1 Ordering a window 5 Sealing the window’s exterior contour
2 Installing a window 6 Installing an outdoor lantern
3 Insulating around the frame: 7 Fastening a mailbox or an address plate
foam or fibreglass?
4 Restoring the interior vapour barrier
1. Ordering a window
Apart from a few exceptions, a window must be ordered custom-made according to the dimensions of the
existing opening and the nature of the exterior wall cladding. In prder to avoid mistakes when ordering, the
dimensions of the opening and the windows are always given in the same order: width x height. For example,
a basement window 60’x23-1/2’’ is 60’’ wide and 23-1/2’’ high. Réno-Dépôt’s installer referral services
recommend having the opening measured by the installation contractor. If you plan to do your own installation
and order according to your own measurements, take the dimensions of your rough opening (from brick to brick)
and not those of your existing window. The width and height of the opening measured from the exterior cladding
will provide the associate with the dimensions he needs to determine the dimensions of your new window. He
will provide for an adjustment space of 1/2’’ on the top, on the sides and under the frame of the window.This will
be followed by discussions on the selection of materials, the type of opening and the glazing and tiling options.
2. Installing a window
Remove the old window and its frame and clear the opening of any encumbrance. Check the condition of the
air barrier sheathing paper covering the wall’s intermediate cladding. Normally, you should stretch it, fold it
back and staple it to the edges of the wall opening constituted by the spandrel at the top, the columns on the
sides and the window sill at the bottom. If you do not have sheathing paper on hand, you can use a self-
adhesive membrane sold in a practical strip format. Insert the window in the opening and adjust it with Cedar
shim shingles. Slip the shims under the sill both from the interior and the exterior to vary the thickness of the
joint until the window is level horizontally. The shims must be positioned as follows: near each corner and, if
applicable, under the window’s central muntin. Then install shims on the sides of the opening, near each
bottom and top corner (also at the centre if the window is high). Make sure that the sides are straight and
level. Do not install shims in the top part. This must remain free of any contact with the spandrel, in case it
sags over time. Fasten two screws at least 2’’ long through the frame opposite each window shimming point.
If the screws do not penetrate at least 3/4’’ into the rough opening in the wall, change them to longer screws.
If you install a PVC window with metal anchor lugs, use shorter screws.
3. Insulating around the frame: foam or fibreglass
Once the window is securely fastened to the wall, fill the shimming space about 1/2’’ wide between the
window frame and the wall with insulation. You can insert fibreglass batts without compromising the
insulation, because its efficiency depends on the air it contains. Use a putty knife or a stick to make it
penetrate the joint. Using wool lets you continue the work quickly with no waiting time. Wool also has the
flexibility required to adjust to a contraction of the structure, which happens frequently when the structure of
the house is not completely dry. There is more reason to fear deformations in large openings than in small
openings. The low expansion foam insulation designed for doors and windows fills the cavities better and
bypasses the obstacles. It seals the opening better and offers greater thermal capacity. To fill the cavity
properly, place your cylinder rod inside the joint so that the liquid foam spreads into both the interior and the
exterior. Let it dry and harden before removing the excess with a utility knife. However, foam does not have
the flexibility of fibreglass to adjust to possible deformations of the structure.
4. Restoring the interior vapour barrier
On the inside wall, it is recommended to extend the vapour barrier to the window frame. Staple the vapour
barrier to the frame and seal the joint. This measure protects the window contour and its insulation against
exfiltration, that is, leakage of hot moist air from the interior of the home to the exterior.
5. Sealing the exterior contour of the window
After installation of a window, a crack remains open between the window frame and the wall opening.
You must seal it tightly from the exterior with a caulking compound. Take the greatest care with this work
and then inspect the conditions of the joints every autumn, because air or water infiltration around the frame
may case premature deterioration, not only of the window but of the wall. If the crack is more than one
quarter of an inch wide, fill the bottom of the joint with a foam sausage sold in the Weather stripping
Department and available in different diameters. Sink this foam sausage into the crack to a depth equal to
half the width of the crack. Applying tube sealant with a caulking gun is not as easy as it looks. If you have
little experience, perform tests on cardboard before sealing joints in exposed locations. Make sure to comply
with the product’s application temperature. The minimum temperatures (never below 5°C) and maximum
temperatures are indicated on the tube. If it is too cold or too hot, there is a risk that the sealant will adhere
poorly or dry poorly. Also ensure that the application surface is dry and free of dust. Remove any trace of the
old caulking with a scraper or a razor blade. You then must cut the tube spout according to the width of the
joint to cover. Since the tip of the tube is beveled, you can cut it exactly to the desired width. The product
must overlap the two edges of the crack. Cut the spout at a 45-degree angle and apply the sealant along the
joint, orienting the opening in the same direction as the joint. Squeeze uniformly and release the pressure a
little before the end. If the joint is well filled, it is not necessary to smooth it. If you do smooth it, use a tool
with a shape matching the shape of the joint, such as a spoon, or a sponge or a wet finger. The sealing
compound adheres to both edges of the joint, and its depth must not exceed the width of the joint. Ideally it
must not come into contact with the bottom of the joint.
6. Installing an outdoor lantern
If you install your lantern on the location of an old light fixture, simply remove the connection, screw the
lantern to the existing electrical box, and seal the contour of the light fixture with caulking compound. A new
installation requires a lot more work. If an electric cable is present, you only have to install an electrical box.
This can be a standard box for insertion in the wall or a flat box for installation on the surface of the wall. To
install the standard box, you must cut an octagonal opening in the wall to insert the box. The flat box, also
known as a pancake box, was designed so that you can avoid opening the wall. Its round flat shape can
usually be inserted under the base of the lantern (check anyway whether the base of your fixture can be
adapted to it). When shopping, don’t forget to buy 1/2’’ connectors to tighten the NM (nonmetallic) cable
inlet in the box. If there is no cable in the wall, you must install one. There are several ways to run a cable
to an outdoor lantern. From the exterior, if you have an outdoor circuit not far from your installation, you can
extend it to the lantern. From the interior, you can extend a circuit from an indoor outlet. This outlet ideally
should be located in the same wall as the lantern. In both cases, you must measure the electrical loads of
these circuits to find out if there is enough power remaining to light your fixture. Otherwise, you will have to
establish a new circuit from the distribution panel. Call an electrician. An NMD90 No 14/2 cable is sufficient
to power an outdoor lantern. Let’s take the situation when you connect the lantern to an indoor outlet located
in the same wall. To bring the new cable to the fixture, drill a hole in the exterior wall and run a fish tape to
the indoor outlet. Attach the new cable to the tape and slide it along the stud to which the indoor outlet
7. Fastening a mailbox or an address plate
Installing a mailbox or an address plate is easy when the wall cladding, such as wood, can be used as a
fastening strip. However, if you have a light cladding, such as vinyl or aluminum, you must locate the wood
furrings to sink your screws, or you must use longer screws (3’’ should suffice) for deeper anchoring in the
intermediate plywood or OSB cladding. If your wall is brick, you can use a set of anchor pins and masonry
screws. You must drill the brick first. Do not anchor in the mortar joints, because they are more friable.