A substantial house lot that included this location was granted to Ipswich founder John Winthrop Jr. in 1633. The east side of the present house was constructed in 1711 by Col. John Wainwright, and the west side was added at the end of the 18th Century, featuring fine Georgian paneling and Rumford fireplaces. The rear ell was constructed during that time frame, but has a massive fireplace, chimney and summer beam that may date to the late 17th Century, when a house on this lot was owned by Nathaniel Treadwell. A reused summer beam in the basement has mortises for tusk tenons, which have been observed only in a couple of houses dating to the mid 1600s. This private home has a preservation agreement with the Ipswich Historical Commission. Read more about the Wainwright-Treadwell house at the Historic Ipswich site.
Ipswich Visitor Center 
What’s the detail on that rear ell summer beam? Photo?
thanks
I don’t have a photo of the re-used beam in the rear ell, but as I recall it’s dimensions are quite wide and tall, and it’s unchamfered. I don’t recall if it has mortises. The ell modernized inside, with the beam exposed in the middle of a cathedral ceiling. I will ask the owners for a photo and will post it to the site.
That Swett-Ilsley fireplace dates to ca. 1720 according to Historic New England
My husband an I lived in this house for seven years and we
loved it! Thank you for your information!