Dome cover: waxed canvas or poly?

[siduri]

I am looking to build a cover for a 16 foot diameter 3v dome. I'm strongly inclined towards waxed duck canvas tarp material, mostly for being breathable, opaque, water resistant, biodegradable, in addition to more aesthetically appealing (to me at least). It's surely a spendy option, but if it'll hold up I'm willing to pay it. I was planning to use grommets at all base dome vertices, as well as a few more higher up.

Additionally, the website has the following caveats about the canvas that make me second guess this option:

Canvas Tarps should not be used as trailer tarps. The Canvas Tarp material is not strong enough to withstand the pulling force from wind generated while in transit.

It is not recommended to use Canvas Tarps for applications that require excessive pulling on the grommets of the fabric. Canvas Tarps do not have the high tensile strength needed for excessive pull force. Please refer to Vinyl Tarps for applications that require force. Canvas Tarps should not be used as divider curtains, canopy tops or as side walls.

Due to the fact that Canvas material is made using 100% cotton fibers, the fabric will shrink over time. The amount of shrinkage is dependent on environmental conditions, such as a weather, sun exposure and humidity.

The other option is 'super heavy duty' poly tarp in white, which I'm sure would take the abuse of the wind, but wouldn't be breathable. It's also cheaper.

Either option will be cut into gores and sewn/glued together to form a good fit. Additionally, I'll be augmenting it with an additional partial cover of aluminet to reflect light. Probably throw a swamp cooler in there too.

So, for experienced dome builders, will the canvas hold up, or should I go with the poly tarp?

[GreyCoyote]

Canvas duck is not UV resistant. It blocks the UV nicely, but it also degrades over time. Cotton is an organic and UV loves to react with it. If you are only using this dome a couple of weeks a year, then this wont be a problem. But for long term exposure there are other options or you can get duck coated with a UV resistant polymer layer.

Canvas is nice because it is fairly quiet in a wind, while poly tarp (and some harder vinyls) make a miserable racket. About the only thing taut can as will do is drum when the wind gets insane.

The dome you are covering is small so perhaps a cheap, helpful suggestion is in order: check out "housewrap" at Lowes and Home Depot. It comes in two basic types: tyvex, and woven poly. A roll 9' wide by 150' long is between 85 and 175 bucks. I use the cheapest stuff for prototyping my covers before committing to expensive canvas. What is not generally known is these fabrics can make a very servicable covering in their own right for a couple of months of exposure.

For a small dome, maybe go this route first. You can sew it and hem it just like fabric. For grommet areas, fold it over a couple of times and stitch it around the grommet, then punch the hole and set the grommet. Another trick is to use Grip Clips (etc) which hold well but dont make holes.

FWIW, House wrap, if double-stitched on the seams and tied to the frame every coue of feet at the base, will withstand whatever the playa throws at it for a couple of burns. Just make sure the cover fits tightly and there are no sharp edges to start a tear.

Last thing: depending on the manufacturer, "parafin" can be either a wax-like coating similar to candle wax, or it can be a smelly liquid rather like a deodorized kerosene. Ask before you buy. It will make a BIG difference in habitabilty (the liquid parafin coating, especially when new and hot, smells like fermenting socks soaked in urine. Really bad stuff until it flashes-off, and then its fine and mostly odorless or just earthy smelling)

[siduri]

Thanks for the helpful info, GreyCoyote!

[MoBo]

Careful using "poly" in a subject line around here...

[siduri]

Careful using "poly" in a subject line around here...

Part of my plan to increase thread views

[GreyCoyote]

Good thing I said "parafins" instead of something really risque like "Polybiphenol". Whats the difference? One is part of a telost fish, while the other is a confused and sticky compound.

(Those guys in the back row rolling their eyes are the chem-heavies, and to them I offer my sincere apologies for the bad pun!)