I'm interested to gather everyone's methods to extend an igloo's useful condition through a season.
In my case almost all my builds aren't for camping use; the locations I build aren't zoned for it - I build them for public amusement.
My methods to date are: (though some are just best building practices)
- Be sure to boot-pack the pad to prevent sagging, and resist compression under the igloo's weight. I tend to build the pad over two evenings, taking 2 hours per evening to get it properly built for a robust 2-2.5' deep, 13-14' wide pad. While this sounds like overkill, my igloos are 'lounges' with a 2-2.5' cube of snow removed from the center of the pad for easy seating, with 6 cushions within. (I've only once cut the entrance deep in to the end of the 'cube', as it ruins part of the igloo's effect. I leave an 8" thickness between the entrance and boot-space)
- Be sure to condition snow before use, to make for denser blocks that will sag/settle less. My method is to make a small pile and trample it, turning in a circle while using a shovel to bring it back to me as it spreads out. Of course this will also make building the blocks far easier also - pick your favored benefit!
- Make the pad at least 2' thick for a low door & easy entry
- After the igloo is built, add a 'cold scarf' covering up to the bottom 2 or 3 blocks. This means shoveling snow up on the rim/ledge and pressing it down with the shovel, building it up as far as possible and as wide as the ledge. I've found that this protects the bottom blocks from the elements; being the base blocks and supporting the rest of the igloo, keeping these levels insulated reduces the amount of sagging. Also, a cold scarf prevents the bottom 2 levels from buckling outwards. My ledge tends to be 1' wide; a 14' wide pad is ideal for this (with 9' model).
- A wind wall! This season's 4' high 2' thick wall has blunted wind around the igloo well. Reducing convection against the wall is a good thing. I used a 4x8' sheet of plywood as material for a giant u-shape 2" wider at the open end. It required a lot of snow and labor, but we had that. =) A simpler approach of just piling up a lengthly ridge of snow is good too, but will require more snow for the height vs. one made with a vertical form. A windwall should be as far away from the igloo as it is high, as there will be turbulence right behind the wall.
- Pick a location out of the sun as much as possible. Reducing radiant energy makes a big difference.
- When chinooks are moving through with melting temperatures, sagging is inevitable. Adding support inside to both sides of the entrance can help reinforce this area from sagging. Picture building up snow 'pillars' 6" thick & wide on both sides.
- During bad chinooks that are so warm as to melt all available snow, it is also an opportunity to use the mushy snow to add thickness to the outside of the igloo with little technique. The slushy snow can be easily packed/smeared on 2-4" thick and will freeze solid. I add less as I get higher up the wall to prevent adding much more weight on high as it will increase the sagging weight pressure. If you miss using the snow while slushy it will re-freeze as ice crystals and be almost useless for packing afterwards, unless melted again.
- If a chinook is very windy, you can put a tarp over the windward side of the igloo and secure it with firewood & snow until the wind dies down. If the igloo is in the sun, a light-colored tarp would be desired; a dark tarp would convert the sun's radiant energy and conduct it to the igloo.
- During melting periods, block the door & air hole as able to reduce air circulation within the igloo. A pair of heavy garbage bags filled with snow works well. (I tape a note to the outside bag so people understand, and know to return when it is colder)
- I advise against trying to ice an igloo unless it has already been reinforced with slushy snow. An original igloo wall with water added will be more massive without benefit of more structure when warm weather comes, and buckles under the weight. On the plus side, an iced wall is more resistant to unattended children and 'sandblasting' winds (while below freezing).
- Pick a location away from wind as possible. Certain hills/features & buildings will funnel wind and increased convection.
- Build with as clean snow as possible. Plant matter & rocks will conduct temperature directly to the wall. A pebble in a wall will convert the sun's radiant energy into conductive energy and sink into the wall. Plant matter is also not insulating like snow, and will take convected energy from the air & wind and conduct it into the wall, creating tiny hollow pockets around bits.
- It is good to patch any wind-blown divots in the outside of the wall as able. Even smearing on a skin of snow that fills in post-chinook gaps/chrystalline finish in a wall helps insulate the wall as it reduces penetration of the energy as far into the wall.
I'm curious if anyone else has tips on how to help their igloos! Please jump in!
Use this forum for more advanced questions.
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