Stave church
A stave church is a medieval wooden Christian church building once common in north-western Europe. The name derives from the building's structure of post and lintel construction, a type of timber framing where the load-bearing ore-pine posts are called stafr in Old Norse. Two related church building types also named for their structural elements, the post church and palisade church, are often called 'stave churches'.
Originally much more widespread, most of the surviving stave churches are in Norway. The only remaining medieval stave churches outside Norway are: Hedared stave church in Sweden and the Vang Stave Church which was built in Norway and relocated in 1842 to contemporary Karpacz in the Karkonosze mountains of Poland. One other church, the Anglo-Saxon Greensted Church in England, exhibits many similarities with a stave church but is generally considered a palisade church.
Construction
Archaeological excavations have shown that stave churches are descended from palisade constructions and from later churches with earth-bound posts.Similar palisade constructions are known from buildings from the Viking Age. Logs were split in two halves, set or rammed into the earth and given a roof. This proved a simple but very strong form of construction. If set in gravel, the wall could last many decades, even centuries. An archaeological excavation in Lund uncovered the postholes of several such churches.
In post churches, the walls were supported by sills, leaving only the posts earth-bound. Such churches are easy to spot at archaeological sites as they leave very distinct holes where the posts were once placed. Occasionally some of the wood remains, making it possible to date the church more accurately using radiocarbon dating or dendrochronology. Under the Urnes Stave Church, remains of two such churches have been found, with Christian graves discovered beneath the oldest church structure.
A single church of palisade construction has been discovered under the Hemse stave church.
The next design phase resulted from the observation that earthbound posts were susceptible to humidity, causing them to rot away over time. To prevent this, the posts were placed on top of large stones, significantly increasing their lifespans. The Røldal Stave Church is believed to be of this type.
In later churches the posts were set on a raised sill frame resting on stone foundations. This is the stave church in its most mature form.
It is now common to group the churches into two categories: the first, without free-standing posts, often referred to as Type A; and the second, with a raised roof and free-standing internal posts, usually called Type B.
Those with the raised roof, Type B, are often further divided into two subgroups. The first of these, the Kaupanger group, have a whole arcade row of posts and intermediate posts along the sides and details that mimic stone capitals. These churches give an impression of a basilica.
The other subgroup is the Borgund group. In these churches the posts are connected halfway up with one or two horizontal double ″pincer beams″ with semicircular indentations, clasping the row of posts from both sides. Cross-braces are inserted between the posts and the upper and lower pincer beams, forming a very rigid interconnection, and resembling the triforium of stone basilicas. This design made it possible to omit the freestanding lower part of intermediate posts. In some churches only the four corner posts remain.
Many stave churches had or still have outer galleries or ambulatories around their whole perimeters, loosely connected to the plank walls. These probably served to protect the church from a harsh climate, and for processions.
Single-nave church, Type A
At the base of Type A churches, there are four heavy sill beams on a low foundation of stones. These are interconnected in the corner notch, forming a rigid sill frame. The corner posts or staves are cross-cut at the lower end and fit over the corner notches and cover them, protecting them from moisture.On top of the sill beam is a groove into which the lower ends of the wall planks fit. The last wall plank is wedge-shaped and rammed into place. When the wall is filled in with planks, the frame is completed by a wall plate with a groove on the bottom, holding the top ends of the wall planks. The whole structure consists of framesa sill frame resting on the stone foundation, and the four wall frames made up of sills, corner posts and wall plate.
The wall plates support the roof trusses, consisting of a pair of principal rafters and an additional pair of intersecting "scissor rafters". For lateral bracing, additional wooden brackets are inserted between the rafters.
Every piece is locked into position by other pieces, making for a very rigid construction; yet all points otherwise susceptible to the harsh weather are covered.
- The single-nave church has a square nave and a narrower square choir. This type of stave church was common at the beginning of the 12th century.
- The long church, has a rectangular plan with nave and choir of the same width. The nave will usually take up two-thirds of the whole length. This type was common at the end of the 13th century.
