Mice get into cavity walls through open perpend joints and broken air bricks. You had better not seal those openings, because they ventilate the wall and the crawl space. The solution is a grille that lets air through but stops rodents. This page brings together such grilles for perpend joints, façades, crawl spaces and eaves, plus steel wool and proofing tape for loose gaps.
Which product for which opening
| Opening | Product |
|---|---|
| open perpend joint in brickwork | SpouwSafe (4 to 50 cm, also per 20) or Bijenbekje Spouw (5 or 7 cm) |
| broken crawl space air brick | RenoFix stainless steel renovation grille 5 x 10.5 cm or GevelFix front-mounted grille 10 x 14 or 25 x 15 cm |
| ventilation opening or hole in wall or shed | Stainless steel proofing grille 25 x 9, 25 x 17 or 25 x 25 cm |
| space under the first row of roof tiles | VentiBrush proofing brush (1 m, Ø 100 or 200 mm) or VentiStrip eaves comb |
| gap around pipes | Mouse & Rat Stop stainless steel wool or Knock Pest proofing tape |
What to look out for
Measure the width and height of the opening beforehand; a grille must fit tightly, otherwise a mouse will push past it. According to the manufacturer, SpouwSafe clamps so firmly into the perpend joint that you can no longer pull it out by hand, and it can be cut to size. The stainless steel proofing grilles have a mesh size of 2 mm and a central bar for strength. With the GevelFix, you can fit insect mesh separately, so insects stay out too.
Stainless steel is the standard here: rodents chew through plastic grilles and foam, stainless steel much less easily. Work from the outside in and check the entire façade, because one forgotten opening is enough.
Points to note
If there is already a mouse inside, a grille will shut it in. First catch the animals that are inside, for example with mouse traps, and then seal the holes. If in doubt about the construction of the wall, have a professional take a look.
You will find more on control in rats and mice, and on martens under the tiles in deterring stone martens. All proofing is in screening and proofing.
Frequently asked questions
Can I seal a perpend joint against mice?
Better not: the perpend joint ventilates the cavity. Fit a weep vent insert such as SpouwSafe or a Bijenbekje, so air can still get through.
Which size SpouwSafe do I need?
Measure the perpend joint and choose the size that fits it. SpouwSafe can also be cut to size.
Why stainless steel and not plastic?
Mice and rats gnaw through plastic and foam. They get through stainless steel much less easily.
Does a proofing brush also help against birds?
The VentiBrush is intended against martens, mice and birds under the roof tiles, while the ventilation stays open.