Thatching Method
Part of Emergency Shelter
Thatching is the art of overlapping natural materials to create a waterproof roof — a technique used for thousands of years and still effective with zero tools.
What Thatching Does
Loose debris insulates. Thatching waterproofs. While a thick layer of piled leaves will slow rain, a properly thatched surface sheds water completely — even in sustained downpours. The difference is organization: instead of random piling, thatching arranges materials in overlapping rows so water cascades from layer to layer without ever penetrating to the interior.
Think of it like fish scales or roof tiles. Each piece overlaps the one below it. Rain hits the top piece, runs down to the next, and so on until it drips off the bottom edge — never passing through.
Materials for Thatching
Not all natural materials thatch equally well. The best thatching materials share three properties: they are relatively flat, they overlap easily, and they shed water rather than absorbing it.
| Material | Water Shedding | Durability | Availability | Notes |
|---|---|---|---|---|
| Palm fronds | Excellent | Good (weeks) | Tropical only | Best natural thatching material in warm climates |
| Pine/spruce boughs | Very good | Good (1-2 weeks) | Temperate forests | Needles shed water naturally; resinous |
| Broad leaves (oak, beech, maple) | Good | Fair (days) | Deciduous forests | Must overlap heavily; curl when dry |
| Fern fronds | Good | Fair (days) | Forest understory | Lay flat, overlap well |
| Long grass bundles | Very good | Good (weeks) | Grasslands, meadows | Must be bundled and tied; traditional method |
| Bark slabs | Excellent | Excellent (months) | Anywhere with trees | Best permanent thatching; hard to harvest without tools |
| Cattail leaves | Very good | Good (1-2 weeks) | Wetlands, pond edges | Naturally waxy surface sheds water |
| Banana leaves | Excellent | Fair (days) | Tropical only | Huge surface area; deteriorate quickly |
| Reed bundles | Excellent | Excellent (months) | Wetlands, riversides | Traditional thatching material worldwide |
The Basic Thatching Technique
Step 1: Prepare Your Framework
Thatching requires a framework of horizontal battens (cross-sticks) to tie or wedge the thatching material against. If you are thatching a lean-to or A-frame shelter, your rib sticks serve as the framework. For better results, add horizontal sticks across the ribs at 15-20 cm intervals. These battens give you something to hook or press thatching material against.
Step 2: Start at the Bottom
This is the most important rule of thatching: always work from the bottom of the roof upward. Each new row overlaps the row below it. If you start at the top, rain runs behind the lower layers and into the shelter.
Begin at the lowest edge of your shelter — the drip line. Your first row of material will hang over the edge slightly (5-10 cm) so water drips clear of the wall base.
Step 3: Lay the First Row
Take your thatching material and lay it across the lowest batten:
- For leaves and fern fronds: Lay them flat, overlapping each piece by at least half its width. The stem end points upward (toward the ridge), the tip end points downward. This way, water runs off the natural curve of the leaf.
- For evergreen boughs: Lay them with the cut end up and the tip hanging down. Overlap each bough by at least one-third.
- For grass bundles: Gather a handful of long grass (30+ cm), hold the root ends together, and lay the bundle across the batten with root ends up and blade tips hanging down. Each bundle should be fist-thick when compressed.
Step 4: Secure the Row
Pin each row in place so wind and gravity do not dislodge it:
- Lay a long, thin stick (a “sway” or “ligger”) across the row, pressing the material against the batten. Wedge it in place or tie it with cordage.
- Alternatively, weave flexible twigs through the material and around the batten.
- For grass bundles, a horizontal stick lashed to the batten sandwiches the grass firmly in place.
Step 5: Add Successive Rows
Move up 10-15 cm and repeat. Each new row must overlap the top of the previous row by at least half. For heavy rain areas, overlap by two-thirds.
