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Polyurethane Foam Installation FAQs

Please email your questions and we will post them here.

Question:  Could you give me a per sq ft price for your foam insulation systems?
Answer: There are many variables we have to consider when quoting a project. These variables make it impossible to have one price per square foot that will be appropriate for every project. Following is a list of some of the variables that determine the final price of a project.

  • Type of access (high, 8' max, behind knee walls, rim joist areas, etc.), finished or unfinished space, one area or small areas spread out over the building or buildings, number of times we will have to hook up to power in new locations, is the work from the inside or the outside (staging, overspray and weather protection), etc. (these all influence our productivity).

  • R-value required (determines thickness and open vs. closed-cell).
    Vapor permeance issues - new code requirements may affect the perm rating you need (determines density).

  • Project sequencing issues (schedule the work at once or in stages around other trades, number of mobilizations, etc.).

  • Air-sealing tasks or just walls (windows jambs, framing cracks, etc. are at a different rate than open walls).

  • Air-barrier standards - new codes or HVAC engineering may require a certain air-leakage standard be met. We can meet any air leakage standard (for the area we work on) and test for compliance (if the tests are not done by an independent third party) - both impact the cost.

  • Location (travel issues).

  • Quality-assurance testing requirements.  (Are infrared, blower door, pressurized fog, adhesion, periodic sample shots, or other testing procedures required?)

  • Warrantee - Does the Client want guarantees against low performance or certain types of building failures? We offer guarantee programs which require QA methods at an additional cost.

  • Ventilation (Who, if anyone, will be required to provide this?)

  • What will the indoor and outdoor temperatures be at the time of our work? If temporary heat is required (not open flame), who will provide it?

  • Who will provide power (determines cost of power connections or if we will need to include generator rental fees)

  • Are you looking for a certain type of foam system (brand the owner knows or was recommended, ozone depletion level, etc)?

Estimates are free, so just contact us with the square feet of the area and access information, and we’ll be able to provide an accurate number.

Question:  What do I have to do to prepare my wiring before the walls or roof are foamed?
Answer:  Be sure the wires are in the middle of the cavity away from the reach of nails used to attach the siding and screws used to attach the interior gypsum board. Where wiring runs parallel to the framing, secure it often enough to the side of the framing to prevent it from being "lifted or floated" away from the middle of the framing cavity by the rising foam.  For more information on the proper installation of wiring, refer to the Electrical Code in your area.  The standard code requirements for Type NMB wiring (Romex is one of the common trade names for non-metallic cable) work well to protect wiring from damage during all construction procedures. NMB wiring came into use during the energy crisis when super-insulated buildings came into favor.   I understand that this wiring standard was intended to deal with higher operating temperatures for Romex in construction with high R-values.

Question:  Can you drill holes in existing wall or roof cavities and fill them with polyurethane foam?
Answer:  Yes.  Foam can be injected through holes in all most all types of typical construction. Both open-cell and closed-cell foams can be used in the appropriate situations. This method requires experience to prevent damaging the finishes by generating too much pressure. Infrared quality assurance equipment allows the Technician to "look inside" the cavity and be sure that all of the space has been filled and locate any voids that remain.

Question: What is the application range of injection foam?
Answer: For each inch of cavity space, the injection foam expands one foot vertically.

Question: How are the holes in the wall made and repaired for injected foam applications?
Answer:  Typically, 1" holes are drilled at intervals in each bay.  The type of drill depends on the material that is being drilled.  The spacing depends on the cavity thickness, bay width, product chemistry, and obstructions; usually holes are spaced every two to four feet vertically.  After the foam is injected and it begins to cure, any foam or cork extending beyond the wall plane is trimmed flush.  The holes can be puttied and painted or covered over with new clapboards or other siding, depending on the project requirements.  An infrared thermographic scan is done during the injection process while the foam is hot to verify that the bays are full and no bays have been missed.  If any voids are located, they are drilled and filled as the injection process progresses.

Question: Given that we are using 2.5" to 3" of foam for the walls, is there any reason why I should not use 2x4 framing?
Answer: 2 x 4 framed walls are fine. A little more trimming, but not a problem.  Framing with 2 X 4s will give the Owner more space in the building - 2" around the entire perimeter adds up to valuable sq. ft.  There is also the savings in material costs and natural resources. 2 X 6 framing would make it easier to retrofit any future wiring in the 2.5" to 3" remaining space.

Question: And in regard to scheduling, besides installing the foam after electric and plumbing rough-ins (or anything else I want in those walls), I assume the windows should be installed as well.
Answer: First, there isn’t a short answer to project sequencing issues.  Every project is different. Framing sizes and mechanical systems can influence the decisions about sequencing on a case-by-case basis. More information about scheduling and project sequencing can be found in the Pricing and Scheduling section of this site.

Secondly, regarding the windows - not necessarily.  Some builders do this themselves.  However; others want us to install the air sealing as part of our work so the rough opening seals can be included in our quality assurance testing.  Architects or energy rating programs often require overall air leakage performance standards verified by blower door testing.  Our quality assurance work performed as part of our installations, which can include infrared, blower door, and pressurized fog testing, can give you the confidence that these standards are going to be met when the Owner’s final compliance tests are done.