Pre flight foamie build sanity check...

Canvas covered foamies (Thrifty Alternatives...)

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Re: Pre flight foamie build sanity check...

Postby RJ Howell » Thu Sep 19, 2019 2:08 pm

tony.latham wrote:
So the question becomes are you for $200 only doing the exterior? Also your cost of finishing over should be added.
What is your cost with both these added in?


The cost of adding paint for either PMF or fiberglass should be similar. I used Monstaliner, but it's expensive. I could have used two quarts of enamel or about $50.

And yes, that's only the exterior. I build with wood... so it's already finished inside.

T


Well, actually not and may be just where the cost difference applies. I gave you my costs to PMF, finish painted, inside and out, because it's part of the system.
Whether TB2 or primer is used the waterproofing is in the final top-coat. So to be fair, by the numbers I showed you, My cost on exterior alone would be $92.50.
That's with high quality paint at 'my pricing'. Now depending how you source your canvas or paint, that number could be easily reduced 75%-50%.

That puts me at half your cost. Is sourcing cheaper paint worth it.. I don't know, yet that could be much less than your costs. I didn't and went for quality. I want it to last!

Then it comes to " I build with wood... so it's already finished inside". Well, something happens there. More of the resin stock you have? This is important if we wish to compare for the OP.
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Re: Pre flight foamie build sanity check...

Postby Pmullen503 » Thu Sep 19, 2019 2:32 pm

Looking back on my notes, my 4x10' with canvas (from Big Duck Canvas) plus TB2, plus paint was around $250. You could save some by doing the inside with cheap bed sheets but I'd stick with canvas on the outside. Drop cloths might be cheaper than canvas, but the finish isn't as good.

I probably could have done it with one layer of 6 oz E-glass and cheap epoxy for maybe $350. One layer of 6 oz cloth would be the minimum I would use, 2 layers would be better but then more resin too. The resin I like to use (Matrix Adhesive Systems) would add another $100. You need to add some for disposables; gloves, brushes etc. Over foam you'd want to paint so you have that expense too ($50?)

PMF isn't free but it costs less than epoxy/glass. You have to remember on a foamie you need to do the inside as well which doubles the area you need to cover.
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Re: Pre flight foamie build sanity check...

Postby dbhosttexas » Thu Sep 19, 2019 2:35 pm

RJ Howell wrote:
tony.latham wrote:
So the question becomes are you for $200 only doing the exterior? Also your cost of finishing over should be added.
What is your cost with both these added in?


The cost of adding paint for either PMF or fiberglass should be similar. I used Monstaliner, but it's expensive. I could have used two quarts of enamel or about $50.

And yes, that's only the exterior. I build with wood... so it's already finished inside.

T


Well, actually not and may be just where the cost difference applies. I gave you my costs to PMF, finish painted, inside and out, because it's part of the system.
Whether TB2 or primer is used the waterproofing is in the final top-coat. So to be fair, by the numbers I showed you, My cost on exterior alone would be $92.50.
That's with high quality paint at 'my pricing'. Now depending how you source your canvas or paint, that number could be easily reduced 75%-50%.

That puts me at half your cost. Is sourcing cheaper paint worth it.. I don't know, yet that could be much less than your costs. I didn't and went for quality. I want it to last!

Then it comes to " I build with wood... so it's already finished inside". Well, something happens there. More of the resin stock you have? This is important if we wish to compare for the OP.



Just for my build, my only intent for wood is going to be to reinforce areas that have to support torsional forces such as bracing the back wall to suport the AC, and the lower lip of the shell / camper where it mounts to the truck , and of course along the sides to allow for holding screws for the awnings and windows...
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Re: Pre flight foamie build sanity check...

Postby dbhosttexas » Thu Sep 19, 2019 2:46 pm

Okay so let's look at the costs...

And of course assuming let's say 8 sheets of 1.5" XPS foam.

8 sheets foam @ $24.72 each. $197.76 Home Depot.
2 gallons (?) Titebond II $20.02 each. $40.04 Walmart
4 bottles 4oz Gorilla Glue original $5.97 each $23.88 Walmart
2 gallons Exterior enamel "oops" paint. $5.00 / gal $10.00 Ace Hardware. I can if I pick carefully, get one tinted to come up with a dark beige that will work with my truck cosmetically.
72" 1,5" Stainless Steel piano hinge. $11.99 Amazon.
1/2" plywood, and 2x2 (ripped from 2x4 stock) $Free, I can source up what I need as discards from construction sites.
2 1x4 pine 14' $4.98 each $9.96 Home Depot.
Kwickset residential lockset. $Free. I have a couple of spares left over from remodels.
Canvas. ????? How much, how to source it, go easy on the budget please!
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Re: Pre flight foamie build sanity check...

