You are here : Home > Information Center > Renovation
Installing a window in a wall
The opening made for the installation of a window must be proper so that the lumber of the structure won't bend with time. The uprights, lintel and sill must be assembled to avoid loss of shape from warping.
The uprights are doubled for strength. The lintel is the timber at the top of the window opening which support the wall above when there is any warping. The sill is the horizontal lower part of the window. An extra inch of space is left in the opening to be able to wedge the frame.
For an exterior wall, two 2x6, 2x8 or 2x10 (depending on the dimension of the window) pine wood lintels are used to build a strong header. Fix one on each side of the wall adjacent to the uprights in order to prepare for the frame installation. Insulate the space left between the lintels with glass wool, a foam sealant or other insulating material. .
The uprights, the lintels and sill are solidly assembled with twisted nails to make sure every part will stay put during warping. You may now proceed to install your windows as well as the lining of the walls.
Insulating the window frame
Within a wall structure, the dimension of the opening must exceed the outer dimension of the frame by an inch to be able to wedge and make proper adjustments. Once wedged, the space left between the structure and the frame must be insulated for airtightness to avoid infiltration which could cause condensation on the window.
If the space between the frame and the window structure is wide enough, you may fill it with wool glass; however, a foam sealant is more effective as an insulator. When using wool glass, beware not to overstuff the space. If the wool glass is crushed, it will contain less air which will diminish its insulating effect.
Foam sealant comes in the form of a liquid spray and expands at air contact. The benefits of this form of insulation is that it fills all the hard to reach spaces between the wedges and the framework. When injecting the sealant, the frame must be well immobilized so that the pressure of the foam will not move it and prevent the window from operating correctly.
Thus, before injecting the sealant, pieces of timber are to be cut and placed at several points between the uprights. This will keep the frame from moving or deforming when the foam expands.
Once dry, the foam sealant is as hard as Styrofoam and contains air bubbles which give it its insulating properties. The excess of the spread may be cut with the help of an Olfa or a utility knife. The next step is the installation of the interior casing and caulking the exterior.
Installing the casing
The casing is mostly for the finishing of the window. It also keeps the frame in place. 1 and 2 inch finishing nails are used to place the trims. They must be driven far from the edges of the trims and at over 2 inches of their ends, and also, very carefully to avoid splits in the woodwork.
To cut the trims that form the casing, a mitre box with a hand saw or a mitre saw is used. For high-density wood moulding, a radial arm saw is better to make tighter joints. The trims are nailed with a regular hammer or an air nail gun. The air gun allows working without a nail punch to drive the nails slightly further than the surface of the wood.
The trims are cut at a 45 degree angle when they are joined to each other. If you add rosette blocks, the trims are cut at right angle. The casing is nailed to the frame at 1/8 of the frame?s interior edge. Installing the head first will permit you to join it to the angles of the upright trims firmly so that they will be less visible.
The bottom ends of the side trims are cut at right angle, 1/8? longer than the base of the window opening. The moulding of the sill is inversely installed so that the thicker side becomes the interior edge. The moulding of the sill will exceed the upright trims by 1/2?, and its ends are cut at a 15 degree angle. (See figure)
You may use wood glue at the joints of the trims to keep the casing still when there is warping. The one inch nails are for fixing the casing to the frame; the two inch nails are used to fix it to the structure of the wall (jambs, head and stool). If the lining of the wall is thicker than regular gypsum, you will need longer nails to drive them in the structure.
Once the casing is well installed, all that is left to do is driving the nails slightly deeper than the surface of the mouldings and cover the small holes with plastic wood. You may now taint, varnish or paint the casing of your windows.
Making a door opening in a wall
To make the opening of a door in a wall, the uprights, header and sill must be well displayed to prevent the wood of the structure from moving with time.
The uprights are the pieces of timber placed vertically on both sides of the door opening. The header is the timber placed over the top of the opening to help support the structure of the wall and prevent any bending with time. The sill is the floor part of the opening.
The header of an interior wall is most often a piece of pine timber of 2x6. 2x8 or 2x10 timbers are used on exterior walls for better strength. You place one on each side of the wall adjacent to the uprights in order to prepare for the installation of the frame. When it is an exterior wall, the space between the two timbers of the header must be insulated with glass wool or a foam sealant.
