This post is part of the Home network v2 series.

We recently moved the twins into their own bedrooms, after sharing a room for nine years — it was finally time for some privacy 🙂

With their own rooms; they also got their own computers — a life long dream 😉 Those computers needs network, proper network, not Wi-Fi.

Table of contents

The plan

Floor plan 2nd floor

The two rooms, marked with 1 and 2, are separated by an insulated interior wall. My plan was to drill down from the attic, into this wall. And pull conduits between the wall boards and insulation, on both sides. Then terminate the new network outlets in the attic switch I installed earlier.

Even though their desks are by the window; I decided to install the outlets by the door (arrow on the floor plan), because:

  • There is electricity inside the wall by the desk
  • I could use the ventilation duct by the door as a reference when drilling
  • Having the network outlets behind the door means it will never get in the way of any cabinets along the wall


The first challenge was figuring out where to drill, the interior wall is not visible from the attic. Luckily there is a ventilation duct passing through bedroom #1, continuing down to the 1st floor.

I measured the distance between the wall and the duct — 5.5 cm.

Ventilation duct in bedroom #1

Then I drilled a 73 mm hole in the interior wall in bedroom #1, I made sure to have it the same distance from the floor as the rest of the outlets in the room.

Now I was able to measure the thickness of the wall plate, 1.2 cm, and the inner width of the interior wall itself: 10 cm.

Drilled 73 mm hole in wall

Using math; I calculated that the center of the interior wall should be 5.5+1.2+(10/2) = 11.7 cm from the ventilation duct.

My reference duct was on the other side of a ceiling joist, so I used a speed square to transfer the measurement as best I could.

After spending an eternity questioning and checking my measurements — I finally drilled through. I started with a small drill bit, to make sure I didn’t come out in the ceiling, or through a molding.

Everything looked good, so I drilled with a 57 mm hole saw.

57 mm hole saw

After a few centimeters, I got through the first “layer”. Beneath was what looked like a 2"4 — it definitely didn’t look like the underside of the ceiling boards. I concluded it had to be the wall top plate 😎

Partial hole from attic into interior wall

Feeling confident I was in the right place; I drilled through it. And voila! I could see the insulation in the interior wall 🥳

Poking my finger down; I could feel the backside of both wall plates. And my hole was pretty much centered — win! 😎

57 mm hole from attic into interior wall

I put my folding ruler down to check for any fire stops, but I got down 2 meters without hitting anything. Another win 😎

Folding ruler down into interior wall

It was getting late; so I put the insulation back and went down to drill the 73 mm hole in the other bedroom’s interior wall.

Attic, insulation below floor boards

I drilled this hole about 10 cm closer to the door, to avoid the wall boxes conflicting.

Drilled 73 mm hole in wall

I cut into the insulation, making space for the wall boxes. With both holes drilled; light was visible through the insulation.

Holes on both sides of interior wall, light visible through

It’s time for the next step 👇

The conduit

My plan was to push my folding ruler down, between the wall and insulation — and pull up a piece of string to pull the conduit.

It’s important that the conduit gets pulled in the space between the wall and insulation, pulling through the insulation is not possible and could ruin the insulation.

My folding ruler wasn’t long enough to reach all the way from the attic to the 73 mm hole, so I duct-taped a piece of stiff mains cable to it 🙂

Folding ruler with cable duct-taped on

The ruler went down easily — the large 57 mm hole made it possible to guide the ruler down alongside the wall. Once through; I taped on a piece of string.

Folding ruler coming out of hole in interior wall

Time to pull it back up, gently — so nothing falls off 😛

Cable coming out of hole in the attic — into interior wall

I had no problems pulling the string through 👍

String going into hole in interior wall

Now; I repeated the same steps for the other room.

Folding ruler in hole in interior wall

Back in bedroom #1; I drilled two small holes in the conduit, and tied the string through those.

String tied to 20 mm flexible conduit

Then I duct-taped around it, to smooth out the sharp edges — making it easier to pull.

