A crawl space has been accurately described as a space that has all of the issues of a full basement (and more) – but none of the convenience. Whether your crawl space has a poured concrete floor or dirt floor, you still have to contend with moist air, penetrations and musty odours – unless you deal with the problem the right way.
Insulating a crawl space will significantly reduce the issues associated with this area of the home. It will eliminate moisture and mildew problems and prevent rot and mould. It will also help with cold floors and drafts. This makes your indoor air quality higher and makes your home more comfortable and durable.
I do want you to read the full article and learn about the “why” behind the ideal solution but lets cover what that ideal solution is first…
Encapsulate the entire crawl space so that it becomes a dry, conditioned space. To do this effectively this means installing a membrane – 6 mil or 10 mil (the thicker the better) across the entire floor and up the walls about a foot along the entire perimeter. This membrane needs to then be taped to all walls and any pillars it needs to go around. Next apply 2 – 3.3 inches of closed cell spray foam on the walls and up into the header space. 2″ of closed cell spray foam creates a full vapour barrier, 3.3″ provides a thermal value of R-20. (Note: Spray foaming the walls generally requires much less material than if you spray foamed the floor.)
This solution seals out the moisture and very effectively seals penetrations and gaps in the space.
Vented or Unvented Crawl Space?
There are two types of crawl spaces: vented and sealed. Vented crawl spaces are associated with moisture problems and mold. Although older building codes required crawl spaces to be vented, newer versions of the code allow sealed crawl spaces. In most cases, a home with a sealed crawl space will use less energy than a home with a vented crawl space.
Venting allows excessive moisture in a crawl space in summer. Vented crawl spaces in summer allow warm air to travel toward the cooler crawl space – heat always moves toward cooler – cooler air does not move toward warmer areas. So the humidity comes in, condenses and cannot escape. Unless your crawl space is built on piers, closing off those vents is the only solution.
In the winter, vents allow heat to escape the crawl space causing any HVAC or plumbing in that space to have to work harder. This also leads to cold floors and drafts.
NOTE: Where radon is a hazard, the crawl space can be safely vented by installing perforated plastic pipe in gravel beneath the polyethylene ground cover and running the stack up through the roof. The membrane gets wrapped around this vent to maintain the continuous seal.
NOTE 2: When HVAC equipment (not just ductwork) is in crawl space, intake must be sufficient to prevent backdraft.
Conditioning this space is an important step to eliminate incidental moisture.
Advantages of Unvented Crawl Spaces
- stay drier
- protect plumbing from freezing
- require less insulation
- if ducts are in the space, lower the load on the furnace
- energy savings
Why are batts not the answer?
Batts don’t deal with the issue of venting and other moisture problems. They also hold moisture and sag causing convection movement that destroys their R-value. This moist moldy air is bulled right up into the home through something called the “Stack Effect”. In a fireplace chimney, the stack effect is invaluable. In your home, it can cause problems as warm heated air rises toward your attic, it creates a vacuum that sucks air up from the basement or crawlspace and through penetrations in the building envelope.
As you may be able to tell from this article each crawl space can present its own challenges and issues as part of your “House as a System”. At Eco Insulation, we provide a full assessment and quote so there are no surprises and you can get a reasonable expectation of the results that can be reached. We look for water issues, foundation problems, penetrations and mould to ensure we don’t put a band-aid on top of a bigger problem – we will help you get any serious issues fixed before we encapsulate your crawl space. We will even take photos of the area during the assessment so YOU don’t have to crawl in to see what the space looks like. 🙂
Fill out the Free In-Home Assessment request to get started.