How disruptive is it to replace a window with a smaller window?

[Housingdestressnotdistress]

trying to redesign a small kitchen. two of the walls are take up by large windows and there are two doors so storage is difficult. If the side window was 30cm smaller, we could build in a decent larder/ pantry cupboard (80cm wide).

how messy/ expensive/ difficult is it to do?

You would need a very good bricklayer and matching bricks, if you have those it's achievable

You have to enlarge the opening and then you can rebuild it with the new bricks (assuming you have a brick and block wall) laid to tie in (physically interlocked I mean not just aesthetically) with the rest of the wall. (Use acro prop to hold lintel up while you do it)
Then put in any cold bridge insulation or other insulation as suits. Put in new window and make the plaster and decor good again.

Not a massive job and any decent builder should be able to do it.

Thanks both. Is it an expensive job? And will they normally ‘refill’ the cavity wall?

Does it require building reg. sign off?

You could put shelving across the window, less disruptive and less permanent(and cheaper). I have shelves across a narrow second window in a study, the light still filters through. They are in front of the window and they are resting on pegs so the window can be cleaned.

@Allthegoodnamesarechosen that sounds interesting. What do you store on them? How did you make them? What sort of pegs?

We did ours as part of a larger job so can't say about isolated expense or sign off sorry. Is the window getting smaller? Don't underestimate hassle of matching bricks I would say it wasn't that straightforward for us, depends on how absolutely seamless it needs to be I think....

Don't know about price, cost of window + materials and labour which can vary quite a bit from one area to another. You'd have to get some quotes and go from there.

I wouldn't have thought it would need sign off unless you're altering a window which is a fire exit in emergency. A quick call to your council building regs dept would answer that.
You're making it narrower not wider so existing lintel will be structurally plenty of support.
Are you in a conservation area where house appearance matters?