Containment and Air Scrubbing in Colorado Springs, CO Enclosures Built Before Demolition Starts

What an enclosure is built out of

Federal remediation guidance describes the construction in enough detail to hold a contractor to it. Limited containment, the level generally recommended for affected areas of roughly 10 to 100 square feet, is a single layer of six-mil fire-retardant polyethylene sheeting sealed to the surrounding surfaces, with a slit entry and a covering flap on the outside of it. Supply and return vents inside the work area are sealed, along with doors, chases and risers, so the enclosure is not quietly connected to the rest of the building through the mechanical system. Full containment, recommended above 100 square feet, uses two layers of sheeting and adds a decontamination chamber at the entry, so people and equipment pass through an airlock instead of straight into occupied space. The complete list of work covered here is on the services index.

The guidance also warns against reading those numbers as a formula. Heavy growth over a small area can put more spores into the air than light growth across a larger one, so the enclosure level is a judgment about disturbance and material, not a measurement of square feet alone.

Negative pressure, and what the machine is actually doing

An enclosure by itself leaks. What keeps debris inside it is air pressure: a HEPA-filtered fan draws air out of the work area and exhausts it outside the building, so the enclosure runs slightly below the pressure of the surrounding space and any leakage moves inward rather than outward. Two details matter more than the equipment brand. The exhaust has to actually leave the building, not dump into an attic, a crawl space or an adjacent room, or the machine has simply relocated the problem. And the sheeting should visibly draw inward when the fan is running, which is the cheapest verification available and takes one second to check.

Where an air scrubber is run inside the enclosure without exhausting outside, it is filtering rather than containing. Both have a place, but only one of them protects the rest of the house, and a scope should say which one is being provided.

The high-altitude, open-window problem this market adds

Most containment guidance assumes a closed building, and a large share of houses here are not closed in summer. Federal energy guidance describes direct evaporative coolers as drawing outdoor air through wet pads and blowing cooled, humidified air through the house, with the air deliberately not recirculated, which means a window or vent must stay open for the air to leave. A building running that way has a strong, continuous airflow path through it that will overwhelm a carefully balanced enclosure.

The practical rule is to shut the cooler down for the duration of the work and close the openings that were serving it, then manage temperature another way. The same applies to a whole-house fan. Leaving either running while an enclosure is under negative pressure produces air movement nobody has accounted for, in a building where outdoor humidity averages around 40 percent in the afternoon and the cooler is the largest single moisture input in the house.

Sequence: enclosure before demolition

Order is where most jobs go wrong. The enclosure goes up, the mechanical system serving the area is shut down and its vents sealed, the negative pressure fan is started and confirmed, and only then does any material get cut. Building containment after the wall is open is the same as not building it, since the disturbance that mattered already happened. Where the room is occupied space, contents come out or are protected before the sheeting goes up, and the floor path from the enclosure to the exit gets covered.

Colorado's habitability statute reflects that same order for rental property: it puts installing containment, stopping the water and adding high-efficiency particulate filtration in the first 72 hours after notice, and requires the containment to be maintained through the remediation and repair rather than removed at the end of the first day. That maintenance point is the one most often violated on longer jobs.

What containment does not do

It also does not end the job. The finish is a separate step with its own criteria, covered on the post-remediation verification page, and the guidance for it includes the absence of visible growth, damaged material and moldy odor along with a corrected water source.

What to look for on site, and what it costs

Five checks tell an owner whether the enclosure is real. Sheeting sealed at the perimeter rather than taped loosely at the corners. A functioning entry flap or airlock instead of an open doorway. Vents inside the work area sealed. Exhaust ducted outside the building. And the sheeting visibly drawn in while the fan runs.

Pricing tracks the enclosure level, the number of openings and vents to be sealed, the equipment count and the number of days it runs, and whether the work area is in occupied space that has to be re-entered daily. Containment and air handling should appear as their own line items with the days stated, because a scope that folds them into a lump sum is the easiest place to quietly deliver less. Where the affected material sits inside a wall cavity, the enclosure decision is made together with the cut boundary described under mold behind drywall.