One question -- Why ?

Suddenly , the doors and windows and possibly even the ceiling will feel all wrong , door frames ( with possible wiring issues etc ) probably needing raising , steps not lining up , and on and on .

And then it looks like you want to remove walls too , which I know may make doors less of a problem , but raises all kinds of other engineering issues . Personally I would give up at that point , because its sounding too close to demolishing and completely rebuilding that end of the house to me .

On a positive note , getting new tiles will be one of the least of your worries .

are the original dining, laundry and study bedroom a later addition with a different shaped roof to the rest of the house?? are all the ceiling heights the same or different in the rear rooms and what are the floors, walls and roof built out of?..some external photos and an aerial view of the roof would help.. and what is the length and width of the block, what is the distance from the house to all four boundaries, where is north and please describe your local climate ..changing the floor levels is not straightforward unless the rooms are already at least 2600 high or more... the drop down may have been done to allow enough headroom for an extension with a skillion roof separate to the main house??...you have shown a garage with plenty of space to one side of your block and it's much cheaper and easier to build at one level than adding upstairs but we need the dimensions of all the existing rooms and the extra information to be specific

I agree with Pottsy, matching existing tiles are the least of your challenges.

yes, separate toilet with a hand basin. This allows a multifunctional space.

I would also look to adding the new rooms at ground level to work with the dropped floor level, Tiles and timber marry very well

Thank you everyone your feedbacks.

Yes, Oklouise you are correct. The step down portion of the house (dining, laundry, and bedroom/study) looks like an extension to the house and currently has a flat sloping colorbond roof. Unlike the front portion of the house which has a traditional tiled roof. As we will be building the second level on top of that extension part. The sloping roof & ceiling will need to be removed and aligned with the other rooms of the house. I just did a measurement of the house now and have the following details:

1. Front portion of the house (Bedroom 1, Bedroom 2, Kitchen, Bathroom, Living room)

- Floor to Ceiling Height = 3m

2. Step Down Extension portion of the house (Bedroom 3/Study, Dining, Laundry)

- Floor to Ceiling (Highest Point) = 2.68m

- Floor to Ceiling (Lowest Point) = 2.28m

It's a single brick veneer house, on brick pillars. The walls are all plasterboards. And the previous owners have tiled the entire floors.

We're located in Sydney NSW near Parramatta, so it's not too humid or tropical.

I'm still looking and asking Why ?

based on the slope of the land and heights of original floors and ceilings it will be necessary to have stairs up from the garage and down to the backyard and the garage ceiling will need to be about 4m high or more to allow the master bedroom floor to be level with the upstairs rooms (do you need such a tall garage?) and, with 3m ceiling the stairs will need to be longer than shown in the plan...has you designer provided a view of the plans showing all the ground and new floor levels and ceiling heights?... and does the easement from your rear neighbour continue through your block allowing for at least 2m or more distance from the south boundary to the new garage?...the site plan doesn't include the distance from the house to the boundaries and how many bedrooms and study do you need/want as you will be horrified at the cost of such a big extension and may need to consider some changes

Pottsy99, two birds with one stone, two areas needing one new roof for both

Sirius , the rear ceiling is 2.7 metres , and the floor is 30cm LOWER than the rest . That means those ceilings drop by around 60cm . So those walls and ceiling have to be extended upwards , or demolished and start again . Then at the same time you have to lift that floor by 30cm , and all the windows and doors are 'funny' or unusable . So basically the rear is unusable in its present form .

The front has brick peaks , and a steepish roof , and I'm guessing roof trusses . So you remove the roof , remove bricks , remove the trusses which means you remove the ceilings . You then add wooden or steel beams , new downstairs ceilings , new upstairs floors , upstairs walls and trusses and ceiling , try and match claddings . In essence you are trying to kill 5 birds with 1 stone , so every bird would have to be exactly lined up .

When you are utilising maybe 25% of the finished build , you'd consider demo and rebuild , or sell and buy something that suits you better IMO .

You missed my point pottsy99

Obviously I did , and still am .

