Build your own blower door machine for 100$(ish)

[KarefulKactus15]

Just thought I'd share my experience.   For anyone who doesn't know, a blower door measures the leakiness of your house.

I built a similar machine to use myself for around 50$ (for the machine) and 50$ (for a manometer) so 100$ and I can use it as much as I want while I air seal.
The blower was 30$ on craigslist.
The wood I got from the scrap pile at home depot and they didn't charge me for it + they still cut it for me lol.
So all I had to buy was various screws, and other hardware and some electrical tape.  Nothing over the top. It also adjust to other size windows, but I got it setup for my windows at the moment.


I'm sure it's not as accurate as a pro machine but it should be close and I should be able to measure my air sealing progress.

For those of you wondering, how do I calculate cfm? I have an annemometer, but because this is an HVAC blower, the manufacturer already has a blower curve for it. With that information I can calculate my cfm 50 and ach 50 with the known variables and put it onto a fan law calculator to spit out the information.

I got the idea from another website also, so this isn't some new original idea of my own.  But it can be made for 50$ + another 50$ for a cheap manometer. Which comes in handy since a blower door test from a pro is 200-250$ a test.

Maybe not the greatest use of money, but I enjoyed it and plan to get my $s worth from it.   

Bonus points: I can flip it around backwards with a fog machine and actually see where the big leaks are.

[zolotiyeruki]

What do you use to track down the leaks?  Do you just let the fog machine go nuts inside your house, and stand outside and look for jets of smoke?

[KarefulKactus15]

Honestly,  I haven't made it that far yet.     I'm gonna foam my top plates in the attic first, I know they arent so swell.    After that I'll start hunting other leaks.         But yeah my understanding is that a smoke pencil can be used around cracks.   Or a fog machine and just see where the flow goes.      Also if it's fair weather you can stand outside and supposedly see fog rolling out of leaky areas.  I haven't personally tested this yet.     

[KarefulKactus15]

Also to find problem areas,   when its cold out, put the house under vacuum and take an IR gun (the cheap lasar kind). And point it at suspected problem areas and cracks and stuff.  Under vacuum those spots will be noticeably colder.  The most useful part of this machine is knowing when you've fixed a problem.  Currently my machine says I'm at  10 ach 50pascal.     I'd like to achieve 6 but I don't think that's going to be possible.   Well see..... Lol

[CowboyAndIndian]

The most useful part of this machine is knowing when you've fixed a problem.  Currently my machine says I'm at  10 ach 50pascal.     I'd like to achieve 6 but I don't think that's going to be possible.   Well see..... Lol

When you get the envelope really tight, make sure you add a heat exchanger to get outside air. Otherwise the house air will become really stale.