Home exterior trim - PVC or wood?

[StillShaving]

I am curious about your long term experience with wood rot on the exterior of your home, especially around windows, doors, and fascia. I believe many home owners and handymen now use PVC trim boards since they will not rot and are becoming less expensive, especially when factoring in labor and potential longevity. I have used PVC a couple of times, specifically to replace some rotten brick moulding and window sill nosing. But I question whether they are the best long term choice.

Two different examples on my home:

Fascia boards. I recently took down all the gutters in preparation to get larger ones and after inspecting carefully found a number of sections than needed replacing that I had not noticed when the gutters were still up. My initial plan was to replace damaged sections using PVC boards, then I comtemplated replacing 100% of the fascia with PVC to avoid mismatching and to better future proof. But after more careful consideration I decided to just replace the damaged boards with wood. My reasons were that wood does not expand length wise like PVC (which needs shiplap joints for expansion and contraction) and should work well enough as the wood damage I found was caused by improper shingle & drip edge installation and overflowing gutters, which should be remedied. And wood is a stronger material to hold up the gutters, though the hangers could be screwed deeper into the subfascia in either case.

Window Sill. I am replacing a rotten window sill (even though the weather is cold). It is a problem window that had its nose piece replaced with a PVC nose some years ago...which might have trapped water to accelerate the rot?? Now the sill and much of the surrounding rough framing is water damaged and getting replaced. I am planning to use a PVC window sill which along with new gutters should make it last a long time. I think this is the best approach, but I am concerned that there will not be any "early warning" if water ever did get back under the sill...as the window sill would look great while the subfloor could be starting to rot away. This is a brick veneer home so it is difficult to see and verify that the exterior water proof envelope is intact, I am able to insure it is water tight from the inside down to about the subfloor but there does not appear to be much if any space for water to drain behind the brick wall without it contacting the subfloor. The house has not had any problems in that area, but I expected to see a more obvious gap there behind the brick veneer, hence the concern.

Have you had any negative experience with using PVC boards on your home? If you have used them, would you use them again?

 

[ColtRevolver]

My house was built in the 1950s. It still has the original wood trimmed windows, fascia boards, ect. I have lived here 30 years. I have painted the woodwork twice.

 

[Whisky]

I don’t have a ton of experience working with PVC but the little I have hasn’t been great. My biggest complaints are that from a distance it looks ok but up close it just looks fake. I’ve also had an issues in the past getting paint to adhere to it, so if painting your house in the future it may be a consideration. Paint initially sticks to it and looks ok, but it can be scraped off easily with a fingernail. I thought it was my prep but after reading/following all the instructions and using the recommended products I still had issues.

 

[StillShaving]

Paint has held up well on a couple of PVC trim pieces installed over 5 years ago. One on the north side of the house that is always in the shade, and another piece which gets afternoon sun. Painted in an off-white color from Lowe's, with some type of Sherman Williams branded paint, so a decent quality paint but not top of the line.

But you make a good point about needing to use more care, as the PVC manufacturer recommends some special line of paint if applying a dark color. And I have read online comments from others recommending to lightly sand PVC to give it more "tooth" to hold the paint. The window sill I got is very slick, so it could be a challenge to hold paint over the change in seasons if some care is not used. Interestingly, my local Home Depot and Lowes stocks replacement window sills in PVC, but wooden ones need to be ordered.

 

[Rhody]

I wasn’t aware of the issue / need for the shiplap joint with pvc. Also my trim is white so I haven’t painted any trim boards and window trim I’ve had replaced with pvc. (White pvc checks all my boxes for quick and dirty repairs) I’ve had an issue with the east facing wood trim and fascia showing real damage and black areas that looked like mold or rot or whatever, just white paint looking terrible, so the pvc replacement has been perfect. My carpenter recommended pvc too and I will go pvc if any other boards need replacement.

 

[EclipseRedRing]

uPVC windows and trim are common in the UK, usually in white, occasionally wood effect, and recently an unfortunate battleship grey seems to have become popular. I do not think I have ever seen or heard of anyone painting the uPVC.

 

[StillShaving]

I am not familiar with the term uPVC, my comments so far have been about "celluar PVC" which is fairly solid but much more flexible than wood and when cross cut it has a slightly grainy or aerated appearance. Not the PVC/vinyl fascia wraps that I have seen used on some homes.

