Foam Board Insulation

[Karin]

I'm wanting to insulate a school bus that I'm renting in Boulder. The rent is low enough that I could put up to a few hundred bucks into it and would still be ahead, given the cost of living here (don't get me started on that, eventually I'll be outta here).

In "Dealing with Heat and Cold," Bob recommended 3/4" Styrofoam foil faced insulation, but I'm not seeing that anywhere (Home Depot or Lowes). Thicknesses available are .5 and 1" and nothing foil backed that I can find.

My landlord doesn't want me using glue for adherence, so I'm planning on using some heavy duty double sided tape.

Ideas, advice?

---

Never mind about the thickness. I just found 3/4" !! But I still welcome advice, ideas.

 

[akrvbob]

The thicker the better, but whatever size is easy to get and that you can afford will be fine. The advantage of the 3/4 is it is flexible and will bend to curve with a wall. Usually, school buses have fairly straight walls, but very curved roofs. So on the roof you will be better off with multiple layers of thinner plywood.

I think the tape will be fine on the walls, however on the roof I'm not sure. Bending the styrofoam puts quite a bit of pressure on it and the tape may or may not hold it. I'm sorry but I can't think of a solution without drilling holes. One thing I did in Alaska once when I put a Travel Trailer in an RV park for a year was to put the styrofoam on the top of the roof and then use a tarp to cover it and tied the tarp down to the bottom of the trailer. If you do that, you want to buy the blue or pink styrofoam, it is much, much tougher than the white.

But just covering all the windows with 4x8 sheets of styrofoam will help tremendously!!

If you can afford it you want to buy Polyiso instead of styrofoam, it is R6 which is higher than styrofoam.
Bob

 

[peacetara]

Hi Karin,

I can't imagine renting a school bus! (land FOR a school bus I could imagine). YAY for cheap rent!

Anyways, around FOAM, this is the stuff I've used
R-Tech 3/4" 4'x8' foam insulation. It's made by Rtech, the link is to homedepot's website, but if it doesn't work, here is a bunch more info on it:
R-Tech Model # 310873 Internet # 202530470 Store SKU # 483214
3/4 in. x 4 ft. x 8 ft. Foam Insulation Sheathing

Basically it's 4 foot wide, but 8 feet long, and 3/4 of an inch thick. One side is white with plastic lettering all over it saying R-TECH, and the other side is shiny, like those shiny mylar balloons, with little styrofoam beads in the middle.

They also sell a pink version (no shiny side), and a grey version (can't remember if the grey stuff has the shiny side). If I remember right, the white stuff has the least insulation, followed by the grey version (you can't see the individual beads) with the pink version having the best insulation factor (R-value).

The thicker the better, but of course the thicker it is, the harder it is to have room inside to stand up and store all your awesome stuff! So 1" would be fine, if it won't hamper your ability to stand up or anything!

Any of them will work, the shiny side is helpful to reflect radiation, like the sun. The white R-tech stuff is the cheapest and works fine.

When I insulated my van, I didn't glue anything really, it's all just held up by pressure. I was just very careful in cutting so that everything was a tight fit. It's all been in there for 2 years now, without falling down from the ceiling or falling off the walls.

I did glue the edges together where they join up, but I didn't glue anything to the van walls. When gluing the white stuff, you need to use 100% silicone, everything else I tried seems to eat away at the styrofoam.


Anyways, I wish you lots of success!!

With Love,
Tara

 

[RogueRV2]

If they can't special order it, use the foam board and the Mylar coated bubble wrap or even plain old 'aluminum foil', or a Mylar blanket... Aluminum does a fantastic job by reflecting back more than 90% of the radiated heat generated by your heater. It also is very useful by blocking heat from a wood stove.... 20" x 10' or even 50' rolls of aluminum flashing can be cut with a utility knife and used as a heat shield. But it ain't cheap! It is basically super duper heavy duty aluminum foil that can be stapled into place... this could also be used in a bus in places that no other and less expensive forms of aluminum will do. Hope that helps............

