This story originally appeared in the Winter 2021 Issue of This Old House Magazine. Click here to learn how to subscribe.
Lincoln and Megan Pasquina took a bold path when they decided to add on to their antique Cape in Concord, MA. Working with architect Andrew Sidford, they settled on a design for their addition that merges modern style with the house’s traditional form.
At the heart of the new plan is a high-ceilinged, open family room with a view onto the backyard. “As you step through from the kitchen into the new family room, you’ll have vaulted ceilings and a wall of glass,” says TOH host Kevin O’Connor. “That is the transition between old and new.” That wall of glass is more than a visual treat, however. It also does important structural work. “It’s trying to hold all that glass, but it also has to hold up the roofline above it,” says Kevin. TOH general contractor Tom Silva adds, “You have to think about the weight, obviously, but you also have to think about the lateral force of the wind against it. So it has to be really stiff.”
The dramatic modern addition also means giving the old house a new ridge beam. “We’re changing the pitch of the original roof, and extending its length to grab that new addition.
So we’re putting a new spine into the old house,” says Kevin. Key to both structural elements is the use of engineered lumber: manufactured beams and posts that offer strength and stiffness that’s harder to get from regular sawn wood.
Up ahead: See how the high-capacity new structures come together.
Making the Most of the View
Engineered posts and beams create a strong wall to support big window openings. To meet the window wall’s structural requirements, Tom and Kevin used laminated veneer lumber (LVL) for the top beam and headers, and parallel strand lumber (PSL) for the posts.
They fastened the posts to the beam with hardened structural steel screws, and hung the lower window headers from the posts using blind-nailed steel connectors. Sheathing the wall with structural panels ensured the necessary shear strength.
- Tom lays out the top and bottom wall plates. These pencil lines on the horizontal members will show him and Kevin where to nail the studs, cripples, and posts that support the heavy windows and the roof load. Anthony Tieuli
- Using a battery-powered impact driver, Kevin screws through the 5.-inch-thick LVL beam to attach a supporting PSL post. The self-tapping hardened steel screws need no predrilling. Anthony Tieuli
- Heavy 3-by-6-foot lower windows will be held up by windowsills supported by cripple studs. Here, Tom and Kevin tap a sill into place, to be attached with framing nails. Ordinary 2X6 lumber suffices to frame this part of the wall. Anthony Tieuli
- Tom sets a steel hanger for a window header. Like the engineered header itself, this steel connector has a lab-tested carrying capacity; this helps an engineer design the wall to carry the required loads while allowing wide window openings in the structure. Anthony Tieuli
- Kevin and Tom tap an LVL header into place above one of the lower window openings (the smaller upper openings will hold 3-by-3-foot windows). Straight, stiff, and strong, LVL members don’t have the potential for crowning, bowing, or twisting that sometimes shows up in sawn wood. Anthony Tieuli
- Kevin nails a sheathing panel into place over the framed-up wall. Wall sheathing like this helps to stiffen the wall against racking, contributes to an airtight and water-resistant enclosure, and provides a good substrate for nailing on siding. Anthony Tieuli
- The crew teams up to stand the wall. “We could have used heavy equipment,” says Kevin, “but when you have the bodies on-site, sometimes that’s just easier.” Push-pull poles at the corners of the wall help keep it from toppling after it reaches the vertical position. Anthony Tieuli
- “This is probably the most significant wall in the house,” says architect Sidford of the new window wall. When completed, it will offer wide, open views over the new deck out to the field and woods at the back of the property. It will also usher plenty of natural light into the high-ceilinged family room and kitchen. Anthony Tieuli
Marrying Old Structure with New
In place of the house’s original 2X10 ridge beam, Tom and Kevin installed a built-up beam using three LVLs. Building the beam on the ground would have been easier, but the hefty assembly would have been too much for the telehandler to lift at the end of its boom extension.
So Tom and Kevin pieced the beam together in place. To account for the roof pitch, they offset the center piece above the others. “If you follow the pitch of the rafters, the center LVL pushes up to stay in the plane of the roof,” Tom explains. “So when you lay the sheathing on the roof, you have nailing at the top, and your sheathing isn’t floating in the air.”
- To make room for the fat new ridge beam, Tom and Kevin cut back the ends of the existing rafters on the old part of the house. Here, Kevin uses a reciprocating saw to make his cuts. Anthony Tieuli
- Using a battery-powered impact driver, Tom screws the first piece of LVL onto the end of a rafter. Anthony Tieuli
- Strapped to the telehandler’s boom, the first of the heavy LVLs are lifted up to the roof and Tom and Kevin’s waiting hands. Staging is in place for needed support as they move the LVL into position. Anthony Tieuli
- The crew uses the telehandler to lift the second LVL up to Tom and Kevin. The machine assist requires some careful maneuvering to make sure the 22-footlong LVL doesn’t hit the existing structure. Anthony Tieuli
- Tom attaches the second LVL, which is raised up a few inches to allow for the slope of the roof. Shims set it plumb. Anthony Tieuli
- Using a torpedo level, Kevin does a final check for plumb. Anthony Tieuli
- Kevin screws the last LVL in place. The three-layer beam will carry a substantial load from the modern addition’s roof. Anthony Tieuli