A variety of ways. When we first moved in we realized the roof leaked. A lot. In about a dozen different places that we could see. We paid about 50% of the roof replacement in cash and then put the rest of it on a 0% interest credit card for 14 months, paid the minimum for 14 months then paid it off.

We got a mass save energy audit which allowed us to access a HEAT loan, which is a $25k loan, paid back over 7 years with 0% interest to upgrade our heating system.

Those are the only two things we've used to finance.

Big However. We also both got promotions with 10-12% salary increases shortly after we closed. Being double income, no kids, with only a $1700 payment allowed us to save a lot over about 2 years. It's only in the last 2 months that we upgraded the heating systems and added solar (used the heat loan and paid cash for everything else, but we'll get about $37k back from rebates and tax credits). There's been other things we've done that combined is $$$ but that's been spread out over the last two years so doesn't feel like $$$.

You can get a mortgage that includes money for renovations, so it’s one payment lumped into your mortgage. Like the Fannie Mae HomeStyle Removation mortgage for example. Or an FHA 203k loan is for first time home buyers that includes reno, though there’s a lot of hoops you have to jump through for those since it’s a government program and needs HUD approval