Spray Polyurethane Foam Insulation in Residential Construction
There is much more that can be taught about SPF in residential homes that can be shared in this column, so I am going to key on the most common red flags a home inspector needs to know.
The worst-case scenario, an existing fuel-fired appliance home that has been retrofitted with SPF.
So we have done our pre-arrival prep (Google , Zillow, etc.) and the information gathered is a home build in 1985, I suspect with a gas furnace that may be in the attic, gas water heater in the garage, based on flue locations and all else electric. I am happy I see gable vents and two turbine type vents. Good so far.
I arrive and start with an initial assessment of the home, walking throughout the living space and head to the garage and pull down the stairs and freeze. Its what I don’t see that concerns me, no roof decking, just this yellow lumpy foam. My brain starts recalculating like my GPS when I take a wrong turn. I look down at the open garage door and start thinking what impact this has on the whole house.
My first thought is life safety, which can kill or harm the occupants. Since I see the foam from the pulldown stairs is the attic truly encapsulated? The stairs look normal. That can’t be right; they would have to be part of the thermal barrier if I am entering the sealed attic environment. I pop up the first three treads and look around. Garage ceiling not insulated but I can see roof decking covered to the far end: incomplete thermal barrier, Red Flag #1. My first thought is vehicle exhaust CO seeping through the ceiling and down into the home. Next, I see the B-vent type flue from the garage water heater in the corner going through the roof and sealed tight in foam, umm, I know it says 1-inch from combustibles. Foam is really just plastic insulation; it burns, Red Flag #2. I head deeper into this abyss. There is a walkway to the HVAC platform, that’s nice. Halfway there I glance to either side and see the ceilings of the front and rear patios, bare Masonite, Red Flag 2(#1 again). I get to the unit, and it is the original 80% fuel-fired furnace installed in 1985, that’s bad. Similar B-vent as the water heater for the furnace and it is also sealed into the roof deck foam, Red Flag #3. The attic is not ventilated, and I am concerned knowing that the furnace needs combustion air then realize the leaky un-insulated garage/patio ceilings are what keeps this unit supplied with oxygen. That’s a double-edged sword, Red Flag #4. I verify that there are no gable or turbine vents still open and wonder how they were sealed over. If the SPF crew did it, we could usually assume they threw something over the opening and sprayed a layer of foam. But I know most of these vents are not real watertight on a sideways blowing rain storm. They will leak water into the layers of roofing materials somewhere, Red Flag #5. As I stand there, I realize that all the original cellulose ceiling inspection is still in place, Red Flag #6. My brain is still in the GPS recirculating mode. I have an idea if I call the client and say I just came down with stomach flu and give them Brads number to come to perform their inspection I’m in the clear.
So here I am, 10 min into the inspection with 6 items that are major and all should have been part of the scope in a bid to retro a home with SPF. I need to put this in the report for the buyer because they are health & safety concerns.
Things they should have done prior to and during the installation of SPF on the roof deck and attic walls.
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Build a dividing wall between the garage/patios and living space attics creating two types of environments, vented and non-vented or commonly called sealed/encapsulated. Imagine the grade floor exterior walls extending to the roof deck. This will help isolate the hazardous fumes from entering the home. I recommend the attic access be relocated to an area inside the home to minimize the chance of leaving the attic door open.
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They should not have insulated the garage attic decking since there is no heat/cooling source in the garage. Removing the vents from the garage attic will cause heat and moisture to build up with no mechanism to control these. Vents need to be added although fewer than normal due to the lower heat gain of the environment. The insulation can be cleared from the water heater flue to provide combustible clearance to the vent.
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Replacing the furnace with a condensing furnace is the smart choice, typically identified by the PVC combustion/exhaust vents. Materials and design vary by manufacturer. They typically start in the 92% efficiency and up and do not exchange air with the attic. Here is the opportunity to match up with better AC. But don’t go overboard, the heat gain will be less so lower run times will mean payback for higher SEER units would be longer.
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Physically remove/repair the existing vents in the sealed attic decking/gable and add vents to the vented attics.
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Remove the existing ceiling insulation to allow for conduction between the living space and the attic through the ceiling gypsum. ASHRAE considers this new environment indirectly conditioned. It may add slightly to the work of the HVAC by adding volume but will be offset many times over by bringing the distribution system (air ducts) inside the thermal barrier. This will usually control the attic environment within 5-10 degrees of the living space and drive any moisture into the lower humidity living space to be extracted by the AC.
My report would have entries in the roof coverings materials, roof structure and attics, exterior walls, heating equipment, water heating equipment, and bathroom exhaust vents.
The energy efficiency of this is home is probably below expectations, and the changes in lifestyle for the occupants of a foamed home are needed to take advantage of the modifications, but that is another story…
Steven Rinehart
Retired Experienced Spray Foam Installer