hard wood over crawl space

Hello, I'm looking to install oak wood flooring over an unheated crawl space. Do I need a plastic sheet barrier for moisture??? Also , this is my time installing hard wood and would be greatful for any tips, basic or otherwise. Thanks Eric

 

Get a $8 moisture test kit for flooring, follow the instructions and see if you have a moisture issue. If you have a 6 Mil moisture barrier on the dirt floor in your crawl space you should not have a moisture issue on your subfloor. If you do not have a 6 mil barrier on your crawl space dirt floor I'd put one down before putting down any type of wood flooring or flooring for that matter.

Roy

 

Crawl space should be dry and no moisture issues. A polypropylene (8 mil minimum) vapor retarder is recommended over soil. Overlap and tape the sheets together and run it up the foundation wall and tape in place. A moisture meter is recommended to test the moisture content of the plywood (OSB acceptable) subfloor and the hardwood flooring. If installing solid 2 1/4" strip flooring, moisture content difference should be no greater than 4%. If installing wider plank flooring, difference should be no greater than 2%. An additional vapor retarder of 15# minimum roofing felt is installed over subfloor and overlapped 4". Doors and windows should be closed and HVAC system running and temperature and humidity within occupancy levels and maintained year round. Wood should be placed in room(s) where it is to be installed for several days, stacking boxes no higher than three. This will give the wood an opportunity to acclimate (adjust) to temperature and humidity. Leave at least 3/4" expansion gap around perimeter of room. Wood should be installed perpendicular to floor joists. Take into consideration height of flooring and the possible need to undercut door jambs and make transitions in doorways to other types of flooring.

 

Thanks for the replies. Is the 3/4 inch gap around the room mandatory??? I noticed the other floors run right to the wall. Again, thanks for all the useful information!!! Eric

 

Because hardwood flooring expands and contracts due to fluctuations in temperature and humidity, an expansion gap is required.

 

Twelvepole, Do I need a 3/4 total, 3/8 north and south, 3/8 east and west?? A 3/4 gap on all 4 walls would a difficult task to find molding for. Thanks Eric

 

Unless your flooring cains moisture right next to the base boards, it will never take up a ¾" expansion gap. The flooring will buckle and heave up, out in the room, before fasteners sheer or adhesive releases and expansion space is taken up at the perimeter. If a board at the perimeter moves more then an 1/8 of an inch, the fastening system will be compromised.

I leave 3/8 on all flooring I install. If a floor moves more then that at the wall, you have more concerns them me not leaving ¾" at the perimeter.

 

Thank you all for the replies!!!!!!! Eric