Closed Cell Rigid Foam insulation Reflection 220RK

[Yoda]

First - thanks to Rob Cate&Rob and the thread https://gdrvowners.com/forum/exterio...eel-underbelly and many other that have gone before me.

I have started on the project and have learned a few things the hard way.. I am about 1/4 done

My situation is a bit different, I am fully sub framed (crack repairs) from the original frame depth by 2" so supposedly 2" thick foam should have fit perfectly........NOT! A lot of the original OEM plumbing and wiring runs extended slightly below the original frame height resulting in the bulges in the coroplast. I determined that 1" was about as good as I could do.

Tip one - use a straight edge across the frame and measure before you buy your foam. Two trips to HD and handling 4x8 sheets of foam (I bought 5) in the wind - priceless. I took the 2" back and got 1", except for one sheet of 2"

Cutting tools - what a pain to cut this stuff clean. I tried using a small circular trim saw (4") withe fine tooth plywood blade - got 6" and it was melting the foam. Then tried my typical Stanly knife - tore the foam as blade is too thick. Finally settled on a single edge razor blade with a good straight edge, - still tough to keep from wandering. It only cut about half way. I finished the cuts with my small Japaneses pull saw - not as clean as what I want, but OK. I an going to pick up one of those razor knifes (think box cutter) to see how that does.. For those that have done this what cutting tools did you use?

Fitment - I am going with a slight compression fit and a dab (10 cent size) of foam glue here and there. I may switch to double sided tape - less mess. Frame measures 68" inside to inside so cut 68.25. Seems to work well. Where possible I am padding the existing cross members out with strips of 1" of foam. so final finished sheet fits flush with the frame. Everything is not parallel, so I plan to go back and fill gaps with foam. Yes this could make removal later a slight pain, but I want this sealed as best as possible. Thoughts?

Thought or tips on where I am going? Ill post pictures of what I have done so far later today - need to run to HD and get supplies

Keith

[howson]

Cutting tools - what a pain to cut this stuff clean. I tried using a small circular trim saw (4") withe fine tooth plywood blade - got 6" and it was melting the foam. Then tried my typical Stanly knife - tore the foam as blade is too thick. Finally settled on a single edge razor blade with a good straight edge, - still tough to keep from wandering. It only cut about half way. I finished the cuts with my small Japaneses pull saw - not as clean as what I want, but OK. I an going to pick up one of those razor knifes (think box cutter) to see how that does.. For those that have done this what cutting tools did you use?

Hot knife is what Nomad recommends. His series is worth watching (how to work with foam) even if a project is not on the list. All five videos are in a playlist. https://www.youtube.com/watch?v=38DM...wozEOunUz4M2Fl

[ncitro]

I have used this when cutting it for model railroad work:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

It is not perfect and you need to go slow, but you get a nice clean cut.

[Yoda]

howson ncitro

Boy you two really want me to make a mess let alone burn myself and everything near me. I have enough trouble with my heat gun not burning myself or something else when I put it down. My soldering iron came with a wire blade - depending on where I put it..

Anyway I picked up one of these today https://www.homedepot.com/p/Husky-9-...-HUS/310955137 Ill need it to trim the coroplast anyway.

Thanks for the good thoughts

Keith

[Country Campers]

A serrated knife or bread knife works well too, just don't let the boss see you with it.

Brian

[Cate&Rob]

Yoda Hi Keith,

I have always used a "utility knife" with a sharp new blade extended most of the way so that the cut is on as shallow an angle as possible. Olfa makes good products and the black blades are sharper than the silver ones.

As for fastening in the foam . . . remember that it has to be removable for eventual service of all the stuff under there. This is why I used twist retainers as shown in my summary that you attached to post 1.

Rob

[Yoda]

Yoda Hi Keith,

I have always used a "utility knife" with a sharp new blade extended most of the way so that the cut is on as shallow an angle as possible. Olfa makes good products and the black blades are sharper than the silver ones.

As for fastening in the foam . . . remember that it has to be removable for eventual service of all the stuff under there. This is why I used twist retainers as shown in my summary that you attached to post 1.

Rob

I understand the removable. I got a roll of Gorilla double sided tape. I can split it and make small mounting squares to hold everything in place until the coroplast is in. Should be easy to undoo. Did you use anything to seal the seams between the sheets - maybe tape the seams? Not sure what will stick...Or do I even need to taps them?

Thanks
Keith

[Cate&Rob]

Did you use anything to seal the seams between the sheets - maybe tape the seams? Not sure what will stick...Or do I even need to taps them?

Thanks
Keith

Hi Keith,

All of my foam panels are friction fit between new crossbars that I added. I added the twist tabs to hold them from lifting and also from dropping until the coroplast was put back.

Rob

[Jlawles2]

I have tried several methods including https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 . The low angle on the super sized snap utility knife works about as good as any other method.

As for using a toothed blade, That sounds like giving a 2 year old an open bag of flower and NOT expecting it to end up in and on everything within 15'. Those little blue flakes would be everywhere. If you could find a sharpened round disk that might be a better solution. Something like say a tile blade without any radial reliefs. https://www.homedepot.com/p/QEP-7-in...003Q/100121214 most have a back cut behind the abrasive to help with heat buildup from friction.

[Ebkent62]

I use a hot knife for this. Keeps you from having styrofoam crumbs everywhere- have a pool in the backyard and they always seem to blow into it if I use a utility knife. The hot knife is faster and cleaner. I bought the Harbour Freight on on sale for $12.99 about 6 years ago.

Both of the hot knives below look the same- probably made in the same factory in China….

Harbour Freight Tools-hot knife ($29.99 on website - put on sale occasionally for $15.99)

https://www.harborfreight.com/130-wa...ife-60313.html

Northern Tools - hot knife ($13.49)

https://www.northerntool.com/search?...ource=bing_PPC