Thank you for the opportunity to work on your project, I enjoyed it very much.
In the following description, I'm going to explain the project briefly, as well as the thought process behind it.
First, I would like to point out that I've kept the demolitions and alterations to the internal walls to a minimum since I find that the current floor plan with minor changes meets your brief, and substantial improvements to that could only be achieved by a changing every single wall in the house, and I find this neither cost-effective nor worth your time.
External changes to the facade were not part of the brief, and there are certain restrictions to what you can do without a permit. To give the house a more modern vibe and to match the aesthetic of the exterior with the interior, the extension on the porch will contribute, and so could a simple change of color or the facade, and installation of new shutters. Vertical linear paneling (floor to ceiling) is an element used in the interior and would tie the two together if used as shutters on the outside of the house.
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Ground floor
On the ground floor, the floor plan layout is kept as was with a change of communications and access to the rooms. I'll now talk through the floor plan room by room.
Entrance hall/dining area
For the dining area I've considered placing it in the kitchen area, or to be precise in the extended part of the kitchen. What decided against it is limited space on occasions when you would like to host more people than your regular family. Also, it would mean less space for kitchen utilities. In regard to the entrance hall, the room you enter is too long and broken up by the kitchen entrance, staircase access, and hallway to work as a continuous lounge space and pit would be a waste of space to leave it only as an entrance hall. In this regard, the switch of the entrance door & window makes sense since it brings the dining area closer to the kitchen and leaves the communication from the entrance door towards all other functions open.
The dining area is visualized with 6 seats but can sit 8 people, and has the potential to be further extended if needed.
Kitchen
The kitchen is fully equipped and is organized in three parallel lines. Low elements towards the street with a view of the front yard from the sink, high elements in the back, and an island with cooking between.
The island continues further into the "glass box" with seating on both sides (4-6 people).
The kitchen is open with the possibility to close it when preferred with glass panels.
Lounge
The lounge is visually connected to the entrance and the dining area. It's furnished with an L-shape sofa and lounge chairs. The staircase is redesigned to feel more open and to achieve more natural light inside the now very dark and closed staircase.
This meant orienting the lounge to the opposite side of the room with a tv unit.
I had an idea to make the wall between the lounge and the study flexible, but I did not have time to discuss it with you and it would also be too indicative of what I'm proposing, I've decided to show the study access from the lounge but not open.
This would be a good option if you would like to use the downstairs lounge for family tv time and the one on the ground floor as an open conversation area. It would give you the possibility to have a larger lounge and study that is merged with it and close it if you need some quiet time to work.
Study
The study area is furnished with a bookshelf along the whole wall facing the lounge, a small reading nook, and a desk that seats two people by the window.
Bathroom
I've changed the position of the door to the shared bathroom to be easily accessible from the entrance and other shared spaces, but also to utilize the space better.
It's equipped with a large walk-in shower, double sink, toilet, and bidet.
Master bedroom
The entrance to the master bedroom has been altered too. It now makes the smaller bathroom an integral part of the master bedroom without making any significant changes to the walls.
As you enter the room a small built-in storage unit is placed on the left side and the entrance to the bathroom is on the right.
The room is furnished with a large built-in wardrobe, king size bed with side tables, and a vanity nook opposite the bed.
Master bathroom
There haven't been significant changes to the bathroom besides the redesign visible in the rendering image.
Bedroom 1
This bedroom is the bedroom for your daughter. To get maximal use of the space I've pushed the bed to the window and made a built-in wardrobe and desk along the wider side of the room. The bed is 120 cm wide.
(I had modeled the first option of the princess room as well but haven't had time to make the renderings, if it's something you are still in some way considering feel free to contact me to send you that option as well)
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-1 level
The boy's rooms have been positioned where there is more natural light. A corridor is placed between them to access the garage. This corridor is closed and considered an entrance to the house, and the open space is organized into a few separate nooks.
Lounge & open space
As you walked down the stairs the area by the stairs is a green corner with a small desk if you prefer to just do some work while still being involved in the family activities. The open space is divided into two areas in regard to the columns that shape the space. The fireplace is positioned by the column and everything is on the smaller side or it is lifted one step and is imagined as a reading space by the fire. The fireplace is visible from both sides.
the lower part of the lounge is more conventional with a sofa and lounge chair.
Bedrooms 2 & 3
The two bedrooms are very similar and they both have double beds since the boys are at the age when they probably prefer a room that is more an adult bedroom than a playroom.
The rooms are also furnished with built-in wardrobes, a tv unit, and a desk.
Bathroom & Laundry
The bathroom is similarly equipped to the one upstairs, and on the outside of the bathroom is the laundry area as a built-in wardrobe with a washer and dryer.
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The overall style and colors are following your instructions, and since there are a lot of custom built-in pieces I would be happy to provide you with drawings and specifications for them if you decide to go in this direction. Especially in the children's bedrooms where the bed is the only piece of furniture to be available in a shop.
I hope I've managed to explain everything. If you have any further questions feel free to contact me.