The rear is lower , it slopes , so you can't take the roof off , plonk another level on and throw a roof over it . Basically , 3/4 of the new design will be completely new , so reusing half a tiled floor or adding a new roof will be relatively minor considerations IMO .

To use the car equivalent , if you take a Lada stationwagon and put a Rolls Royce grille on it , it's not a Roller . So if you cut the back off it , weld on a Rolls Royce boot , its still not a Rolls . Pull out the motor and put in a Rolls Royce one and it still isn't . Add leather seats and it still aint . And by that stage , you've probably spent more than buying a Rolls .

You either start with a run-down Rolls that you got cheap , and do it up ; or you sell the Lada and buy a Rolls .

Hi Xuan, I have a 1950s house where I’m planning an extension. Part of my works will be knocking down an old laundry, porch and powder room that is a sloped roof old extension to the original house. I strongly suspect in your case you won’t be able to just take the roof off the old extension to add a second story . You’ll be looking at demolishing the whole old extension and rebuilding. You haven’t answered the question re your approximate budget. I realise it’s a personal question but there is a lot of advice here, some of it even good :). And for those of us who have been posting on Houzz for a while we’ve seen way too many designed plans that are unaffordable when they get to a builder. Better to find out now.

as usual there are numerous options but, aiming to minimize the conflict between the different levels for garage and master suite and predicting that you will probably have to rebuild the whole rear section and need much more space for a stairwell to reach a 3m ceiling my suggestions has the whole upstairs above the original foot print without any rooms above the garage and, if you don't need 4 complete bathrooms, there's an opportunity to improve the kitchen and pantry if you would consider rearranging the kitchen and plan new floor coverings and i suggest that the increased laundry and a bigger deck would be more suitable to such a big house

OKL, if your program can crank it out what square meterage does your upstairs addition and rebuilt downstairs come to?

total downstairs floor area is 172 sqm (including 48sqm for new garage and mudroom) and my suggested upstairs is 134sqm (original upstairs plan was about 147sqm)

Thanks everyone for taking the time on a public holiday to provide such valuable insights and advice.

A lot of what you're saying makes sense. @potty99 I guess the cost of re-tiling is probably the least of our concerns now :)

We're still in the process of waiting for the builder(s) to provide us a preliminary quote based on the concept plans. Our budget will be around the $300K - $350K range.

From that perspective all of your inputs will allow us to make a few adjustments to align with this.

@oklouise We'll be keeping the kitchen as it, considering it's still very new and functional. Unfortunately with the upper level, as we're going through CDC, there's an 8 meter setback from the rear fence. Hence the dimensions of the upper level (11.7m x 8.51m) will be slightly smaller than downstairs. And we don't think we would need a 2nd bathroom downstairs. It could serve better as a storage space. In saying that your plans look very functional with respect to usage of space and flow. It's just more logical. Also thanks for pointing out the 4m garage height, it wasn't something that we were aware of, we'll take into consideration when speaking to builders.

Another thought, to try and involve the new garage with your extension by dropping the new rooms down to the garage level with adjustments for the slope with the Master suite it could all be done with a Skillon metal roof. I prefer a family room being level with the exterior It helps expand your living space

I have just defined the new ground level extension showing it within the dotted lines. There's a front side door access into the garage which will give direct access to the family room without having to enter via the front door. The front door will be great for visiting clients giving them direct access to your office/bedroom. without intruding into family spaces

This new extension has a choice of roof styles for you to consider but suggest that it is done with metal

Are you considering a future pool?

I’m glad you’re talking to builders. Your original upstairs plan was 147sqm. Conservatively for Sydney and an upstairs addition ignoring all other cost and there are quite a few you’re starting at $3k x147 -$441,000 construction at a bare minimum. You have an easy access block but you need allow to another $10k for demo. I’m not sure what you pay for rubbish removal in Sydney but I can imagine it’s cheap. You’re also touching nearly every room in the original house with shifting windows so about $40k for that work. Plus the deck and downstairs work. Will you need upgrade the electricals? Have you had a professional assess the footings of the original house to check if a second story is possible? Hopefully a good builder will give you good news but I think you’re planning too much for your budget. Good luck and enjoy the process.

