Natural homes up on the Roof: Using natural materials for your home.

These are Italian Trulli, dry stone homes usually made with limestone without any mortar. Dry stone building is part of the heritage of this region of Italy where many of the fields are divided by dry stone walls. The roofs of the trulii are built with two skins: an inner skin of limestone voussoirs (wedge-shaped stones forming the curved parts of an arch) capped by a closing stone, and an outer skin of limestone slabs that are slightly tilted downward to shed rain. Here's a video of a trulli roof being built.

This is Causeway House in Northumberland, England. It is a rare surviving example of a building thatched with heather, a feature once fairly common in upland areas of England and Scotland. Wind blows through heather so it must sit on layers of turf underlay. The heather is a first line of defence shedding much, but not all of the rain. The heather stalk is tied down with brier and stuck with clay. The ridge is made from turf. Amongst the various thatching material heather fares well lasting 20-30 years.

This is an art studio in India built by Biju of Thannal Hand Sculpted Homes. It is made using bamboo with a palm leaf roof and coconut leaf walls. This video shows the palm leaf being harvested and used to thatch a similar building. Biju is using palm leaf for thatching to show locals its value as a sustainable crop to encourage them to plant palm trees restoring them to a viable population in this part of India.

Reed

This is a reed thatched roundhouse at Felin Uchaf in Wales. Reeds grow best in salty water and are common in marshy estuaries. It grows 4 to 8 feet (1.2 to 2.4 m) tall. It is harvested in the winter until the young spring shoots begin to grow. Harvesting the reed encourages the production of tall, sturdy and straight reeds ideal for thatching. Harvesting the reed is a demanding job wading through cold water in freezing winter weather cutting 12 inch (30 cm) bundles and stacking them together in a group of six, known as a 'fathom'. Video No.1 shows how reeds are harvested and No.2 the thatching of a cottage with Norfolk reed.

Bamboo

Bamboo is a grass that grows incredibly quickly, up to 1m (3ft) per day. The high silica content in bamboo means it cannot be easily digested by termites. Additional soaking in borax salt makes bamboo a reliable building material. In this video you will see how to make shingles with bamboo. 
 

A traditional green roof uses turf, not to act as a barrier to the rain but to keep birch bark flat and in place. It's the birch bark which is actually keeping the roof dry. You will see the edges of the bark curling out from under the turf on the left of this log cabin in Sweden. A green roof like this will last about 40 to 50 years. Here are some more green roofs from around the world, although not all built in the traditional way. This video has some sound green roof advice from Michael G. Smith.

This is a roof made using a seaweed called eelgrass. It's one of the traditional homes on the island of Læsø in Denmark. Because of the high concentration of salt in eelgrass it doesn't burn and has a very long lifespan. A seaweed roof typically lasts 200 years, some have lasted as long as 400 years. This video (in Danish) shows how the eelgrass is stacked loosely above a barrier of branches fixed to the eaves of the roof.

The roof of Lisa & Rich's cob home is tiled with western red cedar shingles. The walls are straw bale on the north and east with sculpted swirls of cob on the south and west.

This gives a good introduction to making shingles, in this case oak. A shingle roof, depending on the species of wood and the pitch of the roof, can last between 30-80 years. Overhanging trees near a shingled roof will shorten its lifespan.

This is a blackhouse at Arnol, Lewis, Scotland. It's one of the few blackhouses that survive in the settlement. The timbers of the home were generally made from driftwood and in some cases whale bone. Over the timber roof a layer of turf was placed but leaving an unturfed region on the ridge of the roof to allow smoke from the central fire to escape through the oat straw thatch. A net anchored with stones helps to keep the thatch in place.