Cutting gaps

[zoegraf]

I know that cutting gaps in rails allows for expansion and contraction. Has anyone ever heard of cutting gaps in roadbed?

Why I ask is, I've been doing some research on laying roadbed on extruded foam. I've learned that some model railroaders have experienced minor shrinking over the years ranging from 1/8 to 1/4 of an inch over a length of approximately 6 feet that cause their track to bow upwards in about 3 to 15 years.

Usually I glue my homasote roadbed to plywood when building a layout and probably will do so again of a future layout that will be more fixed/permanent, but this time I wanted to try something different in so I could have a module to move around.

Would it be wise to cut enough gaps along the the homasote roadbed in order to accommodate any future shrinkage its sub roadbed that may cause the roadbed to warp upwards?

 

[joed2323]

I think alot of the issue comes into play with where your layout is located. Is it located in a outside building like a shed, or in a garage that isn't heated?
If your layout is located in a place where it will experience a wide range of temps then yeah maybe you should worry about expanding and contracting..

My layout is in my basement, my basement is insulated so it doesn't get too cold down their and temps somewhat stay the same throughout the summer and winter. In the summer and stays cool and in the winter its about 55-60 degrees im guessing

So i think you have to look at what type of extremes your layout will face..

In my opinion i think one could always at anytime take a dremel with a cutoff wheel and cut gaps in rails and fill in with styrene.

My layout top is foam on top of wood and ws foam roadbed on top of that. My track is glued to the foam so in my eyes this provides little more wiggle room versus being nailed down to wood. Ive had most of my layout trackwork done for over a year now which isn't very long but i still haven't came across any issues. Again alot of the issues is from extreme temp changes, if you wont have any drastic change in temps in your layout room then you should be fine.

 

[zoegraf]

I think alot of the issue comes into play with where your layout is located. Is it located in a outside building like a shed, or in a garage that isn't heated?
If your layout is located in a place where it will experience a wide range of temps then yeah maybe you should worry about expanding and contracting..

My layout is in my basement, my basement is insulated so it doesn't get too cold down their and temps somewhat stay the same throughout the summer and winter. In the summer and stays cool and in the winter its about 55-60 degrees im guessing

So i think you have to look at what type of extremes your layout will face..

In my opinion i think one could always at anytime take a dremel with a cutoff wheel and cut gaps in rails and fill in with styrene.

My layout top is foam on top of wood and ws foam roadbed on top of that. My track is glued to the foam so in my eyes this provides little more wiggle room versus being nailed down to wood. Ive had most of my layout trackwork done for over a year now which isn't very long but i still haven't came across any issues. Again alot of the issues is from extreme temp changes, if you wont have any drastic change in temps in your layout room then you should be fine.

The room my layout will be in has a constant temperature for about 10 months of the year and the climate is temperate with no freezing temperatures, but in the summer the room, which is south facing, can get as warm as 35C (95F) and I can cool it down to about 86F using shades and keeping the air flowing with a fan. This has caused in the past minor expansion of the rails on the parts of the layout that was closest to the window.

I'm guessing that the shrinkage of the foam is so gradual over time that I'll be able to keep an eye on it and cut any gaps accordingly. I think it won't hurt to cut gaps into the roadbed just to play it safe before I lay the track and also have expansion joints in the rails especially before and after turnouts. I've read that not having the track/rail secured to the end plates of a module and using floating connector rails helps.

 

[Selector]

One of the reasons I use DAP Alex Plus with silicone caulk to fix both my roadbed and my track elements in place is for this very reason. Those two don't do much changing, certainly not of the order to cause buckling if you leave three or four joiners free to slide in the rails here and there when you solder the rest. However, wooden benchwork will change dimensions when it dries seasonally, and that of course causes it to shrink. The shrinking brings things once a certain distance apart closer together, including the ends of rails at tight joints. Something's gotta give! With the flexible caulk, the wood under the roadbed can move quite a bit, but the caulk will give a bit, thus leaving the roadbed and rails they carry largely configured as I wanted them to be from the outset.

I also use a dehumidifier in the train room 24/7 with the humidistat set to cycle when the humidity climbs higher than 66%. It cuts out at 45%.

 

[zoegraf]

One of the reasons I use DAP Alex Plus with silicone caulk to fix both my roadbed and my track elements in place is for this very reason. Those two don't do much changing, certainly not of the order to cause buckling if you leave three or four joiners free to slide in the rails here and there when you solder the rest. However, wooden benchwork will change dimensions when it dries seasonally, and that of course causes it to shrink. The shrinking brings things once a certain distance apart closer together, including the ends of rails at tight joints. Something's gotta give! With the flexible caulk, the wood under the roadbed can move quite a bit, but the caulk will give a bit, thus leaving the roadbed and rails they carry largely configured as I wanted them to be from the outset.

I also use a dehumidifier in the train room 24/7 with the humidistat set to cycle when the humidity climbs higher than 66%. It cuts out at 45%.

I just used the caulk, that you use, for the first time - caulking my roadbed to the extruded foam. I tested other adhesives and this caulk worked the best for me. I'm glad to hear from you that it has give and that you can use it to glue down track/ties also.

 

[montanan]

I will agree with the others about temperature fluctuations. I have never had any problems in over 20 years. I do live in a dryer climate. The temps can vary for my basement. I only turn the heat on when I am going to work on the layout. The lows are probably in the mid 40's in the dead of winter with no heat on and probably up to the low 70's with the heat on in the winter. during the summer it probably never gets above the mid 70's. My track is hand laid on Homabed (homasote) road bed glued ad spiked to plywood. A lot will depend on where your layout is, themps it will have to withstand and the average humidity where you live.