In wall or conduit?

VietGnome · Apr 28, 2026

Hey all,

I'm planning my 30x40x12 stick build.

I'm leaning towards metal ceiling and walls. I was originally planning on running electrical in walls, but I'm seeing lots of builds using conduit or emt throughout.

Looking for some pros/cons? I'm sure the conduit is nice since it's easy to get at, and might make runs easier. But obviously more time/work and money.

Unfortunately due to cost I was also planning on building the structure, doing electrical, and insulating/finishing the interior and heating next spring/summer.

I assume there isnt really a way for me to run conduit then insulate and add metal after the fact? I'll need to finish the walls before?

Thanks!

LopezBart · Apr 28, 2026

Conduit really needs to go on inside finished wall/ceiling surfaces, so insulation and wall covering comes first. Note that insulation contractors can often get better pricing on insulation (apparently) than is readily available to DIY folks. They're also much faster putting it in, so it may be worth having that done.

VietGnome · Apr 28, 2026

LopezBart said:
Conduit really needs to go on inside finished wall/ceiling surfaces, so insulation and wall covering comes first. Note that insulation contractors can often get better pricing on insulation (apparently) than is readily available to DIY folks. They're also much faster putting it in, so it may be worth having that done.

I'm talking about the exterior wall mounted. Is that only done with EMT then?

The insulation isn't that expensive. I'm nearly certain I could DIY it for cheaper than installed. it's the metal that costs a pretty penny.

LopezBart · Apr 28, 2026

I guess I'm confused. I thought we were talking about the wiring for the inside of the shop - receptacles, lights, etc. EMT isn't that great for corrosion esp. near the ocean; outside wiring I'd put in PVC.

dcg9381 · Apr 28, 2026

VietGnome said:
Unfortunately due to cost I was also planning on building the structure, doing electrical, and insulating/finishing the interior and heating next spring/summer.

You've got stick build, so you can do all that. Walls go up last.

VietGnome said:
I assume there isnt really a way for me to run conduit then insulate and add metal after the fact? I'll need to finish the walls before?

You could install conduit behind the walls for future use, but no real way to surface mount it without the surface...
Consider that if you do standard "R-panel" metal walls, the offsets can make running conduit a little more difficult.

How about doing both? Run what you need right now behind the walls, put in some drops for conduit that you can pull later?

VietGnome · Apr 29, 2026

dcg9381 said:
You've got stick build, so you can do all that. Walls go up last.

You could install conduit behind the walls for future use, but no real way to surface mount it without the surface...
Consider that if you do standard "R-panel" metal walls, the offsets can make running conduit a little more difficult.

How about doing both? Run what you need right now behind the walls, put in some drops for conduit that you can pull later?

VietGnome said:
I'm talking about the exterior wall mounted. Is that only done with EMT then?

The insulation isn't that expensive. I'm nearly certain I could DIY it for cheaper than installed. it's the metal that costs a pretty penny.

I think theres some confusion. Im talking about the interior of the building, but mounting on the inside of the wall panels. My main concern with flush mounting is/was you would need to layout the boxes perfectly so they don't land on a raised part of the metal panel.

So I thought of doing metal EMT and surface mounted boxes on the interior. The conclusion I've ran to with that, is EMT is stupid expensive.

I'm thinking that my options are as follows

1. Get the exact measurements of my panel and mark it out, install flush mount boxes as normal, but ensure all their placements will not land on a raised rib. Run all wires as normal through wall.

This feels ideal since I can rough in/do all electrical, then insulate/finish down the road as planned.

2. Install a 2x4 blocking at outlet height in outlet stud bays, rough in electrical in wall, surface mount 4x4 boxes to the blocking, run wire though hole in metal into the back of the box. If that makes sense.

I feel this would require metal to be up before finishing.

3. Finish interior complete and run electrical through surface mounted EMT. I think it looks clean but requires total interior finishing first, and is hands down most expensive.

Edit: I can attach photos if I'm not making sense

Last option is to do metal roof and just do OSB walls making the bulk of wiring much easier.

OccupantRJ · Apr 29, 2026

If you mount a cross piece of framing between the studs you can mount boxes now and relocate them later right or left as needed to miss the raised portions of the metal. I did this for overhead hose and cord reels in the trusses of the shop to later allow for a metal ceiling to

insure being able to land on the flats of the metal.

