Most of my house (1920's) has white oak strip flooring except for a porch that was enclosed at some point and made part of the living room. I am installing salvaged (from a 1960's house) white oak strip flooring in this area and fingering it into the existing floor. The new area is about 8' by 20' and the boards run parallel to the 8' dimension. From reading it sounds like installing in the middle of winter and dry weather I should leave a 3/4" expansion gap. Along the 20' wall where the ends of the boards are there is a castiron baseboard heater. My worry is that everything under the sun (I have pets and small children) is going to end up in the expansion gap under the baseboard heater. Is there anything I can use to fill this expansion gap that will allow expansion but keep it from filling up with debris/toys etc? Keep in mind it is not the easiest space to get to but there is about a 1inch gap under the heaters. 
thanks for any help!
thanks for any help!