What is the collective noun for timber?

There isn't a widely accepted collective noun specifically for timber. However, depending on the context, you could use these terms:

General:

* Pile of timber

* Stack of timber

* Load of timber

* Supply of timber

* Stock of timber

Specific:

* Flitch (for a large piece of timber split lengthwise)

* Battens (for thin, narrow strips of timber)

* Planks (for flat, rectangular pieces of timber)

* Logs (for the raw, unprocessed timber)

Ultimately, the best collective noun will depend on the specific situation and what you are trying to communicate.