- The center-post church, has a single central post reaching all the way up to and connected to the roof construction. But the roof is a simple hipped one, without the raised central part of the Type B churches. This variation on the common type of church, found in Numedal and Hallingdal, dates to around 1200.
The only remaining church of this type outside Norway is the Hedared stave church in Sweden, which shows similarities with the Haltdalen Stave Church.
Church with a raised roof, Type B
On the stone foundation, four huge ground beams are placed like a sign, their ends protruding from the lap joint where they intersect. The ends of these beams support the sills of the outer walls, forming a separate horizontal frame. The tall internal posts are placed on the internal frame of ground beams, and carry the main roof above the central nave. On the outer frame of sills rest the main wall planks, carrying the roof over the pentice or aisles surrounding the central space. The roof thus slopes down in two steps, as in a basilica.The tall internal posts are interconnected with brackets, and also connected to the outer walls with aisle rafters, creating a laterally rigid construction. Closer to the top of the posts, shorter sills inserted between them support the upper wall. On top of the posts wall plates support the roof trusses, similar to those of the single-nave churches.
The Kaupanger group consists of: Kaupanger, Urnes, Hopperstad, and Lom.
The Borgund group consists of: Borgund, Gol, Hegge, Høre, Lomen, Ringebu, and Øye.
This form of a church can also be recognized from the holes which remain from earlier earth-bound post churches built on the same sites. Little is known about what these older churches actually looked like or how they were constructed, as they were all destroyed or replaced many centuries ago.
Construction techniques
Palisade work
The oldest technique is often called palisade work and was a self-supporting wall construction with densely placed earthen pillars or planks, which enclosed a room and at the same time carried the roof. Later, split logs were used, which gave the walls a flat inside, and the edges could be leveled or fitted with tongue and groove. Palisade churches have not been found in Norway.To prevent early decay, the posts or planks were tarred, and the lower ends were charred by burning. The palisade rows were often placed in ditches filled with stone. It was long thought that this technique disappeared before the turn of the last millennium, but new research shows that it was in use right up to the beginning of the 12th century.
The only structure in this technique that has survived into our time is a wall in the middle section of Greensted Church in England. This led to this church being for a long time considered the oldest wooden structure in Europe. A common dating of the church was about the year 845, but modern dendrochronological dating estimates the church's year of construction to the period just after the year 1053.
The post technique
By lifting the pole planks up from the ground and placing them on sleepers clamped between more powerful corner or intermediate posts, the risk of rot damage was reduced. Thinner materials could then be used in the complementary parts of the construction. Earthen piles of coarse round timber could stand for a relatively long time before rotting. They may have been scorched at the lower end to avoid premature decay.Postholes, often with remnants of the former pillars, have been found under or near several stave churches and in places where legends say that there must have been churches. Remains of approximately 25 pillar buildings have been identified in Norway, and indirect traces of 7–8 more. Remains of pillar churches are also found under stone churches such as Mære and Kinsarvik.
Many of the earliest churches in Norway were built using this technique, but no such buildings have survived. It is an open question whether limited life was the reason why they were replaced by real stave churches with sleepers, or whether there were other reasons. Some of the older materials found in several of the stave churches are thought to originate from such early pillar churches, in particular at the Urnes stave church in Luster, where many building parts with wooden sheds in the urn style must have belonged to an older church. It has now been proven that the reused building parts originally belonged to the current church's forerunner, dendrochronologically dated to the period 1070–1080. However, this was not a post church, but a real stave church where corner poles and wall planks stood on sleepers.
Håkon Christie assumed that the post construction fell out of use because the posts rotted from below. Jørgen H. Jensenius believes that archaeological material does not provide unequivocal support for Christie's hypothesis; a change in size or transition to a stone church may also explain why excavated pillars fell out of use. Røldal Stave Church may have had some pillars set in the ground until 1913. In Lom Stave Church, the stone foundations have been laid approximately directly over the refilled postholes. Apart from different foundation methods, Jensenius believes that the pillar churches were essentially similar to stave churches.