Duct-tape around flexible conduit with string

Everything was ready 🙂 This was a two person job — I was in the attic gently pulling the string, and my father was on the 2nd floor feeding the conduit.

Again the large 57 mm hole came in handy, as I was able to keep the string in parallel with the wall, preventing the conduit getting caught on the insulation.

String tied to conduit — going into hole in interior wall

Once I had pulled enough conduit through, I mounted an ELKO multi box. The multi box has cut-outs for 16 and 20 mm conduit. I’m using 20 mm, as it will fit who CAT6 cables.

ELKO multi box with conduit mounted in interior wall

Both conduits pulled through the wall — and into the attic 😎

Lots of flexible conduit in the attic

The conduits take a 90° turn after coming out of the wall…

Flexible conduits in the attic — with 90° bend

And follows a ceiling joist towards the pitched roof.

Flexible conduits fastened to ceiling joist

Then under a ventilation duct…

Ventilation ducts and flexible conduits, in the attic

Which they follow towards the attic network cabinet.

Ventilation ducts and flexible conduits, in the attic

And then arrive at their final destination. I didn’t fasten the conduits in this end yet, to make it easier to push and pull the CAT6 cable through.

Flexible conduits ending next to attic network cabinet

Now the hard part is basically done; the conduits are going the from attic network cabinet — all the way to the wall boxes in each room. Oh man, that feels like such an accomplishment 🥳

Time for the cables 👇

Pulling the cables

I used two spools of CAT6 cables, taped the ends together, and pushed them through the conduit from the attic.

When pushing, or pulling, cables through conduits; I always do it from the top, letting gravity help the cables down.

CAT6 cables going into flexible conduits — in the attic

In bedroom #2 I was able to push the cables all the way through with no issues.

Two CAT6 cables coming out of ELKO multi box

But in bedroom #1 it got stuck just as it was about to come out of the conduit in the wall box — so I used a fish tape. I was by myself, and the push/pull technique really requires two people. There was a lot of back and forth between the bedroom, and the attic 😛

But I did get it done in the end 🙂

Two CAT6 cables, fastened to fish tape, coming out of ELKO multi box

Now that the CAT6 cables were through, I tightened down the fasteners securing the conduits.

Flexible conduits fastened to ceiling joist

And used expanding foam to fill the 57 mm hole going into the interior wall.

Flexible conduits going into hole filled with expanding foam

I also fastened the conduits by the network cabinet.

Flexible conduits and CAT6 cables by attic network cabinet

As always; I made sure to leave plenty of slack in the cables by the network cabinet. Making it easier to terminate, and service later on.

Flexible conduits and CAT6 cables by attic network cabinet

This was day 2 in the project, and it was getting late. Now; only the home stretch remained 👇


New day, time to finish this networking project 😎

I removed the outer jackets, and mounted the double CAT6 outlet. Luckily the wall box is quite deep, leaving a fair bit of space behind the outlet. Since the CAT6 cables comes into the box at the top — I found it best to turn 180°, leaving them pointing upwards.

Figure showing CAT6 cable routing inside multi box

Due to the depth and size of the wall box; I was able to do this without kinking or putting strain on the CAT6 cables.

Twisted pairs sticking out of double RJ45 outlet

I terminated the lower block first — using a punch down tool. I also made sure to leave the pair twisted as close to the terminal block as possible. 1 cm of untwisted pair is the recommended maximum.

Twisted pairs sticking out of double RJ45 outlet

On the attic site; I used tool-free keystone jacks.

Fitting tool-free keystone jack to CAT6 cables

Voila! Both cables terminated in bedroom #1…

CAT6 cables, terminated in double RJ45 network outlet

And keystone jacks secured in the patch panel in the network cabinet 👍

Patch panel in attic network cabinet

As always; I checked the terminations and length of the cables using my Fluke network tester.

Testing CAT6 with Fluke MicroScanner²

With the front plate installed; the outlet in bedroom #1 is now complete. Time to repeat the process for bedroom #2 👷

ELKO Plus double RJ45 network outlet

I placed the cables inside the wall box, same as before — and removed the outer jackets.

