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| Steel passenger car roof repairs - what works in real world? https://www.rypn.org/forums/viewtopic.php?f=1&t=24551 |
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| Author: | Doug Debs 2472 [ Wed Jan 02, 2008 7:48 pm ] |
| Post subject: | Steel passenger car roof repairs - what works in real world? |
We have many heavyweight steel passenger cars - mostly with "Harriman" (turtleback) roofs - that have hot tar and/or paint over galvanized steel. These coatings do not remain watertight indefinitely. We want to re-coat with something that will last at least 25 years, preferably 40+ years. One approach is thick spray-on coating, popularly known as "pickup-truck bedliner". This was applied by a contractor recently to several heavyweight cars including S.P. 2979 Harriman-roof lounge, S.P. 141 clerestory-roof business car "Oakland", and clerestory-roof Pullman 10-2 sleeper "Gothic Peak", at roughly $12k-$16k/car. The old roof coating had to be sandblasted or dry-ice-blasted off first. Thick flexible rubberized-plastic membrane systems appear to be a good alternative, and may be more tolerant of less-than-perfect surface prep (so long as the underlying surface is well adhered). Some membrane systems are thermoplastic (i.e. "torch-down"), some are self-adhesive at room temperature. For example, in 1989 we applied an approx. 3/16" or 1/4" thick Johns-Manville "Dibiten" torch-down membrane to the clerestory roof raised-center on Pullman 8-5 sleeper "Clover Plot". This area was originally covered with tarred canvas nailed to wooden T&G boards, which were attached to steel carlines underneath. (Some pre-WW1 steel Pullmans had this composite roof structure.) The canvas was disintegrating and what remained had to be removed. Even though the wooden T&G was rather weatherbeaten, the Dibiten membrane was 100% watertight and looked OK (although somewhat faded) 18+ years later when it left by rail for Feather River RR Society, Portola, CA. Does anyone else have long-term experience and/or recommendations for roofing systems for steel-roof passenger cars? Thanks! - Doug Debs Golden Gate RR Museum / Niles Canyon Railway e-mail: doug.debs@fcimg.com 408-433-2672 work 650-704-1487 cell 650-856-3469 home |
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| Author: | Boyd Owens [ Wed Jan 02, 2008 9:29 pm ] |
| Post subject: | Re: Steel passenger car roof repairs - what works in real wo |
A few years back, Mid-Continent Railway Museum, with a grant from the Institute of Museum Services, re-roofed a number of cars with various materials to find out the same thing. I don't know what the long term outcome was, but maybe someone else in this forum might? |
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| Author: | Brian Norden [ Thu Jan 03, 2008 12:53 am ] |
| Post subject: | Re: Steel passenger car roof repairs - what works in real wo |
Biggest problem with any roof treatment is that even a steel railroad car "works." And it is more of a problem with a wooden car. The Mid-Continent experience would serve for the wooden car. As that is the major emphasis of its collection era. Years ago fiberglass was tried on a number of streetcar roofs and this was found not to be a solution. It was not the solution even for the small plywood and canvas roof section of PCC cars. The fiberglass was just too stiff and it cracked instead of flexing. I wonder how the "pick-up bedline" material will actually work out when the cars are in service. By the way, the CLOVER PLOT, was a re-configuration of a Pullman built during the 1920s. According to John White the Pullman Company went back to using wood roofing to conserve weight after building truly "all steel" cars pre-1920. |
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| Author: | Dave [ Thu Jan 03, 2008 6:43 am ] |
| Post subject: | Re: Steel passenger car roof repairs - what works in real wo |
I'm a big fan of seamless rubber roofing, but have only applied it to wood roofs. I can't imagine why it wouldn't also work over a steel roof. The question in my mind would be whether it needs to be glued down over the entire roof, or just along the edges. dave |
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| Author: | Alan D Siegwarth [ Thu Jan 03, 2008 4:01 pm ] |
| Post subject: | Re: Steel passenger car roof repairs - what works in real wo |
Dave: On the wood roof cars you have used rubber roofing on do they have many vents/roof penetrations. I have always liked the rubber roofing option but one of the big issues with heavyweight coaches are the roof vents etc. How did you deal with those? I have also heard rumors that there might be venting issues using rubber on steel cars (ie. the roof no longer can vent moisture and rusting occurs). Has anyone heard this as well? Alan Siegwarth Pacific Locomotive Association Niles Canyon Railway |
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| Author: | isaksenj [ Thu Jan 03, 2008 4:11 pm ] |
| Post subject: | Re: Steel passenger car roof repairs - what works in real wo |
