Not the OP, but my family has a bunch of Danish teak furniture, as does my mom. The sofas are not super heavy. Cushions on a frame. You can see under it. Now, there's no bed inside. My mom's was re-upholstered once. Ours isn't old enough for that yet. We've re-upholstered the dining chairs a couple of times.

As for other pieces of furniture, e.g., cabinets and stuff, we bought them used from a place that combed estate sales in Denmark for furniture and sold it in the US. One attraction is that the old furniture is smaller, so it works in a smaller house.