checked out before you do anything.

[buildersmate]

This is true. A reputable builder will have seen this before and be able to offer advice as to whether a qualified person needs to look at it.
If you have roof trusses in the loft, generally these are designed such they require support at the ends of the span only (the outside walls) so the internal partitions are irrelevant to loading EXCEPT in the area where the cold water storage tank sits (if you have one). Do not underestimate the weight of this tank with water in it (a full 50 gallon tank weighs about 220Kg) and generally you will find this tank located over a supporting wall - do not remove this partition.