Vapor barrier installation in Missoula MT - a crawl space floor sealed wall to wall
Cold floors, a damp smell or bare dirt under the house? We cover the crawl space floor so ground moisture stays in the ground.
Does my crawl space need a vapor barrier?
Vapor barrier installation in Missoula means covering the bare dirt floor of your crawl space with plastic sheeting, so moisture and soil gases coming off the ground can't fill the crawl space and get pulled up into your house through cracks around the floor.
Most of the calls I get about this come from older houses with cold floors, a damp smell or a dirt crawl space that's never had anything over it. The price mostly comes down to how big the crawl space is, whether water has to be dealt with before the sheet goes down and how heavy a liner it needs. The schedule turns on how easy it is to work down there, because low clearance, lots of pipes, uneven dirt and old junk to haul out all add time. Once I've been through it, you'll get your own number in a written estimate that explains each step.
- Licensed and fully insured.
- Free in-person estimates.
- Replies within 1 business day.
Crawl space, sealing and insulation work
How we handle vapor barrier installation
First I look for water, because a sheet laid over a wet crawl space just hides the problem, a lot like framing a wall on a sill plate that's already rotting. If water is getting in, we deal with that before anything else, then clear out the debris so nothing pokes through the plastic. We lay the sheet across the whole floor, not just the open middle, run it up the walls and overlap the seams. Before any tape goes on, we get the surfaces under it clean and dry, because tape on dusty or damp plastic won't hold.
A crawl space liner handles moisture from the ground, but it doesn't stop heat leaking out the top of the house, which is where attic air sealing comes in, closing the gaps around lights, pipes and the hatch so warm air can't slip through them. In an older house that's cold all over, we can also look at retrofit insulation, adding insulation to walls and floors that were built with little or none. I'd rather tell you what your house needs and in what order than sell you one piece of it.
Why Missoula homeowners call Summit Missoula Spray Foam Insulation for vapor barriers
I check every crawl space myself
I spent years framing houses before we started our own company in 2023, so I know what's under a floor before I crawl in. I come out to look at each job myself and work alongside our crew on the install, so the person who found the problem is there when it gets fixed.
Licensed, insured, paperwork on request
We're licensed and fully insured, and I'm glad to show you the paperwork before anyone goes under your house. You should ask that of anyone you're thinking about hiring for this job.
Permits checked with city or county
For each job I check with the City of Missoula or the Missoula County Building Division, tell you what they say and take care of any permit the work needs before we start. We work in Missoula, Orchard Homes and the cities around them, inside and outside city limits, and you won't have to figure out which office covers your address.
On a vapor barrier, what's under the plastic matters more than the plastic, so book a crawl space visit or call (406) 317-4027, and have a rough idea of any water you've seen, where the access opening is and where the furnace sits. Your satisfaction, guaranteed.
Book a free crawl space vapor barrier estimate
Send the form and we'll get back to you within one business day to set a time for me to come look at your crawl space. The estimate is free, done on site, and there's no obligation.
- Licensed and fully insured.
- Free in-person estimates.
- Replies within 1 business day.
What happens when you call about a vapor barrier in Missoula?
Call or send a request
Call (406) 317-4027 or use the form, and we'll set a time for me to come out. If you've seen water down there, mention it so I come ready to look for where it's getting in.
Walk the crawl space together
I go through the crawl space with you, checking for water, clearance, pipes and anything that needs hauling out. I'll ask a lot of questions about the furnace, past leaks and how the floors feel in winter, because your answers tell me as much as the dirt does.
Read your written estimate
I send a written estimate that lays out each step and why it's there. You can see what's water work, what's the liner and what each one is for before you decide anything.
Install, clean up, walk through
We take care of anything that has to come first, lay and seal the liner, and clean up after ourselves. Then we walk through the finished crawl space together so you know exactly what's under your floor.
Crawl space vapor barrier questions
How much does a crawl space vapor barrier cost in Missoula?
I give you a price after I've seen the crawl space, because the cost depends on its size, how hard it is to work in and whether water has to be fixed first. A thicker liner costs more than thin film but holds up better if anyone goes down there, and drainage work adds to the bill but keeps you from covering a problem you'd have to pay to uncover later.
How do I know if my crawl space needs drainage work before a vapor barrier?
If you see standing water, mud or wet stains on the foundation walls after rain or snowmelt, the water needs fixing before any liner goes down. One liner seller's guide warns that plastic over active water traps it and speeds up rot, and in a cold place like Missoula, water left under the sheet can freeze into a layer of ice that shoves the liner out of place. Fixing the grade outside, adding a drain or putting in a sump pit first leaves nothing under there to freeze.
What is the best thickness for a crawl space vapor barrier?
Go with a thicker sheet if anyone will crawl around down there, because one liner seller's guide points out that thin film tears under knees, tools and furnace service visits. A national building guide also suggests a vinyl runner or extra plastic over traffic paths, such as the way to the furnace, and if your furnace or ductwork lives in the crawl space, that's the setup I'd lean toward.
Do I need a permit to install a vapor barrier in Missoula?
Check before the work starts, because inside city limits the city's building division keeps a list of work that can be done without a permit, and outside city limits the county is the office to ask. On our jobs I make that check for you and handle any permit the work needs.
Does a vapor barrier contractor need a license in Montana?
Yes, every construction contractor in Montana has to be licensed with the Montana Department of Labor & Industry. It's fair to ask any contractor, us included, to show you theirs before they go under your house.
Should I put a vapor barrier on my basement walls too?
Usually not plastic on the inside face, because moisture in walls below ground always moves toward the inside, and building science guidance says tight vapor control there traps it and causes problems over time. Basement walls are a different job from a crawl space floor, so I'd want to look at yours before suggesting anything.
Insulation work in other areas
Work that goes with a vapor barrier
Attic air sealing
If upstairs feels drafty in winter while the floors run cold, sealing the attic tackles the other end of the same heat loss problem.
Retrofit insulation
Older houses often have thin or missing insulation in walls and floors, and adding it after the fact pairs well with a dry, covered crawl space.