VietGnome · Apr 29, 2026

OccupantRJ said:
If you mount a cross piece of framing between the studs you can mount boxes now and relocate them later right or left as needed to miss the raised portions of the metal. I did this for overhead hose and cord reels in the trusses of the shop to later allow for a metal ceiling to insure being able to land on the flats of the metal.

Thanks! I think i kind of thought of that as an option. In that case I would just have to leave slack in the wiring, remove the box, pull the wire/unhook the fixture, cut a small hole in the metal, repull wire, and mount the box where I want?

OccupantRJ · Apr 29, 2026

VietGnome said:
Thanks! I think i kind of thought of that as an option. In that case I would just have to leave slack in the wiring, remove the box, pull the wire/unhook the fixture, cut a small hole in the metal, repull wire, and mount the box where I want?

Just mount the box with screws through the rear. When needed to move, simply remove receptacle or switch, leave wires attached, relocate box, reinstall device into place. Staple cable in place on the framing as required by code. The small rib roofing metal panels are usually on 9” rib centers in my area.

OccupantRJ · Apr 29, 2026

Also look up an old work box if you are not familiar with them. They can be very handy at times after walls are already in place.

VietGnome · Apr 29, 2026

OccupantRJ said:
Just mount the box with screws through the rear. When needed to move, simply remove receptacle or switch, leave wires attached, relocate box, reinstall device into place. Staple cable in place on the framing as required by code. The small rib roofing metal panels are usually on 9” rib centers in my area.

Ah I understand now, and as im putting up metal just cut it to fit around the box?

cannuck · Apr 29, 2026

One thing we can say for sure: once you get shop up and running you will want to add circuits or move receptacles so surface mount is way to go. That said, you could plan your temporary power as other posts have identified but jut give in to the idea you are going to pull it all apart to do insulation and skin. Would suggest that you completely finish the section where your service entrance and distribution panel are mounted as that will make things much simpler next year. In an extreme version: use a temporary distribution skid this year - the kind used in most construction sites so they can usually be found at industrial auctions pretty cheap.

SouthernIllinois · Apr 29, 2026

Big fan of surface mounted electric in EMT.
I have already added outlets as needed.

VietGnome · Apr 29, 2026

cannuck said:
One thing we can say for sure: once you get shop up and running you will want to add circuits or move receptacles so surface mount is way to go. That said, you could plan your temporary power as other posts have identified but jut give in to the idea you are going to pull it all apart to do insulation and skin. Would suggest that you completely finish the section where your service entrance and distribution panel are mounted as that will make things much simpler next year. In an extreme version: use a temporary distribution skid this year - the kind used in most construction sites so they can usually be found at industrial auctions pretty cheap.

I mean interesting! But I don't know if I'll want to change too much to be honest. I have a pretty indepth plan that will have me quite future proofed, I don't know what else I would need.

VietGnome · Apr 29, 2026

SouthernIllinois said:
Big fan of surface mounted electric in EMT.
I have already added outlets as needed.

What size EMT did you use?

I really like the look of this, however I have a hard time justifying the cost when a 10' section of 3/4 EMT is $27, and I have a lot of circuits planned.

MovingAlong · Apr 29, 2026

VietGnome said:
I mean interesting! But I don't know if I'll want to change too much to be honest. I have a pretty indepth plan that will have me quite future proofed, I don't know what else I would need.

I like your optimism!

Conduit allows for easy reconfiguration. Your purpose may change (new hobbies), your health may change (hard to reach high or hard to reach low), tools you acquire in the future may connect differently than the tools you own now (110 vs 220, twist locks, etc..).

And if you put up a run of conduit before the wall finishes, that's fine. Leave yourself a section of flex at the beginning of the run. When it's time to finish the walls, pull the conduit off and swing it out of the way. Don't even need to power it down if done right... Once the walls are up, reattach to the face of the wall and get back to work.

MovingAlong · Apr 29, 2026

VietGnome said:
What size EMT did you use?

I really like the look of this, however I have a hard time justifying the cost when a 10' section of 3/4 EMT is $27, and I have a lot of circuits planned.

It's a different look, but do they allow the gray pvc piping where you're at? Might be a cheaper option..

VietGnome · Apr 29, 2026

MovingAlong said:
I like your optimism!

Conduit allows for easy reconfiguration. Your purpose may change (new hobbies), your health may change (hard to reach high or hard to reach low), tools you acquire in the future may connect differently than the tools you own now (110 vs 220, twist locks, etc..).

