What is a roof tile pointing trowel?
A roof tile pointing trowel (Dutch: pannenstrijker or panstrijker) is a wide, almost spoon-shaped jointing tool used to fill and strike off large joints and gaps with mortar. The blade is considerably wider than that of an ordinary pointing iron and slightly dished, so the mortar stays on it while you work it into the joint.
What it is used for
- Torching roof tiles from below. On old farmhouses, coastal houses and windmills, tiles along the ridge, hips and verges were bedded in mortar from underneath. That kept them in place and stopped snow and driving rain getting in. This trowel is exactly the tool for filling that wide joint from the inside.
- Large joints and abutment gaps in masonry — for instance in large-format bricks or irregular fieldstone work — where a normal pointing iron is too narrow.
- Restoration and repair work in awkward positions that a bricklaying trowel cannot reach.
Types
These trowels come in various widths and blade shapes; the trade commonly distinguishes a Dutch pattern from a Berlin pattern, with the blade ranging from roughly 25 to 45 mm wide and from almost straight to slightly flared. Which one you choose depends on the joint width you are working with.
Working with it
- The mortar needs the right stiffness: too wet and it runs off the blade, too dry and it will not bond in the joint. Work with small quantities at a time.
- Lime mortar on historic work. On old buildings a lime-based mortar belongs; hard cement mortar is stiffer and denser than the surrounding material and causes damage to brick and tile in the long run.
- Dampen the background first so the mix water is not sucked out too quickly, which would leave a friable, dusty joint.
- On torching tiles: torching is a historic technique. On new work, mechanical fixing with tile clips is the normal and far more verifiable solution. Be careful about sealing ventilation gaps: a roof must be able to ventilate under the covering.
- Clean the tool immediately after use; set mortar ruins the smooth blade edge you need for a crisp finish.
Checks when working with a roof tile pointing trowel
- Mortar at the right stiffness: Too wet and it runs off the blade, too dry and it will not bond in the joint.
- Small quantities at a time: Work the mortar in small quantities at a time.
- Lime mortar on historic work: On old buildings, hard cement mortar is stiffer and denser than the surrounding material and causes damage to brick and tile in the long run.
- Background dampened first: Stops the mix water being sucked out too quickly, which would leave a friable, dusty joint.
- Ventilation gaps not sealed: A roof must be able to ventilate under the covering.
- Tool cleaned immediately after use: Set mortar ruins the smooth blade edge you need for a crisp finish.
Related terms
- Mortar
- Pointing
- Tile clip
- Roof tile
- Lime mortar
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