A common method of covering the gap between two types of flooring materials is employing a piece of finishing hardware called a transition molding strip, commonly referred to as a T-molding strip or a T-strip. It's shaped like a fat, short T, and it covers the edges of two adjoining flooring materials, such as ceramic tile, carpet, vinyl or hardwood. Where a hardwood dining room meets a tile kitchen, for instance, the T-strip's half-inch- to inch-high vertical section would separate the tile from the hardwood, while the horizontal part would create lip and a transition if one material is substantially thicker than the other.
At the very least you need to include around one-eighth inch of gap between the two materials. This provides adequate movement spacing when the two floors move separate of each other during seasonal effects on the home. Wood and concrete both expand in the summer and shrink in the winter. A quarter inch is the most common measurement used, but an eighth is the smallest you should go.
Type of Molding
The type of molding you choose will dictate to some degree the spacing you provide between the two materials. While T-molding is generally installed with glue or some type of flexible caulklike adhesive to absorb movement, the type of material you choose for the molding dictates how wide the vertical section is. You will need to accommodate this width and provide at least one-eighth inch on either side of the section.
Similar to how the type of molding you choose dictates the width of the gap, if you are building a custom T-molding, you will also be able to dictate to some degree how wide the gap is. For example, if the two surfaces are different heights and you are making your own molding from wood, your goal is to provide at least one-eighth inch to one-quarter inch on either side of the vertical segment for movement. Without this gap, the materials will potentially press against the molding and force the opposite floor to buckle under pressure.
While you need at least one-eighth inch to one-quarter inch of space between any materials as well as the sides of the vertical part of the T-molding, you generally don’t want to go beyond a quarter of an inch of void or you will be back-filling the gap with backer rod before you can caulk anything in place. Anything more than one-quarter inch is overkill.
- Photo Credit Jupiterimages/Comstock/Getty Images