Heather thatching — Blog 1

Two weeks ago, we were reunited with artist and vernacular architect, Rob Thompson. Terroir first spoke to him in his native North Wales (see Cynefin, Blog 18, February 2021) but last summer we discovered him in Glencoe, having been working on the construction of a historic form of dwelling, called a Creel or Turf House. During our last blog, we quizzed Rob on Creel House basics – the ‘what is it’ and the ‘why on earth build one’ sort of question. Today we’re getting in much, much deeper to the practicalities, and uncovering some surprising stories.

Terroir: Rob – you said that this sort of vernacular architecture used local materials. So where did you get your timber, turf and heather?

RT: on the whole the timber was sourced locally from within Glencoe.

Turf is more tricky, however. It comes in many different types, usually clay, silt, or peat based. Clay and silt rich turf shrink back the least, and are the best choice when building a structure that would suffer if a turf with high shrinkage was to be used.

Peat based turfs are lighter in weight and hold more air. They are used where a high level of insulation is required, as is the case in Glencoe. They do however shrink back the most and this can be a problem if the building’s design does not allow for this to happen.

The turf for the walls at Glencoe was sourced from directly next to the site. The blocks were produced with a diagonal cut, and carried over to the site. I think it is an especially important aspect of the build that the walls, which are unlikely to outlive other parts of the structure, have come from, and can be returned back to, the ground in close proximity to the building.

The walls are up to a metre deep in places and of solid turf block laid in herringbone course.

As the peat rich turf slowly shrinks as it dries out, the joints should close up. Additional height was added to the walls, to compensate for the loss of height due to the shrinkage of the turf. The walls are angled with a batter. This allows the load to spread, reducing the risk of collapse. The batter has also caused some issues, though, as its projection acts as an extended area for rain to hit.

Image above: the turf house steams gently in a brief sunny interval

Terroir: did you say there was turf on the roof as well?

RT: yes, it’s called a turf divot, a layer of thin turf used as an insulation layer. It sits on the cabers (the roof timbers) allowing a levelled off area for the heather thatch to sit on. The thatch is then attached to the divots using hazel staples and spars. The divot also absorbs moisture so acts as a second line of defence against wind and rain.

Above: turf divots being covered by heather thatch

Although we managed to source the wall turf locally, there was not enough left to line the roof as well. This is where the 21st century began to impact on the build. A turf cutting area of sufficient size could not be found in Glencoe due to the glen’s protected status as a Site of Special Scientific Interest (SSSI).

Eventually the turf was cut from the National Trust for Scotland (NTS) site at Kintail approximately two hours north of Glencoe. The cutting site was a flat meadow field close to the road. The cutting process was a difficult thing to get right.

A day was spent attempting to cut turf with a double width machine, the Turfaway 600, which looked an impressive lump of an American machine. It proved to be useless for this work, however, as the blades were unable to stay in the ground long enough to cut any decent turf. A replacement, older and heavier machine arrived several days later together with a mechanical wheelbarrow to pull it!

The turf was cut and stacked ready for the collection. The staff at the National Trust and the crafts people used a trailer and Land Rover to take it back to the creel house site - some 8 trips were needed.

Terroir: no local sourcing there, then. What about the heather for the roof? No shortage presumably?

RT: hah!

Terroir: pardon?

RT: you would think it would be easy, wouldn’t you?

The heather required for thatching is the common native heather (Calluna vulgaris) which thrives on poor acid soil found in the highlands of Scotland. The original intention was to gather heather from the NTS’s Mar Lodge estate, but due to nesting birds, it was not feasible and in the end, it was gathered from the neighbouring Invercauld estate.

The picking of heather suggests the idea of walking through an open field, picking flowers with ease. Heather picking is far from this, requiring the plant to be physically pulled out of the ground, roots and all. It’s hard manual labour with wildlife hazards: adders, clegs (horse flies), midges and ticks all need to be dodged, swatted or removed.

Once pulled, heather is bundled. A bundle size is a tight, ‘oversize hug’ ie a ‘hug’ plus about a foot between each hand. The material is pulled in, and when no more can be hugged it is ready to be stringed together. The twine is tied tightly around each end straightening the bundle out. This process often involves a bit of wrestling with the heather to get it compressed to a point where it is feasible to tie the string around. A length of string is about one stretch of an arm.

For the purposes of the project, 1,000 bundles of heather had to be transported from Braemar to Glencoe - carried by a huge articulated lorry.

15 people took part in the heather gather over 10 days. There was one afternoon off, one visit to the pub, three swims in a river, and one end of gather party! The accommodation was a bunkhouse in Braemar.

Image © Mark Thacker

Terroir: and you still haven’t started thatching!

RT: thank goodness the traditional craft of thatching is still alive and well. Working from the base of the roof, around three layers of heather were fixed with a spar, then another three layers and so on to the roof ridge. The intention was to thatch the ridge but suitable lengths of heather were limited. A decision was made to do a turf ridge instead which is seen on many examples of heather roofs, including the township at the Highland Folk Museum.

A daub coating was added to seal the heather on the final layer. It was a hot period and the daub baked dry in the sun. Turf divots were then used to form the ridge, one layer pegged grass side down, and a second layer, overlapping the joints in the lower layer, placed and pegged grass side up. It is thought that this will last up to two years before it will require replacement. Maintaining this will involve very little; if it required a trim a rabbit on a lead could be used!

Image left: the daubing process Image right: the creel house with the ridge sporting a neat, turf mohican

Terroir: it all sounds a bit short term. Does it really work as a form of dwelling?

RT: I know what you mean. I have always associated turf wall construction with that of the Ty Unnos tradition in Wales. Here it was often used as a quick temporary building method, before a more long term method would be applied to replace it at a later date, such as stone or Clom (compressed earth similar to Cob in England).

Turf has a relatively short life expectancy before it breaks down. Roots that bind the turf slowly rot, and the turf degrades. It is interesting when looking at accounts of the creel/turf houses of Scotland that they were rebuilt very often. There would often be two sites that a dweller would rotate between, taking the valuable parts of the building with them, and allow the walls, and roof to rot away back into the ground. Often the building would become a cattle shed, then as it collapsed, a Kale yard. It is evident that the building went through a variety of uses before finally returning to the earth again. It seems like a very sustainable way of building!

Creel House Tribulations