Depending on the property (and the budget), both options have their merits. A big loft space can be more easily converted to a room but often the structure or space isn't sufficient and an dormer or extension is needed. This can offer a whole new floor to the building and with some imagination you can transform the property completely. www.pwjarchitects.com

You're right that if your '90s semi has the ‘W’ shaped supports in the loft, then it’s a truss roof. These can be trickier to convert than older lofts with traditional cut roofs, but it’s definitely possible with the right structural work. When it comes to the staircase, it’s typically placed above your existing stairs to conserve space and maintain a well-flowing layout. If that doesn't quite work with your layout, it may need to be adjusted slightly to fit into the second bedroom. A good loft designer or builder will be able to advise based on your measurements and ceiling height. They’ll also ensure the stairs comply with building regulations, particularly regarding headroom. For the en-suite, placing it above your existing bathroom is often the easiest option, especially for plumbing. It means you can tap into the existing soil pipe and water supplies, which keeps things simpler and more cost-effective. That said, if the layout makes more sense to put the bathroom elsewhere, it can be done, just with a bit more work. The rear dormer sounds like a great idea. It’ll give you much more usable headroom and open up the space properly, especially if you're looking to fit both a bedroom and an en-suite. That’s what often makes the difference in terms of value. For a two-bedroom home, adding a third bedroom and bathroom upstairs can significantly enhance the feel and function of the house, especially if space downstairs is limited. It’s worth having someone take a proper look and sketch out a few floorplan options. That’ll give you a much clearer picture of what fits and whether it’s worth going ahead. However, yes, it’s totally doable, and many homes like yours have been successfully converted with great results. Hope that helps. Happy to share more if you need. Tom LoftCompare

Yes I've heard of them, but not used them. They appear quite regularly in my newsletters from https://www.homebuilding.co.uk/

Thanks Jonathan – a really helpful response. If you don't mind, here are my thoughts on your points: “I think that eventually at least 2 sisters (possibly all three girls) will move to this floor so you might want to make the shower room just a little larger to accommodate all the products they will eventually ‘need’.” That’s the plan – we’re aiming to move two daughters up there for now, and we’ll see how it goes. Good point on the shower room – would you suggest enlarging it by shifting the wall between the shower room and Bedroom 4? I still need to think about the interior layout of the shower room. “You might want to consider the front bedroom and where you would put furniture – probably moving the doors to the loft space.” I’ve been thinking about this. Here’s how I imagine the furniture layout (still need to add smaller pieces like a desk): I liked your original suggestion of placing the bed on the sloped side – I’m picturing eaves doors on either side of the double bed. “Also the roof windows in there seem ginormous.” That was intentional! I asked for the largest possible windows, ideally using coupled flashing (with either an 18mm or 100mm gap) to maximise head height around the bed (like this). I’m also hoping to minimise the central pillar between them to help the head height and to allow the headboard to go against the vertical wall below the window. Do you think that’s too much? “And if you have a Velux above the stairs consider getting an electrically opening one to help heat escape on hot days.” Thanks – I’ll look into this. Thanks again – Appreciate your input!