# Hardie board siding for roadbed?



## Alan Prichard (Dec 27, 2007)

I have a stack of the stuff and am thinking of using it for roadbed. It’s 8” wide by 5/16” thick. I can double it up if need be. It gets very hot here, no frost heave, and clayey soil. I have a limitless supply of broken shale which I plan on screeding to get a good supply of ballast. I am off grid so importing anything is not practical. I want to fasten the track to it as I will be running AMS rolling stock which is susceptible to derailing due to scale wheel flanges, but I don’t know how to do that and allow for heat effecting the track.


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## Pete Thornton (Jan 2, 2008)

I don't see why Hardie board won't work. It's mostly concrete, isn't it?


Alan Prichard said:


> I want to fasten the track to it


Uh probably not a good idea. You have to let the track move. If you have long track sections, you will need expansion joints. Attach the track flat on to the baseboards using screws but use big washers or a flat loop of metal over the ties to allow it to move with the heat.


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## Greg Elmassian (Jan 3, 2008)

Yes, you need ballast. Also, I did indeed try hardie backer, following the "common wisdom" that switches needed a super flat base (they do), so attached switches to backer... big mistake, heat and cool WILL work ballast between ties and backer board... remove screws, and helped a lot, but realized that the switch was in ballast and the backer board was doing nothing but obstructing drainage.

If you must secure the track do what Pete says, let your fixings LOOSELY hold the track in approximate place.

Greg


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## David Leech (Dec 9, 2008)

Alan,
I would suggest, unless you have already, giving a piece of your material a good test in the 'weather'.
I was given a piece of Hardie Board made for house siding, to try out for track base and it was fine where the surface was left alone.
However at the open ends where it would get wet, it just crumbled and lost all its rigidity.
Your boards might be different, but maybe give a piece a good soaking to see what happens before you lay too much track.
Cheers,
David Leech, Canada


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## Greg Elmassian (Jan 3, 2008)

There are different grades of this material with the same generic name.

I have a waterproof version, cut to size, untreated edges, has been outside in the weather 10 years, no issues whatsoever...

so, get the "Specs" on your backer board before use, but really, don't use it ha ha!

Greg


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## David Leech (Dec 9, 2008)

Greg,
As the title explains, we are talking SIDING, and not your waterproof backer board.
Alan, please read number four of this link:








Problems with Hardie Siding | Should You Install Fiber Cement | Gambrick


5 Worst Problems with Hardie Siding analyzed and discussed. Should you install Fiber Cement siding on your home? Find out here. Pros vs Cons of James Hardie



gambrick.com




Regards,
David Leech, Delta, Canada


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## Greg Elmassian (Jan 3, 2008)

Yes, missed siding in the topic title, then read Pete's reply and he use "board" and I was immediately "off track" 

Thanks for the "re-railing", yeah, don't use this stuff for anything in the ground.

Greg


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## Alan Prichard (Dec 27, 2007)

Thank you gentlemen for your replies. I have a piece soaking in a bucket now. It’s painted, so I’m hoping that I can still use it if seal the cut edges. I like the idea of expansion joints. I don’t of any commercial options, so I’ll search for ideas of DIY ideas. this is my second go at building a new layout, the first was just track floating in ballast, and heat expansion made running AMS cars impossible. One idea Ic have is to use drip irrigation “U” anchors, but flattening the curve so the ties can slide back and forth.


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## Greg Elmassian (Jan 3, 2008)

Alan, if you had free floating track in ballast and heat expansion gave you fits, trying to bolt it down will make it WORSE.

You have already proved you have enough heat/cool to make expansion a problem. There are no forces on earth that will stop the track from expanding under heat. If you bolt the ties out, the rails will rip out of the ties.


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## Pete Thornton (Jan 2, 2008)

Alan Prichard said:


> I like the idea of expansion joints.


Several interesting threads on this site:
Thermal Expansion of Track and Roadbed
Expansion joint


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## Alan Prichard (Dec 27, 2007)

After soaking overnight the siding is unchanged. It’s not actually Hardie board, not sure of the brand. I plan on putting spacers at intervals so the track is resting on a flat surface and pouring the ballast on top of that, so I can lay in a nice deep ballast. I try try floating the track for now.


