Concept Idea for cheap, UL, ultra waterproof, double walled Pyramid type shelter, some questions

[Anonymous]

I recently took out my custom Zpacks cuben poncho tarp and tried it in the more pyramid like style, and was dissatisfied with the amount of room. I and my gear fit in there, but just barely it and it was claustrophobic.

In any case, i'm sort of saving that gear anyways and don't want to put too much wear on it, nor my tipi hot tent set up. So with lack of funds, and no real desire to buy another expensive tent anyway, thought about this.

Materials involved: Thickest polycryo/window insulation film (cross linked polyolefin) i can find, SOL reflective Heetsheets, 2 yards of 1 oz cuben i'm not doing anything with currently (was going to use as a groundsheet or bottom of a bivy) but changed my mind, tyvek tape, Evazote foam, and a water resistant zipper.

I have all the material above except for the thicker, heavier duty polycryo. I'm wondering what is the thickest one can get, what brand is good, etc? I know i need the outdoor stuff, but i can't always find the thickness on the online sites i'm looking at (primarily amazon since i have prime). Some i've seen is only .7 mil thick. Ideally i would like to find at least 1 mil, or even 1.5 mil if they make it??? I'm guessing that 1.5 mil polycryo would weigh about 1 oz per yd?

Concept: Take a piece of thicker polycryo film, some 120 in x 84 in or so, cut and tape heats to similar size (about an inch smaller around the perimeter). On the Polycryo i will tyvek tape a 1 ft square or so of 1oz cuben roughly in the middle (where i will be putting the pole(s) and foam).

A piece on both the outside and inside. On the outside i will tape a small square of evazote foam to the cuben with tyvek tape.

Will do the same with the Heetsheet, except Cuben and foam will only go on the inside.

Guy out areas will be a combo of cuben fiber and tyvek tape (cuben partially covered with tyvek tape and taped on with same).

For the door, i will tape about a 2 to 3 inch wide strip of Cuben partway up the door on both sides (so one on the polycryo side and one of the heat sheet side), taping just the outside. Then on i will slice it down the middle and sew the water resistant zipper on it.

Haven't decided yet if i'm going to go with the one pole or two pole design.

Anyways, in cold weather, the heetsheet side goings in towards me with polycryo outside. Because they will only be taped together at the perimeter, and then held together at the top by the pole(s) pressure, i expect some air space to form in much of the wall area. I don't know yet, but i suspect with the combo of some air space inbetween the films and the reflective, should be noticeably warmer and have less condensation on the inside.

The polycryo will be the primary material taking the load, which will be reinforced with tyvek tape at key points (ridge lines, etc). Also, the cuben will take some of brunt with the pole, as well as the foam where the pole will be placed at. I did this with my Zpacks Cuben poncho tarp and it works great–holds it real well and found out tyvek tape sticks really well to both the foam and to the cuben.

In warm weather and sunny weather, flip it around and have the reflective part on the outside.

I do question the durability some, but i'm thinking with reinforcement of the cuben, tyvek tape, and two layers of plastic film it should last at least a few years and handle some semi strong wind. I primarily want to use it for colder weather, so the reflective stuff will be turned inside most of the time in use, and i will be careful with folding and storing it.

Besides general durability, the other issue i can see with using these materials is some stretching, but i'm hoping if i use the thickest polycryo i can find, or at least 1 mil thick, it should be kept to a minimum, especially with the cuben at the top and the tyvek tape at the perimeter and ridge lines.

Especially looking for feedback on the best and thickest types of polycryo to use.

[Anonymous]

My other alternative idea was to combine a .7 mil polycryo film with Argon fabric. I would purposely try to wash out any DWR that may be in the Argon fabric to slightly reduce weight and more so to increase bonding capacity (not sure how i would bond these, don't think the tyvek tape would work great on the argon, maybe nylon sail tape, but then again not sure how that would stick to the polycryo).

I suspect the combination would give me about a combined weight of about 1 oz per sq yd fabric. A bit lighter than the previous idea, but i like the thermal reflective properties of the other idea more, though i suspect that this latter combo would be significantly stronger. If Argon is anything like M50 material, it's surprisingly strong for it's weight.

Why not just silnylon if i'm going to spend this much (with the polycryo-argon combo) to get a similar weight? True water proofness and no need to reapply coating, double wall design, hence lack of condensation would be the primary reasons and a bit of weight savings.

In any case, i've decided to go with the former idea primarily because it will be significantly cheaper and because of the thermal reflective properties. If going with the Argon combo, i would have to spend at least another extra 48 or so dollars just on the Argon fabric, plus the polycryo, whereas as it is now with the former concept, i only have to buy the polycryo.

