Tech Tip: How to Process and Spray Foam in Cold Weather

As winter settles in, spray foam contractors face the challenge of producing high-quality foam in cold conditions. Cold drums, chilly substrates and low air temperatures all affect foam quality and yield. With the right techniques you can keep delivering excellent results through the coldest months. The targets below come straight from ThermoSeal's technical data sheets.

1. Warm Your Drums to 77°F

Drum temperature is critical to foam quality in winter. Before spraying, warm your drums to at least 77°F. Store the rig indoors overnight if you can; if not, use drum blankets and electric drum heaters to bring the material up to temperature.

• Closed cell (HFO, 5G): warm the drums gradually, ideally by storing them in a heated space and letting the surrounding air bring them up slowly. Never apply an open flame or direct heat to a drum, and do not recirculate closed cell material.
• Open cell (500, 800): the recirculation target is 77°F to 90°F.

2. Set Heaters and Hoses for the Conditions

Start from the initial targets on the data sheet, then adjust for the cold:

In cold weather, raise your hose and heater temperatures 5°F to 10°F above those normal targets.

Keep in mind that your heaters can only add so much heat at a given flow rate. Cold drums make them work harder, and if the gap between drum temperature and heater setpoint is more than your machine can deliver, the material reaches the gun cold no matter what the setpoint says. Many proportioners perform best with a gap of roughly 40°F to 60°F; check your machine's manual for its rated temperature rise.

3. Check the Substrate Before You Spray

Always check substrate temperature with an infrared thermometer before spraying. The substrate must be frost-free and at least 10°F above the dew point, and above the product minimum:

Best practice: start spraying on the sunny side of the building and follow the sun as the day goes on. If the substrate is too cold, warm the space with an indirect-fired heater before spraying and shut it down while you spray. Direct-fired heaters add water vapor to the air and are an ignition source. Always keep the area well ventilated.

4. Protect Your Hose

A cold hose cools the material on its way to the gun and produces poor-quality foam. Keep the hose off cold or frozen ground, and wrap it with tarps, plastic or blankets to hold a consistent temperature from the machine to the gun.

5. Use Winter Closed Cell Below 45°F

ThermoSeal HFO and 5G closed cell come in winter and summer formulations. When substrate or air temperatures drop below 45°F, use the winter formulation, which is rated down to 14°F. Above 45°F, use the summer formulation. Plan your orders around the season so you have the right material on the truck.

6. Read the Foam

One of the best troubleshooting tools you have is the foam itself.

Closed cell: firehosing or running

If foam shoots out in a stream or runs down the wall without curing properly, the material is usually too cold. Check that your drums are at 77°F and raise your heater and hose temperatures toward the top of the cold-weather adjustment. If the A and B pressures stay unequal because the thicker B side is still cold, see our guide to troubleshooting spray foam pressures.

Open cell: pocketing or shrinking

If foam pockets between the substrate and the foam, or shrinks away from studs and rafters, it is likely too cold. Raise your preheater temperatures in small steps and re-spray. If the problem persists, recirculate the A and B sides until they reach the recirculation target of 77°F to 90°F, then re-spray.

The Bottom Line

By warming drums properly, setting heaters and hoses for the conditions, checking every substrate, protecting your hose and using the right closed cell formulation for the season, you can keep delivering excellent performance and yield all winter. Stay warm, and spray smart.

Frequently Asked Questions

Does spray foam work in cold climates?

Yes. Once installed, spray foam performs very well in cold climates because it air seals the building envelope, and closed cell foam also acts as a vapor retarder. The challenge is applying it in cold conditions, which is what this guide covers.

What temperature is too cold to spray foam?

It depends on the product. ThermoSeal 500 and 800 open cell need the substrate and air above 32°F. ThermoSeal HFO and 5G closed cell need them above 14°F with the winter formulation, or above 45°F with the summer formulation. In every case the substrate must also be at least 10°F above the dew point.

What is winter blend spray foam?

A closed cell foam formulated to react properly in cold conditions. ThermoSeal's winter closed cell is rated for substrate and ambient temperatures above 14°F, compared with above 45°F for the summer formulation.

Can you heat spray foam drums?

Yes, gradually, to at least 77°F before spraying. Warm them in a heated space or with drum blankets and heaters. Never apply an open flame or direct heat to a drum, and do not recirculate closed cell material.