I'm wanting to insulate a school bus that I'm renting in Boulder. The rent is low enough that I could put up to a few hundred bucks into it and would still be ahead, given the cost of living here (don't get me started on that, eventually I'll be outta here).

In "Dealing with Heat and Cold," Bob recommended 3/4" Styrofoam foil faced insulation, but I'm not seeing that anywhere (Home Depot or Lowes). Thicknesses available are .5 and 1" and nothing foil backed that I can find.

My landlord doesn't want me using glue for adherence, so I'm planning on using some heavy duty double sided tape.

Ideas, advice?

---

Never mind about the thickness. I just found 3/4" !! But I still welcome advice, ideas.

---

 

[riffraff]

Would this stuff work for the floor as well? The one example I'm sorta following is did this (for the floor): a layer of plywood followed by foam board insulation (looked like it was 1/2 inch) followed by another layer of plywood.

For the sides and top I'm thinking to use the white stuff (shiny side towards van walls & cieling) and on the floor the pink.

Also on the walls, would 1 layer of 1" alone be okay? Should another layer (of plywood or another type of insulation) be desired? Not planning to use any paneling.. ugly is fine.

 

[Karin]

idk, about the flooring, riffraff, but I'm sure someone here will answer.

wow thanks all for the advice! I actually thought about insulation on the roof outside, but dismissed it. I may reconsider, given Bob's experience. Tara's idea might work, too. I thought about buying some used insulation on craigslist, too, though that seems like a hassle.

The hardest part is making a decision. The weather just turned warm here, after being weirdly cloudy and wet for this time of year. I hope procrastination doesn't set in.

I'll check in when I do something. Hmmmm, I hope I do something, lol.

---

I was just wondering - Bob, what kind of tarp did you use?

 

[RogueRV2]

Karen,
Using the shiny stuff in one of many forms, mylar, on both sides of the walls and ceiling, will not only refect heat back in, but also reflect heat away during the hot summer.

Riffraff
Your plan for the floor is a good one. A root cellar I built into an existing basement used the same technique to break the connect to slab floor. The root cellar only needed a 40 watt light bulb to keep it above 40 degrees when it was 20 below zero outside. It worked good. One could save money by using OSB ( oriented strand board, aka., compressed particle board) instead of plywood, and put the save money into more insulation. I would try to use blue foam board, as I know it will not compress. 1/2" is better than nothing and will make a difference. More is better. The white foam on the walls and ceiling will work good. Put the shiny side toward the interior. If you can afford it, use two sheets and use the shiny side of one toward the exterior. This will go far to reduce the temp inside during the summer.

 

[akrvbob]

We kind of have two threads going, but they are very similiar so it's okay.

1) Riffraff, I'm not a fan of insulating the floor. I just accept that the floor will be cold and keep my feet elevated and buy down booties. The loss of headroom isn't worth the slight gain. However, bear in mind I am being a contrarian here and the majority wisdom is to insulate the floor. Make your own decision.

2) For the majority of us 1 inch on the wall is enough, especially if you use Polyiso which is R6. If you are in extreme cold, use 2 inches.

3) There is so much misinformation about reflective barriers out there. For an reflective barrier to work it MUST have at least a 1/2 inch of open air space between it and the heat source. Without it, is is worthless. that includes Reflectix or foil facing. With an air gap Reflectix is GREAT stuff, without it, it has an R value of 1 per inch, which is terrible and a total waste of money. I turned my foil face into the trailer so it reflected light and heat back into the trailer.

4) Karin, you understand that putting the insulation on the outside means you can not move the bus, right? The problem is the curve of the roof on the bus. If the insulation doesn't curve and stay tight to the roof, it does no good. My trailers roof was flat and I just cut out openings for the various things stick through the roof. I had three layers of 2 inch styrofoam. But I was in Anchorage Alaska and it got down to -30 below zero Fahrenheit on a regular basis and stayed that way for weeks at a time.

To keep the wind from blowing it away I put a huge, very heavy duty tarp on top of the insulation and used rope to tie it down to the bottom of the trailer. It worked well, the insulation stayed in place just fine. I also used the pink styrofoam that is nearly waterproof and much stronger than the white.