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## Pete Thornton (Jan 2, 2008)

Alan Prichard said:


> I try try floating the track for now.


I used 'crusher fines' (rock dust, #9 fines, etc.,) and it locked the track in place in my yard, though I did have to reset/replace ballast every spring after winter rains.

As I wasn't using track power (my track was actually aluminum,) I used regular rail joiners with a little gap. Never had an expansion problem (but then I was in MD not AZ.) In summer, when I ran trains, the gaps would be mostly closed.


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## Greg Elmassian (Jan 3, 2008)

Since you had some issues before, might I enquire about your ballast size, and is it rounded rocks or sharp angular bits?


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## Rail_Master4501 (10 mo ago)

Greg Elmassian said:


> Since you had some issues before, might I enquire about your ballast size, and is it rounded rocks or sharp angular bits?


I’m not a shale expert but I would assume broken shale is sharp and angular so I think he is good.


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## Greg Elmassian (Jan 3, 2008)

let's have him respond, perhaps with a picture.


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## Frank65 (Mar 28, 2009)

Alan Prichard said:


> I have a stack of the stuff and am thinking of using it for roadbed. It’s 8” wide by 5/16” thick. I can double it up if need be. It gets very hot here, no frost heave, and clayey soil. I have a limitless supply of broken shale which I plan on screeding to get a good supply of ballast. I am off grid so importing anything is not practical. I want to fasten the track to it as I will be running AMS rolling stock which is susceptible to derailing due to scale wheel flanges, but I don’t know how to do that and allow for heat effecting the track.


Gentlemen: I have Hardiplank (cement and cellulose mixed then extruded) siding on my home with good results. However it is/was very brittle and cracked when nailed too close the the edge. It was difficult to fashion into other shapes and lengths - at the time a guillotine type tool was available from Hardi. Long story short I wouldn't use it for anything on or in the ground. Most materials have a primary use and as an anchorage for model railroad track isn't Hardi's.


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## jd.damrath (Dec 3, 2021)

Alan Prichard said:


> I have a stack of the stuff and am thinking of using it for roadbed. It’s 8” wide by 5/16” thick. I can double it up if need be. It gets very hot here, no frost heave, and clayey soil. I have a limitless supply of broken shale which I plan on screeding to get a good supply of ballast. I am off grid so importing anything is not practical. I want to fasten the track to it as I will be running AMS rolling stock which is susceptible to derailing due to scale wheel flanges, but I don’t know how to do that and allow for heat effecting the track.


I was once James Hardie certified installer. It is cement board which will not rot, expand, or contract. Prime/paint any edges that were cut to prevent moisture from soaking into it and possibly causing issues. Are the boards the pre-painted, or primed? If not they'll need to be primed and painted. The rails will expand and contract of course, so allow for that with proper gapping. The cement board will outlive us all!


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## Greg Elmassian (Jan 3, 2008)

not laying in the ground where it can stay wet for a long time and get fungus and bacteria. Not designed for that.


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## jd.damrath (Dec 3, 2021)

Correct, just as prototypical railroads, must have firm and well-drained roadbed beneath.


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## Jeff Williams (Jan 8, 2008)

I built my track using Hardiboard siding ("wood" textured side down, flat side up) attached to 2x4 steel "studs" about 15 years ago. The Hardiboard has cracked around most every screw that holds it to the steel studs. I live in a part of California that has typical yearly temperature excursions from about 28F to 110F, modest rainfall in the fall, winter and spring and low humidity in the summer. 
I checked the coefficient or thermal expansion of both the Hardiboard (6.7 x 10e-6 in/in/degree F longitudinal) and steel ( 6 to 7 x 10e-6 in/in/degree F, depending on alloy) and thought that they were close enough so as to be compatible. My mistake was that I didn't allow ANY clearance between the holes in the Hardiboard and the attaching screws, so even with similar expansion coefficients, there clearly was enough stress on the Hardiboard to cause cracking. I also didn't consider the fact that the steel studs are shaded from direct sun by the Hardiboard so may in fact stay cooler than the Hardiboard. I think that the Hardiboard likely would not have cracked if I had given the screws generous clearance holes and not screwed them down firmly onto the Hardiboard.
I used "Bullseye 123" primer and then latex house paint on the top surface and edges of the board. That combination has held up well, but then we don't get freezing rain or snow nor do we get enough continuous rain for the Hardiboard surface to stay wet for long periods.
I have Llagas Creek aluminum track (six-foot flex track) which has a coefficient of thermal expansion (11 to 13 x 10e-6 in/in/degree F, depending on alloy), almost twice that of the Hardiboard so the track is attached to the Hardiboard on straight sections in just a few locations and the curves are only attached at the transition from a straight to curved track, so that the curves "float" inward and outward with temperature changes. This has worked well using rail clamps (not slide-on jointers) between track sections. A few small gaps opened up in the first year but after that initial settling in no more gaps have appeared.


