question on ventilation

[mike802]

I have the original ceiling out of the bus and am in the process of installing wood strips over the roof frame members to attach a new ceiling. The original insulation is in good shape and the wood strips will give me an additional 1" for more insulation.  In a house, ventilation is provided by soffit and gable end vents in the attic, but how is ventilation provided in a bus?  Is this something I should be concerned about?  What have others done and how did it work out for you?  I tried the search, but keep getting info on roof vents. 

[Tenor]

Usually there are plenty of air leaks in a bus to make an engineered venting system unnecessary.  I'd really think about getting rid of the fiberglass insulation.  It may look OK, but it never was very good to begin with.  That's why the coaches had such huge HVAC systems.  Spray foam is the best way to go, or (someone help me here with the name  ) the closed cell insulation with the aluminum foil on it.  That's harder to do since you have to cut it to fit.  Good luck!

Glenn

[eddiepotts]

Getting rid of the old insulation will also help get rid of some of the old smell. It will also let you find pin holes that may be present on your roof that you cant see from the top side. You have to much work to stop here. You might want to think about painting while it is all out.

[cody]

Thermax, made by Celotex is a great replacement for the fiberglass insulation, like has been mentioned, it never was much good but for it's time was what was available, thermax will triple the insulating value that is currently filled with the batts without retaining any moisture, the fiberglass batts were notorious for retaining moisture, once it's wet the insulating value is gone and the risk of corrosion skyrockets and takes forever to dryout.  You can get moisture build up by just the normal sweating due to weather changes and the difference between inside and outside temps, it cuts easily with a knife and is available in 4x8 sheets at lowes, home depot and many other places, with the foil facing it is, in my opinion, a great investment for the money, the optimum insulation would be spray foam but that is kinda pricey and should be done by professionals for the best results, tho I've seen some homeowner jobs that turned out great, one approach some have used is to locate a foaming crew at a home and bring the bus to them at the end of the day, I know one guy that got his foamed for a fraction of the cost doing it that way.

[mike802]

Thanks guys, yea, there is defiantly a lot of work to be done and I would like to do it right.  If I do find and seal any pin holes, and use spray in foam, or the Thermax, will that tighten up the air leaks enough to make a ventilation system necessary?  I like the idea of something I can do myself, I am working on a budget just like most these days and keeping cost down, but still getting a quality job is important.

[cody]

Once the finished walls and ceiling are installed, it too late then to go back and update what may have been done, it's important that each step be done to the best of a persons ability and financial situation.  I'm incredibly poor but not smart enough to know I can't afford a bus so I plod ahead, the dividends get paid when you sit in a lawn chair and admire what you've done.  The finished ceiling not only hides the quality that a person puts into it but also the shortcuts that may have been taken, nobody else knows what was done but the one that did it, that is the dividend at the end, either pride or wishes for a different outcome.

[Jriddle]

I used spray foam kits that you do yourself. For 600 board feet kit runs around five to six hundred dollars. I removed all the insulation out of the walls also and will use about three kits. Cody pretty much said it all in his last post. It boils down to the wallet and how well you want it done.

John

[Kenny]

John
You say use will use three 600 sq/ft kits which totals approx $1500-$1800. How much if you have it done?
Kenny

[robertglines1]

spray foam or glued in board needs no vent..my prevost were sprayed in direct to roof skin..use board insulation if you like and spray can foam to seal any voids..would definitely get rid of fiberglass...lots of heat thru ceiling..and lets lots out in cold weather...Bob

[Jriddle]

John
You say use will use three 600 sq/ft kits which totals approx $1500-$1800. How much if you have it done?
Kenny

I live in the middle of know where. I believe it would cost over a thousand to have it done. I didn't have the bus licenced at the time and didn't have a good handle on electrical. I liked the ability to do it in stages. I bought my kits off EBay one kit didn't work well. This stuff has a shelf life and needs to be stored out of the cold. I paid a lot less for my first two kits but paid the price. The last kit I bought was a bit more but but will be worth it. If you have it done you should save some money but need to have the infrastructure done before hand.

John

[cody]

John brings up a good point, the foam hardens into a solid block so any wire that you need to be run should be in place before you foam, same with ducts, the best approach is to install and secure chases (conduit) that you can fish wire thru at a later date if you find more circuits are needed or add things over time. 

[Jriddle]

This was a while back I still need to do the roof. I will be doing it during Sept. I Have been using the bus this year but haven't finished the roof insulation as I wanted to get the lighting down pat before I closed it in.

John

[TomC]

I stripped my interior down to the metal (incredibly dirty!). Inspected the metal and found a crack over each of the two doors-mainly from years of opening and closing the doors thousands of times (transit bus).  I then wire brushed the entire bus, Rustoleum primed it, then installed 1x2 fir strips going fore and aft at 16" center on the roof bows and walls.  Framed out in wood the two Fantastic fans, three roof top A/C's and wired what would be buried in the ceiling including overhead lighting.  Then had spray foam installed even with the 1x2 fir strips that gave me 2.25" of foam insulation on both the ceiling and walls.  Also had custom RV windows made from Penn Glass.  

With all windows and roof vents closed, the interior is so tight that anyone coming in and closing the door will make my ears pop.  To combat that, I leave the bathroom Fantastic vent cracked open just enough to allow the motor to come on if we need it-I used a small piece of wood taped in place to prevent the knob from turning.  Never seem to get rain in.

I can't emphasize this enough-the key to really good heating and air conditioning is to have excellent insulation.  I can keep my bus warm with one 35,000btu propane furnace (coldest I've been in is 25 degrees), and easily keep the bus cool running down the road with just two of the three roof top A/C's running (hottest I've been in is 108 degrees).  I highly recommend you remove that fiberglass insulation and do it right with spray insulation over 1x2 fir strips. Good Luck, TomC

[Jriddle]

The pocket book will dictate what you do.  Tom has it right if you can afford it. I added 1/2 pink board on top of the inch and a half spray foam.

[happycamperbrat]

To help get over the electrical wiring learning hump as well as for future stuff, you could do what I am going to do. I plan on insulating, and then making two (or 4, havent got there yet) hinged boxes running the length of the coach. One will be where the top of the walls meet the ceiling and the other where the floor meets the wall. In the lower one I will run plumbing and in the top one I will run wiring. I havent figured out yet about running wires and plumbing vertically yet and for that part I may have to bury it in the wall.