How To Calculate How Much Wire I Need For Pre-Wire

How did you guys figure out how much wire (CAT 6, etc.) you needed before a DIY job? Obviously I could calculate the exact number of drops x each length but hoped someone had an easier method (e.g. Based on sq foot or number of rooms)

Nope, you get out your plans, make note of the scale on the drawings and start planning the wiring routes with your ruler.
 
It's important to recognize there's going to be stuff in the way, or things you have to route around.  HVAC, plumbing, line voltage, etc.  There's a lot of up, across, over, down, around lengths involved.  That and if you've got a wall where you might want the outlets to be higher or lower (like a TV put up on a wall) you might want to arrange leaving some extra length in the wall.  Low voltage mud rings do make it a little easier to get back in there to snip the zipties used to hold things in place for inspections.
 
And don't plan on 'saving' any money by putting in less wire.  If anything, put in more.  Because putting wire in while the walls are open is CHEAP compared to the hassle/expense of doing it after the fact.  
 
That said, I did make use of a spreadsheet to help tally everything.  Rooms, outlets in them, keystones & wall plates needed, etc.  Along with distances for each and then a count of how many cables (3 CAT6, 2 coax, for most).  Then there's whole house audio.  
 
Given most installs are unique it'd be hard to come up with a standardized approach.  I'm sure pro-installers have some spitballed numbers they work with, but eventually it boils down to just planning it out manually.

Personally here and there over purchased multiple 1000 foot spools of whatever I needed. 
 
I did purchase more than what I needed.  IE: catxx, 22/2, 22/4, speaker 16/4, 16/2 (more expensive than catxx).
 
While helping a friend with his new home build we did create a chase of sorts in the middle of the home that went from his basement com closet to the attic of the two story home in vivo. 
 
Friend initially created / purchased the drawings, modded them over a period of time with an archectect/main contractor.
 
The main contractor built only what he specified in the drawings.   (it did cause issues - but it was going to happen this way or not happen at all).
 
Wood trim stuff was subcontracted separately along with wood floors and tile floors and main fireplace (all separate). 
 
Main plumbing was done by 3 separate entities working together.  Electric was a done by a guru electrician as well as the HVAC stuff.  
 
We over wired a bit on the 2nd floor (4 bedrooms and 3 bathrooms  - all with in wall speaker sound) and never ran out of wire.  Friend's son helped a bunch climbing open ceiling rafters and pulling wire (well over 20 feet over the main floor of the home). 
 
Note that the above mentioned endeavor took 3 years but there was really no rush.

My 1700 sqft house has swallowed over 5000 feet of Cat5e/cat6 over the years. Plus 1-2K of 22/4, 1K of 18/4, and too much RG6/18/2 (when I did CCTV) to admit.  I may have a problem.
 
If your walls are open, just go get 2K of cat5e or cat6 (i'm not getting into that debate), start putting it in, and if you run out go to home depot and spend way too much on more. Lather, rinse, repeat.
 
The question isn't "how much wire do I need", its "how many runs per room". 4 cat5e/6, 2 18/2, 2 22/4 at the bare minimum. I also ran speaker wire to every room.

More like a buy a box/spool/put up for a 2:1 or 3:1 ratio. Plan out your largest pull and most number and buy enough to do that in 1 or 2 pulls. The effort in doing that more than pays for the material. I usually like to have a single box/spool for each device on a pull (area, room, floor, etc.)
 
Yes, you can go anal with the amount you're pulling based on prints, but usually the routing and service loops, waste, what have you, in a real world situation can't really be calculated unless you plan at least a 20%, but more like 25-30% overage on your footage calculations.
 
Wire is cheap (in the scheme of things). Labor and running out mid pull are not.

DELInstallations said:

Wire is cheap (in the scheme of things). Labor and running out mid pull are not.

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Don't forget Amazon Prime for last minute purchases.  I'm certain my overnight shipments of spools of wire will never break even for them.

Personally here helping friend with his new home prewire only took two days or so. 
 
Home is ~ 6000 sf and the house he was living in was only around 300 feet away.
 
