Installing carpet between rooms requires you to install a carpet threshold. The threshold keeps the ends of the carpet from fraying and provides a smooth-looking transition from one room to another. When installing thresholds, use wooden thresholds specifically designed for carpets. Carpet thresholds are available at carpet stores and big-box home improvement centres. The thresholds have slots on each side to accept the ends of your carpet.
Measure the width of the door jamb where you are installing the carpet threshold with a tape measure. Cut the threshold to the measurement with a handsaw or circular saw.
Apply a coat of wood adhesive to the underside of the wood moulding with a caulking gun. Place the wooden carpet threshold into position on the floor surface. Roll over the top of the threshold with a rolling pin to eliminate any air bubbles in the adhesive. Allow several hours for the glue to dry before continuing the installation.
Cut pieces of carpet tack strip to fit the opening and attach the tack strips to the mounting ledge on the threshold. The ends of the carpet nails should point to the centre of the threshold. The mounting ledge is on each side of the threshold under the slots for the ends of the carpet.
Stretch the carpet ends over the threshold and secure the carpet to the tacking strips. Trim the carpet ends and tuck the ends into the carpet slots on the threshold.