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Top 10 Questions about PVC Trim

1. Does PVC trim require a primer?

A primer is only needed if you want the paint manufacturer’s warranty. Excellent adhesion can be achieved by properly cleaning the board before applying a topcoat of paint to PVC trim. (Refer to painting guidelines in the Versatex contractor handbook for more information on painting PVC trim.)

A Note from the Publisher:

WARNING: POTENTIAL CONFLICT OF INTEREST!!

If you are sensitive about articles that seem to favor a particular manufacturer, then DON’T read this one!! It’s written by the President of Versatex! But after years of experience, I’ve found that some manufacturers know more about their products than anyone else; if a carpenter wants to learn the best way to install a product, sometimes the best source of information is the manufacturer. In the future, look for more carefully-screened articles from manufacturers.

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2. What type of paint do you recommend for coating PVC trim?

Just about any 100% acrylic latex, or 100% acrylic latex with a urethane additive, can be used to achieve superior coating durability and flexibility. Lacquers are not recommended with PVC trim because lacquers are a more brittle coating, and will not flex with any movement in the PVC trim. Paints like Duration by Sherwin Williams, Manor Hall paints by PPG and Moorelife by Benjamin Moore adhere well to PVC trim.

Paint on PVC trim will last three to five times longer than paints on wood or wood composites due to the absence of moisture in the substrate. Sherwin Williams also offers a field-applied coating under their “Green Seal®” product designation. Kem Aqua® BP Enamel is a water-reduceable polyurethane, acrylic topcoat that offers fast dry times and no critical re-coat times. Due to its excellent adhesion properties, it is an ideal coating for Cellular PVC.

3. Can PVC trim be painted dark colors?

Only light-to-medium colored paints—with a light reflective value of 55 units or greater—should be applied to PVC trim. For example, using paint with an LRV below 55 units will void our product warranty. LRV is measured based on color and its ability to absorb heat. Thus, an LRV of zero (0) is black, and an LRV of one hundred (100) is white. Don’t assume the paint is a light color. We have had cases where contractors believed that the paint they used was a light beige, only to find out it had an LRV in the 20s or 30s. Consult the paint manufacturer for the LRV of your paint before applying it to cellular PVC trim.

4. How long does it take the paint to cure on PVC trim?

That depends on the weather conditions. Warm/dry weather, or warm/humid weather, will allow the paint to cure faster than cool weather. It can take up to 30 days for paint to fully cure on PVC trim, because PVC trim is impervious to moisture. For the paint to cure, the moisture must evaporate through the surface of the coating that has skimmed over from drying.

5. What is the best glue for joining two pieces of PVC trim? What is the best glue for bonding PVC trim to wood? How about metal?

We recommend PVC pipe glue with solvent for bonding the ends of PVC trim boards to themselves (Weld-On 705 by IPS, TrimTight by Trim Glue, Inc. or Christy’s Red Hot). Be sure the PVC pipe glue has sufficient working time to allow you to apply the glue and push the boards together before it cures.

If you are looking for more of a structural bond at shiplap or scarf joints, miter cuts (window surround), or for gluing sheets of PVC trim, we recommend PVC TrimWelder. For bonding to wood, we recommend Liquid Nails Sub-Floor Adhesive or Heavy Duty Construction Adhesive. For PVC trim to metal, PVC TrimWelder Adhesive works best.

There are three types of PVC TrimWelder Adhesives. Slow and Fast Cure for field joints and small glue-ups, and Laminating Grade for sheet glue-ups. Slow Cure should not be used at temperatures below 40°F. Remember to apply any adhesive to only one bonding surface, thus allowing the adhesive to penetrate into the cells on the other trim piece.

6. What is the best fastening system for PVC trim that also hides the fastener head?

The best overall system for securing PVC trim is the Cortex Concealed Fastening System. It combines the advantages of using screws (strong connection) with the PVC trim tapered plug that fits into the hole created by the screw, thus eliminating the need for fillers or sealants to fill the nail holes. When comparing the cost of this fastening system to nails, keep in mind that you won’t have to go back over the trim filling in the nail holes.

