DIY Positive Pressure Build Log

Trying to bring the Swiss Alps to us!

By Afiq Hatta, Charles Victorio; cross posted.

We're writing this log to track our progress in pressurising large domestic spaces. Afiq wrote the reasons why he thinks positive pressure is a good idea, and we're currently brainstorming ideas on retrofittable methods to do this for houses without mechanical ventilation (like Afiq's flat). After speaking with people who used positive pressure in public spaces to protect against wildfires in South East Asia, we're feeling a bit more confident that this could work. But who knows!

The practical challenge here is to find a easy, cheap and universal way to seal the living space with just one inlet and one exhaust. This means finding an easy way to seal Afiq's large window such that anyone could do it, and also finding ways to seal gaps under doors and other exits. Bonus points if the solution is generally DIY'able for the public, using everyday materials.

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20th June 2025

Afiq's window is 1.45m by 1.7m, made of glass and opens in an annoying way. The general idea is to seal it somehow, then have an inlet where we can filter in clean air through either a box fan or a duct fan via HEPA filter.

1st attempt: Afiq tried sealing the window completely with a painter's dust sheet and copious amounts of gorilla tape. We realise that its too fiddly probably for the public to do themselves because of having to make sure the tape is completely sealing the edges to the wall (try this at home folks). He basically almost gives up half way. It also hurts his arms because of having to stretch to tape the top. And the dust sheet is too fragile to cut a hole to fit a duct tube. We think dust sheet and tape is really not the way to go for DIY setups.

Instead, we order some reticel insulation foam to seal the window, and are going to try mimic a video that Charles flagged by a mushroom grower. After sealing the window, we're going to drill a hole in it, and put in a duct fan, and stick a HEPA filter on the other side.