On some 40 to 30 year old hardwood windows, I noticed channels in the sides of the opening parts of the windows. They look like provision for seals. Someone was telling me they are to allow water to run down to the bottom of the window frames and run out.
Any window experts around? If they are, or not, for seals can seals be inserted and what type of seals?
If they are narrow grooves not much bigger than a sawcut, then they were probably meant for seals - a number of manufacturers offered the same windows in standard and high-performance versions.
If they are wider, they are there as an anti-capillary gap and, as you suggest, to allow any water that blows in to drain out.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.