Postby RJ Howell » Thu Sep 19, 2019 3:00 pm

dbhosttexas wrote:Canvas. ????? How much, how to source it, go easy on the budget please!


What Pmullen503 did seems equal in cost to what the HF canvas costs, yet much better material (and maybe better sizing). I wish I had caught onto this sooner. Even if a few dollars more, still seem s worth the cost for better material. I have had several pills and strands to deal with using the HF stuff. You may wish to follow his lead if you decide to go PMF.
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Re: Pre flight foamie build sanity check...

Postby tony.latham » Thu Sep 19, 2019 4:58 pm

My cost on exterior alone would be $92.50.


Thanks, I missed that.

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Re: Pre flight foamie build sanity check...

Postby Pmullen503 » Thu Sep 19, 2019 5:20 pm

The canvas I bought was either 7 or 10oz 72" wide cotton canvas from bigduckcanvas.com. Current price around $4.50yd. I bought about 20 yds. It came on a big roll.

How much you'll need depends on your exact size and shape. I did mine to give the fewest overlaps. I ran my seam down the center of the roof. The side pieces don't quite meet in the middle of the roof and that was covered with a foot wide strip of canvas. I have a front and rear hatch so the seam is just on the top of the roof.
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Re: Pre flight foamie build sanity check...

Postby pchast » Thu Sep 19, 2019 8:47 pm

I used 20 yards of 4 ft wide 10 oz big duck canvas. on sale at 3.60 per yard
and should have bought 25.... for my 4x8 TD. lapped the top from the sides
then the top was a couple inches down the sides.....
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Re: Pre flight foamie build sanity check...

Postby GPW » Fri Sep 20, 2019 4:58 am

Having experience with both …. each has advantages over the other, but PMF , once covered , then you paint it … with fiberglass , once you cover it , you start Sanding ( lots of sanding) , then filling , and priming , , then painting … The costs may ( or may not ) be similar , but the Labor is waay different …and then there’s the smell and toxicity … PMF you can do in your living room ( if it’s big enough ) …

And then there’s nothing that says you can't “mix" the two … On our foamie trailer #1 , we used a Linen canvas with fiberglass tape over the outer seams … Very STRONG , and the glass fabric was held down with T2 … ( the strength is really in the Fiberglass , not the resin … ) ;)

All what YOU want !!!
There’s no place like Foam !
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Re: Pre flight foamie build sanity check...

Postby tony.latham » Fri Sep 20, 2019 9:39 am

with fiberglass , once you cover it , you start Sanding ( lots of sanding) , then filling , and priming , , then painting … The costs may ( or may not ) be similar , but the Labor is waay different


I sanded mine with a random orbital to get the gloss off. Maybe five minutes for each wall and another ten for the roof and hatch. I primed and then touched the low places (generally screw heads under the glass) with spot filler. That filler sands nicely. Maybe another fifteen minutes.

Image

I didn't think the prep with fiberglass was much labor. At least over wood. Having not worked with glass over foam, I can't speak to that issue but since it too is a flat surface, it should be similar.

Image

The finish looks great and you do become poor after purchasing the Monstaliner. :frightened:

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Re: Pre flight foamie build sanity check...

Postby dbhosttexas » Fri Sep 20, 2019 11:27 am

For starters, I want to say, thank you all for your input. Honestly this is only helping slightly, but kind of what I expected. Everyone has their own idea of what is best, and I respect that...

There are a couple of major issues I have with each method.

#1. Fiberglass. To go glass over foam, I either have to apply an extra cost sealer between the foam and polyester resin, use Polyiso foam, or use epoxy resin.
#1a. Fiberglass issue 2. Offgassing of potentially toxic chemicals. I am not super young, and my health is far from perfect. I know from being around boats for literally all my life, I know fiberglass takes years, if not decades to finish offgassing. I have been in 40 year old boats that still reek of polyester resin. I am not sure I wan tto use that for such a small enclosure my wife and I are going to be breathing in...

