expansion gaps in OO

I have almost finished building baseboards in the loft, and expect to start track laying in a couple of weeks. In the summer, the loft gets horrendously
hot, and I believe rail expansion can result in buckling if gaps are not left. What sort of gap are we talking about between metre lengths? The complete circuit is approx. 12 ft x 7 ft, and the track, already bought, is NS code 100.
TIA
ZD
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Two things here I might recommend, coming from a hot weather climate. Firstly, if you can, put in a track underlay that allows movement. I use a local concrete expansion joint product called Abelflex, which is black foam about 10 mm thick, available in several widths. I glue this to my subroadbed with a white glue variety called "Bondcrete" I just glue the track to it using the same glue. I suggest 75mm and trim off what you don't need with a Stanley knife. Then ballast the track. This allows the track to expand a bit, even when fixed to it, and will also cover movement in the benchwork caused by shrinkage as the moisture in the timber dries out. Or if you put in a/c, which has a de-humidifying drying effect.
Secondly, I would suggest soldering the rails together when they are on a curve. Leave the expansion joints for the straights. If you are laying your track in hot weather, butt them together. They will shrink in the cooler weather. But if you are laying track now, in the UK winter, a 1, or even 1.5 mm gap should be enough. Just make sure each bit of flextrack has its own feeders, sliding fishplates do not equal good conductivity.
Regards
Steve Magee Newcastle NSW Aust
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On Sat, 31 Dec 2005 21:28:12 GMT, "Zipadee Doodar"

I lay each length of track and then gap it with an old blunt craft knife before laying the next run (Peco track slides nicely in the chairs). Results in a gap of about ten thou between rails, which has been fine in my loft. The gaps are still not quite closed at 45 Celsius.
Guy
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start
horrendously
is
I laid the track on one of my exhibition layouts in the loft, in summer. Most uncomfortable, but I never suffered any expansion problems in a warm exhibition hall! Neither were there any contraction problems either in the cold halls (especially one on Bradford, W Yorks!!)
Cheers, Mick
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