Should I put plywood down in crawl space?

Question

My house is around 15 years old. I just bought it in August. It has a full bottom floor, and then basically a full second floor, though I think originally it just had a large attic that was converted into a second floor. There is still a small attic - but you have to crawl around. There are also crawl spaces on either side of the upstairs that run the full length of the house. Right now there are just a few pieces of plywood scattered here and there. The rest is two-by-fours and insulation. I would like to lay down plywood (nail it down) the entire length of the crawlspace - so I can use it for storage, but wasn't sure if there was some reason (e.g. moisture) that I shouldn't. Also, was considering cutting out some of the sheetrock and using parts of the crawlspace to put in receded bookshelves and dressers, etc.

Answer 1

It is o.k. to do so. Just need some additional preparation. Some of the things you will need to do first are:

1. Put down some plastic over the ground. Thus, keeping moisture from coming up through the soil.

2. Make sure that you do not have a problem with termites in your area. If the wood is laying on the ground or on the plastic for that matter and there is a termite problem, this will attract them. You want to keep these insects as far away from your house as possible.

3. If you don't have a problem with termites, put some pressure treated lumber over the plastic. Basically, make a floor system on top of the plastic.

4. On top of the floor system (pressure treated lumber) you can place your plywood. You can even screw it down if you like.

This is only a makeshift floor system. Remember to check to see if there is a problem with termites in your area.

Answer 2

I would only put a "Cat walk" the entire length. You should consider running at least an 8 to 10 inch thick insulation onto those joists to conserve energy during heating and AC season and to make your house more comfortable in those upper rooms.

It is far too late to add plastic moisture barriers and totally un-necessary. The Latex paint applied to the ceiling acts like a moisture barrier, and i am quite certain in your older home Latex paint has been applied to the ceiling probably a couple times already.

So I do not recommend any sort of covering up there with plywood which would decrease the insulation potential of the attic.

Answer 3

Do all that you want, sounds good. With those book shelves I'd insulate them naturally and make sure in that crawl space YOU DON"T close up any soffit vents you want to make sure you get good air circulating in your attic or you'll have one heck of a moisture and mildew problem. You don't need a vapor barrier , people make the mistake of tightening up a house too tight where it can't breath. Remember in winter months when your windows are all closed you still have alot of moisture that has to leave and with it too tight it makes a great time for mold and mildew and also will push the paint of your exterior walls. The vents in your attic are very important.

Answer 4

Most ceiling joists are sized for the load they have to carry ie, the ceiling .If they are at least 2x6 you are ok just for storage, but if they are 2x4 then what with the weight of the plywood and whatever stuff you store, you are going to exceed the designed load. The ceiling may start to sag or worse you may fracture a joist at a weak spot ,say a knot. Being that yours are 2x4 then It would be a risky proposition. Adding bookshelves and you are asking for trouble.

Answer 5

If you put plywood the warm air from the room below will migrate to the cold underside of the plywood and you will have a moisture problem. Before you put the plywood down put 2 inches of foam,r 10 mninimum, This will prevent the warm air from condensing on the cold plywood.

Answer 6

sure just use house wrap between the floor or ceiling joists and the plywood its a vapor barrier dont cover electric boxes permanately they may need acess so leave panels that can be lifted or unscrewed out and also you may want to leave acess to some of the edges for the house to breath in the overhangs ive worked on these typesof attics and found lots of builtins like dressers and bookshelves and such im ahouse painter that helps build for habitat

Answer 7

if you live in a cold weather climate you need to prevent heated air from entering the un-heated portion of the attic.in addition to preventing moisture problems, as previously mentioned, you need to prevent ice dams. ice dams occur when the under side of the roof is warm enough to melt snow and the resulting water runs down and re-freezes when it reaches the colder portion of the roof beyond the side-wall of the house. once the ice dam has begun, the water has nowhere else to go except back up the roof and it will force it's way under your shingles as it freezes,causing serious damage which will be very expensive to repair.

Answer 8

i think what you are talking about are called eves. we had them in a house i grew up in, we used the small attic eves to make forts and hide-outs. we had full floors in them too. if you do have soffits, don't cover them. if you have whirlybirds (metal turbines that help circulate air) you probably won't have a problem with ventilation if you lay floor right to the roof rafters. no reason not to put in built-ins, good use of space.

Answer 9

Sounds like an awesome cool place..just remember to put sheet plastic liner/vapor barriers between all that you can...it'll last forever...enjoy

Answer 10

I would pretreat the wood with a boric acid material. But yeah you can do it.