What is Delamination?
What you should know about the dreaded “Delam”
What is Delamination?
Google defines Delamination as “a structural failure where a material fractures, splits, or peels into separate layers. It is commonly caused by weak adhesion, mechanical stress, or environmental exposure“. We concur.
Some believe that water intrusion is required for delamination to take place. While this is indeed one cause, delamination can occur due to a number of reasons: poor glue coverage or workmanship; subpar quality in adhesive or substrate; frequent and/or extreme temperature fluctuations; and harsh weather conditions. Any one or a combination of these can initiate and accelerate delamination. Let’s take a deeper dive into these causes.
Each image below shows a clear example of delamination. The exterior FRP layer has separated from the wood (lauan) layer behind it.
Water Intrusion
Water intrusion in an RV is any unwelcome penetration of water or moisture, usually into the roof, walls and floor. This is never a good thing but it’s particularly bad when these structures are made of wood.
Wood will soak up and hold water, causing many problems. A slow breakdown of wood fibers and the adhesive that holds lauan plywood layers together is common. Also expected is the growth of mold and mildew, a musty odor, warping of the wood itself, the overall degradation or rotting of any structure that experiences prolonged exposure, and yes, delamination.
This type of delamination is usually due to a combination of:
- Wood warping (or rippling, as seen in the photo)
- Breakdown or rotting of the wood fibers.
- Breakdown and reduction in the adhesive bond between the wood layers themselves and the bond between the wood and the exterior FRP (fiberglass).
Click these links to learn about Azdel’s water resistance, mold testing and resistance, and water soak testing which proves an Azdel bond’s superior ability to withstand prolonged exposure to water.
Subpar Substrates
Adhesive brands and types vary in the RV industry, but manufacturers generally use one that is proven to work. Some substrates, however, are proven to not work or not last. In construction, a substrate is any surface or base layer on which something else is adhered to, laid on or otherwise added to.
In the case of RV walls, we consider the backing layer behind exterior FRP the primary substrate. Whether it is wood, another composite, or something else entirely, using a substrate of poor quality is asking for trouble.
A subpar substrate may degrade for a variety of reasons, some of which are included on this page. Its makeup or inherent structural integrity may be lacking, or it may not be a good match for some glues.
On several of our Testing pages, we explained how we demonstrated and proved that not all composites are created equal.
We saw layers of a competing composite easily peel off, as both videos above reveal. We saw significant inconsistencies in bond strength among other composites, even within the same composite sheet. And we saw other composites, as well as their bonds to FRP, weaken during each of a variety of strength and durability tests. This is not what RV owners want from their unit.
This is why it is crucial that manufacturers thoroughly test materials before adding them to their units, and why Azdel Onboard is at the top of the list for proven durability.
Walls made with Azdel have proven over 20 years to maintain their bond strength and structural integrity, and they’re still going strong today. This lasting ability and peace of mind is what RV and trailer owners want and expect.
Temperature Fluctuations
We encourage you to visit our page on Temperature & Humidity Resistance for a thorough explanation of the movement and expansion of materials during hot and cold cycles.
In short, during cycles of fluctuating temperature and humidity, such as those experienced on cool nights and hot days, wood expands and moves to a greater degree and rate than do both Azdel and FRP. This leaves wood fighting against the layers glued to it, both fiberglass and foam, continually weakening the bonds.
On the other hand, because Azdel composite has a fiberglass base, this and FRP are much more in sync with any movement, which is already a lesser degree than that of wood. So these layers combined to create the exterior skin expand less, move less and do not fight each other. That’s a winning combination!
There is a bit of an overlap between the concept of fluctuating temperatures and that of exposure to extreme temperatures, which we’ll touch on in the next section.
Environmental Conditions
Environmental conditions that may cause or accelerate delamination include prolonged exposure to high temperatures, extreme or rapid changes in temperature and humidity and, of course, rain. Rain would be covered in the water intrusion section above, and fluctuations in temperature and humidity were just explained as well. Please see our Environmental Testing page that prove Azdel’s superiority after being subjected to these conditions. That leaves high temperatures.
View of Sun Load Test from rear of IR lamps
High Heat
High heat can be a problem for various materials, and prolonged high heat is even worse. Glass is a good thermal conductor so, naturally, fiberglass can generally transfer heat from a source to another adjacent material.
We have a dedicated page to explain the Sun Load test, but after high heat is applied evenly to competing wall samples, the Azdel wall remained virtually unaffected, while the other experienced melted foam from the transfer of heat through both layers of its exterior skin. This weakened its bond significantly.
Here is yet another example of Azdel preventing delamination while another material helps cause it.
Left – Azdel Right – Competitor
“About two months ago I Inspected a 2014 Class C RV built with Azdel in the walls. Upon inspection I found serious voids and cracks in the roof sealants. In addition, these cracks and voids were in critical areas. In my opinion, this unit should have had serious delamination issues in numerous areas, but it did not have any — not one. I am now definitely a believer, and it is my opinion that Azdel is superior to other materials in this application, and my next RV will have Azdel in the walls.”
RV Inspector (T.M.), January 2021