Yes. You, everyone who lives there, and your pets need to be out of the house while spray foam is being applied and for a re-entry period after the crew finishes, and you should be given that re-entry number in writing before install day rather than on install day.
That is a less convenient answer than some people are told, so we will say the rest of it plainly too. If a contractor tells you that you can hang around in the next room, or work from the spare bedroom while they spray the crawl space, they are not doing you a favour. They are making the job easier to sell. The chemicals are reacting while they are being applied, the air in the building is not something anyone should be breathing without proper respiratory protection, and the whole point of the containment and ventilation setup is that people are on the other side of it.
The short version
Everyone out during the spray. Everyone out through the re-entry window afterwards. Pets out, especially birds and small animals. The real re-entry number depends on the product, the assembly, and how much ventilation we can get into that space, so we work it out for your house and tell you before the day. Plan a full day away at minimum, and ask about the night.
Why you have to be out
Spray foam is not a product that arrives finished. It shows up as two liquids in separate drums, heated and pumped through separate hoses, and they only meet at the tip of the gun. When they meet they react, and that reaction is what turns them into solid foam a couple of seconds after they hit the surface. While that is happening, and for a while after the last pass, the air in the work area carries material from that reaction along with the blowing agent.
That is why the crew is in full-face supplied air or cartridge respirators, hooded suits, and gloves, and it is why the space gets sealed off and ventilated rather than just aired out with a window. The occupied part of your house is on the outside of that boundary, and so are you. It is not that we expect something to go wrong. It is that the correct way to run this job puts people out of the building, and the correct way is what you are paying for.
There is a second reason that has nothing to do with chemistry. Spray foam work is loud, the hoses run through doorways, and a crew that has to work around a family is a crew working slower and more carefully about the wrong things. An empty house gets a better install.
How long you actually have to stay out
Here is where we are going to refuse to give you a single number, because anyone who gives you one without asking about your house is guessing. The re-entry window depends on three things.
- The product. Every spray foam manufacturer publishes re-entry guidance for their specific formulation, and those windows are not identical across products. We go by the published data for the material actually going into your house, not by a rule of thumb.
- The assembly. Two inches on a rim joist is a different amount of chemistry than five inches on a roof deck across a whole attic. More material and more thickness means a longer tail.
- The ventilation we can achieve. An open attic with gable vents and a big hatch clears much faster than a sealed 18 inch crawl space with one small access door on the far side of the house. The space that is hardest to work in is usually also the space that is slowest to clear.
What you should get from any contractor bidding your job, before you sign anything, is a specific answer: which product, what its published re-entry time is, how the space will be ventilated, and what time your family can be back in the house. We put ours in the quote. If someone cannot answer that quickly, that tells you something useful about how the rest of the job will go.
This is one of the questions we use to separate a careful installer from a fast one. The rest of the list is in what a quality spray foam install looks like.
Pets, birds, fish, and reptiles
Pets leave with you. Dogs and cats are the easy part: they go where you go, or to a friend, or to daycare for the day.
Birds are the part people forget, and they are the most important part. Birds have a respiratory system that is far more efficient than ours at pulling things out of the air, which is exactly why they are more vulnerable to airborne irritants than you are. The same caution applies to rabbits, rats, guinea pigs, and other small mammals. If you have any of these, they should be out of the building well before the crew starts and they should not come back until after you do. Do not park the cage in the garage and call it out of the house. Somewhere else entirely.
Fish tanks and reptile vivariums are the awkward case, because you usually cannot move them. Tell us about them at the estimate, not on the morning. In most jobs the answer is that the tank stays where it is, the room it is in gets sealed off from the work area, and we plan containment and airflow around it. What matters is that we know, so the tank is designed into the containment plan instead of discovered halfway through. If the tank is in or adjacent to the work area, that is a conversation worth having before we schedule.
Houseplants
Houseplants are lower stakes than pets but not zero. Anything in the work area or in the path between the work area and the exit should be moved out or moved well clear, both to keep overspray off the leaves and because they will be in the way. Plants elsewhere in a sealed-off part of the house are generally fine to leave. Outside, if we are working near an entry, we will tell you which beds and pots to move so the hoses and the pathway protection do not flatten them.
Planning the day
A realistic picture of the day helps more than a reassuring one.
Crew arrives early
Setup is a real part of the day. Rig protection, seal the work area, get the rig and hoses staged, bring the material up to temperature.
Spraying
The actual foam goes on in controlled passes. A crawl space or a single attic is often a one day job. A whole-house scope can run longer.
Ventilation runs
Air keeps moving out of the building after the last pass. This part is not optional and it is not instant.
Re-entry, then walkthrough
We tell you when the house is yours again, then we walk the work with you and show you coverage and depth.
Plan on being out for the full working day, and ask us specifically about the evening. For plenty of jobs the answer is that you are back in that night. For larger scopes, or a space that ventilates slowly, or a late finish, the honest answer is sometimes a night elsewhere. We would rather tell you that a week ahead so you can book a hotel or call your sister than surprise you at five o’clock with a sleeping bag problem.
If you work from home, treat it as a day out of the office: a coffee shop, a library, a co-working desk, or a day at a friend’s house. If you have kids, school plus one afternoon of childcare usually covers it. If someone in the house is pregnant, has asthma, or has a respiratory condition, say so at the estimate. It does not change whether we can do the job, but it changes how conservative we are about re-entry, and being conservative costs nothing.
What to do before the crew arrives
Prep is mostly about access. Every minute the crew spends moving your storage is a minute not spent on your insulation.
- Clear the access point. Attic hatch, pull-down ladder, or crawl space door. Empty the closet under the hatch, move the shelving off the crawl space access, and make sure the door actually opens.
