Barbara's tip: "If you have a hill in your backyard, try working with it instead of avoiding it. On this Hillside Hamlet, the slide mirrors the slope of the hill and provides much more interest."
Barbara's tip: "Add a variety of ways to get up and down from the upper levels. Keep the exits easy with a ramp, or add an innovative element like a rock climbing wall."
Barbara's tip: "Redwood is my favorite building material for all of our tree forts. It's strong, stands up to the weather, and takes color beautifully."
Barbara's tip: "A roof not only provides protection from rain and sun, but it also defines the upper play space better. I've found that as kids get older, they want a place to hang out that is higher off the ground."
Barbara's tip: "Kids love playhouses with doors and shutters that they can open and close a million times. We use sturdy hinges and leave a half-inch gap around the openings so little ones' fingers don't get pinched."
Barbara's tip: "When designing a treehouse, I prefer to not have the tree limbs go through the roof because it makes harder to waterproof. So when starting a project, I look for space for the roof first."