Winter Concrete: Blankets, Enclosures, and Heater Fires
29 CFR 1926.150 · 29 CFR 1926.151 · 29 CFR 1926.154 · This talk in Spanish
Why it matters
Cold-weather concrete means blankets, poly enclosures, and heaters running unattended for days, which is a fire triangle we build on purpose. Curing blankets against heater casings, enclosures that trap heat, and nobody on site at 2 a.m. when it starts smoldering. OSHA fire prevention rules apply to temporary heating around combustibles. Today we plan the cure so the pour does not burn.
Hazards
- ⚠ Curing blankets and straw igniting against heaters
- ⚠ Poly enclosures melting and flashing from radiant heat
- ⚠ Unattended overnight heating with no checks
- ⚠ Fuel storage inside or against the enclosure
- ⚠ CO buildup for the finishing crew working inside
- ⚠ Blocked exits in wrapped structures
Controls and safe practices
- ✓ Layout first: heaters at least 10 feet from tarps, poly, and similar coverings, clear of blankets and forms, set level and secured against tipping.
- ✓ Indirect-fired heaters for tight enclosures; duct the heat in, keep the flame out.
- ✓ Overnight heating gets scheduled checks or monitoring; unattended does not mean unwatched.
- ✓ Fuel cylinders and cans stored outside the enclosure, upright and secured.
- ✓ Extinguishers at each enclosure entrance; per 1926.150, no spot should be more than 100 feet from the nearest extinguisher.
- ✓ Ventilation and CO monitoring for finishers working inside heated enclosures.
- ✓ Keep at least one clear exit path in every wrapped area, marked and unblocked.
What the OSHA standard says
Exact words from the official text, with a link to each paragraph.
“Heaters used in the vicinity of combustible tarpaulins, canvas, or similar coverings shall be located at least 10 feet from the coverings.”
“When heaters are used in confined spaces, special care shall be taken to provide sufficient ventilation in order to ensure proper combustion, maintain the health and safety of workmen, and limit temperature rise in the area.”
“Clearance shall be maintained around lights and heating units to prevent ignition of combustible materials.”
“Storage shall not obstruct, or adversely affect, means of exit.”
“Travel distance from any point of the protected area to the nearest fire extinguisher shall not exceed 100 feet.”
Site check before the talk
Walk the site and tick each line. Each line comes from the text quoted above.
- ☐Heaters sit at least 10 feet from tarps, canvas, and similar coverings. (29 CFR 1926.154(b)(4))
- ☐Heated enclosures get enough fresh air for clean burning and for the crew inside. (29 CFR 1926.154(a)(2))
- ☐Keep clear space around every heater so blankets and forms cannot catch. (29 CFR 1926.151(d)(6))
- ☐Stored blankets, fuel, and material never block a way out. (29 CFR 1926.151(d)(1))
- ☐No spot in the enclosure is more than 100 feet from a fire extinguisher. (29 CFR 1926.150(c)(1)(i))
Quotes checked word for word against the official eCFR text on October 5, 2026. This is a summary for a crew talk, not legal advice; the full official text governs. How we check
Crew discussion questions
- What is our heater layout for this pour, and who approved the clearances?
- Who checks the enclosure overnight, and how often?
- Where is fuel stored relative to the enclosure?
- How do finishers get out fast if something lights up inside?
Applicable OSHA standards
29 CFR 1926.150, 29 CFR 1926.151, 29 CFR 1926.154
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