Different Types of Ridges

The ridge has to be thatched very carefully, as it is the highest point of the building and bears the brunt of the weather.

There are different ridge designs depending on the peculiarities of the regionally available materials. The substructure (lathing of the ridge) should be adapted to the particular ridge design.

Reed or straw ridges can be found on reed thatched as well as on straw thatched roofs. For the upper layer young and especially flexible canes or longstraw is used. The ridge batten of the weather face normally has a smaller distance to the end of the rafter (5 cm) than the ridge batten at the side facing away from the prevailing weather (15 cm).

The projecting ear or flower ends of the last layer at the windward side or the leeside are not cut but alternatingly bent around the respective upmost ridge batten and fastened on the other side of the roof by stuffing them into the roofing. Now the ridge layer on the side facing away from the weather (leeside) is applied.
In contrast to the other layers of the main roof area the butt ends of the ridge layer face the ridge line. It is not until now that on the windward side a reed layer is attached to the last two roof battens, so that the end of the reed stalks protrude over the reed layer on the lee side. It is important that the ridge layer on the lee side has a sufficient height and that it tightly abuts against the ridge layer of the windward side, so that when the roof settles down later on no gap can appear.

A variation is the reed or straw ridge with a central joint. In this case the ridge layers of the windward and the lee side are tightly sewn together and then rounded.

The heather ridge

The heather ridge normally consists of mown heather, in some regions, however, tangled straw, sea weed or couch grass is used. In contrast to past times, when heather from the woods and the heathland was used, today, pressed heather bales are available from Hiss.
The two ridge battens of the heather ridge abut against each other at the top of the rafters. The main roof area is thatched as usual. However, instead of the ridge layer, when crafting a heather ridge an underlay of roofing paper is applied. The rounded and stuffed covering layer is then covered with a 30 cm wide layer of heather.
The heather bales are then placed overlapping each other layer by layer and considering the prevailing weather. There are two different methods of securing the heather ridge:

Either cross rods, cleft, round or squared timbers are used, which are placed on the ridge in a distance of approximately half a metre between each other or liggers, with a length of approx. 0.3-0.6 m and a diameter of 15-20 mm. 100-200 of these ligger are needed per running meter of heather ridge.
To protect the heather ridge against birds and wind it is covered with a narrow-meshed net (chicken wire) and then fastened.

A variation of the heather ridge is the oat straw ridge. This ridge design is widely used in Denmark and in the region around Kappeln. Oat straw is known to be very robust.
The thatching of oat straw ridges is similar to the application of heather ridges with the difference that additional ridge lumbers have to be used.

The Sod Ridge

Generally, there are two different types of sod ridges: The grass sod ridge and the heather sod ridge. The main roof area of a sod ridge is thatched as usual. The flat grass sod ridge consists of living grass sods with a thickness of about 5-10 cm, a length of approximately 1.40 m and a width of between 30 and 40 cm. Below the sod layer bituminous felt should be applied to protect the reed ridge.

The grass sods should be well rooted and are placed with the root ends facing downwards, so that they cover the ridge with a width of at least 1.2 m. Neither on the inside nor on the outside should there be a gap between the joints. The sods should overlap at least by half a sod.
A ligger of 50-60 cm is driven into every second sod and horizontally through the roofing to secure the ridge. A variation of the grass sod ridge is the overlapping covering. Here in direction of the ridge the grass sods overlap by half a sod.

The sod ridge made from heather sods is crafted using earth-moist heather.
The heather sods should be well rooted and have a thickness of approx. 8-10 cm, a length of 30-60 cm and a width of around 30 cm. In skew direction, as well as in sideward direction, the sods are placed to bond. Normally, such a ridge has a lateral height of 90 cm and a depth of about 20 cm.
To protect the heather ridge against birds and wind it is covered with a narrow-meshed net (chicken wire) and then fastened.

Other Ridge Designs

The ridge of a thatched roof can also be covered with other suitable materials. If copper caps, special clay bricks (chiefly in the Netherlands) or corrugated panels are used the thatched roof needs an additional ridge framework, which is placed on top of the last reed layer.

Then the clay bricks, copper sheets or corrugated panels can be attached to this wooden structure. The copper ions released by the copper sheets offer additional protection against algae and moss.
A disadvantage is that the sheets form a large metal area on the roof which makes a lightning stroke more probable.