 

[Reducto]

Assuming the landlord wants to continue renting that space after you are gone and you aren't planning on taking it with you, tell them you are adding value and a few screw holes won't be a problem. That's how I would install it - run a 1x2 strip along the wall outside the insulation, drill holes in the wood then run self-tapping sheet metal screws through it and the insulation into the metal. This will hold the insulation in place and give you something to screw hooks and such into. If you want it to look nice you can spray glue some fabric to it or cover with thin plywood.

To do the curved roof you can cut the insulation into 2 foot wide strips and lay them next to each other. Use foil tape to hold them to each other.

 

[riffraff]

Okay I spent the day at the home depot (mostly the parking lot). I might have screwed up a bit. I was thinking about R-values and especially the added value of sound dampening (my father was a very loud snorer.. I know I snore too but not sure how loudly).

Looking at the different foam boards, I went with 7 sheets of this:

http://www.homedepot.com/p/Rmax-The...-Rigid-Foam-Insulation-Board-613010/100573703

I made a floor out of it, which worked very nicely (I don't think I'm going to mind the missing headroom... time will tell).

I also used it to make a layer on the walls. Being so thick (2 inch) it did not bend hardly at all and my walls that I wanted to "snap" into place do so only when I stand them up (leaving a lot of empty space between the insulation and the curved walls). When it came to the bottom of the roof it was already late in the day, so I returned 3 of the sheets for a refund. I really couldn't figure out how I was going to make them stay up there anyways.

On one section of the wall I had cut it wrong so needed to use another piece to keep it from falling down. This section was the only one that came close to following the curve of the van wall since it had a break in it (connected by some really nice very shiny tape which the home depot employee pointed me to).

I'll go back out there tomorrow, and perhaps choose something else for the roof once I figure out how to affix it. Should I make cuts in each section of the insulation I already have up, to try and get it to follow the van's walls better? I don't mind horribly having less space at the moment... but I worry the insulation isn't going to work properly with the way I have it now. Plus I'll have to figure out how to affix the pieces to the walls anyways.. they are not at all stable and definitely will fall down if nothing's done.

I got a roll of Reflectix too for making some quick & ez window blockers or use in a cab/living area separator even if it's just a blanket hanging down for the first few days before I can get something better built. Will also use this stuff in doors or oddly shaped areas.

Surprisingly my "measure once, cut 4 times" method was not that efficient. =) I did end up getting a lot of sun tho.

I'd like to try and get the insulation finished tomorrow if possible. Sunday night I'm going to have to throw the mattress in the van. I can't imagine how I'm going to get plywood down on the floor. They do offer tool rental at that store. Considering how much I've seemingly botched this job already, power tools are appearing intimidating to say the least.

Any ideas on how to salvage this setup are welcome. I could get some of that real foamy type stuff and just fill in the places behind the boards.. dunno. It's probably got way too much insulation as it is.

 

[RogueRV2]

If you've used that expanding foam in can stuff before, you'll notice that it is really stick stuff. It sticks real good to foam board too. You might try that as a glue to hold your foam board, but make sure you use enough expanding foam that it makes contact with both surfaces. Perhaps taping the board to the interior wall until the expanding foam has a chance to harden up would work. Also there could be an air gap at least 1/2 inch between the van wall and the foam board. It is difficult to imagine what you are actually dealing with so I'm reluctant to suggest other methods.

Okay I spent the day at the home depot (mostly the parking lot). I might have screwed up a bit. I was thinking about R-values and especially the added value of sound dampening (my father was a very loud snorer.. I know I snore too but not sure how loudly).

Looking at the different foam boards, I went with 7 sheets of this:

http://www.homedepot.com/p/Rmax-The...-Rigid-Foam-Insulation-Board-613010/100573703

I made a floor out of it, which worked very nicely (I don't think I'm going to mind the missing headroom... time will tell).

I also used it to make a layer on the walls. Being so thick (2 inch) it did not bend hardly at all and my walls that I wanted to "snap" into place do so only when I stand them up (leaving a lot of empty space between the insulation and the curved walls). When it came to the bottom of the roof it was already late in the day, so I returned 3 of the sheets for a refund. I really couldn't figure out how I was going to make them stay up there anyways.

