subject to correct measurements my suggestion includes extending the kitchen into the old laundry and creates a new laundry next to the study with hallway access for a re-arranged bathroom but we need correct measurements to identify positions of existing toilet, taps and sinks to be more precise.Does the existing laundry have external access? do you want/need external access for a new laundry? do you want the kitchen to be open to the living and family rooms or would you prefer separate rooms? is the under stairs space already being used for walk through storage? what about access to the garage from the front entry?.....with correct internal wall measurements we could make more specific suggestions but your plans don't show or we can't see details of existing rooms

correct measurements are the only answer...for your new floorplan you need a room (without any restrictions that would measure at least 2400mm x 2000...it's always possible to squeeze in some minor variations but only if it's worth the cost in convenience, improved value of the property and actual cash outlay.... the front door entry foyer would be lost, the new bathroom doorway wastes more space, the linen cupboards would be too narrow for anything except a few towels and sheets (that can easily be stored in a suitable vanity or bedroom cupboard) the bathtub is gone and you would have spent about $20,000 for a bathroom that is not better than what's already there?? ...the computer programs that we use are called 3D Home Architect and my version 4 is no longer available to buy but i believe siriuskey may have purchased her version recently? these programs do make the plans much easier to see but you must start with accurate measurements and an understanding of spaces needed ...start with a space about 800 x 800 mm for a toilet, 900 x 900mm for a basic shower, 500 x 900 for a single handbasin 1500 x 500 for a double handbasin then add in at least 900 x 900 for a doorway (including space for the frame and space to walk through...same for cavity sliders!) and then you'll need space to walk around in front of the toilet and shower and handbasins ......unfortunately with the plumbing and space restrictions i don't believe it's possible to do more than widen the existing shower space by rearranging the entry wall.(NB you'll still need to spend $5000 to $10,000 for demolition, carpentry, new waterproofing, tiles, shower, vanities wall cabinet, taps, plumbing etc..forget the linen cabinet and store linen in a new vanity and toiletries in a wall hung mirror doored cabinet and keep some width in the entry foyer (minimu 1200 wide) ...removing some of the non structural wall in the kitchen should be the cheapest improvement for the kitchen and add space for a small breakfast bar but removing the end counter would lose valuable counter space that could also be used for a pantry ...before making any decision you need to think about the reason for the changes...are the bathroom, laundry and kitchen in need of immediate repair, is the unit for your own use of needing improvements for rental or resale...?? always happy to draw up your plans but have to nag again about the accurate measurements...try measuring each separate room (ie shower, toilet and vanity, laundry and storage from wall to opposite wall in several places in both directions, ignoring all the fittings but include separate measurement of the diameter of the hot water heater.

Thanks all for the wonderful comments. Ive made some redesign, and taken lots of points from you all. Big Reader: agree to have some window/lights on southern wall of mud corridor to allow light through. clerestory is a great idea Nik Star: Your suggestion make practical sense about having a dropzone once when I walk through. Ive moved that, move the coat hook/bench with below seat drawers north of it, and added a small cabinet for hooks. Ive made a deep shoe cabinet on the east side where dropzone used to be. this keeps it in all one area. OkLouise: Thanks for big advice on laundry: I know now where to put laundry baskets, and have added in that extra linen cabinet. I might just access the whole understairs from the stairwell entrance instead. The southern bench space Ill keep now: can use to drop groceries and maybe could provision space for a future wide fridge, and great idea to make bench with open knee space underneath so can be a work area. Girlguides: Ive move the tough slight so can have elbow room on either side. I have a feeling the builder would want to keep plumbing/drainage of sink/WM close together. Ive attached the next iteration. Thank you. MB

Thanks siriuskey for your design and comments. A bit of background would no doubt be useful, so apologies for this late addition to the discussion. The house will accommodate a reasonably fit and active retired couple in their 60s (us!). We have elderly Mums and expect that 1 of them will end up moving into the guest room/study (hence the desire to have a connection between this room and a shower/WC). We'd also like to be able to access the backyard and have visitors able to access the WC - although we accept that at times we can't have everything...although it's worth a shot! We've struggled with the layout of this space for some time now and picked our builder's brains, but so far no-one has been able to come up with a solution. Both oklouise and you prove that other options are out there.