In my area I have noticed an increase in homes with dark trim, or something other than a light shade of tan, gray, or white. Unpainted PVC would be noticeable on my home, at least until pollen season or needing a power wash. haha

Regarding installation I found different information depending on the source. I think scarf joints can work if the runs are not long, but from what I could learn about best practices, ship lap was preferred to handle expansion and avoid exposing what was underneath. That a 1/8” gap per 18 linear feet was recommended, though that depends on installation temperature. Attached a screenshot of one page from the Royal (Westlake) installation guide for a better description. Where PVC cement is used on corner miters, and a flexible glue on the shiplap joints.

But when searching youtube one will find people installing it in different ways. There is a channel called "Stud Pack" where he uploaded a video named "Dead Straight Fascia on a Wavy Roof" where he did not follow these rules, in part because he was trying to solve an issue with an unlevel roofline. He installed his PVC fascia boards using plain butt joints, leaving a gap that he later covered in aluminum flashing. His reasoning was that the run was so long that he did not trust gluing up the joints. It was up on a second story, so adding such a visual break is probably not obvious to the casual onlooker. Contrast that to another demonstration from a professional installer I saw who used PVC cement and some special driver bit that left a round hole that could be plugged flush with a round piece of PVC, to give a seamless look.

 

[ctr]

If trim is painted and caulked routinely then wood is fine. But most homeowners don't. Leads to underlying rot in window and door frames and stud rot in some locations.

I replaced deteriorated wood trim with pvc as needed in my previous homes. No issue with painting. Prep is required like anything else.

The one downside to pvc is sawing. Nasty splinters and can't even call it dust. Wear a mask.

 

[Rudy Vey]

Our house was built in 1951. A few years ago, I had someone coming in and take a looks at the gable siding, soffits, fascia and frieze boards. They were wood and have been painted. There was a lot of rotten areas, so we decided to have them all fixed. The guy who did the work was a friend of one of our best friends, so I was pretty sure he was honest with me. Btw, our friend was an architect and this guy was his neighbor, friend and he used his services on several of his projects, so we were confident we get a good job done. Indeed, I am so glad that this was done. It looks much better and we chose to go with the highest quality PVC. Often one sees siding that has a lot of algae on it. Better quality PVC has something added that prevents the algae growth. I think we did this project 6/7 years ago, and it looks super, never had an issue with algae growth. I see here a lot of houses that were built maybe 3-4 years ago and one can see where the cheap stuff was used, lots of maintenance need to get rid of the green stuff.

 

[StillShaving]

To follow up, I did replace my window sill with PVC. When I removed the old finger-joined wooden sill I found that the house wrap underneath was not properly installed into one corner so the water damage was much worse than expected. But it was really my neglect as I had known for many months that a repair was needed and put it off.

I ended up replacing all the rough framing around the window down to the sill plate. This repair job was outside of my comfort zone, but with some research I was able to complete it. When reinstalling I was worried that water might find a path back underneath the sill but since the sill and nosing are now both PVC and cemented together using Locitite PL Premium (PL 3x) and having almost no exposed nails on the horizontal window sill surface the only path should be in the corners which have been copiously caulked. (I did shoot one or two nails too low down on the sill so that the closed window does not cover that I may come back and address later)

The most valuable tool for the job had to be the cordless Oscillating Multi-Tool (PBLMT50B) I bought as part of a Ryobi kit last year that included a "sawzall" tool which was also helpful. Doing slow and careful demolition to remove trim and studs board-by-board without damaging the neighboring structure would have been impossible without the thin oscillating blade to cut through nails.

 

[StillShaving]

Information like found in this article is why I decided to make all my fascia board repairs using wood, and window repairs using PVC.

Everything Moves | THISisCarpentry

www.thisiscarpentry.com

Where the shorter distances around a window frame would limit the expansion and contraction, as PVC has about a 10x higher coefficient of thermal expansion as compared to wood.

I think this was another reason why my window failed. As about 7 years ago I replaced the damaged sill nose. Replacing the wooden nose with one made from PVC. Resulting in a material "odd couple", that is wooden window sill that was decades old and probably with some damage out of sight in the corners with a brand new PVC nose cap that was impervious to water. So any water that did get into the old sill had no where to go, which accelerated the decay once it started.

Lesson I learned was to be careful mixing and matching PVC and wood in an area which will get wet. That this is really a bad combination for something with a long interface/seam like a 7 foot window sill nosing. And to use Liquid Nails Flooring (I believe that was the recommendation) at fascia joints that mixed wood and PVC fascia together. Which I might do to repair any rake fascia boards that come close to contacting the roof.