The dings were that it was in the middle of the summer and it was warm (~90 or so outside) and there was no ventilation of any sorts in the new home.  His son (degree in Physics and likes to play computer games even at ~ 27 today) helped us a bunch on the first day.  Second day I disconnected the internet to motivate his son a bit.  By the end of the second day old friend kept asking if we needed that much wire. 
 
We did finish with the LV cabling. 
 
Kids are no longer living in the home and my friend and his wife are the only ones living in the home. 
 
He did want sound / music in every room of the house.  Thing is that him / wife only use the great room and the master bedroom today and rarely venture to different parts of the home (must be an age thing).
 
80% of the cabling is not terminated today and probably never will be as friend is fine just watching you tube videos on his cell phone or just falls asleep at the end of the day watching satellite television (more just noise today).

Last year I pulled 5 miles of wire in my 4000 sf home under construction.   It was my first attempt at this kind of thing.   Here are a few of my lessons learned:
 
1) install your cans and chases first.  I used 6-42 inch cans and 3-28 inch cans.   Probably a bit of overkill, but I have the room in my closet.
2) I built chases to the far ends of the house out of Platinum tools J-hooks.   I tried several types of J-hooks and these seemed to work the best.   I used a combination of 2 inch and 3 inch.
3) run conduit to the areas of the house that you will not be able to get to in the future, and leave it empty for the things you forgot.   I am already planning on what I am going to use these conduits for.
4) Pulling wire in 100 degree Texas heat is hard work.   I averaged 12 runs per day (just me with a little help from the wife) for a total of over 400 runs.   That sounds really slow, but imagine yourself crawling through an attic for 5 miles pulling wires and drilling holes along the way.
5) Get a nice cordless drill and various sizes of nail eater auger bits to drill through studs.   I used a Makita LXT drill and it worked great.
6) I bought a hole saw kit and a heavy duty Dewalt drill that has a clutch that will disengage when the hole saw inevitably locks up.   I think this drill kept me from breaking my arm.   I thought I was pretty smart until I saw a plumber using a 2 inch self feed drill bit.   Those things work much better than a hole saw, however you must watch out for nails.
7) I bought a lot of extra wire because it is cheap compared to the labor.   Especially the 22/2 and 22/4 wire. I also found that having multiple boxes makes the pulling easier.   I was able to tape a bundle of wires together and pull up to 10 runs at a time because I had 10 boxes to pull from.
8) A dirty secret is that cat 6 wire is much stiffer and about twice the volume of cat 5 wire.   It only costs about 10% more, but it fills up your conduit and J-hooks fast.   I ran a combination of cat 6 and cat 5.   I switched to cat 5 on some items mainly because it was a lot easier to run.   Time will tell if that was a good decision.
9) In answer to your OP, I put together a spreadsheet detailing each run with the length, type of wire, and end terminations.  Then I added at least one box to each size of wire.
10) I used a fine point sharpie to label my wires.   I was suprised how well it worked.   Even on the thin 22/2 wire.
11) I ran 22/2 to each window in the house.   I am not sure that I would do that again.   I think I would run one wire to each room, and then daisy chain the wires to all the window sensors.

Yup; here and there I use what I personally installed related to LV cabling. 
 
Here installed a bit at a time and was privy to having a large attic, large chase between the basement and the attic and an unfinished basement.
 
There prewired and terminated as I needed or wanted the stuff.  An alarm company did the prewire for me and I am using it (all windows et al stuff).  
 
I connected it all to the OmniPro II panel that I installed and today still wonder if I needed to do this stuff.

pete_c said:

Personally here helping friend with his new home prewire only took two days or so. 
 
Home is ~ 6000 sf and the house he was living in was only around 300 feet away.
 

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Do you recall how much cable (catx) you pulled in that 6,000 sq foot home? 10,000 linear feet?

 Do you recall how much cable (catx) you pulled in that 6,000 sq foot home? 10,000 linear feet?

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No.  I just remember friend complaining about the need of 1000 foot spools of many different types of cables.
 
I had alloted a time frame to do the stuff and completion of the home.  I have known friend for 30 years and quit listening to his questions about something he didn't know about.  Well and 3 years to build a home was a bit more than I had ever seen before.  I didn't order any cable / LV cans et al until I looked at the unfinished home.   Most important was one chase from the basement to the attic and the chase ended up being above the designated com closet.
 
