how do you keep foam pad rolled tightly?

Way back when I used rolled foam pads, nylon or polyester straps with plastic buckles worked best. Two straps keep externally mounted foam pads stable on your pack.

Cord cuts into the foam, and knots can be tough to tie and untie, especially when they are wet or icy and your hands are cold and wet.

Too old to sleep on foam pads anymore. Now I use an insulated inflatable pad.

— Rex

Personally, I use 1/8″ foam pads, so I can fold them. Years ago, I remember trying to cut “fold” lines into a ccf pad with an exacto – like a Z-lite.

It survived about 18 hours of sleeping on it before it tore… :(

I was recently faced exactly that issue with  Gossamer Gear 1/8″ foam pad. I rolled it as tight as it would go and used the compression straps on a HMG Porter to hold it vertically in place. I usually consider things tied or strapped outside  a pack to be poor form but this worked without issue.

A single small strap around the middle.

Either a thin Velcro strip, purchased at Home Depot and sold to organize / tie-up electrical cords and garden hoses; or a length of 2 mm florescent nylon cordage sold as tent guy lines – the added visibility is nice for finding it the next morning.

Occasionally I’ve had found the right thickness (like the ones around broccoli) and also length (which is longer than the broccoli ones) rubber band.  Those last a year or two before the rubber ages and breaks.

I’ve also used a loop of my smallest diameter shock cord – I have a few spools of 1/8″ and 3/16″ shock cord for restringing tent pole sets.  That lasts for many years.

I mostly don’t sleep on CCF foam pads but they’re exactly what you want in the car trunk if you have to change a tire, put on tire chains, or deal with something under the car in the snow or slush of winter.  So there’s one in each car, plus food, water, snow shovel, sleeping bag, warm gloves and boots, tow rope, jumper cables, flashlight with lithium batteries, etc.

Similar to David’s rubber band offering, I’ve lately become a fan of those rubber “tourniquet” thingies they place on your upper arm for a routine blood draw. I just wrap one around a rolled-up GTX shell or a foam pad and use a simple single over hand knot to secure it. They are strong, they “stick” to themselves by friction, are long enough to reach around most things we might use them for, and they last a long time.

Piece of elastic webbing sewn to size

Gary Dunckel, the “rubber tourniquet thingies” are actually non-sterile latex tubes. You can get them at different stores, often at the drug store. You often need two to keep the roll tight.
A piece of webbing is what I used, also. Line cuts into the pad.

I use an elastic shock cord, I think 1/8″, cut to size for my 1/2″ pads. Doesn’t cut in as bad as you would think. Light weight. I’m sure some of these other answers work out about the same. I attach it to the top of my HMG Southwest lids compression strap if I’m taking one pad. If it’s two of the 1/2″ pads, both get rolled really tight with precut loops of the cord and are strapped to the back of the bag using more of the 1/8″ cord, webbed criss-cross over the back pocket. It actually ends up being less bulky and lighter than 1 full length Z-lite strapped to the back. weird. Otherwise, if I’m taking my Uberlite, I’ll use the Gossamer 1/8″ pad and fold it into a squar’ish rectangle form and put it under the Uberlite folded the same way inside the main storage compartment of the bag.

James, mine are not tubular, and I seriously doubt that my clinic would use latex due to the common allergy to that material. They likely are nitrile.

It’s not like decades ago when there were used inner tubes from bicycle, motorcycle and car tires everywhere, but when you do find an old inner tube, you can make a LOT of very strong rubber bands from it.  And by cutting them at an angle, you can make those rubber bands in various diameters.

When I need to roll anything, I use a “Voile” type strap, a slightly stretchy rubber strap that can be fastened in multiple positions.  I always carry one of these because they can serve multiple purposes:  gear repair, strapping things onto something else, creating a makeshift thing to retrieve a fishing spool out of a river (sigh), strapping skis together, even as part of a splint if necessary.  Earlier this summer I used one to roll up the aluminum liner for an Ursak, into which I then shoved my tent and carried the bundle under the lid of my GG Crown 60.  Slick.

I have the biggest Ridgecrest you can buy and have it stored rolled up in an old Buff.

My Ridgerest lives in the Thermarest nylon stuff sack that came with it.