Insulation

[John316]

We are getting ready to foam our bus. We have been taking small steps to getting it converted, while still traveling in it (we did a temporary "weekend" conversion to keep us going, you know, some sofas, bunk beds, fridge, etc). The guy who will spray it is coming out on Saturday to give us a quote.

My question is this: What is the preferred method of grinding the foam down to the desired depth. I have thought of using a sharpened length of angle iron and using that to scrape it down, but I don't know for sure.

I think some of you have been around the block a few times, so bring it on! I have read all I can find in old BCM, but I though you guys might have additional insight. After foaming it we will cover the walls with 5/8" plywood.

Thanks in advance,

God bless,

John

[JackConrad]

I used a 9" grinder with a 24 grit grinding disk. It was quick and left a very smooth surface.  If using this method, you MUST wear eye and respiratory protection.  Jack

[Jerry Liebler]

John,
    5/8 plywood is heavy!  My preferred plan is to run furring strips at right angles to the metal ribs, then use thin paneling over them.  If you put the furring strips up before foaming you'll get an extra 3/4" of insulation, a real good thermal break, no condensation etc.  I used 2" wide strips of cabinet grade 3/4 plywood for my furring strips with the furring on 8" centers.  Plenty of support for cabinets etc from the furring and 3/16" paneling for the wall surface is plenty rigid.  I primed the paneling and put vinyl wallpaper over it. 
Regards
Jerry 4107 1120

[jjrbus]

Fred put some good ideas on the net.  Except extension cords for wireing is a bad idea!!  Some refer to foaming. Gumpy has a nice site also, but I can never find it.

http://users.cwnet.com/~thall/fredhobe.htm

I like Jerry's idea but did not want togive up 1 1/2 inch of coach. However If my choices were 3/4 furring or 5/8 plywood, I would go with the furring!!

Did anybody mention, covering the framework with masking tape or oil befor foaming?

For trimming the foam I actually used Jacks grinder and disc!!! very messy job, respirator and safety glasses are a must!!  HTH Jim

[Dreamscape]

Here's Craig's site.

http://www.gumpydog.com/bus/

[makemineatwostroke]

John; I have watched the trailer mfg like Fruehauf and  Wabash trim the foam and they use a tool that is flexable about 3 ft long with teeth on it and can trim a 53 ft trailer in a couple of hours, if you have a dealer close to you may be worth looking into. (they used hot foam)  

FWIW 5/8 plywood weighs 48 lbs per sheet I would consider using something else another item to watch for that was pointed out is to not let the foam get between the siding and the frame steel (seal it someway) it will cause it to wave if you are not careful 

have a great day

[John316]

Alright here is the explanation why we were going with 5/8. We ordered our windows from Peninsula for 5/8 thickness on the wall (you know the outer ring is over the plywood, kinda like a sandwich). We were told that the 5/8 would provide good rigidity and strength. Maybe that was a dumb idea (if so, it is the first of many I'm afraid). I wonder if we could use the 5/8 around the windows and then fur the rest out to match?...Ideas???

Somebody want to comment on the prepping. We were going to caulk ALL of the ribs to prevent panning flex. Tape everything that we don't want sprayed. And I think I have read that the ribs need to be oiled...Right?

What does the 8 in. on center mean if we furred it out. Does that mean horizontaly and vertically or just vertically. I would assume vertically. If that is the case how do you attach them. Maybe I am not picturing the right idea??? Any more comments???

Whew, and this is just the beginning!!!

Thanks,

God bless,

John

PS The websites were great. 

[cody]

I wouldn't be afraid to use the 5/8ths plywood, I used 3/4 inch thruout my bus. I wanted the strength, remember that a lot of your interior hangs off the walls or uses the walls for support, those have to be strong and not prone to flexing.  Buses were designed to carry a good payload, figure around 50 people and their luggage, when we set them up for conversions we can approach the load they were designed to carry but I can't say as I've seen too many of them exceed it.  As a thought, have you checked Bontragers for windows, they have a huge inventory of new surplus RV windows made by Hehr, I got thermopane sliders with screens in the size I needed for 20 bucks each, they got a good selection of sizes and styles, would be a big savings if they had the ones you need, not sure where your located but they are in White Pigeon Michigan, about 12 miles outside of Elkhart Indiana.  They also have a lot of clamp rings so the thinkness of your walls can be worked with.

[John316]

Thanks Cody!!!

I don't feel like it was such a dumb choice now.

No really, thanks for all of the input. I think we will probably mix some of the furring and some of the straight 5/8.

Thanks again,

God bless,

John

[cody]

john I added some info to my post about the windows.

[JackConrad]

And I think I have read that the ribs need to be oiled...Right?

We taped our ribs with masking tape. After the faom set up, we used a flat pry bar to hook into the foam and pull it off the ribs (the tape came off with the foam).  Jack

[John316]

Cody, I guess I wasn't clear enough. We have the windows already. The five in the front are duel pane, energy efficient, T-sliders. The two in the back are the same except a little smaller and full sliders. The clamp rings that you mention sound interesting. I will look into those. Sounds like you got a great deal on your windows. Too bad we live to far away from them . I really like all of your info. Keep it up!!!

Jack, I like that idea. We will try that. Thanks!!!

God bless,

John

[Blacksheep]

Although my walls are not sprayed in, I did use 1x3 firring strips vertical on 16 inch centers. This worked out very well as I started in the rear and went forward. I then used foam board from HD and went flush to the firring strips. I taped all cracks and seams using foil tape! Worked very well and didn't cost all that much! Probably not near as good of insulating factor as sprayed foam but when your building it yourself and out of work at the time, you do what you have to to get er' done!

Ace

[VAN]

ace hi ,how many layers of foam board did you end up using to fill it out to the strips,and how thick were the sheets ,thanks,Van

[Blacksheep]

Van my side walls we're factory sprayed and after I stripped the original walls out and firred it, I then used 2 inch thick foam and that brought it to just flush with inside of the firring so then I came back with a 3/4 inch foam board to bring it flush with the outside edge of the strip. After it was all sealed with foil tape I installed 3/8 plywood from ceiling to floor. 3/8 has been more than sturdy enough for my cabinets and such. You can push against the wall anywhere and it doesn't move! Like I said...on a budget at the time and trying to do what would work for me here in Florida. I DO know it is VERY soundproof and warm when needed not to mention cool when hot outside!

Ace