Nothing sticks to Fiberglass

[waverider1987]

So I was able to insulate the mid part of my roof because I could screw into it but the front and back parts are straight up fiberglass and apparently you can't screw into that.  So I've tried reflectix with liquid nails and caulk but nothing will stick.  I'm thinking of resorting to something more heavy duty but idk what.  Any advice?

 

[Dennis]

Is that a vertical surface you are referring to? Using polyiso?

 

[B and C]

When I was trying to adhere to fiberglass, I had to use alcohol to thoroughly strip away any wax or whatever it was not letting my industrial strength velcro stick. Mine was on the outside though. Reflectix needs an air gap to work properly although direct adhesion will help reflect heat back inside. Reflectix is not really insulation but a radiant barrier.

 

[jonyjoe303]

Try hotglue, that sticks to everything. I been using it for years to install my rtech foam insulation in my van. It also dries quickly, less then 5 minutes. In 5 years never had any foam insulation come loose. I also use it in my swampcoolers, usually nothing sticks to plastic but hotglue sticks real well. When I take them apart I have to scrape the hotglue off.

This 20 dollar hotglue gun "surebonder dt-360f" cost less then 20 dollars works very well on fragile materials like foam, it has 2 settings low and high, I use high for the foam. Its one of my favorite tools for building things. Is only 60 watts so a small inverter will run it.
 

This ryobi cordless hotglue gun (30 dollars for tool only) is for more rugged materials, this one melts glue quickly. Too hot for foam. Also you can use the more specialized gluesticks that need a hotter temperature. Very convenient for outside work.

 

[waverider1987]

I should add, i think technically you can screw into fiberglass but the nail would go right through the roof. It's also a curved roof on both ends, which makes it more complicated. Thanks for the suggestions so far

 

[tx2sturgis]

3M Spray adhesive #90 works well also.

It's a green can on the shelves at the big box home improvement stores.

Make sure to clean or wipe the fiberglass surface first. 

Spray both surfaces, wait about 3-5 minutes, then press insulation in place. Hold, brace, or clamp items together for a few minutes.

Ambient temps should be warm, above about 65 degrees if possible, and be sure to have ventilation.

Very easy to work with, but will not hold a stiff foam board against a curved surface.

It's not a permanent bond, so the items can be peeled apart later if needed.

 

[ByeBye]

Possible to fiberglass in some 1x1 or 1x2 wood in designated spots for anchor points.

This link has some really good info. RV fiberglass work is pretty basic, nothing like boats.

http://www.fiberglassrv.com/forums/f55/you-can-repair-fiberglass-52498.html

 

[highdesertranger]

x2 on the 3M adhesive. what ever you use you must properly prep the fiberglass or you are right nothing will stick. I have done Ensolite and 3M adhesive on fiberglass many times. Ensolite will conform to almost any shape. highdesertranger

 

[John61CT]

Use the right solvent and rough up the surface.

Sikaflex and 3M are tops, read the data sheets or call tech support. Especially temperature and humidity conditions.

VHB tape is amazing.

Do **not** use 3M 5200 unless you want it to be permanent, as in centuries

Sent from my Nexus 6 using Tapatalk

 

[MrNoodly]

...and rough up the surface.

Unless the fiberglass you want to stick to is already rough because it has no gel coat, or it's so old the gel coat is no longer glossy.

 

[John61CT]

Sure, there may be times it is not necessary, but where it's not difficult, better to not take chances, do it right the first time.

Sent from my Nexus 6 using Tapatalk

 

[maki2]

I have insulated the ceiling on my vintage fiberglass trailer. It was easy to do but the first thing you have to do is let go of thinking that you will have good luck with the way it is done for regular van insulation.

So instead you use another type of insulation and that type is EVA foam. For insulating the van roof you can buy it in rolls from auto upholstery sources where it is called "landua pad foam. That name is one of those historic references to a type of car, the kind that had padded vinyl on the exterior of the roof. Try to source it locally if you can. I used 3/8" thick material. The Landau foam is not overly heavy so it does work on the underside of the ceiling without coming loose.

EVA foam is a very good, closed cell foam. It has decent R value and it also deadens sound. It will stop the condensation issue of warm moist air hitting a cold metal surface. It can be applied to a curved surface. It also gets used to make those foam floor puzzle mats, fun foam sheets at craft stores, padding for flooring, pads for under sleeping bags and yoga mats. The insulation they put on the floors of truck and cars to help reduce noise and heat, use EVA foam.

It is very easy to stick it to the inside of a fiberglass shell surface. The adhesive is readily available from hardware and stores such as Home Depot. The adhesive that works well and is high temperature OK is the traditional yellow contact adhesive from Weldwood. You can brush it or roll it on. Follow the directions carefully for open time before you put the two pieces together. I prefer using brush on contact cements over the spray adhesives as they cost less and make less mess.

 

[John61CT]

Landau foam is a general usage term, rather than more specific and objective like EVA.

Good idea to buy from a source you can physically handle it first, some can be very fragile.

That glue sounds great!

Forget most consumer-level hot gun glue for uses where the surface gets very hot and weight is pulling in a separating direction.

Most fail in a few years at high temps.

 

[Dennis]

That Weldwood glue is good stuff. Just make sure when you get ready to put your pieces in place to have then aligned the way you want them to be. That is instant stick! Don't get that on opposing bare fingers and touch them together either.

 

[Spaceman Spiff]

So I was able to insulate the mid part of my roof because I could screw into it but the front and back parts are straight up fiberglass and apparently you can't screw into that.  So I've tried reflectix with liquid nails and caulk but nothing will stick.  I'm thinking of resorting to something more heavy duty but idk what.  Any advice?

My advice is to talk to someone who knows adhesives (3M customer service is good) and tell them what two surfaces you want to glue together and how permanent you want it.  They can direct you to an adhesive that will do the job.

And follow their directions EXACTLY, both for how to prepare the surfaces and the temperature and humidity during application and curing.  Adhesive fail by using the wrong adhesive, applying it wrong, skimping on prep or applying it when it is too hot, cold, wet, or dry.

 

[highdesertranger]

in California you can only get the good contact cement in aerosol cans. but I agree if you can get the original Weldwood contact cement in the red can go for it. get the red can not the green can, the green can sucks. highdesertranger

 

[John61CT]

follow their directions EXACTLY, both for how to prepare the surfaces and the temperature and humidity during application and curing.

+1 x1000 that is the key

 

[highdesertranger]

I agree with follow the directions. but that goes for everything and most people don't bother. highdesertranger

 

[John61CT]

Well, other project types you often get a lot more leeway.

Industrial-strength adhesives, dealing with fiberglass, plastics, spraying or pouring foam,

those all require precise attention to detail if you want professional-quality results.

 

[sephson]

3M Spray adhesive #90 works well also.

I'll add a third recommendation for the 3M High Strength 90, with one caution. Don't use it on white, beaded styrofoam. It'll eat right through it. While not as strong, the 3M Super 77 is a better choice for this material.