#2. PMF. Strength. I am trying to design my camper so that the support of MY weight will be held up by structural lumber and / or the structure of the truck bed. Is there any way, videos or whatever that demonstrate strength of PMF? I.E. will it support enough weight to say make a storage cabient to house my cast iron cookware in the camper? I.E. hold a 12" Deep, a 10" standard dutch oven, a 12" and 10" CI skillet etc...
#2a. PMF issue 2. I am going to be making this camper just at 86" side to side. Even using 72" wide canvas, I will need to seam it, and I figure the smart move is to roll the fabric over the edges and seam on the sides. How do I minimize the appearance of the seam and make sure it doesn't leak?

Both methods. question. With 1.5" of XPS foam, which if I recall from the specs provides R10 insulation, not great, not horrible. My truck bed insulation is only a Bedrug which if I am lucky provides R3 and blocks breezes coming through... My primary concern is heat, not cold. Would I benefit from using Henry Tropicool roof coating?
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Re: Pre flight foamie build sanity check...

Postby Pmullen503 » Fri Sep 20, 2019 3:28 pm

1. Don't use polyester resin. Just don't use it........

2. You should make yourself a test plank of PMF covered foam and try it out. If all of the foamy builds documented here aren't enough, you'll just have to see it for yourself. On your roof span, 86" by how long? That's a long span for any material, your may need some wood reinforcement. 2" foam will be much stiffer than 1.5"

It would really help to see a drawing of your design.
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Re: Pre flight foamie build sanity check...

Postby twisted lines » Fri Sep 20, 2019 5:31 pm

dbhosttexas wrote: Will it support enough weight to say make a storage cabient to house my cast iron cookware in the camper? I.E. hold a 12" Deep, a 10" standard dutch oven, a 12" and 10" CI skillet etc...


I am in the prosess of my first build, and enjoyed working with the foam and have been suprised how ridged it is in areas.
What I would consider is a sandwich with thin ply for an area such as this, easy and much stronger but still light; like many of the floors being used on some existing builds. :thinking:
5.5 X 10 Flatback Benroy in a pile,
And it's growing!
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Re: Pre flight foamie build sanity check...

Postby tony.latham » Fri Sep 20, 2019 6:10 pm

2. Offgassing of potentially toxic chemicals. I am not super young, and my health is far from perfect. I know from being around boats for literally all my life, I know fiberglass takes years, if not decades to finish offgassing.


Polyester resin.

And, by the way, I'm suggesting fiberglassing the exterior only.

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Re: Pre flight foamie build sanity check...

Postby Tyrtill » Fri Sep 20, 2019 6:28 pm

#2. PMF. Strength. I am trying to design my camper so that the support of MY weight will be held up by structural lumber and / or the structure of the truck bed. Is there any way, videos or whatever that demonstrate strength of PMF? I.E. will it support enough weight to say make a storage cabient to house my cast iron cookware in the camper? I.E. hold a 12" Deep, a 10" standard dutch oven, a 12" and 10" CI skillet etc...

As far as strength you will be fine with foam to support things. However don't just throw your pans around because it will dent things.

This guy stands on his cabinet at the end of the video

Also here are my tests


Pretty strong!! I'm a 200lb guy standing on ~28" span no obvious damage. The thing you don't see is it flexes down about 3". PMF and XPS seems to be very strong but not very rigid.
This is 2" xps with 10oz harbor freight drop cloth with glidden gripper and behr premium ultra paint.

Here is another test I did with a scrap. Very resilient stuff.


#2a. PMF issue 2. I am going to be making this camper just at 86" side to side. Even using 72" wide canvas, I will need to seam it, and I figure the smart move is to roll the fabric over the edges and seam on the sides. How do I minimize the appearance of the seam and make sure it doesn't leak?


Harbor freight does sell a 9x13 dropcloth (which is what I used) if you prewash it becomes ~8.25x11
Most people around here will tell you to embrace the seams or maybe stick/paint something on them to make them look intentional and part of the design. I will say try your best to make them straight and string free. Some of ghcoe's threads have tips on better seams. As far as the seams leaking just make sure you get good penetration on you paint/primer in both layers of the canvas and it will be fine. It's one of the things that draws people to the pmf it's very simple to make a very waterproof covering.

Both methods. question. With 1.5" of XPS foam, which if I recall from the specs provides R10 insulation, not great, not horrible. My truck bed insulation is only a Bedrug which if I am lucky provides R3 and blocks breezes coming through... My primary concern is heat, not cold. Would I benefit from using Henry Tropicool roof coating?


It wouldn't hurt to do the roof coating but as long as you have good ventilation (or an air conditioner) it probably won't make that much of a difference. I painted my roof white for the same reason.
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