All’s Well With an LVL

Chris is renovating a 120-year-old house and wanted to open up the floor plan. Chris hired PERCH to design a pair of beams that could replace the existing loadbearing walls, spanning the 18-foot room width and picking up the existing floor joists. Chris wanted to procure the beams inexpensively and install them easily, with little or no disruption to the ceiling height.

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“Before.”

Right away, using a steel wide-flange or T shape was out. Steel beams are expensive and heavy, and connecting them to the stringers would have required either complex details or temporary removal of the stringers. Ordinary dimensional lumber wasn’t strong enough for such a long span within the confines of the ceiling height, so PERCH looked to laminated veneer lumber (LVLs) for more strength. A pair of 3.5-inch-wide, 9.5-inch-deep LVLs were strong enough to get the job done. Joist hangers allowed the LVLs to share depth with the 2×8 joists, so the lumber only protruded down an inch from the existing finish ceiling.

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The new header beam on the right requires support down to the foundation at the location marked with a red circle.

PERCH also investigated a hybrid solution called a flitch plate: a steel plate sandwiched by two pieces of lumber. In theory the steel increases the assembly’s overall elastic modulus while the lumber keeps the beam light and enables nailed connections. But in the final analysis a flitch plate was too complicated. The beam would need to be assembled first, with through bolts ensuring the wood and steel share loads, and then it would be prohibitively heavy to lift into place.

PERCH developed an installation procedure (which required temporary support of the floor joists) and checked that a column of dimensional lumber built into the existing exterior stud walls would provide sufficient support. Chris followed the procedure and reported that everything went up perfectly.

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“After.”

Floodproofing

Louisiana got besieged by a 500-year flood a couple weeks ago. I received a firsthand account from my cousin, who lives in Baton Rouge. He was one of the lucky ones – flood waters didn’t reach his house – and he has spent days helping neighbors clean out.

An unnamed, weeklong storm dropped more than 20 inches of rainwater over a third of the state. Rivers reached record flood stage, mixing with mud and sewage as the water submerged low-lying land. Outsiders tend to assume all of Louisiana is low-lying, but many affected houses are not officially in a floodway and many residents do not have flood insurance. Even for those who do, the federal provisions are messy and limited to $100,000 of personal property. In homes where the water has receded, the stench is almost unbearable. Cleanup involves removing personal items from the house, then gutting and replacing everything below the high-water line… and often, because of wicking moisture, well above that line too.

How can you design or retrofit a house to minimize the damage a flood would cause? LSU College of Agriculture developed this proposal, which divides walls horizontally in two. A chair rail hides a gap in the drywall and a partition between lower and upper insulation. Thus, any flood water that infiltrates the house can’t damage anything above the chair rail. The concept is to eliminate “water bridging”, much like a Passive House avoids thermal bridging to keep heat in.

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LSU proposal for floodproofing. For more information, click the first link in the paragraph above.

To further protect the lower half of the house, LSU recommends water-resistant flooring and wall panels, along with insulation that doesn’t absorb water, such as rigid foam. Electrical wiring is as high as possible. None of the details seem overly expensive to install, other than requiring a like-minded contractor to do the work correctly. I’d recommend all homeowners in a floodway, and even outside of it (500-year floods do happen), to consider protecting their property with details like these.

Of course, you could also literally elevate your house, or surround your property with a cofferdam, or (if your house is on wheels) drive it to higher ground when heavy rain threatens. But most folks who take action at all will probably go for the LSU ideas.

To help rebuild the affected communities, you can send funds to the Baton Rouge Area Foundation or the Louisiana Red Cross.

Fit and Trim

David’s dogs did a number on the trim pieces around some doorways in his old house. The scratch marks were unsightly and he wanted to get rid of them before renters move in for the winter. I agreed to help him replace the trim.

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The damage.

Step 1 was to assess the damage. Determined they may be, but the dogs can only reach about three feet off the floor. I proposed to cut out just the lower, damaged portion of the trim, and then to spackle and paint over the joint after I installed a new piece. The partial replacement won’t be aesthetically perfect, but it saves a lot of time and material cost compared with replacing an entire length.

Step 2 was to remove the damaged trim. It looks like a single part, but the trim for one doorway actually consists of NINE pieces of wood! There are three lengths (left side, top, right side) with three faces each (facing outside the room, across the threshold, facing inside the room). The pieces are typically held to the wall’s structural frame using tiny finish nails, which are nearly invisible once a painter covers over them. I worked a cat’s paw behind the wood and pried the damaged areas out from the wall. Then I took a sawzall and cut out the damaged areas, careful not to nick the wall or the undamaged areas.

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Damaged trim removed from the doorway. I had to take the door off, too, for access.

Step 3 was to cut and install new trim. David brought the cut-out pieces to Allen Lumber and came home with stock lengths of trim having the same shape. Then I performed that familiar sequence: measure, cut, install. For each doorway I had to install the threshold piece first, since the outside and inside pieces sandwich the threshold piece in. I also needed to shim out each threshold piece from the jack stud anywhere from ½ inch to 1½ inches to match the width of the doorway.

One threshold piece presented an additional challenge: the door itself. I unscrewed the hinges from the trim and set the door aside. When I replaced the portion where the bottom hinge fits in, I needed to carve out a new niche for the hinge. There’s probably a tool out there that cuts perfect hinge niches, but I don’t have one, so I did the best I could with a hammer and chisel. The result was an indentation one sixteenth of an inch deep in the rounded-rectangle shape of the hinge.

But I haven’t reinstalled the door yet. I want to paint the new trim first, and before I paint it I need to spackle it smooth. That is a tale for another time.