Closed Cell Spray Foam for Multifamily Buildings

The rim joist is the horizontal band where the foundation meets the first floor. In older Chicagoland buildings it is often the largest continuous air leak in the envelope, framed in short awkward bays that batt insulation rarely seals well. Two inches of closed cell foam sprayed on the rim gives you R-value, an air seal, and a vapor retarder in one pass, at a thickness that fits the space.

The same logic drives the rest. Crawl spaces push ground moisture into the building above them. Basement walls sit against soil that stays wet. Vaulted ceilings often have rafter depth too shallow to hold enough of a material with a lower R-value per inch.

• Rim joists and band joists at the foundation perimeter and at each floor level
• Unconditioned crawl spaces, including full encapsulation
• The interior face of below-grade basement and foundation walls
• Vaulted and cathedral ceilings where rafter depth is limited
• Exterior wall cavities already open during a gut renovation, where wall depth is tight
• Cavities next to a known moisture source, such as a pool room or a kitchen exhaust run

Foam is permanent, so everything we check beforehand is about making sure it goes onto a substrate that deserves it.

The crew opens the area and looks for active water first: staining on the sill plate, rot at the band joist, efflorescence on block, standing water in a crawl space. Foam sprayed over a wet substrate hides the problem instead of solving it, so water gets corrected before a spray date is set. We also look for knob and tube or abandoned wiring, measure cavity depth against the thickness the scope calls for, and record substrate temperature. Closed cell foam has a temperature range on its data sheet, and a cold crawl space in January often needs temporary heat before the rig runs.

The rig stays on the truck. Hoses run to the work area, so we need a parking spot near the closest entry and a clear path in.

Foam goes on in lifts, usually one to two inches at a time with cooling time between passes, because manufacturers cap how thick a single pass can be and a pass thicker than that does not cure properly. A crawl space or a full rim joist perimeter therefore takes longer than the square footage suggests. We work one area at a time, with containment and ventilation set up for that area.

Re-entry time is not something we estimate. The manufacturer data sheet for the exact product sets it, and you get that document and the re-entry window in writing before the start date, so your notice to tenants is accurate. Most of this work happens in basements and crawl spaces rather than inside apartments, which is why it fits occupied buildings better than a whole-unit retrofit.

• What we ask you to arrange: a parking spot for the rig near the entry closest to the work
• Keys or access to crawl space hatches, mechanical rooms, and locked common areas
• Tenant notice, using the re-entry window we give you in writing
• One point of contact reachable while the crew is on site

Spray polyurethane foam is generally not permitted to stay exposed. Code requires it to be separated from occupied space by an approved thermal barrier, most often half inch gypsum board. In limited access spaces such as crawl spaces and unfinished attics, an approved ignition barrier or a coating rated for that use applies instead. Which code edition is in force, and how the local inspector reads it, varies by jurisdiction, so we confirm it for your address rather than assuming.

That affects your budget and your inspection. A quote that prices foam alone and leaves the covering to someone else is not a finished scope. We identify which requirement applies to each area during the assessment, and the covering is either in our scope or named as work you arrange.

Rim joist and crawl space sealing can be evaluated with diagnostic testing when that testing is appropriate and included in the approved scope. Any comparable pre-work and post-work results are documented when they are actually collected.

With foam, the closeout record should identify the areas treated and the installed thickness or coverage required by the scope. The rest of the package is written for someone who was not standing there, so a board or ownership group can review what was completed.

• Each area treated, with measured square footage and installed thickness
• The product used, with its manufacturer data sheet
• Before and after photographs of every area
• Diagnostic results when testing is included in the approved scope
• A copy of the utility program submission package where a program applies

Building Energy Experts is authorized for ComEd, Nicor Gas, Peoples Gas and North Shore Gas programs. Whether closed cell spray foam is covered, and at what level, depends on the program and the address, so this is a property-specific review rather than a yes over the phone. Some envelope work is available at no cost for qualifying properties.

One detail is worth knowing before you schedule anything. These programs generally require pre-approval before work begins, and foam is hard to submit after the fact, because the file asks for the before condition, the measured thickness, and photographs taken during application. We handle that documentation from pre-approval through final submission, and the field data we collect on spray days is the same data the submission needs.

Closed cell costs more per board foot than anything else we install, so it is worth naming the cases where we would tell you not to buy it.

Closed cell foam needs an open cavity. If the walls are closed and the units are occupied, dense pack cellulose through small access holes does the job without tear out. If the complaint is noise between units rather than heat loss, open cell foam dampens sound better and costs less per board foot. On a large open attic floor, blown insulation usually buys more R-value per dollar. If the sheathing is already wet, or the assembly needs to dry toward the inside, a vapor retarder traps water instead of managing it. And if you expect to pull new wiring or plumbing through that cavity in a few years, foam does not come back out cleanly.

That call gets made at the assessment, on the building rather than on a product line.