Wood vs. PVC Trim
mchernoff
| Posted in Green Products and Materials on
Hi- I’m having carpentry repair done on my 1935 Cape. The wood trim on the dormers and windows is deteriorating. I’ve signed on with a carpenter. He’s recommending using PVC (I think that’s what he said) instead of wood since it will “last forever”. I’m having second thoughts, wondering about production of this and thinking that perhaps I should ask him to use wood, despite the chance it could deteriorate again. I will be painting the house afterwards. Any feedback appreciated.
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Replies
PVC trim board has a good reputation and holds up well. It's important to treat the ends properly to "close" the structure (usually this is done by wiping with a solvent after cutting the board), and you need to be careful painting it, especially with dark colors. Aside from that, it's a good product. I try to stick with PVC trimboard myself since it doesn't rot, and insects don't eat it. If you are OK with white trim, PVC is essentially maintenance free.
Bill
Here is an article comparing PVC to wood (and wood composite and fiber cement) trim: Wood Trim Alternatives; and another explaining the benefits of PVC trim: Today’s Best Exterior Trim. I hope they help inform your decision.
Thanks very much! I'll read the article. It turns out the work is scheduled this week, although I'm trying to put it off til next week so your quick replies were greatly appreciated!
One thing to watch with PVC is thermal expansion. Even though you are not supposed to, I did some black PVC for my own home and the ones on the west side are impossible to keep tight as they move way too much.
Did you try solven welding the ends? I know they usually say to make a sort of hidden lap joint, but I've always thought solvent welds might work better. I just haven't done a long enough piece to see if there is a tradeoff like ripples or something when it expands.
Bill
The best and worst quality of PVC trim is that it lasts forever. Cutting it generates piles of micro-plastics that are pervasive in our environment, it's made of virgin PVC with all of the associated dioxin pollution and health impacts, it's floppy, expands and contracts a LOT with the weather, is electrically charged and will attract dust, and can only be painted with light colors (with some exceptions). I've trimmed out a couple of large houses with it and hopefully never will again. But your carpenter is right, it will hold up better over time than wood.
I installed Azek trim when I redid the siding and sheathing on my own home. for windows I assembled each trim unit using pocket screws and Azek solvent glue which are still perfect 3 years later. For outside corners I fabricated Azek dominos and used domino and glue to connect each corner. Again, no opening at all at any joint. Same with scarf joints on long runs (glue only). Also, Azek worked with Sherwin Williams to formulate a "vinyl safe" paint formulation. If you go to any SW dealer and tell them you want their vinyl safe paint, it will work perfect with Azek (or I assume any PVC product). You may need to talk to a manager as this still seems to some of the workers, as Azek is still pretty rare in my part of central Texas, but I really like the product as it machine well (cuts, routers, planes pretty nicely). As noted above, the dust is a real pain, so I used good dust collection for all tools I used to process the trim material. Azek also makes sheets of Azek in different thickness for making custom moldings, raised panels, etc.
Do you know if vinyl safe paint can be applied over existing latex paint? I have a house where the vinyl trim was painted dark green and it is warping badly, I wonder if repainting will fix it or if it needs to be replaced.
I doubt if it would, as the vinyl safe paints have specific properties, and the darker paint may already have damaged the trim. my trim is a sorta avocado green, so not really dark, and absolutely not issues. I don't know what brand of trim you used, but if it is Azek, their technical support was pretty gooe