The timbers of the uprights are doubled and sturdily nailed together. Once solidly assembled, the parts of the opening are unmoveable; the header is solidly held by the uprights. You are now ready to install the door and lining of the wall.
Insulating the door frame
The opening in the structure of a wall always exceeds by about an inch the frame of the door to be installed. An opening that is too precise will cause an incorrect installation of the frame. Wedges are placed between the frame and the uprights and header. The wedged space is insulated to prevent air infiltration which would bring the door to freeze.
If the wedged space is wide enough, you may fill it with glass wool, but a foam sealant is more practical and widely used. If glass wool is used, beware not to overstuff and crush it as it is its air content that makes for efficient insulation. When the wool is compressed, it is less effective as an insulator.
Foam sealant comes in a form of liquid spray and is more effective since it expands at air contact and fills in the hard to reach spaces between the wedges. However, its inconvenience is that when overspread, it will apply pressure on the frame and prevent the door from shutting right. Therefore, it is important to keep the frame still before spraying.
Before applying the foam sealant, you cut pieces of timber the length of the inside of the frame and place them at several points between the uprights. This will prevent the frame from moving and deforming when the foam expands.
Once dry, the foam sealant is as hard as Styrofoam and contains small air bubbles which add to the insulating properties. The excess of the foam that has expanded outward can be cut with a utility or an Olfa knife. You are now ready to install the interior moulding and caulk the exterior.
Installing the door casing
Door casings usually have wood mouldings that are fixed to the frame and the structure of the wall. In addition to being the finishing touch, the casing of a door helps to keep the frame solidly in place. The casing is fixed with 1 and 2 inch nails. The nails must be driven far from the edges of the trims and also, carefully to avoid splits the wood.
A mitre box with a hand saw or a mitre saw may be used to cut the trims that form the casing. The nails are driven with a hammer or a nail gun. The air gun allows you to work without a nail punch to drive the nails slightly deeper than the surface. Plastic wood may then be applied to cover the tiny holes.
The trims of the casing are cut at a 45 degree angle when they are fully joined or at right angle if rosette blocks are added. They are then fixed to the frame at 1/8? of its interior edge. You place the first trim on one of the uprights, then the head, and finally the other upright. This will enable you to join the angles firmly for less visibility.
Sometimes, white glue is applied at the joints of the trims to make sure they stay put during warping. The one inch nails are to fix the casing to the frame, while the two inch are to be driven on the structure of the wall, which is usually covered with gypsum. However, longer nails are needed if the lining of the wall is thicker.
Once the casing is well installed, all that is left to do is driving the nails slightly deeper than the surface of the wood and cover the small holes with plastic wood. You may now taint, varnish or paint the casing.
Caulking a door or window
Caulking the interior and exterior of doors and windows is essential. The point is to avoid any air circulation which would cause condensation and damage to the wall lining, doors and windows. It will also make the sill waterproof.
Exterior walls have a thin space between the lining and the inner structure of the wall. If air infiltrates and circulates within the walls and finds its way indoors, there will be condensation. This is why caulking is essential on all outdoor openings.
Caulk comes in a tube and is applied with a caulk gun. The tip of the tube is cut at the very end at a 45 degree angle to be able to let out small quantities. This will make finer joints as you fill and cover the space to seal.
When you are renovating, it is preferable to remove any old caulk that may be present, unless there isn?t much and it is possible to cover it with new caulk. The old caulk can be removed easily by heating it, for instance, with a hair dryer.
To caulk, you push the tip of the tube at 45 degrees against the joint to seal. You must apply the caulk consistently and at a regular speed to achieve good results. If you stop frequently, you will have an irregular seal joint with large beads.
There are interior and exterior caulking products available. However, those designed for the indoors are not suitable to be exposed to weather changes like the outdoor products. They are available in different colors and also in transparent.
Once dry, the caulk becomes rigid but flexible enough to resist to the expansion and contraction of the materials exposed to weather changes. It would be important to check yearly the condition of caulk joints of windows, doors, and all outdoor openings.