What is a sleufrooster?
A sleufrooster (Dutch, literally “slot grille”) is a long, narrow stainless steel grille fitted into an open bed joint in brickwork or into a gap between timber components, to keep out bees, wasps and mice while still letting air through. There is no single fixed English trade name; the closest equivalents are insect mesh, vermin mesh or a slot vent grille. Despite the name it has nothing to do with a slot drain or gutter.
What it does
Many gaps in a facade are there on purpose: they ventilate a cavity or a rainscreen cladding and let moisture escape. Filling them in is not the answer. A slot grille fills the gap with a permeable steel profile, so air passes but larger animals do not.
Related products:
– Weep vent: a small insert for an open perpend (vertical joint) at the base of a cavity wall or above openings.
– Perpend grille: in Dutch practice also called “bijenbekje” (bee hole), a grille for an open vertical joint.
– Flexible mesh on a roll: stainless steel mesh for larger gaps and cracks, against mice, rats, martens and birds.
– Air vent: the general term for grilles that supply or extract air.
Spiders and small insects usually get through. Fine fly screen keeps them out too, but reduces airflow.
Application
- Know what the gap is for. If it ventilates or drains, it must keep doing so after the grille goes in.
- Measure the joint. Height and depth decide which profile clamps in without sticking out.
- Choose stainless steel. It does not rust and lasts outdoors.
- Fit without mortar or sealant. The grille fills the opening; it does not seal it.
- Mind protected species. In the UK all bat species and their roosts are protected by law. Do not block a gap that may be used by bats without expert advice.
Common mistake: pointing up an open joint or ventilation gap against wasps, trapping moisture behind the facade.
Related terms
- Bed joint
- Weep vent
- Bee hole
- Air vent
- Cavity wall
- Natural ventilation
Want to know more about building terms? Visit our knowledge base at fredsdiyplans.com.