It is important when you are working with a joint compound that you know it is not okay to use it between wood and drywall. Many people do use this type of material in the middle and find that it cracks not long after. Here are a couple of reasons why it is important to steer clear of this combination.
Reason 1 – Wood Swells
The biggest reason why the drywall and wood cannot have joint compound between is because the wood will swell and change depending on the weather and temperature and moisture level. This leaves you with a joint compound that is unstable and is caused to crack from the shifting of the wood. While it may make for a temporary fix, this is not something you want as a permanent or long term fix. Most of the time, the cracking occurs pretty quickly.
Reason 2 – Doesn’t Stick Well
The other reason why it isn’t a hot idea to put the joint compound with both wood and drywall is because it sticks better on drywall because that's what it was designed to do. On one side you have a great stick and on the other the grip isn’t as secure. With one side possibly shifting, cracking can and will occur.