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.
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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.

The Work:
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 whole house.

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 hours.

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 R-24.8.

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 30.

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 to help.
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.
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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.
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Chris West is a Certified Passive House Consultant
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