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## fyrekop (Sep 20, 2011)

Alan
Not to promote a certain brand but I have "old" and "new" style Split Jaw rail expansion modules and both work well with the temp. variations here in AZ. Not unusual to have 25 degree differences over night. They have their own base and haven't had issues with ballast getting into moving parts


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## Greg Elmassian (Jan 3, 2008)

How do you like the changes the new proprietor made?


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## Alan Prichard (Dec 27, 2007)

My board (not Hardie brand it turns out)is painted. So I’ll prime cut ends. Gregg, I had previously used what I believe was #4 roof gravel. I sifted the shale 1/4” then 1/8” screen, giving me wo sizes. The shale I am using is silicons, so very tough for shale, almost like sandstone, which it is interbedded with. I’m home so can’t send pics. I am going to lay down loose pieces on the ground and not screw the track down but let it float.


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## Russell C of Idaho (Jul 20, 2017)

Jeff Williams said:


> I built my track using Hardiboard siding ("wood" textured side down, flat side up) attached to 2x4 steel "studs" about 15 years ago. The Hardiboard has cracked around most every screw that holds it to the steel studs. I live in a part of California that has typical yearly temperature excursions from about 28F to 110F, modest rainfall in the fall, winter and spring and low humidity in the summer.
> I checked the coefficient or thermal expansion of both the Hardiboard (6.7 x 10e-6 in/in/degree F longitudinal) and steel ( 6 to 7 x 10e-6 in/in/degree F, depending on alloy) and thought that they were close enough so as to be compatible. My mistake was that I didn't allow ANY clearance between the holes in the Hardiboard and the attaching screws, so even with similar expansion coefficients, there clearly was enough stress on the Hardiboard to cause cracking. I also didn't consider the fact that the steel studs are shaded from direct sun by the Hardiboard so may in fact stay cooler than the Hardiboard. I think that the Hardiboard likely would not have cracked if I had given the screws generous clearance holes and not screwed them down firmly onto the Hardiboard.
> I used "Bullseye 123" primer and then latex house paint on the top surface and edges of the board. That combination has held up well, but then we don't get freezing rain or snow nor do we get enough continuous rain for the Hardiboard surface to stay wet for long periods.
> I have Llagas Creek aluminum track (six-foot flex track) which has a coefficient of thermal expansion (11 to 13 x 10e-6 in/in/degree F, depending on alloy), almost twice that of the Hardiboard so the track is attached to the Hardiboard on straight sections in just a few locations and the curves are only attached at the transition from a straight to curved track, so that the curves "float" inward and outward with temperature changes. This has worked well using rail clamps (not slide-on jointers) between track sections. A few small gaps opened up in the first year but after that initial settling in no more gaps have appeared.


Reading this it is amazing how close garden railroad track building is to the real thing! I’ve worked on the full size narrow gauge Sumpter Valley Railroad track crew more than once and we had our own 18” gauge railroad and track and roadbed construction was similar except of course the pieces were all heavier!

Thanks for your insights into making outdoor track that is low maintenance and usable.


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## fyrekop (Sep 20, 2011)

Greg Elmassian said:


> How do you like the changes the new proprietor made?


The new ones have better connectivity since they provide rail clamps that have "hard wire" connectors included. And the moving parts are thicker than the originals. No problems so far.


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## Greg Elmassian (Jan 3, 2008)

Great the hear, he approached me early on, and every conversation was productive, and his ideas for improvements were well thought out. Nice to see things improving.

Greg


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