MDF stands for Medium Density Fibreboard. It is a product made of wood fibres of medium density. Boards are made from hardwood and/or softwood residue and glue. MDF is widely used in the furniture and kitchen cabinet industries.
Generally, mouldings are nailed into place (see the “Installation Guide” section). However, the scarf joints connecting two moulding ends as well as interior and exterior corners should be glued together.
We recommend pre-drilling solid wood mouldings before nailing to avoid cracking the wood.
You do not need to screw in mouldings, except if you are working with exterior polyurethane mouldings.
If you choose to glue your mouldings, keep in mind that damage may occur to walls and ceilings if you remove the mouldings later on. What’s more, you will still need to use a few nails to hold the moulding in place until the glue sets.
MDF is more affordable, which is a big plus when it comes to larger sized mouldings. However, if you are using thinner mouldings, any cost savings will be negligible. On the other hand, MDF mouldings might have a tendency to expand or contract under temperature fluctuations or changes in humidity. The joints between mouldings and between corners might also increase. This is why MDF mouldings are not recommended for bathrooms.
Whether you opt for wood or MDF, mouldings should be exposed to the room’s ambient temperature for 48 hours prior to being installed. This will reduce the risk of expansion or contraction after installation.
Most of the time, crown mouldings are a combination of a quarter-round (convex) and a cove (concave). The general rule is the quarter-round section meets the ceiling, while the cove section meets the wall.