I have a Federation California Bungalow style house in Inner west Sydney and I'm thinking of either extent or add a level to the back section. The internal and external wall are structural double or single brick.
I would like some advice on the (desktop) comparative cost (structural part) and difficulty in both options.
Option 1.


  1. Knock out most internal walls and add extra 3.8 x 3.5 sq metres of floor area
  2. New gable roof to cover 10.5m x 8.5m of floor space



Option 2.


  1. Knock out all internal walls
  2. Add 1st floor: approximately 6m x 6m
  3. New gable roof to cover 1st floor 6m x 6m ; new flat roof to cover existing ground 4m x 5m.


Due to council regulations, the 1st floor needs to be 1.5m and 0.6m from existing side walls. I plan to place 3 x 8.5m main beams (organ in the pic) and 4 shorter beams for 1st floor wall frame.
I joist for floor joist.

For both options, I intent to use colourbond roof with sarking.

Questions:


  1. Can LVL or Glulam span 8.5m or steel beams are needed ?





  1. For external cladding, I intent to use Hebel or colourbond. For Hebel, cement rendering and painting is required, is the additional cost significant? What are the pros and cons in terms of cost, durability and maintenance?





  1. Is the walls able to handle the additional load ? I suspect the walls are sitting on footings 400mm deep.





  1. What is the ballpark cost to weather-in the 1st floor ? I heard figures of $1k per square metre.





  1. Option 1 Extension require around 6 metres of new footing + wall and a larger span roof. Is the cost difference between Extension and Addition insignificant ?


Thanks
Attached Images




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