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Spray Foam Inspections Part 2

Steven Rinehart  | Published on 8/1/2019

Spray Polyurethane Foam Insulation in Residential Construction (Part II)



In this scenario, I have my city building inspector hat on. These are actually notes from real city inspections in the last week. Last Friday among the inspection requests from one city were two final inspections, and one had spray foam insulation the other blown rockwool. I am always cautious when I see spray foam insulation and new construction from a builder who has never done it before. We know that insulation contractors do not have any requirement for licensing or training. All they need are deep enough pockets to buy the equipment with fantasies of vast amounts of money.

Texas State Law requires a municipality to ensure that all enforcement personnel are IECC certified by the International Code Council (ICC). That certification requirement, along with TSBPE plumbing inspector license are the few non-negotiable credentials a municipality inspector is required to satisfy.

Energy Code compliance really starts long before the insulation phase, even for SPF homes. There are requirements at virtually every stage. At the plumbing rough, I need to see all the hot water pipes insulated; I don’t want to see the water heater way over in the garage corner. We now have a maximum developed distance for hot water pipes. Slab insulation is required in most of the colder climate zones. Framers are now required to insulate exterior wall headers & wall cavities in corners and wall intersections. Many times the framer will insulate the wall behind shower walls. Review the construction documents is needed unless totally prescriptive, which is rare. One of the most common documents is REScheck. It helps provide information about whether the home meets the energy code. It is still prescriptive in nature but provides some tradeoff capabilities by evaluating the home using UA values instead of R-values.

At the “pre-sheetrock” generically called “insulation inspection” although it's much more than that; I arrive at the house and usually find that all the exterior doors are not installed. This is kind of a problem with me because they're all supposed to be. The builder will install the front door and the back door but hesitates on the garage door because they've never done that before, their father never did it, their grandfather never did, but they don't know why. I proceed to tell them to get all the exterior door package complete. In a spray foam house, this usually includes an attic door between the vented garage attic and the sealed house attic. Having the access door in the garage attic is not the ideal location because of the severe conditions on either side of that wall and the potential for accidentally leaving the door open. They usually balk at that because most of the time it's not a full-size door and they have to get one custom made. I've seen everything from OSB on a piano hinge with 3 cans great stuff from Home Depot sprayed all over it to a properly sized weather-sealed insulated preferably metal door. At that point I asked them would they use that homemade one of a grade level door like the garage or back patio?


Having already failed the inspection, I continue noting the insulation depth, which is always a great discussion. Prescriptive requirements in the IRC currently for most of us is R-38. We are allowed to go down to R30 for up to 500 square feet in most conditions, but neither of these standards is typically met with spray foam. We know that foam is more efficient, but how efficient and how do we qualify it. This is where we need supporting documents to show that the depth they have is adequate. REScheck won't work, prescriptive requirements in the IRC won't work, now we're into performance evaluation. The typical response from the builder is the deer in the headlights look; they quickly get on the phone with the foam contractor who says, “We always put 6 inches, and nobody else complains”. The builder has to justify insulation depth if less than prescriptive.


A quick overview of the two types of SPF would be appropriate. By far the most common is an open-cell, named for the cell structure which you can think of tiny air bubbles. It’s soft, flexible and also called ½ lb from its average density of 0.5-0.8 lbs per cubic foot. R-values vary from 3.6 to 4.5, depending on the manufacturer. This adds to your challenge. because the R-value can vary 25%, having the ESR for the particular foam will answer many of your questions. Closed-cell is hard with a density of 1.8-2.3 lbs per cubic foot. Imagine the foam we usually see on the shell of a backyard spa tub. R-values go up to 5.8 to 6.9 range, making for a thinner application to deliver the same R-value. At 1.5” it is also a vapor retarder.


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My personal (SPF insulation) checklist: (maybe more but here are the most common)

  • All exterior doors installed.

  • Walls, windows, and door jambs insulated. Including rim joist, if present.

  • Foam sealed especially at attic walls to patios & garage attics. These areas are a major air & moisture leakage source.

  • Is foam bonded (stuck) to the substrate?

  • Does foam appear to be mixed 50/50? Is it crunchy or slimy? No voids.

  • Chimney’s sealed at the roof deck. Best if using second metal flashing just like ceiling fireblocking.

  • Is there contact with any combustibles requiring a minimum clearance?

  • No damaged wiring from trimming. Turkey carving knives are a big hazard to electrical wires.

  • Exterior walls have moisture barrier penetrations sealed, mastic best.

  • Foam depth verified. Remembering that insulation is not an average. I will accept 3” in 2x4 wall, any less can fail. On the roof deck, I want 7-8”. That’s beyond the standard rafter, so you have to be creative. If you don’t have depth gage a straightened metal coat hanger with tape marks will not cause significant damage.

  • Fresh air system installed. Avoid hazardous locations. Back patio ceiling over gas BBQ piping is no brainer. Roof location causes undue loading on the HVAC with 150-degree asphalt laden air. I like the front patio ceiling.

  • Unconditioned attics ventilated.

  • Exhaust fans exit to the building exterior.

  • Avoid naturally ventilated fuel-fired appliances (gas stuff). Appliance can’t breathe properly and competes with people. If used, is there adequate dilution and/or fresh air?

  • Exhaust fan in the kitchen may require make-up air if over 400 cfm.

 

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Construction documents required to inspect properly per N1101.5 or R103.2 are listed below. They would also include the buildings thermal envelope drawn on the plans per N1101.5.1 or R103.2.1. Unicorn for sure. Actually, almost all of these items can be drawn on a plan sheet just for energy compliance.

The documents provide the following:

  • Insulation materials and their R-values. Manufacture used, and foam depth in various locations used. ESR attached.

  • Fenestration U-factors and SHGCs.

  • If using REScheck or performance evaluations, area-weighted U-factors, and SHGC calculations.

  • Mechanical system design criteria.

  • Mechanical and service water heating system and equipment types, sizes, and efficiencies.

  • Equipment and system controls.

  • Duct sealing (methods) duct and pipe insulation (values) and locations.

  • Air sealing details.

Find example photos of bad installations at the following links:
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