FAQ for Spray Foam Contractors

Question

Are all “A” sides the same or compatible?

Answer

No. Spray polyurethane foam systems are specially formulated to be used in a specific set of ‘A’ (isocyanate) side and ‘B’ or ‘R’ (resin) side. The ‘B’ is always unique to the system manufacturer and is matched to a specific ‘A’ side. The type of isocyanate used in the ‘A’ side is chosen and/or formulated to match to the unique ‘B’ side to give unique and different application properties to the applied foam such as foam cell size, R value, flame retardency, adhesion, compressive strength, dimensional stability, etc. The outward appearances of the isocyanates could be the same. The ‘A’ sides from different sets of systems might or might not have the same appearance, percent isocyanate (a measure of reactive sites), viscosity and approximate acidity ranges. However, they have slight performance characteristics that are different form one another.

Question

Are there any specific weather conditions that foam should not be installed in?

Answer

Spray foam insulation systems must stick to the construction surface to which they are sprayed to be effective.   Any substance that “acts” as a hindrance to this bond should be dealt with.   For weather issues, water (rain or condensation) is the main consideration.  If water or excess moisture is on the construction surface, the spray foam will react with the water and not properly stick to the surface.   In most all cases, this reaction will be almost immediate and the spray foam applicator should see this and either stop spraying until the surface dries, or take action to alter the surface moisture condition.   When there is a question as to surface suitability, the simplest test it to spray a small area, say 5 to 10 feet square and let the foam sit for a few minutes, then check for proper adhesion.

Wind is another weather factor, particularly for exterior applications to roofs and walls.   Applicators planning an exterior application must consider wind effects for overspray and loss of yield.    Wind screens can be utilized in many occasions to control overspray, and this should be determined by the SPF contractor prior to beginning the spray cycle for the day.

Temperature can be another weather factor. Many material suppliers provide variations of their systems for different temperature applications. SPF contractors have to work with the material supplier to ensure they have the proper chemical system for the temperature conditions. This involves both the air temperature and the substrate surface temperature when the spray foam is applied.

Experienced spray foam applicators will be familiar dealing with climatic conditions.   Less experienced applicators should consult with their spray foam system manufacture for proper guidance.

Question

Have a crawl space on a new addition Fiberglas batting under floor, 3-foot block walls with 4 open vents, looking for best way to spray foam, should I remove batting and spray under floor 6" of open cell,or spray block walls with 2" closed cell and close off vents?

Answer

A lot of the answer depends on the climate. If you're going to put foam under the floor, the closed-cell SPF is recommended. The preference is to insulate the walls and make the space much like a basement.

Question

Can you shorten the length of the heat cable at the hose connections? My taped connections are are not smooth and when dragging my hose around the tape wears down quickly at those spots because the heat cable is doubled over.

Answer

The electrical cables on heated hoses do come a little long from Graco. It seems like a nuisance sometimes in situations like you have described, but it comes in handy when you damage an end and have a little extra to make a re-connection. The extra length also allows you to take the stress off the connectors in the daily use of the hose. You can cut these shorter, just keep in mind that you do want to leave a little slack to reduce stress on the connectors. If you are still using the white plug in power-lock connectors, it would be a good time to upgrade to the new power-lock connectors that utilize set screws to secure the wires.

Question

How do I get iso off the exterior of my pickup.

Answer

With dried liquid isocyanate, I'm afraid the only answer I know is to use fine grit sandpaper and sand it off as best you can. This would be a good question for the Q&A Forums to get answers from many different contractors and manufactures.

Question

Hello- When spray foam is applied to a thickness of 2", does this represent an average, some thicker and thinner, or an absolute minimum?

Answer

Generally, you should have a minimum thickness of 0.25" less than the specification with no maximum thickness limit. Therefore, if you're specification is 2.0", your minimum thickness should be 1.75”.

Question

Just wondering are guys spraying open cell directly to plywood under side of shingled roof or in installing a foam soffit to let wood breathe

Answer

Spray polyurethane foam can be sprayed directly to the underside of the roof deck. Drying can occur through the spray foam if the deck happens to get wet from a roof leak. Using a vent chute is also an acceptable option.

Question

Will spray foam stick and expand properly on cold ductwork that has condensation?

Answer

When applying spray polyurethane foam, all surfaces must be absolutely dry. Condensation will be detrimental to the physical properties of the resulting foam. Regarding temperatures, each system has temperature limitations. Check with your manufacturer to make sure you have the right system for the job.

Question

I have a job i am trying to bid on right now. It requires spraying closed cell foam over single pain windows in a warehouse. Do i need to spray the glass with a u.v. ray protectant before applied foam to avoid uv breakdown of the foam? And if so what products can i use?

Answer

Assuming you are talking about spraying foam to the interior side of the glass, yes, you will need to protect the foam from UV exposure. Spray polyurethane foam will degrade over time if left exposed to UV light through the glass. The degradation of the foam will cause the foam to lose adhesion to the glass and discolor to a dark brown color. It is recommended to cover the glass with a coating that is tested to protect surfaces from UV light. Most SPF manufacturers sell roof coatings designed to protect foam from UV exposure. You can find several foam and coating manufactures on this website.

Question

What type of safety equipment do I need?

Answer

This will vary somewhat with the job. Is the job interior or exterior? Working from heights? Fall protection, edge warning and protective gear will be specific to each situation. In general, every job should have at least two chemical rated fire extinguishers—one in the spray rig and one near the point of spraying. An eyewash station should be on every rig, as well as the MSDS for every chemical carried on that rig. In case of a chemical accident involving injury, the MSDS should be given to attending medical personnel. MSDS are required to be on every rig by DOT regulations. A chemical spill kit should be readily at hand for control and cleanup of minor spills and the phone numbers on hand for emergency response if the scope of any incident is beyond the capabilities of crew present.

BE AWARE of the properties of the chemicals beings used and that all involved personnel on site are trained in the handling and use.

PREPARE to work safely. Plan for emergencies and take into account potential hazards presented to each job site.

Additional information is available here: Spray Foam Safety Guide

Question

What could the reason for the too big material usage? Average we use 20-25% more raw material then states technical data sheets! thank you! We use XP2 machine or sometimes E10. Thank you!

Answer

There could be several reasons why you are not getting the yield you are expecting. First, you need to make sure you are following the manufacturer's recommended settings for your equipment. Secondly, many environmental factors such as substrate temperature and humidity could be effecting your yield. The best advice is to work with your spray polyurethane foam supplier and narrow it down. This may be an interesting question for the Sprayfoam.com forums. You'll get all sorts of advice from all of our contractors. Try the ones that make sense.