A structure is hardest to see when it is sunk into the ground, built on the side of a hill facing away from the likely observers, or tucked against an existing feature such as a cliff, boulder or dense hedge. Each of these hides it from some viewpoints and costs you something real, so pick the one whose cost you can manage: drainage and roof load for sunken, cold air for the reverse slope, and a single approach for the feature-backed site.
Part of Camouflage and Concealment
Hiding structures are buildings sited and shaped so that terrain does most of the concealing, using sunken construction, the reverse side of a slope or an existing natural feature.
Terrain Hides A Building Better Than Cut Branches Do
The parent article lists three approaches. Sunken construction puts the shelter into the ground so that the roof is at ground level, covered with earth and vegetation; the article says such a shelter is invisible from 20 m away. Terrain folds place the building on the reverse slope, the side facing away from the most likely observation direction, so that the hill itself provides concealment. Existing features build against a cliff face, large boulder or dense hedge so the structure merges into the feature instead of standing alone.
All three work by removing the building’s silhouette and straight edges rather than painting over them. All three also change how water, air and people move around the building, and that is where they fail.
What You Need
- A survey of the viewpoints — the road, ridge or opposite slope from which you do not want to be seen; see Local Terrain Analysis
- Drainage knowledge — see Waterproofing and Drainage for Earth-Sheltered Buildings
- Structural timber or stone sized for the soil load (see Underground Root Cellar for a stone-walled, earth-roofed example)
- Two separate exits, planned before you dig
Method: Choose The Cost You Can Pay
Step 1: Map where the building can be seen from. Walk the possible sites and look back at each from the viewpoints you listed. A reverse slope hides the building only from observers on the far side; someone on the ridge above can still look down on it.
Step 2: Sunken construction. Dig down, not out, and put the roof at or just above ground level. Three failures dominate. Water: a hole in the ground collects runoff, so put it on well-drained ground above the seasonal water table with a drain; the drainage article explains that underground buildings fail because water got in. Roof load: earth is heavy, and the above-ground cellar article names roof failure under earth loading as the most common failure mode, so size the beams for the load. Air: a room with a fire in it needs a flue and a separate air inlet, and a closed earth room is where carbon monoxide kills; see Carbon Monoxide Risks.
Step 3: Reverse slope. Place the building below the crest on the side away from the observers. Cold air drains downhill at night and pools in hollows, which can be markedly colder than the slope above (see Cold Air Drainage and Frost Pockets), so do not sit at the very bottom of the hollow. Check where runoff from the slope above will go.
Step 4: Against a feature. Build against rock, a large boulder or a thick hedge, but leave a gap you can walk through behind the building so that the feature does not trap you between wall and wall in a fire. A hedge is also fuel; leave a bare strip between it and any chimney.
Step 5: Break the surface and the approach. Follow the pattern guidance in Pattern Disruption. The parent article’s warning about paths applies: a worn trail to a hidden door reveals it, so vary the approach and let vegetation regrow over disturbed ground.
Common Mistakes
- Concealing the building but not its smoke or light. A perfect roof under a plume is not hidden. See Fire and Smoke Management.
- A single exit. A sunken room with one door, a feature-backed building with one approach and a hedge on the other side are all traps in a fire.
- Building where the soil is saturated. Concealment that floods fails faster than one that is seen.
- Forgetting the viewpoint from above. Observers on high ground see the roof; cover it, do not assume the slope shields it.
Safety
A hidden building must still be escapable
The features that make a structure hard to see also make it hard to leave: earth around it, one door, vegetation against the walls. Build two exits on different sides, at least one openable from inside without tools, and keep dry vegetation off the walls and away from the roof. Do not run a stove or lamp in a sunken room without a flue and an air inlet, and treat headache or drowsiness in a closed room as carbon monoxide until proven otherwise. Do not enter or work in a dug excavation deeper than your chest without shoring the walls; the sides collapse without warning.
What’s Next
- Learn next: Light Discipline — a hidden building must also be dark at night
- Combine with: Terrain Selection — picking ground that hides you and stays passable