Azek, Shaper, Lock miter?

[Mark Bolton]

Working on a project for a customer which includes three sided wrapping some engineered beams (LVL's) with Azek and some matching four sided columns beneath them. For the beams and columns I had planed on running the wraps on the shaper with a lock miter as we are in hopes to leave the wraps and columns with no raw edges showing (if we were but jointing) and unpainted.

We had planned on milling all the bottoms of the wraps identical (imagine the bottom of a square sided "U") and all the sides (verticals) identical. This way the parts would be interchangeable. The engineered beams, supporting a roof, are to be in an "L" shape with one leg being 27' and the other being 23'. Columns will of course be spaced along these spans.

I have a few concerns. One is how difficult will it be to assemble these wraps in the field and keep the lock miter, which will be highly visible, dead tight and clean. The Azek will come in 17' lengths but I am not intent on running them at that length however I will want to stagger the seams. Two is keeping the material clean while running it. I am not sure if the table or the feeder will scuff or mark up these boards requiring painting. Third is that there will of course be butt joints along the length of these wraps (columns will be one piece per side) as well as an inside and outside miter at the "L". These will simply have to be but joints as that is what the manufacturer requires for expansion and contraction. I would rather not land these but joints over each column. Painting is not out of the question and will be required eventually however best case would be to avoid it for as long as possible.

Just looking for any heads ups on the lock miter idea and perhaps any input from anyone who has perhaps run any PVC trim.

I have a feeling we will have to paint but I am holding out hope.

Any input is appreciated,

Thanks,
Mark

[Robert Reece]

Lock miter sounds like complete overkill for exterior trim with Azek.
I did some butt joints on my house with Azek. The raw edge is definitely different looking than the face so it sort of stands out. However, I just painted the raw edge once and it looks a lot better. On that raw edge, the paint really soaks in so I think it will be there forever.

The guys that did my porch columns had a good idea. Instead of trying to keep a tapered miter together, they just made a small dado on the edge. It looks good and you don't have to worry about that fragile outer edge of the miter.

Also, where we wrapped the beam above, we just ran the face board long. Eliminated the whole problem of a miter. I'll get a picture here in a minute.

[Brice Burrell]

Mark, I install a ton of Azek every year. I agree with Robert about the lock miter being overkill. I always paint Azek. Filling nail/screw holes, glue joints, scuffs and other damage during the install are a few things to consider. I always end up needing to sand areas either for alignment or filling holes. The sanded areas lose the somewhat glossy sheen of the raw material. Plus, paint resists mildew much better than raw PVC will. I think you'll be better off with butt joints and painting.

[Michael Prisbylla]

I used to work at a company that used a lot of azek in their products. I'm on board with the butt joints and paint idea. No sense making it more complicated than it has to be.

[Mark Bolton]

Robert,
Thanks for the input. I understand exactly what you are saying with regards to a rabbet in place of the miter therefore minimizing the visible edge of the azek. That said, there is still an edge.

We have worked with Azek and similar products, Permatrim, Versatex, Trimtex, and so on, for many years. I am in complete agreement that once painted these products will likely hold paint for a decade or more. For a few reasons, on this particular project we were trying to avoid the painting and also the visible edge.

We have done several large jobs in PVC trim that were done clean and left unpainted and to this day, well over ten years later, still look as good as the day they were installed.

That said, if everything doesnt go perfectly in milling and installation, they must be painted, as the porous edge of these PVC trim boards is very easily made dark/dirty with a swipe of a dirty finger while caulking or many other problems. These edges also dont age nearly as well as the faces of the boards. As I mentioned, painting is inevitable, but staving it off for as long as possible generally our aim.

On this project I was hoping to head for a very clean wrapped surface with the columns being as close to a PVC post sleeve but being much larger. The wraps above would need to match.

Mark

[Mark Bolton]

Brice,
Thanks for the input. We too have dealt with the issues you mention. That said, on several high end jobs we have taken Azek and similar materials (other reply) to a point where installing them extremely cleanly and using urethane caulks we have gotten them in dead clean without painting. I was hoping to perhaps pull that off in this case as there are other elements on this house which we have done years ago in this manner. Given the wraps this will be a bit more involved.

Using the urethanes with these materials allows you to polish the caulk joints out like a gasket leaving them as smooth (in fact smoother and with more shine if you choose) as the trim board.

As you mention however, any misfit, scuff, etc., and your screwed.

Guess I will keep kicking this around....
Mark


Mark, I install a ton of Azek every year. I agree with Robert about the lock miter being overkill. I always paint Azek. Filling nail/screw holes, glue joints, scuffs and other damage during the install are a few things to consider. I always end up needing to sand areas either for alignment or filling holes. The sanded areas lose the somewhat glossy sheen of the raw material. Plus, paint resists mildew much better than raw PVC will. I think you'll be better off with butt joints and painting.

[Robert Reece]

Here is a pic of how we trimmed my porch.
Sorry about all the cobwebs :o.
You get the idea.

On the other hand, I made some of my backporch parts out of 1.25" Azek sheet material. It routed absolutely beautifully and I didn't paint it. The round over is somewhat porous, but I just spray it with a light coat of bleach. It turns up looking great.

I do not believe Azek ever has to be painted and I wholly dispute the claim that painted stuff resists milder better. In fact, my soffit is painted plywood and rakes and fascias are Azek and I can tell you I wish I had Azek soffits because of the mildew.

So I say butt joint and clean it with bleach instead of painting.

I also used square drive trim screws with white painted heads (called HeadCote at McFeelys.) They are nice screws. I put them in 16" on-center so they looked decent and I didn't fill them. It works fine for me, though I probably wouldn't do it on something like my front porch. There I used real wood.

[Mark Bolton]

Robert,
Thanks for the image. Very nice. I think the rabbet/reveal of that post would work very well if we were planning to paint. Its definitely a good solution.

I guess at this point I will have to run some test pieces to show our customer.

Thanks very much for the image and input,
Mark

[Paul Incognito]

Mark,
I have mitered the outside corners in the porch columns I've trimmed. I just run the pieces through the table saw.
In my opinion, there's no need for the lock miter, as the azek glue, once dry, will hold everything together nicely. I generaly install the first piece a tiny bit over the outside edge and then just clean up the overhang with a rasp. If this is done before the glue sets, the shavings will even fill in any imperfections in your miter.
Of course you'll be doing this overhead, so it'll be much harder.
I haven't had any luck with installing and not needing paint. If you have a way to make that happen, it would be great if you'd share the details with us.
PI

[Ed Griner]

I use a whiteside LM bit to make large comtemporary chair legs.These legs are 8" square all sides equal,what I discovered: All plank thickness MUST be the same and opposing sides(if unequal) MUST be the same width. This is a great idea for your project,this joint(when dimensions are correct)just gets glued,snapped together and clamped.Don't count on pre-milled lumber to be correct,close won't do it.This joint looks great when complete.

Good luck/Ed



*****Be come a contributor for less than $.02 a day

[Larry Edgerton]

I run Azek through the shaper to do lock miters. I disagree it is over the top. It makes it a lot easier to put together as the material is so floppy. Long supports are necessary and the power feed needs to be set agressively.

If you are quick you can use plumbers pipe cleaner to clean up stains on Azek, but you have to be quick. Try it on a peice of scrap first, you only have a few seconds before it starts to go too deep. Just a couple of quick swipes and leave it alone, it will dry back to its original surface in about a minute.

I hate Azek myself, but I figure we have just seen the beginning of this kind of product so we may as well get good at it.:rolleyes: