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suetheron_london

Heeelp!! Design advice for extension, it's blowing out

Souzette Lovell
4 years ago
last modified: 4 years ago

Hello Houzzers. If ever I need help from the creative Brains Trust, it's now!!

My small box extension needs urgent design help - particularly the performance under very hot summers. I need a simple way to have the original house and extension meet, so as to enable the extension to have a higher roof, without endangering the original house.

I've already demolished the derelict laundry at the back. The location faces west, on a hill with 1:7 slope. It also faces a potentially lovely garden on a deep site. I've already obtained second-hand bifold windows to take up the whole western elevation, so as to open up to the garden.

The simplest construction will be a 9m x 4.75m box with a portal frame structure. It needs to be self-supporting and not tied to the existing old 1927 house due to structural issues with the existing.

These are some issues and options:

  • due to the need to 'tuck' the new extension under the old roof, there's a big danger right now of creating an unpleasant heat-trap in summer if we follow the existing pitch (image option 1). This is the direction the Structural Engineer and architect are currently going......
  • Is there a relatively safe way to do an oversized box gutter between the two? (image option 2)
  • is there a more elegant simple way to divert any risk of water damage from the old house to the new extension (eg image option 3)
  • what do people think of - say - a 650mm wide reveal around the junctions between the old house and new extension (ie window and kitchen door) - would this put people off if I wanted to sell it, would it look 'weird' ??

My budget for all this to lockup stage is $20K only. Am I dreaming, should I just refurbish the existing remaining shell, and put a pergola up and forget about the third bedroom and living areas?

Thank you for any advice and opinions!!

ROOF JUNCTION

OPTION 1


DETAIL OF CONNECTION


ROOF JUNCTION

OPTION 2


ROOF JUNCTION

OPTION 3


here's the floorplan of the extension only just in case...

orientation West is facing bifolds


Thank You!!

Featured Answer
  • PRO
    MB Design & Drafting
    4 years ago

    Go with option 1.


    Use standard construction processes - skillion metal sheet roof over foil backed blanket. LVL rafters and timber frame walls which the carpenter will make on site. Probably go with a slab on ground and be aware of termite controls between new and existing. Excavate rear yard and build retaining walls with drainage behind them, probably also need a couple pits for surface water. Retaining walls constructed and engineered properly are expensive so be prepared. Treated pine sleepers are nowhere near a suitable solution once you're above 600mm.


    A builder or a carpenter would go through $20k in materials and some labour for plumbers, excavations, electrical, etc. Plans, documentation and council approvals will soak up $10k or thereabouts. Yes its a simple little job but it comes to economy of scale and some areas will cost the same or take the same amount of time as a larger project.

    • Comments (10)

    • bigreader
      4 years ago

      I don’t think you have enough money but I admire your efforts.

    • Souzette Lovell
      Original Author
      4 years ago

      I see that as a challenge BigReader :o)....... or I may just end up leaving the existing frame there rather than demolishing it, do a 'pergola' mounted on stirrups, and then add unofficial second-hand sliding doors (sell the beautiful bifolds). I could knock up a slab with a cement mixer, and get a decent result with plain old floor tiles. I can pull that off for $15K max

    • oklouise
      4 years ago

      i can't believe that there can be a successful result for $20,000 so why make a second best attempt?...if your professionals can't offer an affordable solution with all the available information and on site reality why not invest any remaining funds in a better finish for what you have already started

    • Sophie C.
      4 years ago

      Have you considered a hallway/corridor to link the old with the new? It can be light filled & then allow you to design your main extension as your heart & budget desires. A hallway/corridor can easily fit under the existing roofline & the main extension can have a different roof.

    • PRO
      3DA Design Drafting and 3D Visuals
      4 years ago

      I did my extension with oversized box gutter like in your option 2. No problem at all.
      The problem is the construction comes to well over 200k.

      I recommend getting some finance sorted first.

      My solution for box gutter is to make sure its a single sheet folded. I added 2 normal gutters just in case, and use an oversized rainwater head.

      see attached

    • Sophie C.
      4 years ago

      Souztette this is the sort of corridor I was referring to linking your original part of your home with your new extension. Some people do these in all glass, which helps to visually separate the old & the new as well. https://www.dezeen.com/2016/02/15/modo-architects-melbourne-tunnel-house-extension-australia/ --> This is a fancy architecturally designed place in Melbourne, so not that budget friendly perhaps, but it's more about the concept.

    • JE C
      4 years ago

      Souzette, I love your can do attitude. The answer may depend on how long you plan to live in the house and whether you can justify putting more money into it. ( sorry if you have alresdy covered that in one of your other posts. )Another option to consider following on from Sophie's - some of the 'pod' linked extensions are very reasonable and may work depending on your block - eg Atlas Living start at about $50 k . I know its more than you want to spend but may give you an acceptable outcome.

    • Souzette Lovell
      Original Author
      4 years ago

      Hi thanks for your positive comments and suggestions, and my apologies for muddying the waters with double postings - Ive been a little stressed out!

      • Sophie I love that corridor link idea by making a feature of it - choice of materials are excellent I get the concept.
      • 3DA - excellent idea to double-gutter over the box, thank you.
      • JE C - thanks for the link to Atlas. My best way to manage costs will be to get some degree of prefabrication off site - I'll investigate all options - granny flat kit, SIP panels, factory-made trusses, and residential garage/shed kit (thanks siriuskey).

      Getting to lock-up within budget is the goal - Im allowing $5K for footings etc on top of the amount mentioned above. It's only a 9m x 4.75m box after all! With some fancy guttering.

      Incidentally, has anyone been watching Kevin McClouds The Street on ABC iView lately? inspiring :-)

    • Kate
      4 years ago

      You need a price for the earthworks first. The drainage externally needs to be right.

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