It’s a great idea,
@obeat.
Structural:
I would try to make the area as big as you can. If you or one of your parents becomes confined to it, you will be grateful for any space you manage to get in there.
A carer will need somewhere to put things before coming into the bedroom. A little staging area outside the bedroom would be useful, where they can set down a tray, leave jugs of water, leave/collect laundry etc. It will make things much easier for the carer and much nicer for the person in the bedroom (especially if sensitive to noise etc). Even a narrow shelf goes a long way. If you have room, a sink, mini-fridge and kettle might be very useful.
I always wish my bedroom, which is downstairs, had a door to the outside. If it’s possible for the downstairs bedroom to have a door/sliding door to the outside, that would be amazing. Not essential though.
A window looking onto some nature rather than a wall if possible. Nature can also be arranged after building.
Think about ventilation. If it’s possible to have a window on either side of the extension so that you can get a cross-breeze through to air the place really well, that would be ideal. That matters during heatwaves, if you can rarely open a window because of noise, if someone is incontinent etc.
I can actually get a cross-breeze by opening the ensuite window and propping the ensuite door open when the bedroom window is open. It’s amazing what a difference it makes compared to just opening one or other window.
Think about how it will be during very hot weather. Consider ways to prevent excessive heat entering like careful window placement, exterior shutters (this will affect window choice), solar glass, brise-soleil, and ways to deal with it like air conditioning. Having your contractor do this now will be infinitely easier and more effective than trying to do it after the fact.
As
@Trish says, wide doorways. Really wide. Don’t just do the minimum 90cm. Go as wide as you can. Even if you’re skinny, wheelchairs are not, even the narrow ones, and they’re hard to steer. Walkers/rollators etc need room too. Make your life easier.
Similarly, any corridor needs to be wide.
Ramps need space. If there’s just a small height difference between the extension and the ground outside, it will be nice and short. If there are actually a few steps, you’d be amazed how long the ramp needs to be. So minimise that height difference to minimise the ramp length.
Handrail(s) on the ramp.
A roof that won’t leak. Particularly important if it’s a flat roof. A former neighbour did an extension with a flat roof and it was leaking within a year. Make sure you have a good contractor who really knows how to do the roof right.
Hooked up to main house smoke alarm, or equivalent.
Interior:
A very good fan in the wet room.
Little grab rails everywhere in the wet room, even if none of you need them now. I find the most useful one is right up by the shower. (I can give you exact measurements of where it is in relation to shower head and shower stool if you like!) At least one by the toilet. Have these in the plan so that the builder knows to reinforce those areas, so that when you grab the grab rail the whole wall doesn’t come down.
You might want a raised toilet if the person using it will have difficulty getting up from seated position.
A wall-hung sink, so that you can sit at the sink. Also makes cleaning a lot easier.
Storage in the bathroom, e.g. a wall-hung cabinet, so that the carer isn’t constantly running around getting toilet roll, shampoo etc. Always go for more storage than you think, but don’t let it take up space on the floor which will be needed for medical equipment.
Hooks. More than you think. Towel rails (can be long grab rails). More than you think. Anticipate accidents where you might need to hang things to dry.
Wall-hung shelves and cabinets can be very handy in a small space where you need the floor to be free.
If mobility is already a problem, consider handrails where there is no furniture to hang onto. If you can't bear the idea of that, think of deep panelling that has a little lip at the top that you can kind of lean on.
Blackout blinds and/or curtains, motorised if financially possible, so that you can operate them by remote control and/or from your phone.
As
@Trish said, comfortable door handles. I got this one and it’s very comfy. No sharp edges to hurt hands or hips.
https://www.m-marcus.com/product-details/COL1762-SB.aspx
