| Author | Message | ||
| David Evans (Dmd)
Registered Member Username: Dmd Post Number: 97 Registered: 10-2004 Posted From: 71.251.5.233 Rating: N/A |
We are to the point of replacing the wood flooring in the bedroom.I searched the archives and came up with cork or tarpaper over steel supports and possibly Homasote or plywood over. We want to get soundproofing, heat retarding/insulation but also keep everything from getting waterlogged. This is an older GM with limited headroom so dont want to build it up to much. The final covering will be carpet. Thanks in advance. Dave | ||
| Ed Jewett (Kristinsgrandpa)
Registered Member Username: Kristinsgrandpa Post Number: 271 Registered: 2-2003 Posted From: 64.24.214.233 Rating: |
This website, on soundproofing a generator, says MDF (medium density fiberboard is better than plywood for soundproofing. http://www.soundproofing.org/infopages/generator.htm GSI Inc. in Ft Lauderdale, FL has lead coated sound insulation. 800-763-1844. Soundown at www.Soundown.com sells sound insulating materials in several different materials. Also Dick Wright at WWW.wrico.com has sound insulating material that he uses to insulate generators. He is a very knowledgable guy and supports the conversion community with advise and material. HTH Ed. | ||
| David Hartley (Drdave)
Registered Member Username: Drdave Post Number: 687 Registered: 5-2005 Posted From: 67.78.176.54 Rating: N/A |
You might want to apply a layer of thin aluminum sheet over the braces, also lay strips of tar paper on the steel where the aluminum will be in contact. Then a layer of Pressure Treated plywood to build up the floor. A layer of rubber sound absorbing mat and top it off with another layer of plywood and finish. You can get rubber mat material at most any place that sells horse trailer matting, Even maybe tractor supply will have it locally. The soundproofing stuff is expensive and I paid over $14 a square foot and it wasn't really worth the expense. The rubber mat material worked better and was much cheaper and non hazardous to work with. | ||
| David Evans (Dmd)
Registered Member Username: Dmd Post Number: 98 Registered: 10-2004 Posted From: 71.251.5.233 Rating: N/A |
Thank you both. I like the sheet of aluminum idea and to isolate from other metal. Lets go Mets! | ||
| Stephen Fessenden (Sffess)
Registered Member Username: Sffess Post Number: 654 Registered: 1-2002 Posted From: 67.142.130.12 Rating: |
I would not use fiberboard for the floor. Pressure treated plywood is often wet when bought and GM never needed PT plywood in all their years of production. Try a hardwood plywood at $40 per sheet at Lowes, or a marine plywood at $$$$. Is your bus monocoque construction like a 4104 and later. If so the floor is an integral part of the stucture. Use good plywood. How about a couple of layers of aluminum coated polyurethane 3/4" X 4X8 sheets from Lowes or Home Depot. face the aluminum down. I have been using it to replace the original insulation in my generator compartmene. If there is not aluminum over the steel now, why put dissimilar metals together there. You can buy rubber sheeting of various thicknesses to put as a barrier between the steel and the wood if you are worried about sound transmission. To me, it is a little loud over the engine but the real problem is HEAT for the first night after a stop. I have considered installing a 110 volt fan to cool the engine compartment after stopping. The heat just sitts there and goes up otherwise. | ||
| David Evans (Dmd)
Registered Member Username: Dmd Post Number: 100 Registered: 10-2004 Posted From: 72.80.31.224 Rating: N/A |
Thank you Steve. Yes its monocoque, but Robert the mechanic has run new metal supports and tied into the existing frame work to support the weight of the new powertrain. Heat is the main problem we are trying to eliminate. I wwas thinking/hoping that the aluminum would reflect the heat away from the floors. I'm not sure if putting it on top of the plywood and then a layer of maybe rubber and then luan and carpet would help or not. We open our engine compartment doors after a days run and it does help alot but the new engine and auto trans will put out some heat.I havent seen the aluim/ply combo but will check it out. Thanks for the post. | ||
