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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

14 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

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