Bringing Back the Beauty
The MacKenzie House
3501 Bryant Ave. S.
Minneapolis, Minnesota
An Unusual Porch Roof
Having a historic photo and physical evidence to guide the work of the upper porch was incredibly good fortune. However this good fortune didn't extend to the porch roof bracket. One of the unusual design features of the MacKenzie House is a porch roof
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| Porch roof is temporarily supported so that old roof bracket can be removed and new bracket installed. Large Image | | |
that extends beyond the end of the lower porch to the 2-story bay on the north side. At some point in the home's history a rather crude bracket was put in place to prop up this roof. Clearly not original to the home, the bracket was a 4x4 that rested on the continuous sill at the bottom of the window, supporting a piece of plywood under the beaded ceiling. In addition to being out of character with the home, it extended out in front of the side window, interfering with the view.
Unfortunately in the photo this area is hidden from view behind the porte cochere, creating the mystery of what, if anything, originally supported this roof. A careful investigation found no physical evidence indicating an earlier roof bracket or post. Physical evidence inside, which indicated that the upstairs side window of the bay was originally a door providing access to the upper roof, suggested that this roof was probably original and wasn't extended later. Most likely the roof was built unsupported and as it sagged over time the 4x4 was a quick fix to stabilize it. However even though a bracket was not original, decorative roof brackets were commonly used on Queen Anne homes and such a bracket was still the best method for supporting this roof. An appropriate bracket would need to be designed as a replacement.
A review of period plan and pattern books didn't turn up any examples of similar porch roofs. However these books, along with period millwork catalogues, were helpful in suggesting a very common design for the bracket. The design incorporated 2 triangular sawn-wood panels held in place by a heavier frame. Since the original bargeboards also incorporated triangular sawn-wood panels, the new panels could use the same design.
 | | Assembled bracket with wood plugs covering recessed screws attaching final layer. Large Image |
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When the deteriorated bargeboards were taken down in the late 1980s, the pieces were stored in the basement. The remnants were adequate to determine the original pattern after they were stripped of caked-on paint and pieced together. The design was then rescaled for the bracket panels. With the basic design worked out, it was time to consult Christian Soltermann, the structural engineer, so that load calculations could be done and the structural issues worked out.
Christian was quick to focus on issues of anchorage after first determining that the basic bracket design would be adequate to support the roof. We decided to shift the new bracket to project from the angled face of the bay instead of directly out from the sidewall of the house. This kept the bracket from blocking the window and it also meant the bracket could be smaller and still extend to the corner of the roof.
Finding the best way to anchor the bracket was a bit more difficult. Working again with Christian various ideas for anchoring finally evolved into a plan to use a steel angle that was lag-bolted into the wall framing and notched into the back of the bracket. Special 6 inch long bolts, typically used for landscape timbers, were also screwed through the studs into the back of the bracket from the inside.
 | | Installed bracket awaits final painting. The design incorporates sawn-wood ornament that matches the restored bargeboards. Large Image |
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There was one more structural issue to solve. The bracket needed to specifically support the framing, and not just the beaded ceiling, of the roof above. While the position of the new bracket provided support in the area where the previous bracket ended, there was no way of knowing the actual framing at this juncture of the roof or even if the previous bracket supported any framing. Since holes needed to be cut into the roof above to securely attach the new railing newel posts, the holes could also be used for further investigation. Unfortunately, this investigation revealed that there wasn't any roof framing located above either the old or the new bracket. This required that the roof be opened further and additional structural members added based on Christian's recommendations.
The bracket frame was designed to be built-up from three layers, with the center layer being the same thickness as the panels and the two outer layers being thicker. This made it possible to create a channel that would hold the panels in place without other fasteners. The panels were slightly smaller than the space created by the frame. This made it possible for the individual panels to move freely as they expanded and contracted. It also allowed the panels and the frame to be painted their separate colors before final assembly. The final layer of the frame was glued and screwed to the other layers after the panels were put in place. The screws were recessed and the holes filled with wood plugs, which were sanded and painted. After the porch roof was jacked up slightly to move it closer to it's original position, the bracket was installed; an appropriate period solution to fix a problem with the original design.
Read more about the MacKenzie House Rehabilitation:
