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A superior moisture barrier, which increases durability and reduces floor maintenance costs

Especially in climates with extreme weather conditions, water-based paint systems currently used to protect the underside of trailer floors can break down when subjected to intense water spray and road debris. Specific areas, like trailer wheel locations, are more prone to degradation.

Once water-based paint breaks down, the wood absorbs moisture, causing warping, swelling and deterioration of glue bonds. What’s worse: once the undercoating has been breached, water can migrate into the trailer itself, resulting in severe cargo damage.

PROLAM takes on the challenges of water-based paint

PROLAM’s P•u•R solution provides never-before-seen protection for wood trailer floors. The hot-melt polyurethane reactive P•u•R undercoating is used on the underside of laminated trailer floors and eliminates the degradation issues associated with traditional water-based paint undercoatings.

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PROLAM’s P•u•R undercoating provides protective features for wood trailer floors that standard water-based paint undercoatings cannot match, including:

  • .010" P•u•R thickness compared to a .0035" water-based undercoating.
  • P•u•R "bridges" wood defects, knots as well as critical areas, such as butt-end joints, providing a single uniform barrier against moisture penetration from the underside of the trailer floor.
  • P•u•R viscosity forms a perfect adhesion to laminated hardwood, creating a solid bond.
  • In sandblast tests, P·u·R was 11-times more abrasion-resistant than water-based undercoatings.


P•u•R can be applied to target areas most exposed to weather elements, like above the wheels.

A cut above traditional water-based undercoatings

Weather and elements weaken water-based paint coatings under trailer floors, leading to warping, uneven swelling stresses, and degradation of glue lines. Once the coating has been breached, water can migrate into the trailer itself, resulting in cargo damage.


Tensile tests measure the force required to break a sample material and the extent, measured in percentage, to which the specimen stretches or elongates to that breaking point.

Water-based undercoating elongation: 5%

P•u•R elongation:


Determines resistance to abrasion, or the ability of a material to withstand rubbing scrapping, or erosion; Measured by the number of cycles needed to create weight loss.

Water-based undercoating abrasion test: 20 cycles

P•u•R abrasion test:
225 cycles


Measures adhesion of an undercoating material to metallic samples by applying and removing pressure-sensitive tape over cuts made in the undercoating. Measured on a scale of 0 - 5, with 5 representing the least amount of lifting.

Water-based adhesion: Class 4

P•u•R adhesion:
Class 5


Measures amount of water absorbed after sample material is exposed to moisture; Measured in grams per 100-square inches.

Water-based absorption: 29.9 grams/100 sq. inch.

P•u•R absorption:
3.4 grams/100 sq. inch.

*Thickness of coating tested was 4 mils
**Empirical test
***24-hour exposure to water



With the P•u•R protection, the bottom side of the floor looks pretty much the same as it did 8 years ago!

These pictures show how the P•u•R solution looks above the wheels at the front and rear area of a Northeast trailer built in April 2006. The deterioration is minor: the hardwood is still fully protected and the glue lines of the laminated floor are not damaged at all!

These pictures show how the water-based protection looks above the wheels at the front and rear area of a Northeast trailer built in December 2006. The deterioration of the water-based undercoat is major.

90% of the protection is gone, leaving the hardwood and glue lines without protection.
We can see that the glue lines are starting to deteriorate, reducing the mechanical properties of the hardwood laminated floor.

Based with what we see on these two trailers, we can conclude—without a doubt—that after 8 years, the P•u•R protective barrier did not deteriorate. It still protected the bottom of the floor. Considering its condition after 8 years, there is no reason to believe that the P•u•R solution will not do its job. It will protect the bottom of the floor for many more years to come.