Old houses can be made super energy efficient as well!
What is The Little Dig?
The house, as described in earlier blogs, is a raised ranch from 1975. This construction has two types of walls. One is the
frame wall. This is the standard 2x4 stud wall (16" on center). The frame wall sits upon a cinder block wall. The cinder
block wall starts above the ground but goes below ground to the footing.
Inside the house, the cinder block wall forms the bottom three feet of the wall on the ground floor.
Post: January 17, 2013
Dates of work November 23, 2012 to December 17 2012
Deep Energy Retrofit in Jericho, Vt!
Part 3 - The Little Dig part 2
Pic of the wall in the garage. The cinder block wall is 28" here from floor
to where the wood starts. The wood is the 2x4 frame wall. The plywood
you see is the outside sheathing. Which means on the other side of that
plywood is the great outdoors.
In the pic to the left you can see the two types of wall: cinder
block on bottom and wood frame above. You can also see in the
bottom right of the photo the pink XPS (extruded polystyrene)
insulation. This is the thermal break between the outside wall and
the slab floor.
The Little Dig is digging around the foundation of the whole
house to put insulation onto the outside of the cinder block wall.
A big job, you might say. Yes it is. Fortunately I had the time
and the tools to do it. The time because I choose my hours with
my work. The tools because I have a backhoe. Not a big backhoe
you drive around with treads and a little cabin you sit in. A small
backhoe that you can pull around with a truck, or leap-frog with
it using the bucket of the backhoe to pull you along.
Here is a pic of the West face of the house. You can
make out the cinderblock wall at the bottom of the
siding just below that white strip.
You can also see that the ground varies in height. This
is true around the entire house. In some places the dirt
is only one foot from the frame wall. Others it is as
much as two and a half feet from the frame wall.
So what has to happen here?
The dirt needs to be excavated down to the footing. The
footing is a poured rectangular slab upon which the
cinder block wall is built. It is the same level around the
So, first dig!
You can see the backhoe in the lower right corner of this
picture. The black tarp is covering the dirt I excavated.
This is to prevent the dirt from being washed back into
the excavated hole by rain. It wouldn't make much sense
to spend all the time and effort to excavate only to have
to excavate again.
With the help of the backhoe I was able to excavate the
West wall to a maximum depth of four feet in about four
Once the West wall was dug out the old perimeter drain
could be removed. As part of the sub grade renovation I
was replacing the old black flex perimeter drain with a
more sturdy pvc drain pipe.
This is the Southwestern corner of the house. The hose-like
bit at the top of the picture is the old perimeter drain. This
stuff fills with dirt easily and in places was so full of dirt it
was clearly not draining anything.
The green line on the cinder block wall is where the grass
level was before the excavation.
The wires in the bottom of the pic are the power supply to
my barn. This is standard practice to put wires (rated for
outside use) directly in the ground. I don't like it much but
it seems safe and is code.
West wall fully excavated with perimeter drain removed. In
the back see the first piece of EPS (Expanded Polystyrene)
insulation. This is the first course of 3". The total thickness in
the end will be 6". The R-value is 4.13 per inch giving a
As you saw above there will be another 2" of insulation on
the inside of this wall bringing the R-value up to just above
The two rows of insulation is installed. I used a special EPS glue which is used for ICF work (Insulated Concrete Form).
It is an expanding foam that needs only twenty minutes to set. The white sticker with the blue words is a bituminous
waterproofing called Soprema. It is also a specialty product that is made specifically to waterproof EPS insulation below
ground. Many people think that EPS and XPS are waterproof. This is not true. Both can become waterlogged, which
reduces the thermal insulative value to almost nothing.
How do you know if your EPS is full of water or not? Pick it up. A 4x8 sheet of 3" thick EPS is easy to lift if it isn't full of
water and almost impossible to lift if it is waterlogged. We used repurposed EPS on this project. Three of the sheets we
got were waterlogged - not the fault of the supplier. They actually sent extra sheets to make up for these waterlogged
sheets. They used the waterlogged sheets to protect the dry ones during transport. I now have these waterlogged
sheets drying out in my barn for use in some future project (once they are all dried out that is).
Thank goodness for neighbors with cool tools. My neighbor
Dave has a Kaboda tractor. Just like the backhoe it turned
what could have been days of shoveling into a half hour.
Within no time the hole was covered and I was ready for
the next bit. Dig the North face out. Unfortunately this
wasn't something I could use the backhoe for. It was down
to digging by hand. Fortunately I had my nephew and son
Ok, a perfectly superfluous picture of my backhoe. It is a great little toy and just big
enough to make easy work of digging a big hole. I have also used it to dig out tree
stumps - no small bit of work in and of itself.
This is what the glue looks like. It has its own R-value like one part foam to seal windows.
It didn't like the cold so I kept the can in the warm house between courses. Lots of walking
back and forth but it worked - the glue flowed fine as long as it was warm.
Didn't want to forget the footing. It also got 6" of insulation glued to the
bottom of the overhanging wall insulation.
The trough is dug along the footing so that the footing insulation can
be installed. The bucket of tools was my way of keeping the tools off
of the damp ground. I was blessed with a few weeks of weather
without rain though it was often cold. Ah Vermont winters!
Perimeter drain in, landscaping cloth over to keep the dirt
from clogging my coarse stone. The pipe in the corner is a
cleanout pipe for the perimeter drain. You can just put the
hose in it and it will wash out any dirt you suspect might
be in there.
Thanks to Ward Smyth for bringing me onto this idea. I
saw it in his presentation on the Moretown Passive House.
I am very grateful to all of the builders I have come to
know in the past few years. They are fonts of building
wisdom and always happy to share their knowledge.
Eco Houses of Vermont, LLC
North, East and South walls still to go. I had already done some insulation work on the south wall when took the old
garage doors out and made it a wall. There I had put in 4" of pink board (XPS) and needed to beef it up to 6" to fit the
rest of the outside wall.
The sub-soil insulation was finished on December 17th, 2012, just one day before I went on vacation with my family.
The contractor will begin with his part of the work in January which at that time in December was still to be scheduled.
Copyright 2013 Eco Houses of Vermont, LLC
Chris West is a Certified Passive House Consultant
Affiliated with the PHIUS and PHI 2013