Unexpected costs when renovating a house are unfortunately a fact of life. You really cannot know the true condition of your floors, walls, roof until they are revealed, and unless you have easy access this may not be until you start demolition. However there are also some sneaky unexpected costs that seem to pop up time and time again that you should keep in mind when planning your budget and discussing your project with your builder. 

Sneaky Unexpected Renovation Costs

Number 1 is asbestos. Widely used in building materials pre-1980’s including fibro sheeting, water, drainage and flue pipes, roof shingles and guttering, asbestos testing and removal can be an unexpected but necessary expense.

Damaged floor joists, beams, and structural framing. Once the floor coverings and wall linings are removed the condition of your house frame will be seen. You may need some remedial work to replace rot, termite damage, water damage, or just general structural repair due to movement over time or previous work not up to standard.

This also leads into foundations and underpinning! Renovation work could show that your building foundations need to be strengthened to last another 50 years….

Rising damp can also rear its head and require remediation. Damp course and sub-floor ventilation may require installation however it will improve the health of your home as well as the structural integrity of your new building works.

All of these cannot be seen in your final works however repair and remedial works are part and parcel of renovating an older home and ensuring your new bathroom, kitchen, living or bedroom space stay standing long into the future!

Other sneaky extra building costs that seem to pop up or be missed when budgeting include:

  • Appliances – ensure you costed these in as these can be a big expense.
  • Landscaping – pots, plants, paving, fencing, retaining walls, letterboxes, driveways, the list goes on. However it is the final ‘dressing’ of your home so well worth budgeting / saving for.
  • Rubbish removal – skip bins add up!
  • Small things; all those trips to Bunnings add up; sealant, hinges, door handles, primer, paint…I mean how many tubes of no more gaps or sika are needed?!!
  • Electrical – depending on your existing home and your requirements (new water heater or induction especially) you may need a mains upgrade, board upgrade, new private power pole…
  • Mis-calculation of materials; it happens. Generally this is my error when juggling kids and trying to get my head around sizes and I just add an extra ‘sheet’ or item while a kid screams and my brain fries. 
  • Replacing old drainage pipes – terracotta for PVC
  • TV Aerials – don’t forget these!

With old homes when renovating there will always be something unexpected that pops up and needs to be solved so ensure you have a contingency of at least 15% allowed for.

Just a few things that have come up in our current renovation and extension to our old farmhouse that have blown my budget have included a new roof over the entire house (building inspection stated it was fine, it wasn’t…). Putting the new roof on required us to raise and level an old extension to the house by 50mm and repair footings so the roofline was level. We had planned on this work in stage 2, however as the new roof was urgently needed this remedial work was brought forward. When the old roof was removed off the kitchen area the battens came off too….they just fell off!! So they required replacing. Then our gorgeous old solid hardwood trusses were a bit twisted so the builders packed them out to help give the illusion of the straight roofline from the road. The new roof looks stunning, and was needed, but all unbudgeted extra labour and materials that adds up.

unexpected building renovation costs new roof sydney
New Surfmist Custom Orb Colourbond roof being installed over both existing house and new extension.

My most important snippet of advice; take a step back and reassess. 

With old homes the remedial work can really eat into your budget, and if it is limited, may stop you in your tracks. Review what needs to be done; does it need to be done now? Does it affect your current works? I.e. will you need to remove works you are currently doing to repair, or will they be unaffected and can you stage the works and do the repair in 6mths, a year or more? Our roof could have affected the condition of ceilings and future structural integrity requiring a more $$$ fix in the future. As we already had a roofer on site to install the roof on the new extension it just made sense to do the whole house.

Happy renovating

Marissa x

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  1. Crown Relocations Interstate Removalists

    This is the best place to start and gather information before renovating! Thanks for this wonderful article Marissa! Renovation really is the one expense you can control. It is tempting to change your mind during the renovation process. And that’s not to say it isn’t sometimes necessary or what we really needed. However, it is very important to consider how those changes will impact your budget, and this article of yours is the best answer to it!

    I am so glad that I am able to stumble upon this post! Many thanks and and good luck! Cheers!