Recommendations for exterior molding material
whitenack
| Posted in Green Products and Materials on
Hi all,
I am working on the trim design for our front porch. I have an idea for how it should look, but our builder is recommending an aluminum wrap to protect it from the elements. I appreciate the concern for the maintenance of wood, but worry that the aluminum wrap will flatten all the details and kill the look. I see there are PVC mouldings that you can get that obviously require less maintenance, but our builder said that PVC will move a lot in the heat and we’d end up with gaps.
Do they make anything else, other than wood and PVC, that could be used for moldings? If so, any recommendations on where to get it?
Thanks,
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Replies
Clay,
It's true that cellular PVC trim has a high rate of thermal expansion and contraction.
You might consider using fiber-cement trim, or one of the many other products discussed in this Fine Homebuilding article: Today's Best Exterior Trim.
Clay. If you don't have a Fine Homebuilding account, you might want to read this article: https://pro.homeadvisor.com/article.show.Engineered-Exterior-Trim.13687.html. I provides a good overview of different trim materials currently available.
Steve,
Thanks for providing the link. I wrote that JLC article a long time ago -- back in May 2000 -- but it still includes useful information.
Here's the link to the article, "Engineered Exterior Trim", on the JLC site.
Ha! I didn't notice your byline. But I'm not surprised that you authored the piece.
There are many trim products out there that are great materials - fiber cement, MiraTech, etc. As you may have noticed, if you are looking for designed shapes, the options are fewer, but many shapes are available in pvc trim.
You can easily mix 1x fiber cement or MiraTech material and pvc moulding shapes, giving you fewer locations to be concerned about expansion & contraction.
Your porch may not be large enough to worry about expansion & contraction. If it is, is it the inside of the porch or the exterior? If you are trying to trim out the inside like a crown molding, tell your contractor to use the pvc product you selected, do a great job coping the corners, and don't caulk the corners. The pvc will be able to expand & contract but you will never notice it.
If it is the exterior, and you have very long runs, you can try breaking them up with some decorative blocking, and caulk the butt joints. That might be enough to take care of expansion & contraction.
If you are just trying to trim out around boxed porch columns, and the pieces are only +/-12", you don't have anything to worry about. 12 years ago I trimmed out porch columns with no name big box (read: very inexpensive) pvc trim and it has held up just fine. I think I cut the pieces slightly larger than the boxed (in MiraTech) columns, and joined the miter ends with pvc cement. I wanted to make sure the pvc could expand & contract, so I made extra sure the pvc cement only got on the cut miter ends, and none ended up on the columns. Put one nail in each piece at the center.
Thanks all.
C L, yes, unfortunately this is going on a 26 foot porch, on the outside, which faces southeast. Decorative blocking won't fit with the design we are going for, so we've got to find a product that doesn't expand/contract or install the pvc in a way that prohibits movement or allows for it to be unnoticed.
Fortunately, most of the design is flat stock, which, as you say, I could use a material that doesn't have the movement risk and then plug in the pvc in the places where I need the shapes. That way, if the pvc is a total bust, I don't have much invested in it.
Clay, Boral TruExterior is a fly-ash trim product that does not move with heat or humidity. Personally, I prefer to use local (to me) white pine for trim when possible, but Boral is a good product. PCV does move thermally but I've trimmed out large home exteriors with it with no issues; the trick is to use a lot of screws and PVC cement on well-crafted joints.