If your crawlspace is plagued by moisture problems then it could be time for you to start considering adding a crawlspace vapor barrier. Crawlspace vapor barriers are intended to prevent moisture from collecting on the floor of the crawlspace and to prevent moist air vapors from rising up into the room above it.
Preventing Crawl Space Moisture
If prevention is better than cure, then preventing moisture getting into the crawlspace in the first place is something you need to work on; it will also help the crawlspace vapor barrier once installed to be more effective.
First of all, check that water downpipes from the gutter are throwing rain water well away from the sides of the building. Installing a simple soak-away area running away from the sides of the building will help here along with adding extension pipes at the base of the down-pipes to carry the water further away from the walls.
Also, angle the earth around the crawlspace wall down and away from it, so as to further encourage good drainage. Don’t forget as well that moisture can accumulate in your crawlspace due to condensation when cold air meets warmer air. So fix any gaps in the flooring above the crawlspace and check that any crawlspace vents are OK.
If you don’t want to go to the expense of installing a concrete crawlspace floor with a vapor membrane, the next option is to fit a plastic vapor barrier. Plastic crawlspace vapor barriers are typically 6mm plastic sheeting that requires only a sharp knife and a waterproof tape to fit, all of which you can get from a local or online DIY store.
When ordering the vapor barrier and tape make sure you order more than enough to just cover the crawlspace floor area – you’ll see why in a moment.
Preparing the Crawlspace
Having already made sure water that you’ve done your best to make sure moisture is prevented from collecting in the crawlspace, as described above – give it a thorough clean and make sure there’s nothing sharp on the crawlspace floor.
The last thing you want to do is fit the plastic vapor barrier only for something sharp to pierce it, allowing moisture back in to the crawlspace. Make sure the crawlspace is clear of any standing water and is in generally good repair. If there is any moisture present you need to make sure it is thoroughly dried out, hiring a dehumidifier from your DIY store if necessary.
Installing a Crawlspace Vapor Barrier
Open out the roll of plastic sheeting allowing it to rise up the wall by 6 inch or so and use the waterproof tape to fix it to the walls. If one continuous sheet is insufficient, overlap extra sheets by at least 1 foot and join together with the waterproof tape to create a water-tight seam.
Any obstacles you come across, joists or uprights need to be treated like a wall. Cut up to and around them, so that the vapor barrier can be taped to them at least 6 inch above the crawlspace floor.
As well as adding a crawlspace vapor barrier you have, unwittingly added a layer of insulation to your home, which you will probably notice straight away by how much easier it is to maintain a temperature in the room above the crawlspace.
Ultimately, adding a crawlspace vapor barrier will thus save you money; but think how much more money you could save by now insulating the crawlspace properly.