We've used a bedliner-type material in the rebuilding of the roof on our Diner 741. A turtleback roof with the typical canvas/tar covering was applied over the original clerestory roof in the Erie's circa 1949 modernization of the car. We removed and replaced the conversion to repair chronic leakage at the junction between the roof and side sheets. Although at the moment I don't have the specs for the material with me, you can see some of the process and results on our website: http://www.eldcps.org/equipment/741/741 ... ation.html ...and click on "Previous Updates" for a photo-documentary of the car repairs; October 2004 through April 2005 concentrate on the roofing repairs. I'll post particulars on the roof coating later. Best Regards, John Isaksen ELDCPS |
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| Author: | Doug Debs 2472 [ Thu Jan 03, 2008 4:32 pm ] |
| Post subject: | Roof vents and trapped moisture (condensation, etc) |
The J-M "Dibiten" membrane applied in 1989 to Pullman sleeper Clover Plot's roof was just flexible enough to flare up around roof vents etc. The somewhat thinner version is significantly more flexible (stiffness increases by the thickness cubed). Alan has a very good point about how to get rid of trapped moisture (from condensation, etc) if the roof is 100% sealed. If the old rooftop carbody ventilators do not allow air exchange from the space between the interior ceiling and the roof underside, then seperate roof exhaust ventilators are needed. These should be screened to keep bugs and critters out of a space you can't easily inspect. The same approach applies to steel car sides at the side sills: installing screened 1/2" pipe drains allows condensation to drip out, rather than collecting and rotting out the bottom of the car sides. - Doug Debs |
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| Author: | junior [ Thu Jan 03, 2008 6:01 pm ] |
| Post subject: | Re: Roof vents and trapped moisture (condensation, etc) |
Ventilation ability was my question when I saw that WK&S and NH&I both removed the roof vents from their former Reading Company Coaches to prevent leaks which were prone to the areas surrounding the vents. There is a reason these vents were placed where they were, what have been the consequences of removing them so far? I imagine people from both companies will say that there is little damage, but most of this damage would be unseen withing the roof line, under the ceiling and will take place over the years, rather than "overnight." Will this be something that 10-15 years down the line will make itself well known with major damage and will the ensuing repairs and their costs in the future be comparable to the "savings" in cutting the vents off now? |
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| Author: | dr dodge [ Thu Jan 03, 2008 8:26 pm ] |
| Post subject: | Re: Roof vents and trapped moisture (condensation, etc) |
I have no experience with rail cars, but... I live in a styrofoam geodome. 2 years ago I needed to do something with the surface as mildew, dirt and leakage were a becoming a serious problem. I used an elastomeric roof compound from Lowes called Blackjack (I think) White, latex, easy cleanup, and (label says, but I didn't do it) easily colored with a standard latex exterior paint mixed in. My house flexes alot. It actually pops as the good old Houston summer sun tracks across its surface The roofing stuff is amazing!!!! It sticks to ANYTHING!!! I mean anything, and when you get it on it its there! for many years I am sure I didn't ever wash the house, and it stuck right away, covered excelent with a roller, handled multi coats (about 5-6 thick ones) It also has a companion product, which is a nylon type screen for patching holes. I used it (and Great Stuff) to bond 4 new windows in the house, and as long as you don't miss any pin holes, it seals completely. After this summer it still looks just like when I painted it In January, I bought an old Dodge van to drive around the country in. The roof had 6-8 holes bigger than a quarter, and a billion little ones. I had the elastomeric roof stuff from the previous summer still in the shed(which had lightly froze a bunch of times)and figured, what the heck. I slapped it on the van roof (again no wash...yea...I'm lazy) and one year and 40k miles later (15K in the salty northern winterwonderland) not a single spot is pealing, leaking or blistering. (I have a big splotch of it on the side that I have given up trying to remove) An add the fact that summer surface temp from absorbtion of sun dropped well over 40 degrees (I think closer to 60) If you talk to them at Lowes, they'll drop $10-15 of the list if you buy a bunch. I got mine for about $47 for a 5 gallon pail (used 20 pails) I used to use self applied bedliner on car interior floors for preservation, but no more. Its elastomeric for me now (and I still haven't washed the van...lol) dr dodge |
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| Author: | Al Stangenberger [ Thu Jan 03, 2008 9:49 pm ] |
| Post subject: | Re: Roof vents and trapped moisture (condensation, etc) |