On one section of the wall I had cut it wrong so needed to use another piece to keep it from falling down. This section was the only one that came close to following the curve of the van wall since it had a break in it (connected by some really nice very shiny tape which the home depot employee pointed me to).

I'll go back out there tomorrow, and perhaps choose something else for the roof once I figure out how to affix it. Should I make cuts in each section of the insulation I already have up, to try and get it to follow the van's walls better? I don't mind horribly having less space at the moment... but I worry the insulation isn't going to work properly with the way I have it now. Plus I'll have to figure out how to affix the pieces to the walls anyways.. they are not at all stable and definitely will fall down if nothing's done.

I got a roll of Reflectix too for making some quick & ez window blockers or use in a cab/living area separator even if it's just a blanket hanging down for the first few days before I can get something better built. Will also use this stuff in doors or oddly shaped areas.

Surprisingly my "measure once, cut 4 times" method was not that efficient. =) I did end up getting a lot of sun tho.

I'd like to try and get the insulation finished tomorrow if possible. Sunday night I'm going to have to throw the mattress in the van. I can't imagine how I'm going to get plywood down on the floor. They do offer tool rental at that store. Considering how much I've seemingly botched this job already, power tools are appearing intimidating to say the least.

Any ideas on how to salvage this setup are welcome. I could get some of that real foamy type stuff and just fill in the places behind the boards.. dunno. It's probably got way too much insulation as it is.

 

[akrvbob]

If you want to follow the curve of the wall or roof you need to use multiple layers of thinner sheets. I haven't tried to bend Polyiso to a curve so i don't know how it works, I have only used it on flat walls. But I know 3/4 inch styrofoam will bend to the curve of a roof. I used 3 layers of it on my roof. I also know the pink styrofoam bends quite well.
Bob

 

[SternWake]

Foam boards can be made to bend with precision cuts to the backside, like if the board is 1 inch thick, set the sharp blade to go no further than 1/2 inch and cut parallel lines, close together where there is more bend, further apart when the bend is less. Since you should be taping the edges you will be effectively getting a dead air space which insulates well.

I call this cutting releases, and I did so in a few parts when I insulated my fiberglass roof with just 1/2 inch of foil faced isocyanate.

Nashua Flexfix tape is awesome stuff. Wipe surfaces with Denatured alcohol before application for maximum adhesion.

Great stuff expanding foam should not be used against painted metal. I so wish i was never aware of it. Evil stuff, avoid.

 

[riffraff]

If you've used that expanding foam in can stuff before, you'll notice that it is really stick stuff. It sticks real good to foam board too. You might try that as a glue to hold your foam board, but make sure you use enough expanding foam that it makes contact with both surfaces. Perhaps taping the board to the interior wall until the expanding foam has a chance to harden up would work.

Expanding foam stuff might be the way to go. There is a lot of space to fill tho unless I cut the strips I made horizontally and tape them so they can more easily follow the curve of the van's walls.

Also there could be an air gap at least 1/2 inch between the van wall and the foam board. It is difficult to imagine what you are actually dealing with so I'm reluctant to suggest other methods.

Could or should? I'm afraid with the stiffness of the 2" foam there are 2+ inches of empty space at the moment (at the worst spots).

If you want to follow the curve of the wall or roof you need to use multiple layers of thinner sheets.

This is the lesson I learned today.

Some photos I just took:

---

Foam boards can be made to bend with precision cuts to the backside, like if the board is 1 inch thick, set the sharp blade to go no further than 1/2 inch and cut parallel lines, close together where there is more bend, further apart when the bend is less. Since you should be taping the edges you will be effectively getting a dead air space which insulates well.

I call this cutting releases, and I did so in a few parts when I insulated my fiberglass roof with just 1/2 inch of foil faced isocyanate.

This looks like a really good way to do it! Maybe I can salvage something... now if I only knew what Denatured alcohol was. =)

 

[RogueRV2]

I've never use that expanding foam on painted metal surfaces and SternWake warns not to use there, and perhaps for a very good reason. Perhaps he'll elaborate.

