Horizontal Rib Debris Hut

Article, drawings and photos by Mike Booty
(Page 1 of 2)

A debris hut is a survival shelter constructed from small limbless dead trees 8' to 10' long, sticks and leaves. Debris huts are designed for fast easy construction without special equipment and capable of keeping the body dry and warm with the body as the only heat source.

The conventional debris hut constructed in Tracker School’s Standard and Advanced Standard has vertical ribbed walls running from the ground to the ridgepole. The horizontal ribs debris hut ribs are laid like log cabin walls. In log cabins each horizontal layer of logs is referred to as a course starting with the 1st course, 2nd course, etc. Chinking describes both the material and the process of sealing the spaces between the logs.

The Standard’s vertical rib debris hut is the simplest to construct using universally available materials. Structurally, the vertical rib debris hut requires one 8' ridgepole, many short, small diameter sticks for the vertical ribs and large quantities of leaves. In wet, cool [40’s & 50’s F] conditions where hypothermia is a risk, 24" of debris covering the top is required. For vertical rib huts, the leaves covering the walls support the roof leaves. Therefore, 24" depth of leaves on the roof will require 24" deep on the walls. An entryway with a door is added on the front of the debris hut to retain body heat within the shelter in colder weather [<40F]. The depth of the leaves covering the tops and sides is also added for warmth [36" to 30F, 48" to 0F and 60" -40F].

Conversely, the wet weather horizontal rib debris hut requires at least eight 8’ long logs or ribs for the walls, sticks to cover the roof and 24" of leaves just for the roof. The cold weather debris hut requires sixteen 10' long 3" to 6" diameter logs for the walls including the entryway, two rows of sticks for the roof and leaves for chinking the walls and roof.

The optimal conditions for heating a space with body heat are: space conforming to the body shape, no heat leakage and optimum insulation material. The optimum shape that most closely approximates the body is a trapezoid. The trapezoid area should reduce in size with the body size from hips to feet. Heat leakage around the door and structural members should be minimized with the most impervious layer possible so heated air does not leak out or into insulating debris. The optimum insulating material available should be used.

Advantages

The horizontal rib debris hut design provides advantages to heating. Some of these can be applied to the vertical ribbed hut. The design advantages of the horizontal debris hut are itemized below in order of importance.

1. ADAPTABLE FOR SPECIFIC WEATHER CONDITIONS: Horizontal ribbed walls are one rib thick for wet, cool weather and two ribs thick and chinked with leaves for cold weather. The roof ribs are covered with 24" of leaves for wet weather. The horizontal hut’s rib walls support the flat roof that in turn supports the debris on the roof while the vertical rib debris huts, the wall debris supports the roof debris. Consequently, to have 24" of debris on the roof of the vertical rib debris hut requires 24" thick debris on the wall for supporting the roof debris. On a horizontal debris hut twenty-four inches of debris can be stacked on the roof supported only by the wall ribs. For cold weather with no potential for rain, the roof ribs can be covered with 4" of leaves and compressed with a second set of roof ribs. The thickness of the leaves over the second layer of roof ribs and wall ribs greater than this would depend on the outside temperature.

2. SUBSTITUTING THE INSULATING QUALITY OF WOOD FOR LEAVES: Ten inches thickness of wood has the insulating ability of 3-1/2" of fiberglass that is approximated by the horizontal rib wall with two 4" diameter ribs chinked with compacted leaves. Loosely piled leaves contain large air spaces the body must heat along with the material containing the air spaces. Heat can penetrate deep into loosely piled leaves. The double log wall and roof design displaces part of the leaves with wood, which when chinked with compacted leaves, has a higher insulation value. I’ve been in the hut in the diagrams shown down to 10F in a stiff wind. The inside temperature was 45F. I’m guessing that a 10" log wall chinked with leaves equals 20" of large oak leaves. A side-by-side comparison has not been complete yet. For cold weather with no potential for rain, cover the roof ribs with 4" of leaves and compress with a second set of roof ribs. The thickness of the leaves over the second layer of roof ribs and wall ribs will depend on the outside temperature

3. ADAPTABLE FOR MULTIPLE OCCUPANCY: The debris hut can be modified for two people by widening the distance between the walls. The longer roof ribs and roof debris required would take much less time and effort than building a second debris hut. Plus there is space heating advantages with two person hut. Multiple two person huts could be nested with common un-insulated walls for additional material and construction time savings.

4. TRAPEZOIDAL SHAPE REDUCES SPACE HEATING REQUIREMENTS: The trapezoidal shape of the enclosure eliminates the triangular area over the body in the vertical rib hut. Yet the 5th course allows room to turn over.

5. SIMPLE & EFFECTIVE ENTRYWAY AND DOOR SEAL: A simple, effective heat retentive entryway and door is part of the standard construction. The door is sealed from the inside with leaves over the entryway. From inside, 4 roof ribs are removed and dropped down on the threshold. Four 2" diameter bundles of stems are pulled in and stacked over the threshold. The bundles remain in place by wedging against sides walls of hut. Leaves stored above the entryway are pulled down through hole in roof and packed 12" to 24" thick against the stem bundles. This entryway and door can be used on the vertical rib debris hut. See #12 below.

Material for Wet and Cold Weather Horizontal Debris Hut

Photo #1: Material for construction of one-person horizontal debris hut in wet cold weather is shown above and itemized below. The two piles of long logs are 1st, 2nd, 3rd, 4th and 5th rib courses. The long pile of leaves under the A-frame and between the two piles of logs is the chinking between the wall’s ribs. The large pile of leaves is for 4" of insulation between roof ribs and the 24" for roof rain-proofing. The small pile of sticks is the first layer of roof ribs [item 8]. The large pile of sticks is the second layer of roof ribs.

NOTES:

* The interior rib has to be one continuous length in order to remain in place from only the support of A-frame at one end and the cross supports at the other end. The 4th course for cold weather applications only extends to the upper thigh where the 4th course cross support would be located. Using A-frame at the doorway and half the length of the hut would permit the use of shorter interior wall ribs.

** A cold weather debris hut will have thicker walls. Each course will have double log walls on each side with debris stuffed [chinked] between them. For double log wall thickness construction, the quantities for each course double to four. The outside logs are non-load bearing and the length can be composed of shorter lengths to meet the overall requirement. The pictures are for the cold weather design.

The outside allows for chinking with leaves between the ribs to make the wall more airtight and efficient at retaining heat. Lay leaves on top of each course as it is laid so the weight of the rib will compress the leaves. This airtight layer next to the body-heated air space is important so additional airspace does not have to be heated. The outside course can be composed of multiple logs for required length.

*** The second layer of roof ribs compress 4" of debris against the first layer of roof ribs to make the roof more airtight and efficient at retaining heat.

Note: The diameter of the wall ribs will determine the number of courses needed and whether there is room for insulation under your body.

Drawing # 1: Front View of Single Person Horizontal Rib Debris Hut

Drawing # 2: Side View of Horizontal Rib Debris Hut

© 2002 Mike Booty

Previous Page     Next Page