Twisted pairs sticking out of double RJ45 outlet

Punched them down into the terminal blocks — taking care to not untwist more than needed.

CAT6 cables, terminated in double RJ45 network outlet

Checked with my Fluke network tester.

Testing CAT6 with Fluke MicroScanner²

Secured the keystone jacks in the patch panel.

Patch panel in attic network cabinet

And mounted the front plate 😎

ELKO Plus double RJ45 network outlet

Now I have four new CAT6 network runs — two to each bedroom 🎉

Finishing up

The expanding foam had hardened; so I cut off the excess.

Flexible conduits going into hole filled with expanding foam

I cut and placed insulation around and under the conduits as best I could.

Insulation around flexible conduits

Then put the large pieces back. Now the floor boards can be put back as well — and it’s like nothing ever happened 🙂

Attic, insulation below floor boards

There are two additional keystones in the patch panel that I haven’t explained yet. I did another network — to the 2nd floor den, just pretend they aren’t there. I’ll write about those in a future post.

Patch panel and switch in attic network cabinet

Anyway; I patched the new network runs into the attic switch, using 0.5 m patch cables.

Patch panel and switch in attic network cabinet

The small network cabinet, 4U 10", is filling up 🙂

Attic network cabinet — with door closed

Electrons flowing

From the computer in bedroom #1… 👇

Alexander playing Fortnite

Through a 3 m CAT6 patch cable — to new network outlet #1 👇

Patch cable going into network wall outlet, in bedroom #1

And the computer in bedroom #2… 👇

Niklas playing Fortnite

Through a 3 m CAT6 patch cable — to new network outlet #2 👇

Patch cable going into network wall outlet, in bedroom #2

Into 1 Gbit ports on the switch in the attic — then through 20 m 10 Gbit fiber… 👇

Blinkenlights on attic access switch

To the 10 Gbit core switch in the homelab rack 👇

Blinkenlights on homelab core switch

And finally; 10 Gbit DAC cable, into my virtual MikroTik CHR 👇

DAC and Ethernet cable going into hypervisor

Closing thoughts

Of all my network cabling projects — this is probably the one I’ve dreaded the most. I just wasn’t sure it would be possible, and I spent way too long thinking about it — all the things that could go wrong.

I considered a few other options:

  • Going outside, and in through the exterior wall
    • I’d like to keep the cables inside, if possible. And I would have needed a lift to get high enough.
  • Down alongside the ventilation duct
    • But when where to put the network outlets?
  • Through the wall from the adjacent storage rooms
    • The network outlet would end up very far from the computer desk
    • Getting to the storage room by bedroom #2 would have been a pain

The best solution was to go down into the interior wall — as I did. And I am glad I followed through with that plan. I did need a bit of moral support when drilling down into the wall, and luckily my father was with me to provide that ❤️

I’m going to mount a small cable duct between the network outlet and the computers — to prevent the cable getting pulled, and make it a bit more tidy.

Another successful network run completed 🖖

Last commit 2024-04-05, with message: Tag cleanup.

Home network v2 series

  1. Replacing Unifi switches with MikroTik
  2. Getting started with MikroTik CCR1009 and RouterOS
  3. Altibox fiber — straight into Mikrotik CCR1009
  4. Running underground CAT6 to detached garage
  5. Plans for my home network
  6. Running two CAT6 cables to the play room
  7. Running three CAT6 cables to the living room TV bench
  8. Moving CAT6 cable for access point; inside the wall
  9. Altibox fiber — straight into Ubiquiti EdgeRouter
  10. Two CAT6 cables and a fiber — from the basement to the attic
  11. A few Wi-Fi improvements
  12. Updated plans for my home network
  13. Knot Resolver — with ad blocking
  14. Pulling CAT6 cable in existing conduit
  15. Running CAT6 to the twins' rooms — inside interior wall
  16. Running CAT6 to the 2nd floor den — another interior wall