The pictures are indeed worth a thousand words. The board could be left as is or cut as SternWake suggests, and secured several different ways. You'll have to discern what you are most comfortable with attempting. I would start with the driver's side as it appears to be the easiest and will be good practice for the rest of project. Hopefully enough options will be given for you to choose from. The tape you have is very good tape and will hold even in hot temperatures. Try taping the top and then the bottom, then the seams. Consider taping across the gap instead of running down the seam. This might be the easiest method for you. Another way is to cut the back side with relief cuts and contour the board to the van wall, and tape into place, running the tape with the seams. Yet another option might be to use 1"x3" pine board along the top, bottom and middle, secured by long screws into the posts in the van wall and then panel if you'd like.

I believe you'll end up with a comfortable interior that'll be cheap and easy to heat.

 

[SternWake]

About the Foam, I used it above my windshield and went a little to happy with it.

Somebody on this forum a while back talked with a "great stuff" engineer and was told that if it was not allowed to expand as much as it possibly could, it would remain corrosive to the constricting surfaces.

My windshield had the added issue of moisture infiltration, and When I dug out the foam, it was dragging rusty pieces strongly adhered to it.

Other reports exist from other forums where people used some spray foam insulation on the walls of their van only to have it rust from the inside out and only where the spray foam was. Obviously not all foam in a can or spray foam is going to be corrosive, but It will never come into contact with steel again in anything I own.

Here is a piece I dug out . Ughhhh.

If cutting 'releases', the depth of cut must be precise and consistent, The cuts should be perfectly straight, knife along a straight edge, and parallel to each other. If not it will just destroy the foamboard and turn into a tool throwing curse fest, if you are prone to such things.

If you want to get fancy you can cut slim wedges to push into the releases and tape over them to "hold the curve" but this is largely unnecessary and just adds complexity.

I found the thin rectangular razors work better than the Ones which go into razor knives, but they are harder to hold perpendicular. When the razor gets dull and starts tearing just a little, just get a fresh one, it will save frustration in the end .

 

[Karin]

Riffraff, good for you, you're getting somewhere, unlike some of us.

I might scrap the idea of insulation on the outside, what with the curved surface. When you first mentioned the outside insulation, Bob, I figured you had a flat surface. That's quite the accomplishment, though, living in Alaska like that.

Reducto, what you mentioned is something that I have considered - that is, the need to have some kind of frame to hold the foam board. I've seen it online but am confused about how it's done.

You wrote:
"That's how I would install it - run a 1x2 strip along the wall outside the insulation, drill holes in the wood then run self-tapping sheet metal screws through it and the insulation into the metal."

Do you suggest the same for the ceiling?

I get what you said about adding to the value. My landlord is strangely noncommittal about all this. He's a nice enough guy, but I would think he'd be more interested.

One of the reasons I'm doing this is that my landlord only provided me with a small space heater and seems to have trepidations about me buying one that might suck more energy. (The bus is on the property with a power cord extending from the house.) Last March, when it was cold, the space heater was almost useless. I would sit right next to it in order to change clothes for work, shivering. I'm considering buying a Mr. Buddy.

Also, there's an old woodstove in there, a bit loose in the seams. You have to get a good fire going to pull the smoke up the stovepipe. I did get a fire going once and it seemed to be OK - the bus was almost too hot. But in the middle of the night it was freezing and I didn't want to get up to stoke the fire. Another night, I had a fire going, and when it died down, I turned a piece of wood over to rekindle the fire. Went back to bed and noticed it getting smoky inside, but I was reluctant to get up. Bad idea. In a few minutes, the bus completely filled with smoke. I had to open windows and doors. That was a funky morning, going to work stinking of smoke!

---

I'm glad to hear about people's experience with expanding foam. My landlord suggested spraying it into the space between the inner and outer skin of the bus. I'll nix that one, for sure.

