Slow Leak in Thermarest-

So my Thermarest will fill, but by the time the night’s over all the air has leaked. I cannot find where the leak is since it is so slow. Anyone have suggestions on how to find it?

nothing aside from the obvious
fill it up with air and submerge it in the bath tub–find out where the leak is

when you have a general area of the leak
spread a little dish detergent over the area to pinpoint the leak.

Sleeping pad blues
First, to your question, second the bath tub method. If you don’t have a tub, sponge a soapy solution over the pad and look for bubbles. In fact, before you start, put a little soapy solution over and around the valve, a common fault area. You can get a replacement valve set. Sometimes I think it is just foreign matter stuck in the valve, but don’t know a sure-fire way to clear it.

I’ve had a therma-rest, and Airtec and a Big Agnes inflatable mattress. All have eventually left me on the ground in the middle of the night. I think I am careful with the mats, and am frustrated. The Therma-rest and Airtec were self-inflators that roll up. Their weakness seems to be pin-hole leaks along the side seams, perhaps due to creasing when you roll them. The Big Agnes’ problem hasn’t been diagnosed yet.

I’m ready to spend more for something that is more reliable. I looked at Stevensons Warmlite pads which have a very strong reputation, but I don’t like the sizes they have available, because I’d like one that fits inside a bivy, and Stevensons are too wide. Another pad that is supposed to be good is the Exped, but I think it will have the same, size issue.

Of the three, the Therma-rest lasted the longest, so I think it is worth trying to salvage. Mine had a hundred or two uses on it, and I suspected it was just getting old and would continue to have problems, so I gave up on it and returned it to REI (satisfaction guaranteed).

Good luck, let us know how you make out.


Wait until you’re my age, and every
two hours when you’re up to add to the container, you can blow up the pad.

Seriously, though, you can try making thick soapy water and painting it on likely areas, or you can drag the thing into a pool or lake to watch for bubbles. But some Thermarest leaks I’ve dealt with were too slow to detect that way. The valve may have something in it that prevents it from sealing. Some of their valves, the plastic ones, allow the core to be pulled out, perhaps allowing cleaning.

While leaks might occur anywhere, they tend to happen more often in the creases of the part of the pad that is at the core of the roll-up. Also watch for worn fabric suggesting damage from being rubbed on sand.

Once found use GOOP
Good stuff. Nothing else is worth the effort.

Big Agnes pads suck…
Overinflate the pad before putting it in the water. I’ve also had luck folding the pad on itself to increase the pressure. Have a pen handy to mark the puncture. Thermarests are pretty easy to find holes in as they are all smooth.

The Big Agnes pads (which I think are crap) are almost impossible to find punctures in, because the tubes create so many different surfaces it’s hard to locate the hole. I’ve had three of these pos fail on me, one 6 days into a 26 day trip. The material was delaminating, and pinhole leaks seemed to appear exponentialy. I located and fixed about 45 leaks before I gave up and just reinflated it 4 times a night. Comfortable pads, but so unreliable, and take forever to blow up. Total crap, and Big Agnes’s customer service didn’t seem to care. Thankfully REI took it back…

What’s your current pad
JS–are you back to thermarest?


The pad dance
The older I get the less comfy the Thermarests that pack small are. (I have limited space)

Big Agnes has a valve design that rubs very heavily on the fabric when its rolled up. I sent two back. I am done with them. I could find the leak but it was damn near impossible to fix and stay fixed.

I had two MEC air mattresses…the Kelvin summer series…so comfy except twice the seams let go and poof you have a big hernia in your pad.

Now I am onto the Exped Synmat. Hopefully the valve design on this is better. You have to do a minute of CPR on your mat. Its good exercise.

Of all the Thermarests are the ones that DONT leak. Wish the Basecamp (its well over twenty years old) could fit into a smallish pack.

Yes on the thermarest…
And have 75 good nights on it so far. Not one of the ultralight models, but packs down reasonably and is comfy. The self inflating feature is nice as well…

Thanks for all the help, but
I’ve had no luck in finding the leak. Tried the bathtub and spraying with soap and nothing. It kind of frusrates me since I have less than 15 nights on this thing and already fixed one hole and now can’t find the other.

Guess this will be te last time I buy an inflatable-

belts and suspenders
I started just using thermarests then went to thermarest over short z-rest. It gave an extra layer of protection and the z-rest has multiple uses outside of sleeping.

I’ve had complete success with
Aquaseal and Seamgrip. Not sure why you push Goop so exclusively.

I wouldn’t give up on inflatables…
I’d just return/exchange it for another Thermarest. Probably one of the better sleeping mats in the business, sounds like you got a lemon.

I know I’m stating the obvious but…similar “challenge” for me at times in the past. I’ve been guilty of not tightening the valve adequately to support my weight through the whole night. Not so much with the Thermarest, but with my “other” brand. Check the valve and o-ring closely for any contamination, possible damage etc. I’m very careful with mine outside the tent, it’s at least 10years old (camprest)…multiple multi day trips each year…no punctures thus far. Guess I lead an enchanted life!

We have a pair of the old original UL Thermarests and haven’t had problems yet. I don’t know if this helps, but I never roll mine. I let out the air and fold it, lay on it, fold it in half again, lay on it again, etc., until it’s about 1/8th size, then tighten the valve and pack it like that. Presumably that should wear out the same folded areas, but in practice they haven’t failed yet. Sounds like you just got a lemon. Maybe follow Johnnysmoke’s advice?

They don’t sell that stuff
round here is all. GOOP works is all I’m saying.

slow leak in thermarest pad
try filling your bathtub with water and putting the mat under the water. watch for bubbles.