• should be can’t imagine it’s cheap.

one way to avoid some of the extra expense and problems of building on top of the existing house with the different ceiling and floor levels would be to consider building the rumpus downstairs at the same level as the garage with bedrooms above the garage and rumpus the stairs would lead up from garage/rumpus level to the dining room at original floor levels and then continue to the upstairs levels ie (depending on accurate floor and ground levels) the bedrooms are half flight up and garage is half flight down from the dining room and, with any luck, the new roof will almost line up with the height of the original roof... you can add the raised floor in the new family room laundry and pantry and keep the original laundry as a utility space at ground level with a new raised skillion roof over the new raised family room, pantry and new laundry instead of attempting to raise the old laundry

this arrangement should be much easier, quicker and cheaper to achieve than having to change the original roof although it would be a great opportunity to replace the old tiles with new steel roofing...this suggestion includes about 158sqm (plus decks) compared to the original reno that is about 195 sq m

I had a similar idea to your one oklouise , of building above the new garage , but I had a couple of alternative tweaks -- I wondered about coming 'forward' with the garage and upstairs , thereby having the upstairs front rooms closer to the street . The one slight problem I can see with your plan is that the dining area could be a dark area -- by coming 'forward' you keep an extra window on the downstairs side profile .

The problem with that suggestion though , is that the roof may look funny , with a lower centred peak and then an upper one , so I then wondered about still going above the garage , but having the upstairs wider in profile , effectively 'stepping' 3 metres or so over the 'old' house , effectively removing that 'corner' of the existing roof and having a floor above instead of roof trusses , and have the existing roof butt up to the new upstairs side wall -- it would look more balanced IMO , you won't need to remove all the existing roof and strengthen it -- by utilising the existing brick walls it may not need any additional strengthening ? By tying the existing roof trusses to the new side wall it won't need too much strengthening either . It should also look a lot less like an add-on if the styles and materials are matched correctly IMO .

with the right CAD equipment and local dimensions it would be useful for xuan to try various options to see what roof and building shape works best...i suspect that with the slope of the block and the height of the original ceilings and steep roof pitch that a standard 2400 ceiling double storey extension could be made to work much better than replacing the whole roof structure and the site plan does look like there could be a little extra space to build closer to the street but the critical point is the location of the stairs and a roof window would improve the brightness in the dining room

I should add that with the new master suite being dropped down, the kids rumpus/study should be able to have highlight windows on the Western wall which will provide great extra light and winter sun, the eaves should protect them from summer sun

I know we shouldn't assume , but if the side wall is brick too , adding windows is more difficult .

Maybe I just like easy , but right from the start I would have been investigating knocking down , or selling and moving .

For me it is an unattractive home to start with, I'm trying to work out what era it is or is trying to be. So hopefully with all the money being spent on the extension that the facade is also being thought about.

We're definitely going to have to re-wire the electrical, as it's just not up to safety standards.

And with the reno, it makes sense to do it collectively.

As we're not planning for a pool. There isn't a concern about extending rooms in the backyard.

So the designs that @siruskey and @oklouise suggested could definitely be an option.

Plus @bigreader's estimates on costs puts things into perspective.

But we were originally thinking that adding a second level would add more value in the future if we sell the house, since the area demographic is young family moving in so having a backyard might be ideal.

Thanks everyone. There are so many helpful suggestions and inputs here.

We're still at the very early stages, so it's given us some great direction.

Shall keep everyone posted on how we go once we talk to a few builders :)

Hi Xuan, the Buildher Collective are doing a podcast this week with a topic of the costs of an upstairs extension versus a downstairs extension. I thought I’d you when I saw their Instagram post. The also have a lot of other information you might find handy. Their primary audience is women but the information is valuable for everyone

https://buildhercollective.com.au/

Thank you bigreader, I’ll check it out.