7. What are your recommendations for dealing with expansion and contraction?

Use 8d stainless steel annular shank nails, or screws that are designed for wood trim, and are long enough to penetrate the solid substrate a minimum of 1 1/2 in. Simpson Strong-Tie makes an 8d nail with a 7d head in a 12-gauge thickness, available loose or collated, allowing it to be gun-nailed. The nail is called the “Trifecta.” It is half annular (tip) and half ring-shanked, and made from 316 stainless.

Screws are better for limiting the thermal movement of the trim. Allow PVC trim to acclimate to outside temperatures before installing. Bond PVC trim joints to prevent separation. Be sure to allow adequate expansion and contraction space at the end of long runs. If possible, decrease the on-center spacing between fasteners to 12 in. or less, and bond boards to substrate when practical.

Where you have an expansion joint, leave a full 3/16-in. gap when installing on a day where temperatures range from 30°F to 40°F. Leave a gap just large enough to accept a bead of sealant, or no gap at all (adhesive bond), when installing on a day when temperatures range from 80°F to 100°F. Shiplap joints are superior to scarf cut joints, especially on long runs.

If practical, install long runs of trim when the outside temperature and the temperature of the PVC trim board is 55°F to 65°F, in order to minimize thermal movement in the trim.

8. What is the best way to secure PVC trim to masonry?

Trowel the masonry with a sealant or adhesive to provide a level surface to accept the PVC trimboard. Then secure the trim to the masonry with Tapcon masonry fasteners.

9. How do I seal the open cells if I cut the PVC trimboard? Also, how do I clean PVC trimboards?

Handle PVC trim as you would a piece of premium lumber. Be careful not to damage the visible surface of the board. To seal cut edges or clean a cut edge that has gotten dirty, sand them with 320 grit sand paper, and then wipe the edges with Acetone—this will help to re-seal the cells.

To remove dirt and grime from the visible surface or edges of PVC trimboard, use Soft Scrub with Bleach, one of a variety of Clorox products (Clorox Outdoors, etc.), Mr. Clean Magic Erasers® with a little water, or Corte Clean, a composite deck cleaner that has been found to clean cellular PVC trim. As with any new product, try the cleaner in an inconspicuous area before cleaning the trimboards on your project.

10. What are the recommended sealants I should use with PVC trim?

As with adhesives, look for products that contain some type of solvent. NPC Solar Seal #900 Sealant/Adhesive in Trimboard white #111 has been found to be one of the best sealants for sealing and bonding PVC trim to itself, as well as many other substrates. Other recommended sealants include Quad and EP-1000 Enhanced Polyurethane by OSI, and Geocel 2300, or other polyurethane sealants. Do not use silicone sealants, as they are not compatible with cellular PVC trim.

Comments/Discussion

27 Responses to “Top 10 Questions about PVC Trim”

  1. David Stuack

    I have found that “Spray Nine” works great for cleaning PVC. Once in a while I will use paint thinner to get off small stubborn black marks.

    The big question I have concerns filling the nail/screw holes left after installation of the PVC trim boards. Because most people just want the PVC left it’s natural white ( and so avoid painting) it would be nice if someone made a white nail/screw hole filler that wouldn’t turn yellow. Any suggestions? Thanks.

    Reply
    • John Pace

      Good afternoon David:

      The very best solution for filling nail holes is the Cortex screw and plug. FastenMaster sells the screws and plugs as a system with a bit that countersinks the screw to just the right depth to accept the tapered Versatex PVC plug. Visit the FastenMaster website to find a dealer in your area. There are other companies that offer a stainless steel screw with a painted white head. A couple examples of these are Headcote and Simpson Strong Tie. Also, check out Simpson Strong Ties, white painted Trifecta nail it comes in 316 stainless. If you click the following links, you’ll be able to download some info on the Headcote and Simpson stainless steel screws with painted white heads along with a flyer on a white painted Trifecta nail offered by Simpson Strong Tie.

