A timber-framed house offers very little protection from cold and hot air flow, which can go right through the walls. That's why insulating the walls during construction is especially important. Standard insulating procedure is to tuck fibreglass insulation between the studs of each exterior wall before you put the drywall over it. See your local dealer for the correct insulation to use with your type of project.
Measure the wall from top to bottom along one of the exposed studs.
Stretch out a length of batt insulation over the floor. Lay the tape measure alongside it, pulled out to the measurement you took from the stud.
Lay the square across the width of the insulation at that measurement. Cut the strip at the measurement, running your razor knife along the edge of the square to keep it straight.
Set the cut piece of insulation into the space between the first two studs, filling the space completely. Set it so the paper-covered side of the insulation faces out into the room.
Drive staples through the edges of the paper along the long sides and into the edges of the studs. Use one or two staples per foot.
Cut the insulation away around any electrical sockets or other obstructions in the wall, using your razor knife.
Repeat to fill the spaces between each set of studs on the wall. Install the drywall right over the insulation.