The correct use of rafter purlin anchors

Anyone who builds a roof needs many different parts to firmly connect the wooden elements to one another. One of these parts is the rafter purlin anchor. Due to its special shape, it can only be used at individual points on the roof.

Use of the rafter purlin anchor

The rafter purlin anchor is an angle, the two surfaces of which are not opposite each other, but are shifted in height. This structure was specially developed to connect intersecting surfaces on a roof structure. Such areas are created with the combination of rafters and purlins (horizontal beams) in a purlin roof (hence the name), but also with flat or pent roofs (garage, carport, terrace), where the rafters lie on supporting beams.

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When installing rafter purlin anchors, a high tensile strength connection is created between the wooden elements. Forces such as the wind that act on the roof cannot harm the construction.


Rafter purlin anchors are attached to the wood with nails. There are so-called special nails for this purpose. They have a corrugated shaft so that they do not come loose. As standard, these nails are 40 mm long and 4 mm in diameter. When purchasing the rafter purlin anchors, make sure that they are the right size. Rafter purlin anchors that are too large protrude over the wooden surfaces, which is not desired. Rafter purlin anchors that are too small, on the other hand, not only look a bit undersized, they also don't hold up as much.

The two wings of the rafter purlin anchor are each equipped with two rows of holes. This gives you relatively flexibility in choosing the nail positions. The nails should not be driven in too close to the edge, otherwise they will weaken the wood. In general, you have to use at least two nails per side. For a stable construction, however, all existing holes should be used if possible (the number required for maximum stability was calculated when the rafter purlin anchor was manufactured), unless they are too close to the edge of the wood.