      I hope I have answered your question and thank you for the info on cleaning Versatex trim.

      Reply
  2. Matt

    This is a very informative article. I wish I had this last year … wondering if my previous PVC project will hold up, as I didn’t use any glue. I used a plastic putty to fill my screw holes and then sanded flush, hoping that seals properly.

    Reply
  3. Keith Preston

    I read with interest your admonition to not use silicone sealant on PVC trim. My PVC deck is sealed with GE Silicone I to the house stucco and I suspect the bond to the PVC will not be durable. It bonds better to the stucco. What sealant would you recommend for this type of joint? Polyurethane glue (Gorilla glue) bonds very well to PVC but it is (1) brittle and (2) (I suspect) degrades in UV.

    Reply
  4. Cory H.

    A very good article, I just wish I had found it a few days earlier as I also didn’t think to glue my ends together. Also appreciate the disclaimer at the beginning of the article stating who it was written by. Wouldn’t it be great if every news article you read was this up front and honest about their agenda?

    Reply
  5. adam

    So can water penetrate the open cells? I had to rip down some pvc brick mould for exterior window trim and I’m hoping I didn’t screw it up. I just siliconed all the edges…

    Reply
  6. John Pace

    Cellular PVC is much like a honeycomb. If you examined it under a microscope it will look like an array of cells in a random geometric pattern. When you cut, rout, mould or mill cellular PVC, you break open a layer of these cells but you do not affect the integrity of the entire cell structure of the cellular PVC board or sheet. This is why cellular PVC is basically impervious to moisture and has a moisture content value of less than 0.5% when tested in accordance with ASTM test methods. So to answer your question no water will not penetrate cellular PVC because the cells are not openned throughout the thickness just the surface cells that you cut are open. As for the sealant you used, I would recommend you stay away from silicones in the future. Although some commerical silicone sealants will stick to cellular PVC when a primer is applied most over the counter silicones that you buy at your local lumber dealer will not. The best sealants for cellular PVC are polymer based sealants containing a solvent. To determine if a sealant contains a solvent check the inside lining on the tube if it is a thin metal/aluminum wrap and if the cap is also metal then the sealant contains solvent. Examples of good polymer based sealants with solvent include Solar Seal #900 by NPC Sealants and Quad by OSI. We like the Solar Seal #900 for a few reasons it is as much an adhesive as a sealant, it stays flexible for decades and it carries a warranty that I believe is either 15 or 20 years. Check with the manufacturer on the length of their warranty and availability in your area. You can find them on the Internet. Just Google NPC Sealants.

    Reply
  7. Mark

    I have a job where I have to double up the thickness of the trim by using two 1x boards laid one over the other. To minimize thermal expansion, should I cement them together or will that exacerbate the problem? Thanks

    Reply
  8. John Pace

    Mark:
    Laminating two boards together is a very common practice and has no affect on the potential thermal expansion and contraction of the board. I also wanted to let you know that Versatex produces a true 1 1/2″ board and sheet. F you want to eliminate the material, labor and time to laminate two pieces of 3/4″ you might want to consider this new product thickness.

    Reply
  9. Tom

    I’ve read conflicting advice on cutting PVC trim and would appreciate anyone’s input. For circular saw blades some say to use a tooth count of about 40 (to avoid heat build up) while others say to use a 140 tooth blade (to ensure a clean cut). Insights on saw blades most appreciated as I’ve got about 500 feet to install next week. Thanks.

    Reply
  10. John Pace

    The answer is simple. The fewer the teeth on the saw the better. We recommend a carbide tipped blade with 32 teeth. However, 40 teeth will be just fine. The more teeth the greater the frictional heat build-up in the cut causing you to melt and potentially burn the cellular PVC.

    Let me know if you have any other questions concerning the installation of cellular PVC trim.

