Placing decking in attic

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james_mcquade

Senior Member
Hi all,

my new job required us to move 250 miles to middle TN and buy a new home.
now that we're getting settled in, we want to store some items in the attic.
we have some metal containers that we put our summer/winter clothes in for the family.
in our old home, i had it wired so that the wiring ran with the 2 x 4 ceiling joists and secured in the middle.

in our new home, the electricians drlled holed in the middle of the 2x6 ceiling joists which is ok i know.
trouble is, most of the wiring is ran on top of the ceiling joists, wiring pulled tight.

can i drill holes close to the top of the ceiling joists so i can put the wiring inside and protect the wiring? i know that
the wiring in at the top of the joist, but i cannot put the decking on top of the wiring. i plan on spraying red paint on the decking
to indicate where the wiring is so i dont nail the decking near the wiring.
as i said, all i want to do is place some decking in the attic so we can place the metal containers on them for storage.
there is not enough room to add an extra room upstairs, the roof is 6 1/2 ft at the highest point.

thanks,
james
 
1793

1793

Senior Member
Location
Louisville, Kentucky
Occupation
Inspector
You may want to consider putting down some furring strips first, then as you said, mark the deck where the wires are to help avoid hitting them as you put down the decking.
 
Ponchik

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
I agree with augie & 1973.

It is easier to install furring strips than notching the cable. However, you want to make sure the decking that you are installing is not going to put too much weight on the ceiling joists. Are the 2x6 joists 16" or 24" on center? and what is their span?
 
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james_mcquade

Senior Member
the joists are on 16" centers.
most of the wiring is over a hallway 5 ft wide.
the span over the boys room is 11 ft wall to wall.
our bedroom is 16 ft wide. no wiring in this area and i know i mut be careful in this area.
i must ask, what is furring strips?

thanks in advance,
james
 
Rick Christopherson

Rick Christopherson

Senior Member
I'm not an expert on code, so you should verify this yourself (I'm just a dumb EE :dunce:). To the best of my knowledge, in the attic areas, you just need to protect the wire from damage. I've been told (locally) that if the attic is accessible, then any romex run across the top of the joists has to have a wooden strip run parallel to it to prevent damage from it being stepped on.

If that is correct, you could simply pull the staples to ensure the runs are parallel with the flooring, and then run a single romex line between two decking boards.

If you're going to take the time to drill holes and re-pull the runs, then you may as well drill them low enough to meet the required clearance. However, if you were talking about notching the tops of the joists, and completely covering the wire run with flooring, then even a "hack" like me would use steel plates over the notches. I would not conceal them under a deck board without protection. Some day that paint will wear off, or the next owner won't know why it is there.
 
jxofaltrds

jxofaltrds

Inspector Mike®
Location
Mike P. Columbus Ohio
Occupation
ESI, PI, RBO
If you use a furring strip make sure that it is 1 1/4" away from the edge of the strip. Some (I do not) think that <1 1/4" needs protection.

Protection against protection. LOL
 
gadfly56

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
If by "drill hole near the top" you mean "cut a notch", don't do that. I'm doing this off the top of my head, but IIRC, penetrations through a joist should only be made through the center third of the member, and ideally be symetrical about the long axis. Notching is the same as reducing the depth of the joist, and the load bearing properties of structural members go as the square of the depth. Notch a 2x8 by 2" (assuming full dimension lumber) and you reduce it's load carrying capacity by 50%, not 25%.
 
jxofaltrds

jxofaltrds

Inspector Mike®
Location
Mike P. Columbus Ohio
Occupation
ESI, PI, RBO
Can you install junction boxes then simply staple to the bottom of the roof rafters? You can install the junction boxes under the decking IF they are accessable.
 
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Gregg Harris

Senior Member
Location
Virginia
Occupation
Electrical,HVAC, Technical Trainer
gadfly56 said:
If by "drill hole near the top" you mean "cut a notch", don't do that. I'm doing this off the top of my head, but IIRC, penetrations through a joist should only be made through the center third of the member, and ideally be symetrical about the long axis. Notching is the same as reducing the depth of the joist, and the load bearing properties of structural members go as the square of the depth. Notch a 2x8 by 2" (assuming full dimension lumber) and you reduce it's load carrying capacity by 50%, not 25%.
Click to expand...


IRC 802.7.1 Notches in solid lumber joist, rafters and beams shall not exceed one sixth of the depth of the menber, shall not be longer than one third of the depth of the member and shall not be located in the midle one third of the span. Notches at the ends of the member shall not be one fourth the depth of the members. etc
 
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jeremysterling

Senior Member
Location
Austin, TX
I disagree with most. Forget boring or notching or nailplates and furring strips. Make it easy. Cut the offending wires set a box, reroute the wires around the areas that are going to be covered, set another box. You may have to spend some money on romex, but I think the penny pinchin' route of drilling joists is just not worth the hassle.

Edit to say I agree with jxofaltrds
 
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Ponchik

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
jeremysterling said:
I disagree with most. Forget boring or notching or nailplates and furring strips. Make it easy. Cut the offending wires set a box, reroute the wires around the areas that are going to be covered, set another box. You may have to spend some money on romex, but I think the penny pinchin' route of drilling joists is just not worth the hassle.

Edit to say I agree with jxofaltrds
Click to expand...

But this way you are giving the circuit two more additional points of future failure.
 
M

mlnk

Senior Member
Do not notch beams, joists, rafters. The strength in a joist is in the top and bottom 1 inch of material. Compression on the top, extension on the bottom. Think of a steel "I" beam. The strength is in the top and bottom steel. Boring holes in the center is much better. Splice boxes and re-routing is a good idea. Also, storage boards typically only need a few screws in them so they do not move around. This is not a habitable floor, I hope.
 
R

realolman

Senior Member
jxofaltrds said:
If you use a furring strip make sure that it is 1 1/4" away from the edge of the strip. Some (I do not) think that <1 1/4" needs protection.

Protection against protection. LOL
Click to expand...
Wouldn't it have to be a 2 x 4 since furring strips are only 3/4" thick. I'm not seeing how a furring strip would be any use.
 
augie47

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
If you like, run the furring strips 1-1/4" away from the Romex. There primary job is to keep the flooring from laying on the Romex. As mink mentioned, a dew screws will hold your flooring in place and you should be able to install them at the edge so you can assure you will clear,
 
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