Waterproofing Oil-Painted Trellis

I'm having a cedar trellis built over my patio and am having it painted with a white, oil-based paint (to match the rest of the trim of the house).I plan on having wisteria or other vine grow up over the trellis, but my contractor told me that only a stain is recommended if foliage will be on the trellis, because the white paint will turn green, get mossy, etc. I live in Seattle so there are 9 months of very damp weather.
My question is this -- is there a way to paint the trellis white to match the rest of the house, but also water seal over the paint?
Thanks.
Mike
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Mildew can feed on the organic compounds used in oil-based products. I'd be surprised if the average general contractor knew this, though. This is not to say that you shouldn't use oil-based products outdoors, obviously. Exterior paint is designed to deal with being rained on. There is no reason you shouldn't prime the trellis with an oil base primer (make sure you choose one that is spec'd for exterior use - original KILZ is not, for example), and finish with a solid color stain - acrylic latex or otherwise. I'd recommend using the latex solid color stain. I'm especially fond of Cabot's products like their PRO-VT. If you want to use stain but also want a bit of sheen, you can use decking stain. Otherwise, just use exterior paint. There are plenty of exterior latex paints that would work just fine.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It 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.