Not sure about that wood itself, but in my opinion building structures out of wood with a floor for rats is a bad idea. Wood is a porous material, it it kinda absorbs liquids when its not painted/sealed with something (and paint and stuff ould harm the ratties if they accidentally ate it while chewing) and when it has rat pee in it, there isn't an easy way to clean the wood, and it smells. Really bad.
Even though this doesn't really answer your question, I would strongly advise against building anything with a floor out of wood for rats.
Or at least expect to have to ditch the wooden item. It might still be a worthwhile project for you, but don't expect it to last. I have a dozen blocks of poplar that I drilled into to create little shelves. We've soaked them in vinegar and will be ready to put them back up, but I don't expect the vinegar trick to make the blocks a permanent toy for them (it'd be cool if it did).
I've only heard bad things about cedar and pine. Those can play havoc with a rat's respiratory system. Other wood seems to be okay, but Rattus is right that they will start smelling bad so they won't be permanent.