i have a commerical job that requires me to install 1/2" hard wood (glue down) inside a store. At this location large metal frame picture windows run the lenght of one side. I've seen installations that butt directly to the metal frame is this correct? What is the cleanest method? Im aware of the expansion gap.

Rip one side off a "T" molding or buy endcap molding..

Condensation off those windows and metal, if they are outside windows, is going to play havoc along those windows.

Perry is right if your climate creates those situations so be mindful ...

You may try leaving a very clean 1/4" expansion gap and filling it with the right color of silicone caulking so it looks sharp but will give and take as the floor shrinks and grows. We've had a customer that wanted NO trim ... so we installed with 3/8" ripper strip of ply wood about 1+" wide stood on edge and installed directly against it. Then removed the strip (hope you don't pinch it in too tightly or you'll play h*ll getting it out) and filled the gap with silicone caulk that was a pretty close match to the wood. Looked real sharp and the customer was thrilled. Personally ... I like trim ... different strokes etc...

That's also a good trick for filling your expansion joints around a tub should you ever find yourself installing up to one.

Hope that helps

The best way to finish that is with a header. Just use an elastomeric sealant.

There are plenty of elastomeric sealants on the market. I like one called "Big Stretch". It is designed for setting windows in block buildings. You can always color it with a stain marker after it dries.

Thanks guys i'll try the sealent, I think thats the look the customer is looking for.