Energy Efficient Foundation: Concrete Pour into ICFs

By using Insulating Concrete Forms (ICF’s), reinforced concrete is sandwiched between two layers of lightweight insulating EPS foam. The wall that is created provides a combination of air tightness, strength, sound attenuation, insulation and mass.

This is a LEED Platinum construction project using sustainable materials. We are using a special concrete mix which replaces half of the Portland Cement content with flyash. Flyash is a waste by-product of coal-fired power plants. We save embodied energy contained in the concrete at no loss of strength while keeping the flyash out of a landfill (…and this sustainable concrete mix doesn’t cost any more than standard concrete!)

No wood forms to strip!! …saving wood and labor.

We just have to remove a few wood stakes used for bracing and recycle them.

Next up: waterproofing the exposed foundation walls.

Moisture Management of the Foundation: Liquid Rubber and Stucco Coatings

The crew is applying a special blend of adhesive, high strength, elastomeric liquid rubber to the exterior ICF walls which will create a water-proof membrane around the foundation. This coating is waterbased and contains no petroleum. It is non-toxic and VOC-free.

On the protected, interior side of the crawlspace we spray on a thin hard-coat stucco product and back trowel it over the relatively soft EPS foam walls of the ICF’s. No water proof membrane is required on the interior side. It’s easy to apply the stucco with an air compressor, hose and sprayer and provides a uniform protective barrier.

On the exterior side we spray on the same hard coat stucco over the water-proof membrane and then embed a fiber glass mesh material into the base coat for added strength. We finish with a second coat over the fiber glass mesh and trowel the finish.

It’s time to install the perimeter drains and backfill.

Moisture Management of Foundations: Perimeter Sub-Surface Drainage

The finished soil grade will be sloped away from the building so that surface water will naturally drain away from the structure. As an additional best practice for managing site and foundation drainage, we have installed a sub-surface “French drain” system at the base of the foundation walls to insure that sub-surface water can never accumulate and seep into the crawlspace. Storm of the century or flood?? …bring it on. This house will stay high and dry.

The building pad is graded so that sub-surface water will naturally flow to the sides and then the rear of the lot. Gravity put to good use.

A French drain or sub-surface perimeter drain is a trench filled with gravel encapsulating a perforated pipe at the bottom. The pipe and gravel are wrapped in a protective “geotextile” fabric to prevent fine soil from entering and clogging the pipe holes. Moisture accumulating in the trench percolates down and enters the pipe which transports the moisture to a point of discharge away from the building.

Here is where it all comes together at the rear (lower grade) of the foundation. The drain pipe coming from under the crawlspace floor from the 4″ gravel drainage plane joins the exterior perimeter drain pipes and runs down and away 20 feet to a gravel pit. There is a backflow preventer as well so that neither air nor water can enter the building through the drain pipe.

The perforated pipe used for French drains is typically manufactured with two parallel rows of perforations (round holes) which are positioned on the under side of the pipe. This guy must be praying to the gravel gods or something?

The perforated drain pipe has been fully encapsulated with at least 6 inches of 3/4″ drain rock on all sides.

The landscape fabric is carefully folded over the top of the gravel to form a barrier against soil intrusion into the drain trench. This foundation drain system is complete and ready for backfill.

The French drain system properly designed and installed below grade at the base of the foundation walls relieves hydrostatic pressure and is a very valuable component of our site and foundation moisture management. This is a best practice required by the EPA Indoor Air Plus certification we are following on this project.

Mudsills – Where the Framing Meets the Foundation

The framing meets the foundation at the mudsill and the space between them can be the cause of serious air leaks which transport moisture and waste heating/cooling energy. In order to insure an airtight crawl space we made a tight seal between the mudsill and the top of the foundation by placing polyethylene sheeting between the mud sill and the top of the foundation.

The mud sill assembly starts with a 1/4″ closed-cell polyethylene foam gasket directly over the rough surface of foundation wall concrete. The gasket fills gaps and protects the 10mil poly sheeting strips which are placed on top of the gasket. The pressure treated mud sill is then placed over the poly sheeting.

