Dismantling the Pennell Ell

 

Pennell Ell Frame

Pennell Ell Frame

Over this long spring, we’ve been so elbow deep at the Pennell project in Brunswick that I’ve been remiss in writing about it. The James Pennell House, on Pennellville rd., is a two-story Greek Revival house built in 1838. It is a high-style home, with the later addition of cupola and ell. The project is a collaboration with Taggart Construction, which specializes in green building, and the architect Elizabeth Newman. PTF was hired to repair extensive damage to the timber frame, and we are glad for the opportunity to work on another project that combines historic preservation and high performance energy efficiency.

Another post, with a wedged half dovetail

Another post, with a wedged half dovetail

After an initial assessment, our first step was to document, tag and dismantle the attached cape ell.  The damage to the ell, and to the undercarriage of the house it was attached to, led to the conclusion that the ell would be most efficiently repaired on the bench.

Ell, being prepared for crane day

Ell, being prepared for crane day

Bent 2 post-tie connection, wedge removed, note original label

Bent 2 post-tie connection, wedge removed, note original label, “2 East,” written in crayon

Both the house and ell reflect later developments in timber frame design. Regular readers of this blog will recognize the drop tie secured with a wedged half dovetail like the one found in the carpenter’s shop.  Unlike the carpenter’s shop, however, the eave walls are studded, rather than framed with horizontal nailers.

Gable end, note rafter-plate connection

Gable end, note rafter-plate connection

The undercarriage was badly rotted and required complete replacement, in addition to the repair of a couple post feet and replacement of two tie beams. The plates, however, were full length, 32′ and in good condition. The rafters had a birdsmouth at the foot which fit into a rabbet cut along the interior edge of the plate.

Crane removal of full-length plate

Crane removal of full-length plate

Crane day went smoothly, largely due to our ability to dismantle the purlins and rafters by hand the afternoon beforehand. The purlins were full length, but thin, and could be slid down the rafters and lowered to the ground on ropes.  The rafters were short and could be reached by a pick that was laid across the tie beams.

Butterfly bolt detail, wedged end inside ell

Butterfly bolt detail, wedged end inside ell

The most unusual feature of the frame was the hardware connecting the ell to the main house frame. The ell’s bent one tie beam was bolted to an eave girt in the main house and one of the ell rafters was bolted sequentially to the adjacent studs on the house’s second floor. The hardware was an older style, consisting of a long bolt which was drilled through the two framing members, with a head on the house side and the other end extending a couple inches into the ell.  A slot mortise was cut into this tail end, and a wedge was driven through the slot and peened over. The adjacent ell gable sill and eave house sill were also bolted together in this manner. Arron referred to this as a butterfly bolt, and noted that it was an older technology in comparison with the design of the rest of the frame. Removing these bolts was a process of delicately straightening the wedge, knocking it back through the slot mortise, and then slamming the bolt back into the house. I remember the sound of the bolt falling to the concrete foundation inside the house as a terrifically satisfying clatter.

Giggling guys

Giggling guys

After the ell was fully dismantled and transported back to the shop for repair, the crew cut two additional, identical, bents that will extend the ell by 22′ for use as a contemporary kitchen. The combination of renovation, frame preservation and green building technologies has been a fascinating learning experience. Repairs to the main house have been complicated, intensive and are good fodder for future blog posts.

For more photos of the Pennell House and the ell frame dismantling, visit our Flickr album.

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