New Footings and Foundation Forms

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.

 Our staff then place wooden "keyways" into the wet footings that ensure the foundation wall is locked into the footing when it gets poured.

Our staff then place wooden "keyways" into the wet footings that ensure the foundation wall is locked into the footing when it gets poured.

 The foundation wall forms begin to indicate the new larger footprint of the house with additions to be built. 

The foundation wall forms begin to indicate the new larger footprint of the house with additions to be built. 

 Here too, the new larger footprint at the front of the house. 

Here too, the new larger footprint at the front of the house. 

House Lift & Foundation Demo — 27 Madison Ave

Getting caught up on some blogging.  Here's some progress shots.

 Facade, just before demo.

Facade, just before demo.

 Siding removed and foundation prepped for lifting beams

Siding removed and foundation prepped for lifting beams

 Remnants of "knob and tube" wiring.  A few light circuits were still live.  A good reason why gutting and rewiring is better and SAFER.

Remnants of "knob and tube" wiring.  A few light circuits were still live.  A good reason why gutting and rewiring is better and SAFER.

 Years of condensation have begun to grow thick mold along the meeting rails of the 2nd floor windows.  The new tilt-turn triple pane windows will eliminate this weakness. 

Years of condensation have begun to grow thick mold along the meeting rails of the 2nd floor windows.  The new tilt-turn triple pane windows will eliminate this weakness. 

 Up we go.  We'll be on cribbing stacks for the next few weeks while we demo the old foundation, excavate for the new deeper basement, and pour the new footings and walls. 

Up we go.  We'll be on cribbing stacks for the next few weeks while we demo the old foundation, excavate for the new deeper basement, and pour the new footings and walls. 

 The most glamorous part of the job!  The old foundation and slab floor are nearly gone.

The most glamorous part of the job!  The old foundation and slab floor are nearly gone.

 Rock bottom.  Clean and ready for footings.  Up next...!

Rock bottom.  Clean and ready for footings.  Up next...!

Baseline Test Day

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...!