The tough poly sheeting over the top of the foundation acts as a capillary break and vapor barrier preventing moisture in the concrete foundation walls from wicking into the interior wooden structure or evaporating into the interior crawlspace area.

Photos showing the inside foundation wall edge flashing sealed with foam and roof edge flashing screwed to the plastic ICF web. This cap acts as the interior side air seal

Inspection is a constant activity at our job site …but this guy looks confused.

The exposed flap of poly sheeting will be sealed to the exterior sheathing to create a durable air seal at this critical foundation to framing intersection. Next, we begin the crawl space girders and joists.

Deconstruction Part 3: Recycling the Used Building Materials

Our goal for the deconstruction of the building envelope is to transfer the least amount of building by-products to the landfill as possible. This goal informs the way we organize the on-site sorting of materials.

Metal ductwork, satellite dish, metal windows, gutters – anything metal from the site is collected here.

Wood not sold at the salvage sale is put into a pile for recycling.

Someone buys the hardwood floors.

The old roofing materials will be taken to a biomass energy facility.

There’s a designated dumpster for clean roofing lumber and another for sheetrock.

Used 2×4’s will be de-nailed and used in another building project.

The 4×6 floor beams from the old house will be de-nailed and become the corner posts for the new house.

Pablo de-nails lumber for use on-site.

The old furnace was sold for $100. “One man’s junk is another man’s treasure.”

The pavers from the walkways…

…and the bricks from the facade can be used again.

All of the hazardous material was collected on-site and delivered to the hazardous waste disposal site closest to us. We appreicate these guys.

Someday this wood debris will break down into rich soil again.

Besides the wood, metal and glass from the old house, the foundation was broken up and the clean concrete will be crushed and reused as gravel in new concrete mix or used as base rock for new highway construction.

Sorting and thereby recycling and reusing has a significant impact in the fight against global-warming and has the added benefit of creating jobs.

Deconstruction Part 2: ‘Unbuilding’ the House One Layer at a Time.


The traditional way to demolish a building is to bring in the ‘Cat’ to smash and crash its way through the structure ending up with a huge mixed debris pile that is transferred to dumpsters and trucked to the landfill.

Many times hazardous waste gets thrown into the mix and there is a real danger of ground and water contamination at the landfill.

The ‘best practices’ and sustainable alternative to demolition is “Deconstruction”. The goal of deconstruction is to take apart the structure in such a way that most of the original building materials can be reused or recycled in some way. The landfill is the last resort and is only used for a very small percentage of building materials which could not be reused or recycled. In the first stage of the deconstruction, reusable and recyclable materials are stripped from the building and sold, donated, reused or reintegrated into the project. In the second stage the envelope is is deconstructed and sorted into piles (i.e. concrete, wood, metal and glass).

Deconstruction Part 1: The Green Salvage Sale

At the absolute core of sustainability is the reuse of materials whenever possible. The first stage of green site deconstruction is to strip the existing stucture of any reuasable and recyclable materials.

We had a house-full of building materials that could be reused in other people’s projects so we contracted with Whole House Building Supply out of Palo Alto to conduct a Pre-Deconstruction Salvage Sale. A few days before the sale the organizers came to our project, tagged all the saleable items, took photographs and sent information about the sale to their 8,000 plus email contacts.

Whole House Builder’s Supply provided the signs, cashier and the re-movers. They provide proof of workman’s comp and liability for anyone working at the property. The proceeds from the sale are retained to cover thier costs and they haul away anything that isn’t sold after the weekend sale. We got an itemized list of what was salvaged and we can take a tax deduction that is equivalent to how much was sold and removed from the site.

Buyers signed a release from liability at the entrance.

Crew members help buyers load their purchases.

Sale crew taking unsold materials to the warehouse to sell off-site.

The deconstruction crew from Whole House Building Supply and Salvage were awesome.

We sold the playhouse on Craigslist ourselves and the buyer removed it with a small crane.

The garage door and opener were sold.

…and the old furnace for $100.

Once the sale was finished and the remainder of the building contents hauled away, we are ready to begin Deconstruction of the existing structure.