What fabric for pop-top roof sides?

[ExploringNH]

I've been looking into different fabrics to use for a pop-top roof and wanted to see what other people are using.

Pop-top like this:

Breath-ability and water resistance are, I think, the two biggest factors.

It seems that Cordura 330D is pretty popular. I was thinking of going with Cordura 500D. It is a little thicker than the 330D which should make it a little more durable. The pop-top will be used in weather from 90F to about 30F. If it gets too cold, the roof will stay closed and we will sleep on the floor.

 

[Ozarker]

I may be using something similar. I'm thinking of looking into hypolon (sp?) material. It's bullet proof (almost) it's used to make inflatable boats and pontoons. Jack's Plastic Welding a raft maker might have a line on it. It's also used for better boat covers and commercial awnings. I had a boat cover made from it and never noticed any condensation problems. It's also very UV resistant and dries quickly. My boat was not air tight so "breathablility" was not an issue, not sure what that would be, I wouldn't want air passing through.

 

[ExploringNH]

Thanks for the response. I have not heard of that material and will look into it.

Since this post, I've found that many of the chinese made roof top tents are made with 420D. A lot of people are happy with the construction, but I would think that 420D would be the bottom end of acceptability standards.

I have found some neat fabrics in my travels. One is called Evolution, or Block It, made by Kimberly Clark. This material is designed to be used for car covers. It also seems like it would be a fantastic fabric for rooftop tents. Very durable, waterproof, but still breathable, and decent insulating qualities due to the extra padding they add to protect a cars finish are just a few of the benefits. The price is up there at nearly $13/sq ft.

WeatherMax is a fabric that I am considering, in 8oz/sq.yard flavor. It seems pretty ideal, but it pricey.

Sunbrella is a name that keeps popping up. A lot of people rebuilding Westy pop-tops are using some sort of Sunbrella fabric.


Some high end roof tent companies list their fabric as having a weight of 420g/sq.m. This worries me a bit, as the heaviest of the materials I am considering comes in at 8oz/sq.yard or roughly 275g/sq.meter. About 30% lighter than they are claiming. I'm also running into issues of weight/linear yard vs weight/sq.yard. For instance, I think Sunbrella is listed at 8oz per linear yard by some companies. This doesn't mesh with my understanding of what a linear yard is.

 

[ExpoMike]

My understanding (which is limited) is that linear yard is whatever the width of the material is x 1 yard. Basically linear as it rolls off the roll. At least that's how fabric stores work.

 

[AEV Conversions]

On the pop up pictured above I used a polyurethane coated Cordura 1000D which is waterproof, but required seam sealer to be totally waterproof. Cordura by itself is not waterproof, you need to get the coated stuff. We shingled all the seems on the above unit so that water intrusion was no issue. PVC or Hypalon is commonly used on the commercial pop-ups like FWC and Dormobile. The issue with all these materials is the lack of breath-ability, they all tend to be hot and humid with two people in even moderate climates. Not a real problem if you pay a lot of attention to ventilation in your design.

I slept in the above unit down to 30 degrees, but we still had the windows opened.

dh

 

[Lemsteraak]

Fabric is really a key component to a pop up or RTT. Really is a lot of differing approaches. I was involved in some of AutoHome designs and the engineering of the fabric was taken very seriously not only the fabric but the colors.

I would steer away from the fabrics used in car covers, totally unsuitable, really different requirements. The reason why Sunbrella is so popular is that it is really durable and breathes well. The drawbacks are it isn't inherently waterproof and requires a DWR coating to be water resistant and Sunbrella can't take chaffing so it is OK for an application like a Westy pop-up but would suck for a folding RTT.

AutoHome has the scale so they can have the fabrics engineered for them. An example is the fabric on the Maggiolina, it is called Dralon and the work was done by Bayer in Germany. If you look at a light source through the fabric, you will see thousands of little holes, it is really just a mesh. You can actually feel a draft through the fabric in very high winds. That is why the tent works so well, holds in warmth, strips the water out of the air and breathes like crazy. You then stay dry because there is so little condensation. AutoHome uses different fabrics for each of their designs. For example, Dralon would be totally unsuitable for a folding RTT, but is perfect for the vertical walls of the Maggiolina.