I did run chases in the basement to the first floor and attic down to the second floor.  Basement was a PITA because of the high ceilings.
 
That said I believe the leftover cables are still sitting in his basement (that he will probably never finish or use) and I do somewhere have copies of the invoices for all of the cabling as he paid for it and I was tracking the costs.  I will look.

I said to my wife, I'd have been able to be the GC on our house.  We'd have saved quite a lot of money.  But it also would have taken at least two years (instead of one) and we'd likely have gotten divorced due to the stress.  So, yeah, it was worth paying someone else to 'ride herd' on the process and know the subs.
 
High ceilings are indeed some added work.  I now own a 8' Werner electrician's ladder as a result.  Rickety aluminum painters ladder just wasn't tall nor sturdy enough for the task.  Upside was having drop-in slots on the top of it to hold their job buckets and hooks for tools.
 
I did not keep track of how much cable I used.  I don't want to know.  I'll say this, do not order only large spools.  When you're pulling several runs at once it helps to be able to pull from multiple boxes.  I went so far as to make a jig to hold the spools together in a row.  Made it much easier to pull 3 CAT5 and a duplexed RG6 all at once.  

.....and we'd likely have gotten divorced due to the stress.....

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Well a bit more relating to the above 3 year home build...a couple of years now later....per last dialog....last conversation ...."kids are gone" and I have nothing more to do ...from one side...."waiting to see who dies first"....from the other side...stress took 5 years of fermenting (not relating to food)....(3 years to build plus 2 years after build)....this is told to me and basically I do not want to know about it...as it is the beginning of taking sides which I also want no part of.

pete_c said:

Personally here helping friend with his new home prewire only took two days or so. 
 
Home is ~ 6000 sf and the house he was living in was only around 300 feet away.
 
The dings were that it was in the middle of the summer and it was warm (~90 or so outside) and there was no ventilation of any sorts in the new home.  His son (degree in Physics and likes to play computer games even at ~ 27 today) helped us a bunch on the first day.  Second day I disconnected the internet to motivate his son a bit.  By the end of the second day old friend kept asking if we needed that much wire. 
 
We did finish with the LV cabling. 
 
Kids are no longer living in the home and my friend and his wife are the only ones living in the home. 
 
He did want sound / music in every room of the house.  Thing is that him / wife only use the great room and the master bedroom today and rarely venture to different parts of the home (must be an age thing).
 
80% of the cabling is not terminated today and probably never will be as friend is fine just watching you tube videos on his cell phone or just falls asleep at the end of the day watching satellite television (more just noise today).

Click to expand...

 
On discussing the backyard and positioning of a swingset, my architect's comment was "those are temporary".  Essentially putting the kibosh on integrating it with the plans.  Hmmm, well, isn't everything in life temporary then?  
 
There's absolutely something to be said for avoiding wasted time & materials putting in things that'll never get used.  There's also something to be said for doing it anyway because it's a whole heck of a lot cheaper and easier, even if it doesn't get used.
 
For us it was a matter of the space literally never existing before (custom plans) and thus we couldn't really 'guess' just how much would or wouldn't be used.  But I really put a lot of time into thinking about how the space was truly going to get utilized.  Most of the RG6 coax pairs will definitely not get used.  But in two bedrooms my wiring of more than one location turned out to be a wise choice, as the furniture placement that looked good on paper wasn't ideal (due mainly to morning sun).   The whole house audio has yet to get installed (lack of round tuits) and we're not missing it as much as I would have expected.  Sonos and now Amazon Echo handles quite a lot more than I figured.  That and a very open floorplan with wood flooring lets music carry quite a lot more than I would have guessed. 

Yup; friend asked me to wire up his new home such that he could do in his new home what I have done in my home.
 
I did.
 
My wife has a friend who wanted to automate similarly to what was in this home.  She built a very large home (way to big for herself to live in).  She went with Control 4 and wasn't a happy camper for a couple of years.  Not really sure if it was related to her expectations or lack of a knowledge base.
 
Here we put a wall mounted LCD TV in the kitchen nook a few years back.  It was never on or used until recently.    Turned it on in the last few days such that the parrot can watch television and I noticed that she is watching television.