Hi. I am a total newbie @ flooring, so I'll try my best to describe my problem, sorry for any omissions.

I have begun installing a nail-down 3/4" x 2-1/4" prefinished oak wood floor. Prior to install I laid a 3/4" T & G plywood subfloor over the original pine plank floor. I have opted to install diagonally due to this being in a 125 year old church that I am remodeling into a home, and the walls are not true to one another.

My problem is that after beginning the diagonal in one corner and now having laid about 9 feet (at the peak of the "triangle"), the center is growing faster than the ends of each run of planks. I began noticing it about 16" before now (I just quit until I figure out what's going on) and when I did notice it, I started trying to make up the difference by topnailing the ends and predrilling and hand nailing the end planks of the run. It didn't help.

I read in another thread someone talking about "cheater gaps". I get the idea of a cheater gap, but I don't know how it's accomplished, and moreover I don't know if it will help me. I don't even know what's causing the middle to "grow".

I'm not sure if this is important, but the diagonal of the floor is not laid at a 45 degree angle, it's closer to a 60 degree angle to match a couple of architectural features (archways) in the house.

Any help would be much appreciated. If you need more information I'd be happy to tell all that I possibly can - anything that would help anyone out there form an opinion about how to proceed,

It is a common problem. The reason is the way the floor is nailed. When nailing in the "middle" section, the "nails" (fasteners) are not always placed in exactly the same spot along the boards length. However, at the ends, one is always nailing in the same location. This eventually causes the rows to slightly pull in at the ends. Try this: Keep the field (middle) tight and well nailed. As you progress toward the ends, allow the boards to gap slightly. You can accomplish this by placing putty knifes between each row at or near the ends. You can use playing cards, doubled up, or even washers, if you need to go that wide. Use a straight edge to check how this is working for you. The idea is to slightly gap the ends until you are straight again. Got it?