Marine Grade Polyurethane

[RickT]

I'm installing a new patio door, and the guy at Home Depot suggested using a marine grade polyurethane on the interior to prevent problems from condensation dripping onto the bottom of the door. It's a french wood door with clearn pine on the interior and vinyl clad exterior. Does that make sense? Is spar urethane the same thing? Where can I find the stuff?
Thanks,
Rick

[MilDoc]

No, Spar Urethane (such as Minwax) is not the same thing! Marine-grade (such as Interlux Goldspar) is a whole different animal, usually found only at marine supply stores.

[SARGE..g-47]

Was the guy at Home Depot wearing a "life jacket" and a possible "sunami" survivor? Maybe he is on to something I am not aware of, but people have used french doors as exterior rear doors before and I am not aware of any major problems coming from the inside with paint or standard poly.

As MilDoc pointed out, spar and marine are apples and oranges. I personally wouldn't use either on an interior component as to this point, I see no need!

Good luck...

[cwsmith]

I think the amount of protection needed will depend on how subject this door is going to be to the wind and rain. I don't think any interior condensation would be a problem; but if it's exposed to the windy side of the house where the weather is really going to lash it, the extra protection might be worth further investigation. I personally have no experience with either the marine or spar varnishes.

However, I do have a steel door that we put on the utility entrance several years ago. it was a fairly goo quality door, but that particular side of the house gets a pretty good beating. It is the entrance area on what used to be an attached garage and it has a relative flat roof with no overhang. Not a problem with normal rains and snows, but durng heavy storms, the rain beats against the door, running down and onto the threshold. The bottom door seal keeps the weather out, but the lower edge of the door has picked up rust and every now and then I take the thing down and repaint the lower edge, bottom, etc. I would imagine that, had this used a wood core, there would be some damage after a few years.

CWS