    Reply
  11. Tony Carey

    Hi I have a composite door about three years old, and the outside lamination is beginning to separate in three locations about two inches long each. Which adhesive would you recommend for repair the temperature range in Ireland is minus ten to 30 degrees centigrade. Any help would be greatly appreciated. The door is a Palladio door manufactured by Profile developments.

    Reply
  12. Russell

    John, what is wrong with using a silicone sealer to bond a long yet thin trim board (with those fake wood grain paper finishes) to a sheetrock wall? Silicone should hold tight — and– some day be removeable, without tearing into the wall as a glue will, and it likely will come off the wall in one piece, to allow use of the trim board again someday (once the back side is cleaned up and flat again).

    Reply
    • John Pace

      Silicone sealants or sealers are not compatible with cellular PVC and will not hold a board or sheet to a sheet rock wall. In fact I’m not sure what I’d use to hold cellular PVC trim to a sheet rock wall. No matter what you use as a base sealant, you still need to mechanically fasten cellular PVC to the frame of the wall.

      Reply
    • John Pace

      Yes you can definitely use cellular PVC trim and sheet indooors. Just because most contractors use it outdoors doesn’t limit its application. I have seen cellular PVC used in foyers, hallways, mud rooms, bathrooms, laundry rooms, basements and garages. The only recommendation I have is check with your building code official to see if there is a maximum amount of cellular PVC you can use inside a home. Typically it is listed as square feet per room. I don’t think you’ll exceed the maximum allowable value but just to be safe I’d ask my code official.

      Reply
  13. Jim Morrison

    Sir,
    I have a 1/8″ gap between 2 strips of pvc trimboard used as a drip cap above my windows. The carpenter & I used various caulking to seal it but they fell out. I have now used Ultima Caulking Sealant but when the hot sun beats down on it the caulking expands out of the crack. It stays intact but rises up about an 1/8″ out of the crack. When it cools off it goes back to its original shape but the process occurs again when it heats up again. Should I be concerned over this? Thanks

    Reply
  14. John Pace

    Good morning Jim:

    First please call me John. Sir sounds too old for me.

    As I read your e-mail below, my first question is why are you getting so much movement between two boards used as a drip cap above a window? What are the lengths of the boards and what type or nail or screw was used to install the PVC trimboards? Do you happen to know what the temperature was when the boards were installed? That information will allow me to determine why the boards are moving?

    Now on to your questions. Ultima Caulking Sealant is a compatible product that will bond well to cellular PVC. The reason is because it has a solvent base that chemically breaks down the PVC and fuses to the trim. Other caulkings that are similar to or better than Ultima are NPC’s Solar Seal 900 and Quad by OSI.

    The sealant is moving up and down as the PVC trimboards expand and contract. There is no need to be concerned about this since you used a good caulking/sealant in the joint. The reasons the other caulks fell out is most likely because they were not solvent based. The way you can tell a the difference between a tube of sealant that has solvent in it and one that does not is by the tube and plug. If the tube and plug in the tube is plastic the caulking is not solvent based and will not bond to cellular PVC trim. If when you look at the bottom of the tube and see a metal foil lining the inside of the tube and a metal plug, you know the caulk/sealant is solvent based and will give the best bonding results with cellular PVC.

    In the future, to minimize movement between the two boards I would use a better nail (8d), or screw (Cortex screw and plug system). How I apply the caulk would depend on the time of year and the length of the run. In your instance, I can’t imagine the run was more than two boards (36′). If this was the case and with proper installation, I would have ship-lapped the ends of the boards and glued them together. I did a project this past summer on my home where the trim run was roughly 33′long. The install temperature was probably around 70F, the low reached -16F in Pittsburgh for a couple of weeks. The gap in my trim never got to be more than 1/32″ or less. Interestingly the gapping in my Miratec and wood trim was as much as 1/8″.

    Let me know if you have any further questions concerning cellular PVC trim.

