Emily Henderson just revealed her shocking hidden remodel costs – I've done two renovations, and these are the most surprising costs I also didn't see coming

After watching designer Emily Henderson's candid new video on the surprising costs of a renovation, I finally felt seen. Having tackled two full-scale remodels myself, I know all too well the cost (financially and emotionally) of those unexpected budget-blowers.

From surprise damp to under-budgeted finishing touches, renovating a house often costs a lot more than you think. But why does no one talk about these hidden renovation ideas until you’re in the thick of it?

Inspired by Emily Henderson, from my own lived experience to the lessons learned by my team, I'm sharing our list of unexpected ways your budgets might balloon, where to spend and where to save in a home renovation, and what we wish we knew from the start.

Whether you're mid-remodel, planning your first renovation, or simply renovation-curious, this is the reality check I wish I had before I ever swung a sledgehammer.

Going into both of my renovations, I had spreadsheets, plenty of quotes, and a little contingency fund. I thought I was being sensible. But as I’ve learned (the hard way), your “budget” is rarely what you actually end up spending. You can have every item or tradesperson accounted for, but all it takes is one structural issue, a change in scope, or an unavailable material to throw everything off track.

And I can't blame that all on my 100+ year old house, even new builds have surprises.

Of course, we all know that remodeling is expensive. You'll likely have to fork out a small fortune on things like electrics, plumbing, heating, and any structural changes. But more often than not, you'll come across some rather surprising areas that cost you lot more than you anticipated.

While I wouldn’t change the end result of either of my remodels, I would go into it now with clearer eyes and more realistic expectations. Emily's video is a must-watch for anyone planning a project, not because it’ll scare you off, but because it gives a realistic picture on those hidden jobs that surprise you with their price tag. Here are just a few of the ones we, and Emily, have come up against.

Hidden renovation costs to know about

1. Painting and decorating

Painting and decorating is a somewhat divisive topic among renovators. Of course, interior designers and color experts will urge you to get the professionals in to do your final finishes like paint ideas or wallpaper ideas.

The other argument is that if you put enough time, care, and effort in this is one of those jobs that people like to DIY in order to save money. Which is exactly the camp I fell into, as chief painter at our home. And while I've spent many a day crying into a paint roller, it has saved us a lot of cash.

For those looking to go down the professional route, Emily Henderson warns that her exterior painting on her renovation cost between $20,000 and $100,000. Ouch. To give you an idea of indoor costs, I've had quotes to wallpaper our tiny entryway of $1,000-$1,5000 in a simple stripe (and that's just the labour cost), and having just our stairs repainted cost $1,500. So I'd also recommend keeping back a chunk of money for the finishing touches like paint, wallpaper, woodwork, and paneling.

2. Damp treatment

A recurring theme among our editors was having to tackle damp (and therefore, common types of household mold) problems in their properties.

'We moved forward a freestanding cabinet in our first home to paint and found creeping mold between the baseboard and the lower area of the wall,' explains head of solved, Punteha van Terheyden. 'It needed some mold remediation work to get to the bottom of, otherwise the mold would have spread/come through the new paint! We made sure to have a moisture channel in that spot thereafter!'

Similarly, content editor Chiana Dickson struggled with mold in her small kitchen. 'No matter what we tried, the problem always came back, growing on the walls and inside cabinets – even on some one our cookware. We initially installed constant running extractor fans, but they didn't help. In the end, we discovered that one of the walls was leaking water from outside,' she explains.

'The initial plan was to remove one wall of cabinets, remove the plaster, dry everything out, tank it, and replaster before putting everything back. However, what started as a one-week task turned into ripping out the entire kitchen, digging up the whole floor to relay the foundations, tanking and replastering the whole room, and fitting a whole new kitchen as there was no moisture barrier – water was getting in everywhere. It took over a month and a half in the end and cost tens of thousands.'

3. External structures

When it came to our garden makeover, similarly to Emily, I was taken aback by the costs outdoors. We live in a hilly area, so the back of our garden slopes upward, meaning we've had to dig right down to create flat areas like the patio and lawn, which are separated by brick steps.

Quotes were much higher than we expected for levelling and laying turf, so to be able to spread our modest landscaping budget further, my husband spent every weekend of last summer building his own brick steps – which are pretty impressive for a first-time bricklayer. Meanwhile, in her video, Emily shows just four cement steps in her garden that cost a whopping $10,000.

She also goes on to explain that you're going to want to budget between $15,000 - $50,000 for a driveway makeover (depending on size) and around $3,000+ for garden fences, which is a job we're yet to tackle but is one on the list that I am certainly not looking forward to paying for.

4. Waste removal

Unfortunately, in the 'first fix' stage of a reno you're going to have to prioritize a few rather boring things over pretty finishes before you can get to selecting soft furnishings and decor. Sure, it’s tempting to splurge on your dream sconces now, but fixing bad wiring or leveling the floor is money better spent. Start with the bones, and the beauty will follow.

One of the biggest shocks for us was waste removal. It can be hard to get rid of all the construction mess and dumpsters are expensive to hire, generally costing about $250-$350 for a 10-yard and $300-$700 for a 20-yard depending on your area.

As with everything, I always recommend getting three estimates or quotes at a minimum as the price range can be significant.

5. Bespoke tiling

In the entryway to our Edwardian home, I had a vision of beautiful mosaic-style ceramic tile for the hallway, but the quotes were coming back about $4,000 for an extremely small area, similar to the image above.

And while I expected this to be a bit of an investment (especially as it needed to be custom-designed to fit the pattern into the space perfectly), I didn't expect that much. In a bit of a recurring theme here, we bought the tiles and set about DIY-ing it ourselves. The result is exactly as I'd envisioned, cost a third of the price, and it only took about 8 more weeks than the professionals would've needed...

These micro-decisions feel small at the time, but they can add up to cost you thousands more. If you kept justifying things because they were ‘only’ a few hundred dollars, suddenly you've overspent by a vast amount. Renovation math rarely adds up the way you think it will.

6. Replacing doors

Back to Emily, in her video, she explains that replacing all of the internal doors in her home cost around $100+ each, while the framing is an additional cost on top of that.

Our head of interiors Hebe Hatton faced the same issue. She explains, 'When I moved into my period apartment, a lot of the original features had been stripped out. The doors were cheap wood and gave zero charm to the space, and with it being relatively small, you really noticed them. I had a vision of thrifting some beautiful old doors that would have been in the apartment originally and hanging them in place myself. I did the first part, found the doors, and then realized hanging doors is not a job for a DIY novice...'

'So I brought in the professionals, and since the doors were a steal, I was willing to pay for them to do the job. When they saw the doors and tried to put them in place, they very kindly let me know there was no way these old doors would hold up to the job,' she explains. 'They recommended I buy new doors – a hidden expense I did not envision – and they would come and do the surprisingly big job of fitting 4 doors. The result is lovely and does make a big difference to the space, but this went from what I thought would be a DIY that cost a couple $100 max, to a huge job that cost over $500.'

We also replaced all the doors in our home, but managed to get them second-hand from a neighbour who was stripping out her solid teak doors for something more modern. The warm wood and slight rustic nature was what made me fall in love with them. One man's trash is another man's treasure, as they say.

The hard truth is, renovation sticker shock is almost inevitable. No matter how much you budget, always expect to spend 20 to 30 percent more, and be sure to have a contingency budget to fall back on. There are always surprises behind the walls or under the floorboards – especially in older homes – but if you plan well and take things one step at a time, you can hope to avoid expensive home renovation mistakes.

And if you're looking for some money saving tips before renovating, check out our dedicated feature.