Vinyl Structural Properties 101

I’m going to be evaluating the deflection of some vinyl window frame members. This will be my first time working with vinyl and I’d like to solicit some general advice from anyone that might be familiar with it as a structural material.

  1. Are vinyl material properties highly variable such that, like aluminum, one really needs to pin down the manufacturer’s material specification?

  2. Is vinyl a material that undergoes significant creep?

  3. Does UV exposure degrade vinyl’s material properties?

  4. Does vinyl weaken when exposed to the light of a full moon?

Like I said, I’m a newborn struggling to stand when it comes to Vinyl. I’ll take anything…

Note that I’ve simul-posted this over at Eng-Tips too so, for anyone working over there, know that I’ll see that too.


@KootK Answers that I can provide…

  1. Yes

  2. Yes It also has a high coef of linear thermal expansion

  3. Very much so… it can be stabilised with UV screens so it can last 100 years or more.

  4. I suspect that if not treated, the reflected UV may have some effect… but, maybe over a real long time.


  1. Only if it’s been bitten by a werewolf

I understand that garlic acts as a UV screen…


@KootK Your vinyl structural properties on Eng-tips has been removed. Not likely at your request.


Darn. I wonder if that was because I mentioned SE. Regardless, thanks for the update.

@KootK Can you post a copy of what your signature was?


@dik There was no signature per se. It was identical to the post that began this thread except that, in the last line, I linked to SE instead of Eng-Tips.




Agree with Dik’s answers on vinyl. Similar applies to almost any thermoplastic or thermoset material.

I did a forensic report about 20 years back… the farmer had a cow barn with PVC panelling that was buckling all over… it was terrible. The product was installed completely different than the manufacturer’s printed recommendations.

The other engineer was one of the best forensic guys in town and he worked with the first company I ever worked for… he had all sorts of excuses, but, missed the installation feature… I don’t know how it turned out… was headed for court and I was never asked to testify… Studied up on vinyl materials at the time.

In the report I noted that the original investigation failed to note at specialty items are often installed in accord… and that this is essential.


Has the penny dropped?
Is this the thread deletion that was the topic of discussion at the RT?
Lots of speculation but no answer from Skylar as I recall.