Begin your installation with the sill strip, which should fit as it comes from the package. To prepare the channel strips for installation, cut the top flange off at a downward angle to prevent snagging on the sash channel or sash cord. (Like bronze V strips, the flanged channel strips extend past the top of the meeting rail.) Then cut the bottom to conform to the angle of the sill, and to fit around the stool (the indoor sill). Note that the flange should be angle-cut high enough to saddle the bottom weatherstrip. Facing the window, install the left-hand piece of stripping using only three to five brads—one near the sill, one about midway up and one near the top. Again, avoid nailing into the sash-weight door. Next temporarily insert the sash, making sure the groove and flange mesh at the left and the sill. Then check to see that the window moves up down appropriately.
Remove the sash and prepare the right-hand weatherstrip in the same way. Insert the sash cord into the knot hole in the stile and install the left side of the sash into the left-side weatherstrip. Then insert sash cord in the right side, and weatherstrip into the groove of the right sash. Using a thin blade putty knife, gently push the sash and strip into the sash channel. Once the sash is seated, pull or push the right-hand weatherstrip down until it saddles over the sill strip. It is important to thoughtfully locate the brads on this piece so that you can remove the sash in the future by reversing the process. Insert the bottom brad near the sill. Insert the upper brad at the inside edge of the sash and weatherstrip edge so that it can be removed if necessary. Before installing the stops, make sure the windows glide up and down.
Storm windows should not form an airtight seal but, instead, incorporate weep holes or be raised on lead shims to let moisture escape.
Illustration: Rob Leanna
Install Storm Windows
Energy studies conducted by the federal government and many universities indicate that the combination of an adjusted prime sash and good storm sash is as efficient as most replacement windows. The best storms—thermally and aesthetically —are wood-framed but, alas, these have worn out their welcome with all but a few die-hard preservationists. Many sash and lumber companies still make wood storms and, when consulted, I recommend mahogany, Spanish cedar, or western red cedar for the frames. These are usually made from 5/4 lumber (actually about 1″ thick) and double-strength glass. Wood storms should not fit too tightly into the window frame, but they should be screwed or fastened snugly.
Storm windows should not form an airtight seal but, instead, incorporate weep holes or be raised on lead shims to let moisture escape. (Illustration: Rob Leanna)
Aluminum Storms. Triple-track storm sash made of aluminum is typically used on most older houses where the original windows are intact. Triple tracks allow the lower storm panels and screens to be reversed with the changing seasons, minimizing the biyearly switcheroo chore, but this savings in time and energy has its cost. Aluminum is an excellent thermal conductor so it is not much of a barrier to heat loss. The real job of triple-track storms, then, is to prevent wind infiltration, and when installed properly they do this adequately. Some older storm sash—say, from 20 to 40 years ago—did not have integral weatherstrips but relied on cams to tighten the windows in the frames. These usually still work fine after many years. However, older storms that were manufactured with thin-pile weatherstrips often need to have the pile replaced. Many hardware stores or glass companies specialize in this work. In general, it is economical to replace the screen or a glass in a storm sash, but if both screen and glass are shot, it is more economical to purchase a new storm sash.
The problem behind the poor operation of many aluminum storms is that they were installed carelessly. On their own the aluminum frames are flimsy so it is important to install them with both sides plumb. If the frames spread at the center, the screen or storm latches that slide in the frames will fall out of their channels, making them useless. If the frame is racked, the panels will jam.
Many installers set the frame in a bead of caulking for a good seal. This is acceptable, but I like to omit this bead and instead apply a thin bead of caulking after installation. This makes it easier to remove the frames for painting and glazing windows and makes for a better job in the end. Finally, never fill the two or three small weep holes at the sill level of the storm. These holes allow condensation to dissipate during the winter, and rain to drain if it enters the screen panels in summer.
Interior Storms. Storm windows can also be used on the inside of the prime sash. Interior storms are popular when exterior storm sash obscure unusually attractive windows, and in impractical situations like extremely high windows or swinging-out casements. Interior storms are usually made with a large piece of Plexiglas in a frame that attaches to the prime sash frame with magnets, Velcro, or screws. In some applications, the interior frames must be altered to accept the interior storm sash. There can be tradeoffs to interior storms, however: first, there is no exterior protection of the prime sash; second, the sash is cumbersome to open if ventilation is needed; third, condensation trapped between the storm panel and the prime sash can deteriorate the prime sash. Still, interior storms can be a blessing when exterior storms are not feasible. Many companies specialize in interior storms and some hardware stores and glass companies also make them to order.