Great soil bearing conditions and a nice dry site. Perfect for a worry-free basement to begin from. Nonetheless, we're still installing complete perimeter drainage systems to ensure the lower level stays dry.
Getting caught up on some blogging. Here's some progress shots.
First things first, we wanted to get some data on the pre-renovated home in its existing state. The gizmo in the entry door you see below is a "blower-door" and it is a diagnostic tool used to test how drafty the home is by depressurizing the interior with a very powerful fan, connected to a manometer that can measure how fast the air is leaking into the house in cubic feet per minute (CFM) of air flow.
The number at left (below) is the level of depressurization in "Pascals" and the number at right is the CFM at roughly 50 Pascals. This is pretty leaky for a modest sized home!
The next step is to convert the CFM 50 number into a more relative metric called "Air Changes per Hour (ACH/50). This is simply the number of times in one hour that all the air in the house can be replaced by the blower door fan. ACH 50 is figured by first multiplying the CFM x 60 (to convert minutes to hours), then dividing it by the volume of the building. So this building (pre-construction) has a volume of 15,097CF. Therefore the leakage rate is 18.3 ACH 50. That's more than 6 times the allowable limit for a house built to current building code...!!
Our goal for this project is to achieve a 30X REDUCTION in the air leakage rate, down to 0.6 ACH 50 or less.
Stay tuned to this blog to learn more about how we do it...!