[Sam Farrington]

Justin,
You've got to have diagrams or photos of models for this type of thread. The ones without the diagrams etc., are worse than Dante's descent into He**.

[Anonymous]

I suppose you're right Samuel. Wasn't looking for feedback on the general concept so much, just throwing the ideas out there if anyone else had any interest.

What I do need help/feedback with is what kind of, and who makes the thicker polycryo, and where to buy. I would like to use at least 1 mil thick stuff, but having a hard time finding it.

[Dale Wambaugh]

I don't think you'll gain much insulation value from the inner layer. I think the weight would be more productive invested in your sleep insulation. Otherwise, you have to heat up the volume of the tent before the wall insulation kicks in. Better to have it close to you.

A net inner can calm some air and you get the anti bug and ventilation qualities. Part of an inner tent is to block direct airflow (wind) while still allowing ventilation. That's where those bathtub sides kick in, keeping the breeze off you while lying down.

Keep things simple and strong.

[Anonymous]

It depends Dale. Body heat alone, not so much. However, i sometimes like to bring a couple small beeswax candles with me. With combination of double wall with air gap in most areas and ability to have full coverage, IR reflective lining, candle heat, and body heat, i think it would be noticeable enough in cold, winter temps.

Investing in warmer sleep insulation is always a good idea, however, one doesn't always want to be under covers to be warm–sometimes i want to sit up, be a bit more active without having a quilt on me or being in a bag. Also, good quality insulation tends to be on the expensive side. Especially down. I suppose i could rip up my down quilts some and add some extra down, but even a little extra down is kind of expensive, and having no experience in ripping out seams, adding down, etc, i'm a little hesitant to do that. I have the quilt i can add extra apex but i wouldn't want to put anything but 2.5 oz stuff in there because the Apex starts to make things bulky real fast (i tend to use rather small volume packs–often the S2S Ultra sil daypack or MLD Newt).

Durability and strength are my main concerns with combing Polycryo with heat sheets. For that reason alone i'm tempted to the Argon-polycryo combo.

Weight would be nice too at about 1.17 oz per sq/yd (beats most silnylon, but silnylon is definitely significantly stronger and more durable). A thicker polycryo (1 mil or so) with reflective heet sheets would be heavier at about 1.5 oz sq/yd, and weaker.

I'm trying to balance weight, with cost, with aspects of convenience (i.e. not being stuck under a quilt or bag to be warm, not having to deal with much condensation, etc), with decent durability and strength. Hard to do.

I think these are pretty decent alternatives considering from a holistic perspective of all the above factors.

[Anonymous]

In my research, i have found that not all window insulation film is polycryo. First, a definition of "polycryo" (actually called cross linked polyolefin). It is polyethylene combined with polypropylene, and then irradiated with X rays to produce cross linking. That treatment that produces the cross linking affect, combined with the combination of materials is what gives cross linked polyolefin it's unique toughness and interesting properties for low weight material.

It seems that some of the thicker window insulation stuff (like the 1.5 mil stuff sold in Canada hardware stores), is NOT actually "polycryo", but rather a form of vinyl. Despite being thicker and heavier, such vinyl probably is not going to be as tough or strong as the polycryo–especially not on a weight to weight basis.

I found some 1.2 mil stuff on the online ACE hardware site, but it does not specify whether it's the vinyl version or the cross linked polyolefin version. I got the tele number for the product specialists and plan to give them a call tomorrow to find out for sure. If it's the cross linked polyolefin film, 1.2 mil thickness is quite good for my purposes and i expect it to be fairly durable and tough.

[Anonymous]

Not that anyone is all that interested, but i found out that the 84 in X 120 in and 1.2 mil thick window insulation sold online at Ace hardware IS indeed cross linked polyolefin (in BPL slang, "polycryo").

Sweet. Decided to go with a double hiking pole design to give more room because in reality, 7X10 feet is not that much more space than my 8'8" X 6'6" poncho tarp. So the poles will be placed in the middle now.

[Jerry Adams]

Post pictures and how well it works

[Anonymous]

Will do. Might be awhile since i have to order the stuff online, and i only get every other weekend off from work.

[Redacted k]

Your tent wall concept sounds like the stephensons warmlite, from what I have read about it. No experience, but as I recall it used double walls with a IR reflective inner. Some reviews think it is amazing, others doubtful.

fair warning, searching for their products might not be completely safe for work computers, some images have nudity.

[Author]

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