Hello everyone tonight

Hi DL

Just to summarize just alittle further

Remember that we are talking about a dairy barn not a house--very different situations, normally homes do not have high interior moisture content so no interior rotting would take place--these sash would look excellent on the inside, but the outside or exterior surfaces would be the one that would rot from moisture.

Even painted the esterior surfaces would be suseptible if the paint layers cracked and allowed moisture to get trapped underneath, in this case the sash would last alot longer without paint just bare wood

take the case of wood shingles, they actually never rot but wear away from the friction of the water running and dripping from row to row.

horizontal or vertical wood siding is another example better left bare, not so niceto look at but weather hardy

NH