Extra photos

if the question is how to connect the two building with a single roof? the most expensive options would be to add a whole new roof shape (the height of the roof would have to be raised to spread over a bigger area) then add a hip roof over the three building with an open breezeway in between..perfect in your climate with small verandahs to make up the places where the building don't align but, the most economical way to connect would be to replace the existing roof cladding with the same roof structure and add a "flat" roof over the gaps between the buildings and tucked under the existing eaves with roof sloping north and south and wrapped around teh north side of the donga in a very low angle using a low profile steel roofing like Trimdeck or similar and also consider a stepped deck to make it easier to walk around between the two spaces ..the collection of different heights of roof would retain the charm of the original building but you need to close in the gaps between the old eaves and new roof to discourage possums from moving in

I would do a simple enclosed walkway linking the two structures with windows both sides to let the breeze through. If you want the rooves to flow better you will need to restructure the two. By using windows you would tie the two buildings together by the cladding in the solid walls.

Ok yes thanks oklouise and Kate. I should have said that yes we are definitely getting a new joined roof.
Roof pro has suggested extending gable roof out from donga to line up with the laundry/ kitchen end of the house. See diagrams he drew up quickly to show his idea. Would end up with a covered area for a new deck on the north west corner of house. This will reduce light into the house but can include some skylights.
My question I would really like help with is how to reconfigure the layout of the 2 buildings to make the best use of space. Do you think we should try to fit 4 bedrooms? or 3 with a more spacious living areas and storage. Should we lift the floor of the current laundry and enclose it where it is or move it to the gap between the 2 buildings. Any ideas or opinions appreciated, thanking you in advance :)

Roof sketches

The roof looks way too complicated ( read expensive ) for what it would achieve IMO .

Both places need a new roof , and insurance is paying some ? The rear , more modern but more basic building is on piles ?

I'd get the rear place done , and sell it for removal , or sell as is and take the insurance $$$ if they would let you , and while doing the roof on the front house , which you have an emotional attachment to , expand that -- one roof line , one floor level , an inside laundry , and do whatever suits , or suits your budget .

A damaged or even repaired place won't be worth much , but even if insurance is paying , I assume they will only pay a fraction of this 'monsterous' new roof , and then a lot of the rest won't match up , and cost more . The only justification I can see would be you want to see where the 'original' house finishes , but if thats your motivation , just repair the 2 places and keep them seperate . Otherwise its always going to have some Frankenstein features , or you'll spend a fortune hiding stuff .

I don't understand your logic that if you are renting out the rear building in the future for a non-family member surely you should be trying to get the two structures more separate, rather than linking them together under one roof? If I was a tenant I would prefer to have my home as free-standing, and as individual to my landlord's home which is only a few metres away.

Best of luck with your thinking,

Dr Retro of Dr Retro House Calls/Dr Retro Virtual Visits

Ok so you want to end up with one large family home. Cost of new roof, matching the two structures and the different sidings., new floor to level. Etc
In the addition I would capitalise on the bathroom making a master suite on south side. Study and 2nd living needed. The laundry moves to the new section between the two buildings. Larger kitchen in the exisiting house..

Have you considered rotating the newer unit 90 degrees ? Without knowing where you are and costs , and even the extent of existing damage , it would make aligning the rooflines a lot easier , the doorways wouldn't point at each other , most existing external walls would still be external , you could place the 'newer' unit at a suitable distance to fit the laundry or another bedroom or 6 in between , etc .

I suspect the overall look would be better , and I also suspect the cost would be less than the proposed plan , so probably win/win .

Thanks all, its a humble home, just trying to work with what we have to make 1 family home. Floor of both buildings is at same level, ceiling height is different. Not bothered if it’s recognisably 2 buildings originally. Bedrooms in cottage are a good size but lounge kitchen dining area is very tight. Would love some help with how to configure the rooms. New master bed on south side sounds good with new laundry between bed 2 and bath. But leaves a long skinny area which I’m not sure how best to layout. As it’s all on stumps kitchen can easily be relocated. Rotating the newer part 90 degrees would have been a good idea when it was built.

When it was built , it was intended to be 2 seperate houses , so if it had been at 90 degrees , it would have been essentially living in each others pocket , so I understand why it was done like it is . The problem is trying to make it into one now .

Even so , I'd still be tempted to at least get a price ( and costings for power , water , etc under both 'schemes' ) just as a comparison .

the new roof looks ideal but the eaves over the south and west sides of the house may need to be deeper which may not be such a bad idea in tropical storms but my suggestion include using the "gap" for new laundry, new kitchen and meals area and rearranging the kitchen laundry allows more space in the cottage living areas and the new deck makes an outdoor dining area that can be shared or kept for use by occupants of the donga (with privacy controlled with screens across the sliding doors from the meals area) and i would retain the original oven space for a (gas?) fireplace

Thanks pottsy & oklouise that is very clever. Some great ideas and food for thought. Love idea to use oven space for fire.