| Dallas (Dal300)
Registered Member Username: Dal300 Post Number: 134 Registered: 3-2006 Posted From: 172.128.78.12 Rating: N/A |
David, A monocoque shell, being designed for certain stresses, normally can't be strengthened by adding supports and cross members. The body has to be able to flex and move. If it is made too stiff, it will have a tendencey to crack and break. GMC describes this in many of their service bulletins. Personally, I wouldn't let ANYONE modify your structure without having a mechanical engineer OK it first. But, do it your way and let us know after a few years how it's going. Dallas | ||
| David Evans (Dmd)
Registered Member Username: Dmd Post Number: 101 Registered: 10-2004 Posted From: 72.80.31.224 Rating: N/A |
Thanks Dallas, Robert Moore at Deans is doing the work. We spent several years checking out different approches/ideas and went with Robert and Garry. You have probably seen their work in Arcadia and at other rallys. His specialty is 6v92 into 4104's. I have all my faith ($)in Robert's work. He does not know how to do any halfassed work on a coach. Garry death this summer kinda took the wind out of our sails for awhile but its getting back on track. It wont be ready for our trip south at Christmas but hopefully by spring. He had to beef up the bulkheads and replace alot of 57 year old metal, which was the real deal steel. The new suspension is a work of art. Its gonna be the bionic bus! david | ||
| Bill Glenn (Homegrowndiesel)
Registered Member Username: Homegrowndiesel Post Number: 8 Registered: 7-2006 Posted From: 71.242.135.69 Rating: |
Hey David, Sounds like a cool project. I understand you want to keep it that way also. FWIW, Isolation, Insolation,, sound and heat. My suggestion is to use foam tape, like used under a pickup cap, taped on all floor support structures.(less than 1/4" thick) Next install 3/4" ductboard with aluminum foil on 1 side, facing down as a water- heat barrier. this is made out of compressed fiberglass, and used for HVAC ducts. This comes in 4x8 sheets and cuts with a razor knife. This will compress some as you install plywood down for the floor. As this is most likely under the bed add more sound deadening and insolating material as allowed. Just one way of doing it. Good luck with your choices. Bill | ||
| don (Bottomacher)
Registered Member Username: Bottomacher Post Number: 145 Registered: 12-2000 Posted From: 72.15.81.101 Rating: N/A |
Hardwood plywood is rarely meant for exposure to atmospheric moisture unless it is marine trim grade. I would suggest exterior grade sheathing plywood, or pressure treated if it will actually get wet. | ||
| Stephen Fessenden (Sffess)
Registered Member Username: Sffess Post Number: 657 Registered: 1-2002 Posted From: 67.142.130.39 Rating: |
Most plywood today has good exterior glue. If you want to be sure, boil a piece and let it sit 24 hours in the water then try to separate the plys. What would be ideal would probably be industrial grade plywood. The original GM plywood floor does not look at all like sheathing plywood. Maybe underlayment? If he is changing the plywood floor in a monocoque bus it is like changing the aluminum siding. It needs to be done with the right material, something close to the original. Even though the bus has been strenthened with new supports, it probably still depends on the floor for part of its structural strength. Luke told us at Busin 2005 about a 4905 that had a bad floor and was not handling right until the rear floor was replaced. This is the time to do it right, David. The engine support itself may be effected by the stiffness of the floor. The floor is one of four sides of a box that the bulkhead is attached to to support the engine. Its not going to be rocket science, just put the floor back in the way it was, then add the insuallation and vapor barrier material. I still think you will be happy with the foil faced polyurethane sheets from a building supply store. Take a piece of the material and do your own burn test to be sure it is ok over an engine. Just light it watch how it burns and be sure it does not feed a fire to well. It will probably produce thick black smoke, but it is not going to be in the living area. Black smoke will just get quicker attention if there ever is a fire. |
