Home>Discussions>INTERIORS>Molding & Carpentry>attic storage & subfloor options?
9 posts / 0 new
Last post
polishcarpenter
attic storage & subfloor options?

Hi. I have a home built in 2006 with an attic with nearly 20ft. tall ceilings. I've installed a pull down ladder so I can access this attic for storage. There is blown in insulation in the attic and the ceiling joists are exposed from the ceiling below. I'd like to put in a subfloor so I can easily walk around up there and also store items. Does anyone know what can be used for the subfloor, if I need to be aware of anything like jepordizing my R value of the insulation, wieght on the celing joists, etc.?

JLMCDANIEL
Re: attic storage & subfloor options?

3/4" plywood or OSB would work for subfloor. You will need to determine the size and spacing of the joists and the load limit of the design.

Jack

jkirk
Re: attic storage & subfloor options?

it depends on what dimension of lumber was used for the bottom chord if the roof is a truss system. if its only 2x4 i wouldnt even consider it as the added weight from storage could seriously compromise the structure unless a engineer is consulted first

canuk
Re: attic storage & subfloor options?

Ditto to what the others posted.

To add ----- in order to achieve proper insulation ( R 40 ) in the attic, you would need around 12 inches of blown in or batt material. The tops of the joists should always be covered with insulation to prevent thermal bridging --- with blown in that's easily done --- with batts that requires filling each bay flush with the top of the joists and running subsequent layers perpendicular.

In order for you to lay a floor in the attic you would need to build a sub-frame to raise the floor above the insulation.

jkirk
Re: attic storage & subfloor options?

if you have the budget for it spray foam performs much better, i was talkint to my insulator two days ago about a similar project, with spray foam you get an r-value of r-7 per inch, if you modify the framing to a 2x6 joist you can easily achieve an r-40 rating

canuk
Re: attic storage & subfloor options?
jkirk wrote:

if you have the budget for it spray foam performs much better, i was talkint to my insulator two days ago about a similar project, with spray foam you get an r-value of r-7 per inch, if you modify the framing to a 2x6 joist you can easily achieve an r-40 rating

Spray foam is a great product , however , unless the exposed side of the joists are also covered there is still the short coming with thermal bridging. Also, the cost for spraying R 40 would be huge -- can you say "second mortgage " ?

What some of the better insulation contractors are doing around here -- spray 1 to 1-1/2 closed cell on the backside of the ceiling --- blow in around 12 inches of cellulose. The spray foam seals all penetrations --- provides the vapour/air barriers -- the cellulose provides the rest of the R value.
This system works very well and is more cost effective.

jkirk
Re: attic storage & subfloor options?

this is something we do for attics which arent used for storage. very effective for after drywall is up

Timothy Miller
Re: attic storage & subfloor options?

Howdy consider contacting the truss maker to see if there is any additional built into the truss to carry additional loading.. As the others have mentioned it sounds like you'd be better off adding more insulation and doing storage elsewhere.

bush ze
Re: attic storage & subfloor options?

you can buy a self leveling cement/concrete. get some wood to block off/box in the area and use the self leveling cement to straiten it! then put whatever you want on there. you can get some excellent large tiles, or wooden click type flooring.

Sponsored Stories

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.