SUCH A STRETCH

This is such a stretch...but it's driving me NUTS - I remember a book from way back when I was maybe 10 (same time I was reading Ramona books and stuff like that). I read this book ALL the time when I was little and cannot remember the name!!!

The cover of the book was an old yellow house with all kids faces peeking out of the windows. The word Key was in the title, and the story was something about these kids (I think it was a family) in this old house and it was sort of a treasure hunt - notes in the walls, stuff like that.

Can anybody help?

I think I found it!!!! Key to the Treasure by Peggy Parish! Just ordered it on amazon. I hope that's it!