So, what I'm getting at is that the fabric is integral to the design. The less fabric you use, the more it has to breathe. More vertical, less water resistance, more horizontal, more water resistance is needed. You get the rough idea. Once you get the design done, I think everyone can give more detailed advice.

Here is a little story to give you an idea of the fanatical attention to detail that AutoHome goes through. I was in Italy when they were designing the first of the aerodynamic Maggiolinas about 15 years ago. Gioseppi, the designer was asking me about how I like the new gray fabric. This is after a year of testing in the field. I loved it and told him he should use the new fabric on all the Maggiolinas. They previously used a blue fabric. He said that blue was used for the "quality of light". I was totally confused and asked him to clarify. He said, let's say you are in Morocco and just tired of the journey. You can climb into your tent, put on your music and the light inside the tent is soothing and you will be right in no time. You know, it is true. The blue fabric Maggiolinas are really cool and if I were going to go on an extended journey, I would specify their "expedition" blue.

 

[r_w]

Not RTT experience, but outdoor industry:

Do NOT equate a higher D number as "always" better. 330 is usually more abrasion resistent than 500 or 1000. Not as strong for load bearing, but does better with abrasion. That is when staying within the same brand, some brands are obviously better than others.

You also need to watch for fabric weights as being measured pre-treat or post treated. A DWR adds a lot more weight than you think it would.

 

[AeroNautiCal]

I've been thinking of using eVent fabric, which is used in the construction of high end outdoor clothing.

Lightweight, hard wearing, wind and waterproof... And it breathes! It's the fabric used in my Montane Superfly XT jacket (which gave me the idea to use it for a roof!).

Whilst it may prove more costly than a non breathable fabric, I won't need much.

 

[NOAH'S ARK]

Simpler solution?

I am planning a front hinged popup for the back of my colorado , and was considering nylon tent material for the sides and rear opening. Why wouldnt it be durable and weather resistant enough for the upper sides of a popup, when it works fine for a tent- as far as constant folding/ unfolding and proven waterproof ability is concerned? Not to mention low weight and cost. Any advice is greatly appreciated.

 

[Lemsteraak]

I agree with AeroNautiCal that GE's eVent fabric is brilliant. I've been using a drysuit made of it and am very impressed. For your applications where you need fabric for a single walled tent with a highly breathable membrane, I think it would be a good choice. Another advantage is that the fabric is quiet, very important in a hinged pop-up tent where you can't really get the fabric super tight. In high winds, your fabric will flap a little.

GE's eVent fabric seems to have done GoreTex one better with what they call direct venting. GE has a good explanation of how the process works here http://www.eventfabrics.com/index.php. This is similar to the Dralon fabric I talked about in my last post where water vapor passes directly through but water does not. That being said a GoreTex fabric will also work very well as both eVent and GoreTex may be overkill for your application. A good PolyCotton fabric I think would be less expensive, easier to work with and have a very nice old fashioned feel.

Please realize that I don't have a proper background in the outdoor field, my background is sailing.

Oh, I'm not a big fan of nylon for a tent fabric because it expands and stretches when wet and naturally wicks moisture so it has to have some sort of coating. That being said, I like some of the old nylons. I have an old school super light nylon mountaineering jacket that has always traveled with me. Nylon doesn't do well in sunlight, the colors fade and the fabric breaks down. But what can I say, if it is well made, it works well too.

So my advice, get samples, and then torture them, see which properties you like about each material.

 

[ExploringNH]

I decided to run with a coated Cordura 1000D. I will post back and let everyone know how it worked out. I sampled a ton of fabrics under my faucet, and I think the Cordura is the best compromise for my situation.

 

[Lemsteraak]

Here are a couple sources for fabric to torture and the tools you may like

SailRite - http://www.sailrite.com/

Seattle Fabrics - http://seattlefabrics.com/