Junior raises a very good point about rust damage from the inside vs. damage from the outside on car roofs. I was the lead rust-damage fixer a couple of years ago when WRM refinished the roof of our Pullman, Circumnavigators Club, which has a clerestory roof which was modernized by adding steel sheets from the top of the clerestory to the edge of the car. Prior repainting jobs had removed the tar which had been applied previously and contributed to rusting from the outside. Most of the damage I had to repair was coming from inside the car. The spaces between the original roof and the new panels added to hide the clerestory are very poorly ventilated, and condensation ran down the inside of the panels and collected at the bottom of the panels where it proceeded to rust out the panels. We sanded the roof down to bare metal. There were lots of spots with very small holes caused by rust. Hitting these spots with a ball-peen hammer revealed that the spots were just the surface indications of major rust pits which originated from inside the car. I think that coating the outside of a car's roof is the easy task. Probably any good grade of paint, sealing obvious holes and seams, and preventing water from pooling on the roof will work for that. The big issue is humidity control inside the car. Possibly, if the car is well-sealed, a dehumidifier might be a good investment. (We solved our problem with the CN Club by putting it inside our new car house.) |
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| Author: | Dave [ Fri Jan 04, 2008 7:27 am ] |
| Post subject: | Re: Steel passenger car roof repairs - what works in real wo |
Alan D Siegwarth wrote: Dave:
On the wood roof cars you have used rubber roofing on do they have many vents/roof penetrations. I have always liked the rubber roofing option but one of the big issues with heavyweight coaches are the roof vents etc. How did you deal with those? I have also heard rumors that there might be venting issues using rubber on steel cars (ie. the roof no longer can vent moisture and rusting occurs). Has anyone heard this as well? Alan Siegwarth Pacific Locomotive Association Niles Canyon Railway Hi Alan; The roof membrane can be cut to fit around the vents, and formed into a sort of flashing and sealed with the glue used for the product. You can cut and fit bits of membrane like flashings around things, small tears and holes patched with glue and caulk, and larger holes patched by gluing on a scrap. Pretty easy stuff to deal with. Find a local source for a good line of membrane and appropriate adhesives. I have used the elastomerics as repair for old metal roofs - usually small soldered seam metal "tiles" - and found it to be a very good and reliable repair also. It is a very good glue for laying on canvas patches, and for top coating canvas too. Once dried, it can be overpainted with latex, or tinited before application as Doc Dodge recommends. If you seal the water out and have no leaks no water will infiltrate between the menbrane and roof deck. This is a very different issue than condensation forming on the underside. Gluing down the whole roof membrane would most likely guarantee total sealing from the outside. Nothing will eliminate any possibility of condensation inside the cars skin apart from temperature and humidity regulated interior storage. I have had some experience working on the Bethlehem battleship coaches from the Jersey Central and Reading, and other steel cars - all share the common denominator of roof vent leakage. It is probably just something we will have to constantly deal with as did the railroads. I did xcover a really leaky roof vent on a heavyweight at Spencer back in the '80s from the inside by gluing a flashing in behind the vent cover, and then caulking the whole vent cover down in place. Covered with paint it looked original, no idea how it held out in the intervening couple decades. dave |
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| Author: | Jim Lundquist [ Fri Jan 04, 2008 7:27 pm ] |
| Post subject: | Re: Steel passenger car roof repairs - what works in real wo |
We are very interested in this topic. |
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| Author: | Randy Hees [ Sat Jan 05, 2008 2:28 am ] |
| Post subject: | Re: Steel passenger car roof repairs - what works in real wo |
Our California wooden narrow gauge cars use soldered terne metal (lead washed iron plate) roofs. On our restored passenger car the roof appeared to be in generally good condition. We cleaned it, we blasted it with walnut shells. We then painted it with a roof coating (primer and coating) designed for metal roofs. Within 10 years it had dissolved into its native iron oxide. We are now planning the new replacement roof (in the mean time we are relying on the traditional blue tarp as we work on the new car storage building.) We can still get terne metal from Follansbee. Glen Guerra did a new terne metal roof on the Lake Shore car at Mid Continent. We have been talking to him about a weekend course at our site in Fremont to teach the techniques needed to successfully replace one of these roofs. Assuming we do this, it would be at least a year off. Would anyone else be interested in attending? If so, what would such a course be worth? |
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