ᐅ How to Properly Seal Cables Passing Through Masonry for a Blower Door Test

Hello everyone,

how do you properly drill a 3x1.5 cable for an outdoor light through solid masonry? The drilling part is clear, using a long drill bit and going through. But I’m actually asking more specifically how to seal the cable airtight on both the inside and outside walls?

Should you enlarge the hole on the outside and then apply about a 2 cm (0.8 inch) thick layer of silicone around the cable? Or are there special collars or sleeves for this? Or is it enough to seal the cable on both sides with a smooth coat of something like tile adhesive or similar? How tight is a blower door test exactly?

Thanks a lot for your answers
annab377

A blower door test is not that precise. Even if you leave your 12mm (0.5 inch) hole for your cable open and don’t insert the cable, the test would probably still pass.

Nevertheless, it must of course be professionally sealed.

Install on both sides within or beneath the plaster

Seriously? A 12mm (0.5 inch) hole really won’t be detected by the blower door test (so it’s within the tolerance range)?

And is plaster enough? When is the blower door test carried out? Only after the exterior plaster?

It depends on the plaster, since the plaster is what creates the airtightness.

Plastering is sufficient.