And if you put up a run of conduit before the wall finishes, that's fine. Leave yourself a section of flex at the beginning of the run. When it's time to finish the walls, pull the conduit off and swing it out of the way. Don't even need to power it down if done right... Once the walls are up, reattach to the face of the wall and get back to work.

I mean FWIW I am planning 24 outlets, and 240 outlets for a welder, lift, and EV charger i don't have yet, but I get what you're saying.

The concept of starting a run with flex is actually a very interesting idea.

Finishing the garage first is $10k in materials I just won't have right away, especially if i spend whatever it costs for EMT. Knowing I can attach it to the studs then just slide metal in behind it later makes it more enticing.

VietGnome · Apr 29, 2026

MovingAlong said:
It's a different look, but do they allow the gray pvc piping where you're at? Might be a cheaper option..

It's less than half the price, but I may look into it.

William Payne · Apr 29, 2026

In a house it doesn’t matter but in a shop I am a big surface mount fan. i never want to have to cut into walls or remove boards to change or fix something. Surface mount it’s just a matter of unscrewing it and then putting it back on.

cannuck · Apr 29, 2026

VietGnome said:
It's less than half the price, but I may look into it.

Not sure what code allows today, but when I did my EMT installations 42 years ago the EMT was the ground conductor, so cheaper wire. I also set most receptacle stations up with 240 in, splitting up to a pair of 120s at each combined location, saved a lot of wire, but no idea if still allowable under current code. Another thing to think about is how long you expect to be using this shop. I just used whatever panel and breakers available, not realizing that 4 decades later no longer supported. Ask a friendly electrician or supplier what the latest, greatest, most likely long term brand is.

JohnX14 · Apr 29, 2026

If you're intent is to get the shop up and running now, and install the metal interior panels in the future, I'd wire everything with romex, "in-wall". Wire the 120v outlets, lighting outlets, the lift, and EV now. Put up metal panels when time and budget allows and then run EMT for whatever you add in the future. If you were installing the metal panels now, I'd pipe everything with EMT now and not do anything in-wall. (Well I'd do network and other low voltage in the wall)

@SouthernIllinois - that shop looks great.

The nice part of surface mounting everything as SI did, is that you can start with a few basics and add. You have a few ways to approach this. I will say this. If there is any way to do the interior panels now, it will save you so much time. It ***** doing so after the shop is up and running.

PCustoms · Apr 29, 2026

VietGnome said:
What size EMT did you use?

I really like the look of this, however I have a hard time justifying the cost when a 10' section of 3/4 EMT is $27, and I have a lot of circuits planned.

3/4 emt holds a LOT of wire. Map out your you plan/circuits, count the conductors and look at a fill chart to see.

Also, it's $10.47 around here. Where the hell are you getting $27?

VietGnome · Apr 29, 2026

JohnX14 said:
If you're intent is to get the shop up and running now, and install the metal interior panels in the future, I'd wire everything with romex, "in-wall". Wire the 120v outlets, lighting outlets, the lift, and EV now. Put up metal panels when time and budget allows and then run EMT for whatever you add in the future. If you were installing the metal panels now, I'd pipe everything with EMT now and not do anything in-wall. (Well I'd do network and other low voltage in the wall)

@SouthernIllinois - that shop looks great.

The nice part of surface mounting everything as SI did, is that you can start with a few basics and add. You have a few ways to approach this. I will say this. If there is any way to do the interior panels now, it will save you so much time. It ***** doing so after the shop is up and running.

I should mention I haven't even started building, I'm building this summer. I also don't have an EV, or welder, or lift. So I suppose surface mounting would really allow me to cut back on the "do all electrical now" approach and add as I go.

I appreciate what you're saying about doing walls now vs later and agree. I'll reapproach my plans and see if maybe it's feasible.

PCustoms said:
3/4 emt holds a LOT of wire. Map out your you plan/circuits, count the conductors and look at a fill chart to see.

Also, it's $10.47 around here. Where the hell are you getting $27?

Very fair, I can probably get away with 1/2 in cases. I was just anticipating for multiple runs of 12/2, and things like 6/3 for bigger circuits down the road.

I'll reach out to some local construction distributors and see (their wire prices were much better) but everywhere (Homedepot, Kent, Rona) all have it priced at $26.99 CAD (19.74 USD). Makes me wonder what else I'm getting screwed on.

