Hypervent Alternative?

[CRM]

I have some of this DMX-1 Step underlayment leftover from a flooring project and I'm thinking of installing it under the cushions in my Ollie. I'm fairly certain that it will allow more than enough airflow to prevent condensation under the cushions plus it is a moisture and thermal barrier too.  Additionally, it's much thinner than Hypervent and only costs around 70 cents per square foot. Any thoughts, pro or con? Seems to be a superior solution to me, but maybe I'm missing something?

https://dmx1step.com/

[Katjo]

15 minutes ago, CRM said:

I have some of this DMX-1 Step underlayment leftover from a flooring project and I'm thinking of installing it under the cushions in my Ollie. I'm fairly certain that it will allow more than enough airflow to prevent condensation under the cushions plus it is a moisture and thermal barrier too.  Additionally, it's much thinner than Hypervent and only costs around 70 cents per square foot. Any thoughts, pro or con? Seems to be a superior solution to me, but maybe I'm missing something?

https://dmx1step.com/

We have the Hypervent that Oliver options however we used this in our Airstream and it worked great. 
 

https://www.tochta.com/product/hypur-flo-moisture-protection/

[CRM]

Well, got around to installing the DMX-1 Step underlayment and very happy with the results. Lays flat right from the roll and was easy to cut and fit.  About $30 worth of materials and (I think) it will perform better than Hypervent. Time will tell..

[SeaDawg]

It may work. Looking forward to your comments.  I just use heavy duty ikea shelf liner, but I have cushions with a mildewproof coating (krypton), not a mattress. 

I don't see a way for the moisture ( we all emit it, breathing and sweating, etc.) to move through the underlayment.  That's the beauty of hypervent, and similar.

With that liner, if you start to see moisture in the pockets beneath, I'd tip the mattress or cushions  up a bit daily to let it breathe.  That's what we do on the boat. No underlayment,  just painted plywood,  in Florida, but breathable mesh on the bottom of the cushions.

[CRM]

24 minutes ago, SeaDawg said:

I don't see a way for the moisture ( we all emit it, breathing and sweating, etc.) to move through the underlayment.  That's the beauty of hypervent, and similar.

With that liner, if you start to see moisture in the pockets beneath, I'd tip the mattress or cushions  up a bit daily to let it breathe. 

The idea is that if moisture builds, it will form between the hull and the air gap on the bottom of the underlayment. The underlayment is a vapor barrier so that no moisture can penetrate through to the bottom of the cushions. I have a dehumidifier that is always on set at 50% or below so that should quickly remove any condensation that forms. If not, I'll add another section along the walls behind the upper cushions to increase airflow and give any moisture another route to escape.

This underlayment is also a thermal barrier so moisture shouldn't ever build in the top pockets. "Shouldn't",  we shall see..

[SeaDawg]

Like I said, it may work just fine. We have nothing on our boat, and shelf liner in the trailer, but no dehumidifier.  So, we resort to lifting the cushions... always when in storage.

I'll look forward to your reports. 

[CRM]

Update- It's been 6 months now and I've had absolutely no issues with moisture or condensation forming under the mattresses. Left one of my dinette cushions without this underlayment as a test and found moisture under it at least 6 times during that same time. Definitely recommend it for anyone looking for a low cost Hypervent alternative..

[SeaDawg]

Good news.

Which mattress do you have, or cushions, like us? 

 

[CRM]

9 hours ago, SeaDawg said:

Good news.

Which mattress do you have, or cushions, like us? 

 

I have the original factory cushions. Says they're upgraded on the original invoice, though I have no idea what that means. All I know is they're pretty darn comfortable so I haven't felt the need to replace them.

[SeaDawg]

The reason I asked is that cushion fabric is often treated, or at least more impervious/tightly  woven  than mattress fabric.

If we went to true mattresses, I'd likely add hypervent, a froli system,  or something like it. 

[SeaDawg]

On 3/12/2023 at 10:00 AM, CRM said:

I have the original factory cushions. Says they're upgraded on the original invoice, though I have no idea what that means. All I know is they're pretty darn comfortable so I haven't felt the need to replace them.

So do we. Plus a foam mattress pad.

[CRM]

On 3/12/2023 at 7:54 PM, SeaDawg said:

The reason I asked is that cushion fabric is often treated, or at least more impervious/tightly  woven  than mattress fabric.

If we went to true mattresses, I'd likely add hypervent, a froli system,  or something like it. 

These are the factory cushions we have.. They do have a rubberized waterproof backing on the inside so the cushions themselves never got wet when we were having condensation issues.