Layout advice on a first-floor side extension

[fandyman]

Hi all, looking for opinions on a first-floor side extension layout (UK). I’m considering adding one additional room on the first floor to the side of the house (not rear). I’ve attached the existing first-floor plan with the new hallway marked in red and black.

Because of the existing stair position and structure, one option involves forming a short internal corridor that is carved out of the current main bedroom (through existing wardrobe space and en suite), rather than walking directly through the bedroom itself.

Important clarification:

• This would not be a walk-through bedroom
• The new room would be accessed via a dedicated corridor
• The corridor would have a full-height window for daylight
• The sleeping area would remain separated by a door

So practically it would be closer to a small internal hallway arrangement, not circulation through the bed space.

My questions:

1. Is this type of solution generally considered acceptable in UK extensions if proportioned well?
2. Are there any resale or usability red flags you’d immediately see?
3. Would planners / Building Control typically object to this, assuming room sizes and light are compliant?

Happy to hear both professional and homeowner perspectives - especially if you’ve seen similar layouts work (or fail).

Thanks in advance.

[G and J]

Hi, what will the room that is currently the main bed be used for in the future? I ask because if your happy losing ensuite/wardrobe anyway a corridor in front of the bay/ changing what I guess would be opaque glazing in the rear window may be an option......could even make corridor a little wider and have a seat/study area in the bay?

[fandyman]

It will be a secondary bedroom and the new room added to the right will become a master bedroom with ensuite. The window in the bathroom is a standard wide non-opaque window. Are you suggesting the bay window may be presented as a functional desk space or bench, desk, reading nook? That might be one option that I have not considered yes.

[fandyman]

This is what it would look like @G and J

 

I would have to move the ensuite out of that bedroom and create a new one in a new master bedroom

 

Would it be acceptable or look odd?

 

 

 

 

Edited 16 hours ago by fandyman

[Conor]

Need to see the whole floor layout and the ground floor for context.

 

And don't be afraid of moving stairs, not as difficult or as expensive as you might imagine. In your first drawing you're losing  a lot of valuable space to corridor. 

[G and J]

That's what I was thinking.....just makes the approach to main bed more straight forward.....the corridor could be  either 'public' or part of the main bed eg. drawers/ dressing table/window seat?

[fandyman]

@ConorSee the house floor plan as is currently.

@G and J Good point with 'part of the main bedroom' suggestion. I like this approach a lot.

 

All in all, if well executed, do you think it wouldn't kill the value? I know think that as long as the new wide bay hallway serve a purpose  eg. drawers/ dressing table/window seat it could make the plan work. WDYT?

[garrymartin]

I'm with @G and J and @Conor with regards to using the bay window area as the access to a new master suite. I'd be inclined to see if you could lose a little more space in the existing bedroom so that you could run a wall of wardrobes opposite the bay window. It's currently shown as 1.37m - if you extended that by a mere 130mm you would have a 900mm corridor, and a 600mm deep bank of wardrobes. That way, your corridor becomes even more functional as a dressing room leading into your master suite. Depends on how close your existing bedroom door is to the stairs, but it might be possible. I would also look at differing arrangements of your master bed position, window position, and the ensuite "block" to create something that flows a little better and looks more pleasant visually.

 

 

[G and J]

3 minutes ago, garrymartin said:

and a 600mm deep bank of wardrobes. That way, your corridor becomes even more functional as a dressing room leading into your master suite.

Can't judge on value, but the above is also worth thinking about, can even get shallow wardrobes with rails the other way round...... maybe rather than on opposite side to bay, have shallow units either side and over......having said all that sometimes keeping simply and airy works....

 

Re the ensuite you could reduce the "intrusion" into the main bed by pushing it throughout the wall and using the return in the original room for a built in wardrobe and that way you could possibly still make use of some of original plumbing?

[fandyman]

Thanks for all the great ideas - I think this could work. Will now be checking other aspects of it including the lower floor as well.

Edited 10 hours ago by fandyman

[fandyman]

I guess you must have been thinking about a detail like the below @garrymartin:

 

 

 

In terms of the en suite @G and J I have actually made it even less intrusive with the above and also downstairs will have a relocated kitchen (new drainage through the front garden connecting to the existing as a new branch inside the existing chamber on the drive) so it should work all fine.

 

Edited 6 hours ago by fandyman