I interviewed nearly a dozen people this year who renovated or built their homes, and there are 3 common things they wish they had known going in

• I interviewed more than 10 people this year who have renovated or built their own homes.
• I asked every interviewee the same question: What do you wish you had done differently?

As Insider's real-estate reporter based in Singapore, I interviewed more than 10 people this year who have renovated or constructed their own homes. Some of them chose to DIY the projects, while others worked alongside professionals.

I asked every interviewee the same question: What do you wish you had done differently, or what do you wish you had known when you went in?

Here are the three most common things they told me.

1. Understanding of the amount of work required before starting the project

Many of those I spoke to said the scale of their projects turned out to be bigger than expected.

In particular, people who bought fixer-uppers often went in focused on cosmetic changes without realizing the amount of structural work that needed to be done.

A couple living in an 1840s Hudson Valley farmhouse, for example, told me their renovation process has never ended — even though they moved in 13 years ago. The couple has had to redo the roof, the foundation, and the septic system.

"We were too naive to understand how big a project it was. We thought we could just paint it and it would be fine," owner Kat O'Sullivan told me earlier this year.

2. Managing expectations about how much things cost

In June, I interviewed a Texas woman named Katy Krebs who turned a shed into a family home on a $16,000 budget. She told me the conversion was right within budget — but she was an exception.

Quite a few people I interviewed told me their renovations turned out to be much more expensive than they anticipated.

After all the structural work, O'Sullivan estimated the amount she spent renovating her Hudson Valley farmhouse was "much more than the house is worth."

One homeowner in the UK told me she spent close to £60,000 renovating an abandoned townhouse, only to run out of money to complete the job because she had been naive about the true cost of the renovations.

And then there's George Dunnett, the Scottish millennial who spent 11 months turning an abandoned cottage into a tiny home. He told me he tracked every single expense in an Excel sheet — and that the project ended up costing twice as much as had expected.

3. Knowing that living on-site can be tough

A few homeowners told me they lived on-site while their house was under renovation.

For financial reasons, O'Sullivan and her partner moved into their farmhouse before renovation started. They hung up tarps to protect themselves from the dust, and she told me that for years after, it felt like they were living in a never-ending construction project.

Another homeowner, Laura Genevieve, said she moved into her Spanish bungalow in LA with her family on the day they received their keys. For the first three weeks, they did not have a working bathroom.

It was also difficult to make dinner in the house while renovating the kitchen, Genevieve added: "Our whole kitchen was basically in the dining room and we just felt like we were camping for three months."

And a couple who built a tiny house in Portugal said they tried living on-site in their camper van as they worked on their house, only to find that the rainy December weather kept them from getting enough sunlight to power their solar panels.