D.E.R. Deep Environmental Retrofit







D.E.R.  Deep Environmental Retrofit, the process of adding large amounts of insulation and wind proofing to older buildings.  The concept is simple; Add more layers of insulation and wind proofing to cut down on the amount of energy needed to heat or cool a building.

The layers are:

1. Blown in cellulose insulation in the original wall cavity.  Most turn of the century homes in this area didn’t have any insulation.

2. Wrap the entire inside wall with Tyvek, then fur out the walls and add another layer of blown in cellulose.

3. On the exterior wall add 8+ inches of rigid insulation with staggered seams. All seams are taped on each layer and another layer of Tyvek is added.

4. Indicates the 2 layers of Tyvek inside the house, 1 of which is wrapped under the floor.

The end result is 16+ inches of insulation with very little chance of air infiltration.  All of the areas that cannot be filled with blown in or rigid insulation is filled with spray foam.  Even the windows are triple glazed to prevent air infiltration.  The vendor says you could heat the finished room with a hair dryer.

You can see the before and after mock up  in the picture.  In the before picture there is no insulation and plenty of cracks and voids for air to permeate the building.  These leaks help heat from a fire escape and allow fresh air to be sucked in, which is great for firefighters but bad for heating bills.

Firefighters are all too aware of what happens when fresh, oxygenated air runs out at a fire.  The fire darkens down and the temperature continues to rise until something fails or something is opened by a firefighter.  When this happens you get a back draft or a smoke explosion.

We have all been taught that building contents are far different than they were for previous generations of firefighters.  Flashover is being reached at a shorter time than a couple decades ago, and I can post a side by side video if you’d like.  The lower times are caused by a combination of better sealed buildings and the composition of the contents.

So after that overview, how long would it take to starve a room and contents fire of oxygen when the room is sealed and insulated this well?

A couple side notes:

The floor joists were notched during the original construction.  That’s pretty common in these houses.  But you can see in the after picture that the floor is still notched.  How much extra weight has been added to this building and it remains on the original inferior construction?

The vendor indicated they have done dozens of houses in my area and the biggest concern they heard was from electrical inspectors who wanted the power lines from the solar panels to be candy striped.  PV power too?  I think that is a discussion for another day.

Stay Safe.


1 Comment

  • Donovan:

    Glad to see a new posting on the site! Also, nice to see you’ve been able to identify a potential hazard in your area. The photos you’ve included really help demonstrate the extent of modifications. Definitely, the building is now “tighter” and doesn’t allow as much air in (or out, for that matter).

    I agree with you that the newly updated and insulated buildings will hold heat better and not allow as much fresh air inside; however, I don’t believe these two points are necessarily bad things for firefighters. First, modern homes have been energy efficient for a number of years. The fire service has been succesfully containing and extinguishing fires within these well insulated homes. Companies operating in older sections of some cities may only have these inefficient structures within the response area. It would appear the construction type and inefficiency provides some of the structure ventilation firefighters need. Long time members assigned to these stations may not have had much exposure to burning buildings of the energy efficient type. If so, the companies will have to go “back to the basics” for some “reminder” training in how to remove heat from a building.

    Secondly, our basic fire suppression training helps with a solution to the heat and fresh air problem: VENTILATE! Also, I recommend ventilating in the quickest, easist method possible: horizontal ventilation. Hey, we’re all having to work with fewer firefighters, so we may as well work smarter and not harder. Horizontal venting is an option that works well when you have an aggressive engine company kicking in the door, getting ready to move down the hall, and you’re pushed for time.

    Not trying to throw rocks, just offering some thoughts about the thread in an effort to generate discussion.


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