The overlap rule of thumb: The steeper the roof angle, the less overlap you need because water runs off faster. The shallower the angle, the more overlap required.
| Roof Angle | Minimum Overlap |
|---|---|
| 60 degrees (steep) | 1/3 of material length |
| 45 degrees (standard) | 1/2 of material length |
| 30 degrees (shallow) | 2/3 of material length |
| Below 30 degrees | Thatching alone will not waterproof; add bark or debris underneath |
Step 6: Finish the Ridge
The ridge (top line of the roof) is the most vulnerable point. Water wants to soak in right at the peak. Options:
- Fold-over: If using large leaves or fronds, drape them over the ridge so they hang down on both sides.
- Ridge cap: Lay a thick bundle of grass or a row of bark strips along the ridge, overlapping both sides.
- Inverted V: Place two rows of boughs meeting at the ridge, tips pointing down on opposite sides, stems interlocking at the top.
Thatching with Specific Materials
Evergreen Boughs (Pine, Spruce, Fir)
The most accessible thatching material in temperate and boreal forests.
- Cut or break boughs 60-90 cm long. Choose ones with dense needle coverage.
- Lay them shingle-style, cut end up, tip end down.
- Overlap each bough by at least one-third its length.
- The natural curve of the branch should face outward (convex side up) so rain slides off.
- Pin with horizontal sticks.
Advantage: Resin in the needles naturally repels water. A well-thatched evergreen roof can last 1-2 weeks before the needles dry and fall.
Broad Leaves (Oak, Beech, Maple)
Common in deciduous forests, especially in autumn when the forest floor is covered in them.
- Select the largest, flattest leaves available. Freshly fallen leaves work better than old, crumbled ones.
- Lay them in thick, overlapping rows — each leaf overlapping its neighbor by half.
- You need many more leaves than you think. A single row should be 3-5 leaves thick at every point.
- Pin each row with a horizontal stick.
Limitation: Individual leaves are small and curl when dry, creating gaps. Compensate by using extreme thickness (multiple leaves deep at every point) and layering with other materials.
Long Grass Bundles
Traditional thatching technique used worldwide for permanent structures. Also effective for emergency shelters.
- Gather long grass or reeds — minimum 30 cm, preferably 50 cm or longer.
- Bundle a fistful together with root ends aligned.
- Lay the bundle across the batten with root ends facing up toward the ridge.
- Compress with a horizontal stick or tie down with cordage.
- Each bundle overlaps the one below by at least half its length.
- Stagger bundles left-right so seams do not align vertically.
Advantage: Grass thatching, when done properly, is the most waterproof natural option and can last weeks or months.
Common Thatching Mistakes
| Mistake | Result | Fix |
|---|---|---|
| Starting at the top | Rain runs behind lower layers | Always work bottom to top |
| Insufficient overlap | Gaps where water penetrates | Minimum 50% overlap at 45 degrees |
| Not pinning rows | Wind strips thatching off | Use horizontal sway sticks on every row |
| Vertical seam alignment | Water channels straight through | Stagger each row so seams do not line up |
| Using wet material | Rots quickly, adds weight, poor insulation | Use dry or recently dead material when possible |
| Roof angle too shallow | Water soaks through instead of running off | Minimum 45-degree angle for thatching to work well |
| Thin ridge | Worst leak point left unprotected | Double-thatch the ridge with fold-over or cap |
Combining Thatching with Debris
For emergency shelters, the most effective approach combines both techniques:
- Build your stick framework and lattice.
- Apply a thick bulk debris layer for insulation (see Debris Layering).
- Thatch the outermost layer for waterproofing.
This gives you insulation from the debris and water-shedding from the thatching. The debris layer underneath also helps support the thatching material and fills gaps.
Key Takeaways
- Thatching works by overlapping materials so water cascades from layer to layer without penetrating — always work from bottom to top.
- Each row must overlap the one below by at least half (more on shallow roofs).
- Pin every row with a horizontal stick to prevent wind from stripping the thatch.
- Stagger seams between rows so water cannot channel straight through.
- The ridge is the weakest point — give it extra attention with a fold-over, cap, or double layer.