As the host (and contractor-in-chief) on home-redo shows like DIY Network’s “Sweat Equity” and “This New House,” Amy Matthews knows her sledgehammers from her stud finders. Her new HGTV show, “Renovation Raiders” (Thursdays at 9 p.m.), follows her and her crew as they spring kitchen and basement rehabs on unsuspecting homeowners.

On the show, you conspire with spouses or other family members to redo rooms. Do people like to be surprised?
Well, we always do it with the permission of at least one other person who owns the home. But the people we spring these projects on are often in shock, because we go into these homes and, in a very short time, do these mind-blowing things.

What’s the biggest challenge for people going through an ordinary renovation?
I always joke that rehabs are like marriage therapy and project planning rolled into one. You have to manage your expectations and be very organized.

What’s the most common mistake DIY newbies make?
People think they can do a huge project in one weekend. But you really have to prep! And it usually takes a homeowner three times as long to do, say, a tiling job as it would a professional.

So when does it make financial sense to hire a pro?
First, factor in what your time is worth, and then the costs to buy or rent tools. Weigh those things versus what you’d pay a pro, and you’ll have your answer.

How do you know when it’s time to redo, say, your bathroom?
It depends on the house. A lot of houses have been restored so poorly that they don’t have a long shelf life. To give a project staying power, choose classic materials and quality.

And say I live in a historic home — are there different rules for rehabbing it?
If your home is architecturally or historically interesting, your rehabs really should stick to the era of the house. Stay away from kitschy, trendy materials.

If I want to hire someone to redo some tile or install a light, how do I find someone good?
Go based on a referral, a personal connection or an online service like Homeadvisor.com [sort of like an Angie’s List for home pros]. Then get three quotes. Then hire someone based on your gut, keeping in mind that, if it’s a big project, this person will be in your house all the time.

What’s the hardest project you’ve done?
My own basement! I’m so picky I can’t back off, and I do things I tell other people not to do. But at least that way I can feel their pain.