A stave church is a medieval wooden church with a post and beam construction related to timber framing. The wall frames are filled with vertical planks. The load-bearing posts (stafr in Old Norse) have lent their name to the building technique. Related church types are post church and churches with palisade walls.
All of the surviving stave churches except one are found in Norway, but related church types were once common all over northwestern Europe. The only remaining medieval stave church outside of Norway is one from 15th century located at Hedared in Sweden and one Norwegian stave church relocated and re-erected in 1842 in the outskirts of Krummhübel in Germany, now Karpacz in the Karkonosze mountains of Poland.
Construction
Archaeological excavations have shown that stave churches, best represented today by the Borgund stave church, descend from palisade constructions and later churches with earth-bound posts.
Similar palisade constructions are known from buildings from the Viking era. Logs were split in two halves, rammed into the ground and given a roof. This was a simple construction yet very strong. If set in gravel the wall could last for decades, even centuries. Remains of buildings of this type are found over much of Europe. An archaeological excavation in Lund uncovered the post holes of several such churches.
In later buildings the walls were supported by sills, leaving only the corner posts earth-bound – post churches. Such churches are easy to spot at archaeological sites as they leave very distinct holes where the posts were once placed. Sometimes the remains are even preserved, which makes it possible to give a very good dating of the church building. Under Urnes stave church remains have been found of two such churches, with Christian graves discovered below the oldest church.
A single church with a palisade construction has been refound as a floor in another medieval church, the Hemse stave church. This church used a palisade wall, yet the walls were supported on sills. One other church, the Greensted Church is also described as a palisade church, but is most probably of Saxon origins.
The next phase resulted from the observation that earth-bound posts are susceptible to humidity, which will cause them to rot away over time. To prevent this the posts were placed on top of large stones, significantly increasing their lifespan. The stave church in Røldal is believed to be of this type.
In still 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 other with a raised roof and with free-standing internal posts, usually termed Type B.
Those with the raised roof, Type B, are often further divided in two subgroups; the Kaupanger group with a whole arcade row of posts and intermediate posts along the sides and details mimicking stone like capital. These churches give an impression of a basilica.
The other subgroup is the Borgund group. These churches have cross braces joining upper and lower string beams and the posts, forming a very rigid interconnection, and resembling the triforium of stone basilicas. This makes it possible to omit the freestanding lower part of intermediate posts. In some churches in Valdres, only the four corner posts have been retained (see image of Lomen stave church).
Many stave churches had or still have outer galleries running around the whole perimeter, loosely connected to the plank walls. They probably served to protect the church from a harsh climate, and for processions.
Single nave church, Type A
Reinli stave church with the old pillory, Sør-Aurdal
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 (stavene) are cross-cut at the lower end and fit over the corner notches and cover them, thereby protecting them from moisture.
On top of the sill beam is a groove, into which the lower ends of the wall planks (veggtilene) fit. The last wall plank wedge-shaped and rammed into place. When the wall is filled in with planks, the frame is completed by a wall plate (stavlægje) with a groove on the bottom side, holding the top ends of the wall planks. The whole structure consists of frames — a 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 (bueknær) 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 is 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, (Langkirke), 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 13th century.
•Center post church, (Midtmastkirke) has a single central post reaching all the way up and connected with 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 in Numedal and Hallingdal, dated to around 1200.
Single nave churches in Norway: Grip, Haltdalen, Undredal, Hedal, Reinli, Eidsborg, Rollag, Uvdal, Nore, Høyjord, Røldal and Garmo.
The only remaining church in Sweden, in Hedared, is of this type and shows similarities with the one from Haltdalen.
Church with a raised roof, Type B
Interior from Lomen stave church depicting cross braces between upper and lower string beams and posts. Intermediate posts have been omitted.
On the stone foundation four huge beams (grunnstokker) are placed like a # sign, their ends protruding 1-2 metres from the notches 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 large beams, and carry the main roof above the central space nave (skip). On the outer frame of sills rest the main wall planks (veggtiler), carrying the roof over the pentice or aisles (omgang) surrounding the central space. The roof thus tapers down in two steps, as in a basilica.
The tall internal posts (staver) are interconnected with brackets (bueknær), and also connected to the outer walls with aisle rafters, creating a laterally rigid construction. Closer to the top of the posts (staver) shorter sills inserted between them support the upper wall (tilevegg). On top of the posts wall plates (stavlægjer) 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 (Hurum), Lomen, Ringebu and Øye.
This form of 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.
Architecture and decoration
Portal detail from Tønjum stave church
Even though the wooden churches had structural differences, they give a recognizable general impression. Formal differences may hide common features of their planning; while apparently similar buildings may turn out to have their structural elements organized completely differently. Despite this, certain basic principles must have been common to all types of building.
Basic geometrical figures, numbers that were easy to work with, one or just a few length units and simple ratios, and perhaps proportions as well were among the theoretical aids all builders inherited. The specialist was the man who knew a particular type of building so well that he could systematize its elements in a slightly different way from what was the case in the buildings known hitherto, thus carrying developments a stage further.