Shed -> Office Conversion: Insulation?

[Ferrino]

I have a 12'x10' shed in my back yard (SoCal), which I would like to convert into an office. I would like to finish the interior with drywall and cool/heat with a small mini-split A/C system. I'm clueless about how to insulate it for sound and keeping cool.

It's already powered, with Romex feeding through the stud bays. It's not on a concrete pad - just treated lumber and pavers. Typical 2x4 construction. The outer walls are simply a single sheet of 0.315" thick wooden panels which also serve as the siding (not sure what the name of this is). The roof is "cathedral style" and is composed of sheets of 0.418" sheathing, with shingles on top. There is currently a single vent at the top of one of the walls. There is no form of moisture barrier anywhere that I can see.

I'm looking for advice on how to insulate the stud bays of both the walls and roof, before I cover with drywall. I have no idea what's needed. I'd like it to be as acoustically insulated as possible. A source of confusion for me is how to insulate the roof. I would prefer to retain the "cathedral style" ceiling (rather than adding joists and having an attice space). But I read about the need for ventilation. There are no eaves/soffits on my roof at all (this was done because 12x10 is at the limit before a permit is required and apparently they include eaves in the surface area!). Do I really need to make a ventilated attic in this small shed (gabel style vents)?

I'd also love to hear if you think I need to insulate the flooring? I believe the floor is 3/4" thick.

Thanks so much for your help!

https://imgur.com/EariM30

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[Stuart in MN]

Rock wool batts are generally considered to provide more sound insulation but they are more expensive than fiberglass batts, so you'll have to look at your budget. For additional sound insulation, look at resilient channels - they're a piece of plastic that fastens to the studs and then the drywall fastens to them, to provide a way of decoupling the drywall from the wall or ceiling system. Note that the window will be a source of sound transmission as well; double insulated glass will help but replacing the window is another budget consideration. It is possible to insulate the roof directly underneath the roof sheathing so you maintain the vaulted ceiling, do a little research on 'hot roofs'. Of course if you do it that way, that ventilation louver in the third photo will have to be blocked off. Insulating the floor is always a good idea, but since you're in San Diego it's not going to be that important.

 

[Ferrino]

Rock wool batts are generally considered to provide more sound insulation but they are more expensive than fiberglass batts, so you'll have to look at your budget. For additional sound insulation, look at resilient channels - they're a piece of plastic that fastens to the studs and then the drywall fastens to them, to provide a way of decoupling the drywall from the wall or ceiling system. Note that the window will be a source of sound transmission as well; double insulated glass will help but replacing the window is another budget consideration. It is possible to insulate the roof directly underneath the roof sheathing so you maintain the vaulted ceiling, do a little research on 'hot roofs'. Of course if you do it that way, that ventilation louver in the third photo will have to be blocked off. Insulating the floor is always a good idea, but since you're in San Diego it's not going to be that important.

Stuart - thanks so much for your reply. I'm glad to hear that I can get away with an unvented "hot roof" and preserve the vaulted ceiling! In that case, would I use the same rock wool insulation on both the roof and the walls? I will look into the decoupling channels too.

Question about patching holes in the vertical sheathing/siding (for example, when I remove the vent that you pointed out). What's the best way to do this, to prevent water ingress? Would I bond/caulk a blanking plate from the inside and the outside?

 

[no704]

Window shaker is plenty for that.

 

[bluedog225]

San Diego is not that hot. I would put in a ceiling, cover it with cellulose or fiberglass. Put a vent at each end. You already have one.

put whatever on the walls for insulation. Probably fiberglass. sheetrock. Window unit. Done.

spend as little as you can to get the job done. It’s never going to be more than it is. And that’s ok.

You will end up with a little insulated sheet rocked room. The window unit will provide “white” noise” to help with outside sounds.

 

[bluedog225]

Duplicate deleted

 

[mike93lx]

Unrelated to the insulation, but I hope that isn't romex feeding the shed from the house. It's not allowed outdoors.

 

[Dig Doug]

Figure out your mini split AC & lighting/ ceiling fan What ever you want for electrical

Then call around for a drywal quote you can have the drywall guy insulate it (included in his bid ) before hanging drywall.

or
swing by depot and get a bag or 2 of R-13 - count out how many stud bays and are they 16 or 24 on center

This bag has 11 batts of 15 wide x 93 long, unfold the paper edges and staple onto the stud edge to hold it in place
wear a mask, long sleeve shirt lay the batt down and cut with a straight edge & razor knife for the size you need.