    Reply
  15. debbie

    What should I have used to fill in the screw holes in my pvc trim? The chalk my carpenter gave me turned yellowish even after I had it painted.

    Reply
  16. John

    Debbie:
    If installing cellular PVC trim with screws, I’d use Cortex screws and plugs it eliminates the need and use of nail hole fillers. If you plan on painting the trim, use any vinyl spackling. One type that is commonly used by contractors is Crack Shot by DAP. You’ll find it at any local lumber dealer location. Are you sure the yellowing is from the caulk? My concern is the contractor used galvanized screws and the galvanizing has peeled off exposing the steel screw which is now coroding. I’ve seen this happen before. If the issue is truly the caulking yellowing, it must be a very poor performing sealant. The best sealant for use with any cellular PVC trim is NPC’s Solar Seal 900. It is both an adhesive and sealant with excellent long term flexibility, weatherability and paintability. It also bonds exceptionally well to cellular PVC trim and comes in a wide array of colors.

    Reply
  17. BrentF

    I scanned through the various Q & A of this thread, but didn’t see an answer to this:

    I have Versatex cellular PVC trim on the exterior of my cottage. Last winter one of the trim boards sustained a fairly deep gouge (3/16″ deep) from a falling tree branch. This trim board would be very difficult to replace. What can be used to repair this gouge?

    Thank you.

    Reply
  18. John

    Good morning Brent:

    A small ding or dent can be removed with a heat gun. It will activate the residual foaming agent in the cells of the product and cause it to raise much like a cake repairing these small dimples or dings in our trim. In your case, a 3/8″ gouge is most likely too deep to raise up using a heat gun but you may want to try it first beofre filling the void. Any filler you use is going to require you to paint the boards since no filler is an exact match to our trimboard or anyones trimboard for that matter. Here are some possible fillers. TrimWelder by Extreme Adheisves, PVC TrimWelder Nail Stick, vinyl spacklings like DAP’s Crack Shoit and others and even Bondo. Although I’ve heard both good and bad results using Bondo as a filler with cellular PVC. You can find any of the above products on Google. Good luck and thanks for using Versatex PVC trim.

    Reply
    • BrentF

      Thanks John for your fulsome answer.. The gouge is 3/16″ deep and not 3/8″, so my chance of success with the heat gun approach is better than otherwise. I will certainly try this approach. Sounds like the cellular PVC equivalent of using a steam iron to fix a gouge in wood.

      One question: Is the heat gun likely to cause discoloration?

      Reply
  19. John Pace

    Not if you do it correctly. Just wave the heat gun or commercial hair dryer over the spot you are trying to raise. Don’t put it in direct contact with the Versatex trim. You should notice results in less than one minute. If not, then you’re going to have to use a putty and most likely paint the board.

    Reply
  20. Steve Wailes

    I plan on using 1×8 PVC boards as a ledge, 2 sides of an old clawfoot tub, sloping slightly into the tub. I will need to cut the board into a curve to match the tub (likely using a jigsaw on slow speed). Edge will be rough sanded with a belt sander on slow & finished with 320 grit by hand, and the new finished edges resealed as you’ve mentioned 2012 article.

    Questions:
    1) What tpi (tooth per inch) jigsaw blade would your recommend for cutting the curve?
    2) Can a Router be used to:
    2a. provide a drip kerf on bottom edge of new curved edge, &
    2b. provide a rounded-over edge on the top side, say 3/8″ rad.?
    3) I will be bonding various pieces together with PVC pipe solvent/cleaner & cement, but want to seal the edges to an existing old lath & plaster wall. I’ve used a polyurethane sealant (ie Vulkem) to seal PVC Trim on exterior projects in the past, seems to be holding up well, & wondered if it would work here?

    I would appreciate your response directly to me, but you’ve my permission if you wish to include in the questions attached to the article. Thanks in advance. steve

    Reply
  21. J

    Can versatex be bent to accommodate a circular patio? Thank you for your helpful information.

    Reply

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