Ship-lap normally does not hold the floor down on the lap edge as well as T&G.

There is more chance of moisture changes in the flooring causing one edge to rise.

In T&G the tongue is fastened down (nails or staples) while the groove side traps the next tongue to prevent movement vertically of the groove side of the plank.

In ship-lap the lap side is not held down.

Thanks! That helps a lot...

My husband and I are looking at apitong. It is also ship-lap, but the thinnest dimension is 1-1/8" with a 7" face and 8-20' lengths. I would if the edge would pop up. This is the stuff they use in truck beds and trailers. It is very strong. At that width, we could probably have a local mill T&G it. ?

We do not want a 'refined' floor. We also want to oil it. I'm not sure if this is what you are looking at? We've just begun our research so we are not sure how well it would work. Also, I'm wondering about nailing through the top - like you see in old wide plank homes?

harbormom - we are going for the old house look, so the nailing through the top doesn't bother me at all. And, I don't want them to be 'perfect' looking by any means. I did get the samples from the company and like them a lot (colonialplankfloors.com). And the pricing is very reasonable. Here's a pic from their site of what they look like close up...

BUT, I also just received samples of the antique/reclaimed oak from a local company this afternoon. They are more expensive, but not as much as I anticipated, so I have a feeling I will cave on these. They are absolutely gorgeous! :)