I would try to keep the vaulted ceiling for a spacious open feel

 

[Dig Doug]

As for a flooring I would go w/ a LVP - Luxury Vinyl Plank 20 mil wear and waterproof - Floor and Decore return unused material before 90 days


BIG D @Miramar Rd
add a underlayment pad see pics below the flooring - I got a roll of 2 mil rubber padding $150 at Big D’s on Miramar road. Softens the feel and sound - doesn’t sound hallow or echo

 

[Dig Doug]

Run gutters / down spouts and direct rain / water away from the shed to a area drain.

You don’t want moisture under the shed.

 

[cvairwerks]

Fix the roof leak first......

 

[Dig Doug]

Not sure where you are in San Diego area if more coastal you could go w/ a 9k mini split

if more inland I’d go 12k

My friend has the Ductless Air in his garage and it’s been excellent!

he also had a pioneer 9k in his shed / office and never had an issue.

 

[CraigStu]

You can keep your roof/ceiling if you like. There are 2 theories on overall insulation. One is the attic is separated from the house. It is vented w/ soffit inlets and roof vent outlet (or similar) and the attic floor is insulated very, very well to keep the cold or heat from the house. Advantage here is that you don't spend the $ heating or cooling the attic space. The higher the roof peak is the more important that becomes. The other theory is the attic space is part of the heated/cooled house. So tons of insulation under the roof but none or very little on the attic floor. Of course you spend the $ to condition the attic. In your shed make the whole thing one conditioned space. Since the peak is so low, the added volume that you need to condition doesn't ad much to your costs. I really like rock wool insulation. The bats are very firm so you may want to slice them where they fit over the romex. For me the huge advantage is much less itching after install. I will let others recommend roof insulation since I have no experience w/ that. Your air vent I would leave as is and just glue/tape some plastic over the inside to shut off air flow. A caution; I may have missed it but have you checked on whether code will allow a shed to be turned into a office/living space? Often code requirements for an office will be way more stringent than for a shed so I'd check into that before I did anything.

 

[Ferrino]

Fix the roof leak first......

What makes you think there’s a leak?

 

[Ferrino]

Not sure where you are in San Diego area if more coastal you could go w/ a 9k mini split

if more inland I’d go 12k

My friend has the Ductless Air in his garage and it’s been excellent!

he also had a pioneer 9k in his shed / office and never had an issue.

I agree that a 9K mini split would be sufficient. How are folks DIY-ing these installs (for the units that don’t come with pre-charged lines, like Mr Cool)? Are they buying the tools to pull vacuum and flare lines or can I pay someone to come out and do that once the hardware is all in place?

 

[cvairwerks]

What makes you think there’s a leak?

The photo marked 271 shows evidence of the osb having been wet. The color change is below the vent and up around the peak of the roofline.

 

[Dig Doug]

I agree that a 9K mini split would be sufficient. How are folks DIY-ing these installs (for the units that don’t come with pre-charged lines, like Mr Cool)? Are they buying the tools to pull vacuum and flare lines or can I pay someone to come out and do that once the hardware is all in place?

You can pay a HVAC company, might want to have your other system checked while they are out installing the mini. Talk to neighbors / network to see who they use and are happy with. You can do some of it yourself get a buddy / friend to help. Watch a few u tube vids to decide.

The idea ( for me is to ) to create a relationship for when you have an issue.


Years ago I had a problem when I was out of town, wife was like - fix it now! She was working from home during a heatwave ….

I spent over $400 for a capacitor replacement

but
wife was Happy = Priceless !!

 

[CraigStu]

Agree. I bet if you check local people selling mini-splits there are a few who would be glad to sell you a unit, let you install it, and then come charge it. Might cost a little more than buying online but there usually comes a point where you need expertise and having bought local it will be available.

 

[hobie18]

Spray insulation? Seal, quiet, comprehensive.
Moisture venting?
Redo floor.
Okay, codes first.
Decide if you want a different building to start with. Or this is the hill....
Then electric. Test how noisy it is at all hours. Safety. Including fire and people. Theft. Bathroom. Coffee? Connectivity for internet and tv. Do you have a swmbo. Points in favor. Lockability? Sturdy? Secure. Windows in right spots vis a vis sun and desk. Lighting. Lightning. Loss of storage when office. Trees, bugs.

 

[acer66]

I would go with R15 in the walls & roof unless they make a higher r value insulation for 2x4’s.

Using 5/8” drywall over 1/2” supposedly helps with the sound.

We used a premade sheetmetal between two layers of drywall sheets once which worked great but expensive.

If you do not talk on the phone a white noise app might do the trick too.

 

[racecougar]

I agree that a 9K mini split would be sufficient. How are folks DIY-ing these installs (for the units that don’t come with pre-charged lines, like Mr Cool)? Are they buying the tools to pull vacuum and flare lines or can I pay someone to come out and do that once the hardware is all in place?

A decent vacuum pump, gauges, and flaring tool cost less than having a tech come out, and you end up with useful tools.