Though I can scan Facebook and see if I can find a deal on marketplace.

mm08822 · Apr 30, 2026

VietGnome said:
I should mention I haven't even started building, I'm building this summer. I also don't have an EV, or welder, or lift. So I suppose surface mounting would really allow me to cut back on the "do all electrical now" approach and add as I go.

I appreciate what you're saying about doing walls now vs later and agree. I'll reapproach my plans and see if maybe it's feasible.

Very fair, I can probably get away with 1/2 in cases. I was just anticipating for multiple runs of 12/2, and things like 6/3 for bigger circuits down the road.

I'll reach out to some local construction distributors and see (their wire prices were much better) but everywhere (Homedepot, Kent, Rona) all have it priced at $26.99 CAD (19.74 USD). Makes me wonder what else I'm getting screwed on.

Though I can scan Facebook and see if I can find a deal on marketplace.

Regardless of conduit size, the number of current carrying conductors causes a derating of permitted ampacity IN THE NEC.
So you need to have forethought of what/how much is going into it.

Point being, a singular conduit is not always the answer. Secondly, box fill needs to be considered for these conductors just passing through any box.

I'm sure CEC has similar constraints.

VietGnome · Apr 30, 2026

mm08822 said:
Regardless of conduit size, the number of current carrying conductors causes a derating of permitted ampacity IN THE NEC.
So you need to have forethought of what/how much is going into it.

Point being, a singular conduit is not always the answer. Secondly, box fill needs to be considered for these conductors just passing through any box.

I'm sure CEC has similar constraints.

It sure does. Ill need to verify everything again for conduit, but I had that all somewhat accounted for when I was thinking of in wall.

All my 240v circuits would be in their own run, and i shouldn't have more than two 120v circuits in a run.

SouthernIllinois · Apr 30, 2026

VietGnome said:
What size EMT did you use?

I really like the look of this, however I have a hard time justifying the cost when a 10' section of 3/4 EMT is $27, and I have a lot of circuits planned.

1/2" and 3/4" depending on what all I was running in it.

Mostly 1/2"

EMT here at Menards in central/southern Illinois is $6 (1/2") and $10 ($3/4") a 10' stick.

cannuck · Apr 30, 2026

SouthernIllinois said:
1/2" and 3/4" depending on what all I was running in it.

Mostly 1/2"

EMT here at Menards in central/southern Illinois is $6 (1/2") and $10 ($3/4") a 10' stick.

Without getting all political about it: this is a good display of why it costs so much more to do the same thing North of 49 as GJ members do in their South-of-49 back yard. Almost everything here has one or two added layers of markup for importer and distributor(s) plus we have only one VERY long road coast to coast so transportation costs are incredible. Also doesn't help that our money is near worthless.

txvwnut · Apr 30, 2026

I vote for wiring in the walls, you'll spend less on materials and the install will look cleaner.

dscheidt · Apr 30, 2026

VietGnome said:
I'll reach out to some local construction distributors and see (their wire prices were much better) but everywhere (Homedepot, Kent, Rona) all have it priced at $26.99 CAD (19.74 USD). Makes me wonder what else I'm getting screwed on.

Transportation is a big part of the price of conduit. It's heavy, it doesn't fit in boxes, etc. I'm not sure where you are in 'Atlantic Canada', but it's possible if you go to a big city, it'll be cheaper. You'd have to transport it yourself, of couse, so it might not be any real savings. Around here, the box stores often have the best prices on things like conduit, at least for small quantities, because they get it by the (literal) truckload, and supply houses don't.

KenC · May 9, 2026

VietGnome said:
What size EMT did you use?

I really like the look of this, however I have a hard time justifying the cost when a 10' section of 3/4 EMT is $27, and I have a lot of circuits planned.

Wow! Local lowes has it at 9.98 for 10'. Even considering Canadian dollar to USD that's a huge difference.

VietGnome · May 10, 2026

KenC said:
Wow! Local lowes has it at 9.98 for 10'. Even considering Canadian dollar to USD that's a huge difference.

I made some phone calls and a few local electrical/construction places have it for around or just under $8/stick. *phew*

alfredeneuman · May 11, 2026

You could use flexible metal conduit in the walls, and switch to surface mounted EMT, with these, for an easier (and neater installation).>>

https://www.homedepot.com/p/4-in-21-cu-in-Steel-Pre-Galvanized-Square-Box-Extension-Ring-531511234UB-25R-531511234UB-25R/206166716

It attaches to the flush box's plaster ring, or a switch box.
The best of both worlds

In wall or conduit?

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