- Get stored items out of the work area. Boxes in the attic, bins in the crawl space, anything stacked against a wall we are spraying. If it stays it gets covered, and if it gets covered we work around it, which is slower and worse.
- Move anything you care about away from the route. The hoses come in through a door and travel to the work area. Rugs, art near that path, and anything fragile on a hallway table are better off elsewhere for the day.
- Sort out parking. The rig is a truck or a trailer and it needs to sit reasonably close to the entry point, because hose length is finite. On a Seattle street with permit parking or a tight alley, tell us in advance and we will plan it.
- Leave us a key plan. Who lets us in, who locks up, and how we reach you during the day. Most jobs you are not there for most of it.
- Say the awkward things out loud. The fish tank, the bird, the tenant downstairs, the neighbour who shares a wall. None of it is a problem if we know.
Pathway protection and masking are our job, not yours. We run floor protection along the route, mask what needs masking, and seal the work area off from the rest of the house. You should not be buying plastic sheeting the night before.
What happens to your heating system
In almost every job the HVAC system gets shut off and its openings sealed for the duration of the work and the ventilation period. The reason is simple: a furnace, an air handler, or a ducted heat pump is a machine whose entire purpose is to pull air from one part of the house and distribute it everywhere else. Leave it running while we spray and it will happily take the air out of the work area and deliver it to every bedroom in the building, which defeats the containment completely.
So the system goes off, returns and supplies inside or near the work area get covered, and it stays that way until the ventilation period is done. In practice that means the house will be cool when you get back on a wet Seattle day in January, and it may take an hour or two to come back up to temperature. That is normal and it is temporary. If anyone in the house genuinely cannot tolerate an unheated day, tell us and we will plan the schedule around it.
If your ductwork runs through the crawl space or the attic we are working in, which is extremely common in this housing stock, that is worth a specific conversation at the estimate. Sealing and protecting ducts properly is part of the scope, not an afterthought.
What a well-run job looks like from your side
You will not see most of it, which is exactly why it is worth knowing what to look for in the ten minutes you are there at the start.
| What you should see | What should worry you |
|---|---|
| A re-entry time you were given days ago, in writing. | A number invented on the doorstep, or none at all. |
| The work area sealed off from living space before any spraying starts. | Spraying beginning while the house is open through to the kitchen. |
| Ventilation moving air out of the building, not just stirring it around. | One window cracked and a box fan. |
| Every person in the space in a full-face respirator and a hooded suit. | Anyone spraying in a polo shirt and a dust mask. |
| Floor protection down the whole route before the hoses come in. | Hoses dragged across your hardwood. |
| A walkthrough at the end where coverage and depth get shown to you. | The crew gone before you get back, with no call. |
If you want the deeper version of that list, including what to check weeks later, read how to tell if your spray foam was installed correctly.
What it should smell like when you come back
Expect to notice something. A faint new-material smell on the first day back, strongest near the hatch or the access door, fading noticeably day over day, is the normal tail end of a cure. Open some windows, let the house breathe for a day or two, and it goes.
What is not normal is a strong chemical, paint-like, or fishy smell that is still obvious after a couple of weeks, or one that is getting stronger rather than weaker. That pattern points at foam that went in off ratio, and it is not a ventilation problem you can solve with more open windows. If that is what you are dealing with, do not sleep in it, ventilate, and get the install assessed. We have written the whole thing up in does spray foam insulation smell go away.
Common questions about leaving the house
Can I stay in the house if you are only spraying the crawl space?
No. A vented crawl space is not sealed off from the living space above it in any meaningful way, and your floor is full of penetrations for plumbing, wiring, and ducts. Air from down there gets upstairs. The same applies to an attic. The work area gets contained and ventilated as well as we can manage, but containment is a control measure, not a guarantee, and the correct plan still has people out of the building. This is true for a two hour rim joist job as much as a full crawl space.
How many hours before I can come back in?
It depends on the specific product being sprayed, how much of it is going in, and how much ventilation the space allows, so a number quoted to you before anyone has seen your house is not a real number. Manufacturers publish re-entry guidance for their own formulations and a competent installer works from that document plus the conditions on your job. Ask for yours in writing at the quote stage. We give ours before the day, not on the day.
Do I need a hotel, or can I sleep at home that night?
For a lot of single-area jobs you are back in that evening. For a larger scope, a slow-to-ventilate space, or a late finish, the answer is sometimes a night somewhere else. We tell you which one it is when we quote the job so you can plan, and if the schedule slips on the day we will tell you as soon as we know rather than at five o’clock. Nobody should be finding this out at bedtime.
What about my cat, my dog, and my parrot?
All of them leave, and the bird leaves first and comes back last. Birds and small mammals like rabbits and guinea pigs have respiratory systems that are more sensitive to airborne irritants than ours, so a garage or a closed bedroom is not far enough. Send them somewhere else entirely for the day. Fish tanks and reptile enclosures usually cannot move, so tell us at the estimate and we will design the containment around the room they are in.
Why does my furnace have to be off?
Because its job is to move air from one part of the house to every other part, which is precisely what we are trying to prevent while we spray. The system gets switched off and any returns or supplies in or near the work area get sealed, and it stays off through the ventilation period. Practically, that means the house will be cool when you come back and will take an hour or two to recover. If your ducts run through the attic or crawl space we are working in, we will cover how they are protected before we start.
Can I watch the install?
Not while spraying is happening, for the same reason the crew is in full-face respirators. What we do instead is walk you through the space before we start so you can see the prep and the condition it is in, and walk it again with you after re-entry so you can see coverage, depth, and how it was finished. We would rather you looked closely at the finished work than watched the middle of it from a doorway.