More than a third of the houses here in southeastern Pennsylvania were built before 1950, and many of them have structural masonry walls. We've worked on lots of these homes in our 21 years as remodelers, so we've learned what to look for when a homeowner wants to make major changes.
The big challenge when working with old masonry - whether brick or stone - is making sure the walls stay put, especially when the job requires making a large opening. Old stone or brick exteriors often depend on the surrounding earth, the interior framed walls, and the rafters to hold them in place, so if you disturb the surrounding support, you may weaken the masonry to the point of collapse. This is no hypothetical worry: I know of a contractor in the area who had a two-story stone wall come down during a remodeling project.
Every job is different. For that reason, most of the towns we work in require the plans to be stamped by a licensed structural engineer or registered architect. But even with proper design, the contractor still needs to know how to approach the structural changes so as to avoid big problems. In this article I'll describe a couple of recent masonry jobs that illustrate some of the issues we face.
Opening a Wall in a Brick House
The owners of a 1920s brick home called my company hoping to expand and modernize their awkward L-shaped kitchen. They wanted to build an 8-foot-by-6-foot one-story addition on an inside corner in back of the house, break through the walls, and create a larger rectangular space for the kitchen. The biggest challenge was that we would need to remove sections of the exterior bearing walls and insert new support beams while holding up the second story.
The original home was built with double-wythe structural brick - two brick walls mortared together with an occasional brick turned 90 degrees to tie the courses together. A later addition - the ell that formed the inside corner - had been stick-framed and clad with brick veneer. We worked with the client's architect to design structural steel beams that could be assembled in place to pick up the weight of the brick walls and the second-floor and roof loads. The plan for the double-wythe section called for two 9-inch C-channels - one on each side of the wall - bolted back-to-back. Steel angles welded along the bottom edge of each channel would be let into kerfs cut in the mortar joints, thus picking up the weight of the wall above. That way we would be able to install the steel supports before disturbing much of the existing brick, eliminating worries about the second-story walls coming down as we opened up the kitchen. The brick-veneer wall would have a single steel channel against the brick and an LVL under the framing.
First the Addition
We began work by digging the hole for the addition and laying up the foundation. Our own crew, which is trained in masonry, laid the block. (On small jobs, we try to keep as many tasks in-house as possible; it helps us control the schedule, as there are fewer subs to manage.)
The clients wanted to retain the original bulkhead access, so we had a new precast unit installed, after first framing the deck to brace the new walls. We were ready for the steel; the subfloor gave us a convenient place for staging the exterior work.