 

[RogueRV2]

Hi Karen,
If it is a choice between insulation and an adequate heat source of some type, If possible, I'd go with a better wood stove that you take with when you leave, or fix up the one that's in there and learn how to run it. It does take practice to get to know a particular stove. I've made several stoves from scratch that worked well and could hold a fire reliably up to 10 hours using inferior pine. A modern airtight stove is not cheap, yet one can find an older lower tech stove at a much lower price that can control and hold a fire overnight. My RV has the M1941 WW2 era tent stove. A bit smoky for low ceilings, but it is easy to use, and is easy to cook on. Because of it's good and simple design it was kept in service for over 40 years. The temperature can easily be controlled and remain stable enough to use a pressure cooker! And it can boil a gallon of water in only 3 minutes!!!. It can also be 'shut down' for a long slow burn. A new one can be bot on the net for only $165 including shipping. It includes 11' of pipe and all the implements including a shovel. All of the parts together weigh about 70 pounds and break down into a portable package that can be sledded into the wildness or stuffed into a back seat of a car. http://www.imsplus.com/m-1941-military-tent-stove-nsn-4520-927-4214.html However, if the stove that is in there is sound, namely, not 'burnt out', it should be possible to improve it's performance. I would get an 'expert' to look at the pipe to make sure that it is not full of creosote, choking the flow and a chimney fire risk, and to see how the draw could be improved. Perhaps adding a few feet to the pipe end to would help it catch a breeze and improve the draw. Double or triple wall pipe does draw better, but it is expensive. Starting and building from a small hot and fast burning fire that is clean burning, will heat up the pipe so that draw is increasingly better and to the point that larger slower burning wood can be added. If the draw is inadequate for a long burning fire, open the windows and run it hot and fast to build up coals for the night, and to heat soak the space. Have your kindling ready for the morning fire, or use a product that can assist you in start a fire quickly. Eventually it will be cinch. I do use a temperature gauge on the pipe and keep it below 600 degrees. It will be safer and the stove and pipe will last much longer. Make sure yours has a flue that controls the burn rate. Working a wood stove can be tricky and does require time and patience to get to know and work a poorly operating stove.

 

[akrvbob]

Karin If you have the money to spend you can just muscle the cold with heaters. I have friends with 30 foot 5th wheels who heat their whole rig with a Mr. Heater Big Buddy heater. You'll burn lots of propane but it will do the job.

I personally think you will be better off with a Wave 6 Olympian heater. They are a true catalytic and they are safer than the Buddy. However, they are expensive and the Buddy is cheaper and a good heater.

Insulating the roof is very important, but the most important thing is all the windows. They will make you miserable so putting 4x8 sheets of polyiso over the walls will help tremendously. Since you can't drill holes, I'm sure double sided tape will hold it in place.
= = = = = =
RifRaff, I think you did a great job. You do lose some space but it doesn't seem like a big deal. I'd call it good and move on.

You are going to insulate the roof right?
Bob

 

[riffraff]

RifRaff, I think you did a great job. You do lose some space but it doesn't seem like a big deal. I'd call it good and move on.

You are going to insulate the roof right?
Bob

Thanks! I felt kind of silly in hindsight going with the 2 inch stuff but I think once I cut some relief notches to help it curve to the walls I'll be in better shape. Maybe some 2-sided tape to fix it to the walls and some on the outside (facing the van's interior) to finish it off.

Because of time constraints I may have to put off finishing the roof for a day or 2. I'm moving the remainder of my belongings into storage today so I've put the roof on hold as I wasn't sure how to do it with the materials I had. I do have about 2/3 of a board left over as well as a bunch of scraps.

Today is supposed to be the last day I'm in this house and I still have lots to do. I don't have any kind of cab/living space separator yet. I don't have curtains for the back or side windows... all this needs to be done today if possible (I might just go with reflectix stapled to cardboard for a quick fix today.. the windows are tinted already).

I can probably sleep here tonight and finish up tomorrow. Labor day will take on a new meaning for me this year =)

Oh one thing I wanted to point out. That 2-inch board that I got is quite strong. I was able to move around on the floor quite easily without damaging/squishing it. The only times I noticed it giving way much was if I put a knuckle to the ground. (walking on it with shoes, knee-pads didn't phase it in the least)