Fiberglass vs PMF cost estimation

[Terra6]

I have wondered this question myself as to the real cost difference. We have many builds with lots of technique info but not as much on the cost side. I've never used fibreglass except for small repairs so no knowledge there.

But my PMF is getting there. Am in the midst of covering my trailer due to plywood blistering issues on some of my heavily painted panels. The plywood is blistering in random sheets.

Here is my current cost breakdown for 350 ft2 of surface area, my 6.5x16 trailer. More details on my build thread fyi.

$125 of paint. Going to take me about 2x 5 gals of oops paint to glue and recoat the canvas. $30 per 5 gallon which isn't 5 gal anymore btw. And 2 gallons of a finish top coat paint color at $30 each.

If one were to use primer and or TB2 for the adhesive, the cost will obviously be higher. Can't get cheaper than $6/ gal of oops paint as glue and the adhesion is acceptable. Assuming that the application usage rate is similar, which may not be the case.
I'm coating both cloth and surface with paint to adhere at layup btw. IIRC from Terra6, even diluting TB3, used allot so don't think
It's less in quantity or cost from my experience.

$52 of 10 oz.dropcloth canvas from HF. 4 - 9x12 at $13 each. Regular $15 but use the 20% coupon comes out to $13.09 with tax.

So at $175 total cost, this comes out to $0.50/ ft2.
Actual cost will be slightly higher due to ancillary like staples, rollers and brushes but the above gives an easy number to work with.

Now if some one has recent total costs of fiberglass, we could make a direct cost comparison.

Imho, for PMF to be considered a viable economical option, it would have to be about half or less the cost of fiberglass to be worthwhile. My logic argument is that if coating 350ft2 costs me $200 PMF, what's another $200 for a much stronger and more durable fiberglass? And $200 is nothing in the overall cost of most build. More than double makes the value proposition better for PMF from my perspective except for extreme low cost budgets.
There are other considerations as well but would only side track this cost discussion.

[tony.latham]

Now if some one has recent total costs of fiberglass, we could make a direct cost comparison.

Raka 6-quart epoxy kit: $103
Epoxy pumps: $10
Gloves & squeegees: $10
7 yds, 2 oz glass cloth for walls: $24.50
5 yds, 4 oz glass cloth for roof/hatch: $32.50

$180 (for a 5 x 10'.)



No peel testing needed. PMF needs a name change. Maybe GC for glued cotton.

Tony

[Terra6]

Great info, Thx Tony.

Couple questions;

What's the per ft2 cost as missing info on cloth and trailer width.

Does the epoxy require a top coat for UV protection, if so would have to add that cost.

Is there adhesion issues to foam or plywood thus requiring extra processes and cost? Read that fiberglass doesn't adhere well to plywood and will lift. Don't know if that is poly or epoxy resin.
Thx.

[tony.latham]

Couple questions;

What's the per ft2 cost as missing info on cloth and trailer width.

Since I don't know the square footage of my teardrop-shaped side walls (4 x 10), I can't say. But it's a 5 wide. But lets just say it's 214 square foot ÷ $180 = $1.18.

Does the epoxy require a top coat for UV protection?

Yes, but the cost of that varies considerably on what you use. I used Monstaliner and it's spendy.



You could use spar varnish for the woody look or an oil-based enamel. Since both glass and PMF need a topcoat, perhaps that shouldn't be in the equation.

Tony

[Terra6]

Yeah many variables for top coat.
Simple choice with PMF.
My $0.50 ft2 cost includes top coat.
Would be $0.33 ft2 without top coat.
Actually $180/214 is about $0.84 ft2

On a 200ft2 project, the cost is $70 PMF vs $170 epoxy. Or $100 difference which isn't huge in the probable overall cost of the project. Imho the price difference isn't much overall and PMF is advantageous for the extreme price conscious with a simple max low budget build. If your going to the trouble of building something with lots of hours, more durable skin worthwhile.

With fiberglass, could you use house paint for an acceptable finish for adhesion and durability? In which case they would cancel for top coat.

[Terra6]

Actually a 4x5x10 gives 170ft2.
$180/170 = $1.05ft2

PMF approx 1/3 the cost.
Insignificant really on a small build for the extra cost of fiberglass. And even with a larger build, the extra cost is still a small percentage of total build cost. The cost difference will probably be small compared to what you're going to be paying for the things you will be putting in the rig.
Appears to me basic and thrifty build with PMF are worthwhile. Spend a little more and get more durability with fiberglass which will be worthwhile if you're spending more time to build.

Imho of course.
Your mileage may vary.

[GPW]

It’s so NICE to have a choice !!!

[Terra6]

So I've been contemplating the aspects of the question some more.
PMF vs fiberglass cost. Here's an analysis with caveats and realities.
PMF is cheap in cost, has durability equivalent to paint and the strength of cotton canvas fabric which i consider acceptable for the cost. It can be very inexpensive as an available weatherproof coating IF you can get cheap low cost mistint paint and canvas.
Paint reality. Mistint is available frequently at HD and Lowes. I've also bought some at Walmart and Ace hardware. Having all of these close by when I've had painting projects made this option possible. But for those who don't, could be a long time before it's available and not a realistic option.
And it's cheap mistint paint which makes PMF cheap and valid. If one were to pay full retail for paint, PMF would not be attractive or cheap as Tony has mentioned.
And if your using a full cost Primer and or Gripper, have to ask how much that total cost will be. Could end up costing more than fiberglass with inferior qualities of strength and durability.

But if you can get the paint for a fraction of it's cost, can't be beat. And interestingly, just last week on Craigslist, someone was giving away 10+ gallons of leftover renovation paint for free. Would have jumped on this if I hadn't already bought paint.
Now it's unusual and infrequent but if you search for a deal, patient and keep looking, can be found.
Canvas is the same thing. HF close by so cheap and convenient, works out to $0.14 ft2 for 10 oz fabric and can be ordered online.
As I'm currently completing a project, will have the final cost and details on my thread for PMF.

[GPW]

Consider a good part of the Foamie philosophy is The Fine Art of Salvage … “ Thrifty Alternatives” …

[rruff]

PMF is cheap in cost, has durability equivalent to paint and the strength of cotton canvas fabric which i consider acceptable for the cost. It can be very inexpensive as an available weatherproof coating IF you can get cheap low cost mistint paint and canvas.

PMF is a nice heavy duty coating, but it's nothing like fiberglass... they really aren't comparable. FG is much stronger, harder, lighter (for the same durability) doesn't creep, etc.

I see people using $100/gal epoxy in comparisons. I've been using $30/gal epoxy from Ebond and I'm quite happy with it. Shipping across the country (from FL) adds ~$15. It's about the same price as Titebond...

FG cloth isn't that expensive either. I've been buying from Thayercraft and FiberglassSupply. Cost of cloth and epoxy for 10oz cloth (50/50 weight ratio) is < $1/ft^2. I'm building a big camper and using ~33oz of cloth in each skin, though... each skin weighs 0.50 lbs/ft^2.

[tony.latham]

I've been using $30/gal epoxy from Ebond....

I just bookmarked their page. Thanks.

Tony

[GPW]

It all comes down to what YOU enjoy using !!!!