Need help building some walls

[TNW]

Hi. First-time poster here. Our house has a laundry room that used to be a detached 1-car garage. At some point, a previous owner built an addition between the original house and garage to turn the two separate structures into one (the addition became an extension of the living room), and they put up a wall in the garage to make two rooms - a smaller garage and a laundry room.

The laundry room/garage is a concrete slab with a stem wall (I think that's what it is called) which is 1 layer of cinder block. The walls are on top of the stem wall, and the stem wall sticks out about ~2.75 inches from the sheetrock (there is concrete "ledge" along the bottom of the walls). This room is not insulated, which is problematic now that it is connected to the house.

I want to insulate the laundry room and I would like to make the stem wall go away (I just want drywall going from floor to ceiling). I was thinking I would build new walls on top of the existing ones by fastening new studs to the existing studs (thus bringing the walls in 3.5 inches, unless I rip the boards thinner), then insulate (so the insulation would attach to the new studs directly on top of the existing drywall) and then place new drywall. This way I could hide the stem wall with the new walls.

The pictures aren't the best, sorry. They show the stem wall and how the sill is 2" back from the edge of it, and then the existing drywall is another 3/4" or so back from the edge of the sill. There's also a metal flashing between the sill and the stem wall that has a pretty wide overhang, which I've cut off except for one section shown in the picture as that's where it goes behind the laundry machine (I haven't moved it to cut it out yet).

What I need help with is how to deal with the stem wall and putting drywall over it. I would get some pressure-treated 2x4 and bring the existing sill out to be flush with the edge of the stem wall. I don't know whether to a) rip the new studs to also be flush with the edge of the stem wall, or b) take the time to cut a notch out of each stud so that the interior-most aspect of it would stick out beyond the stem wall and come all the way down to the floor, or c) make each stud stick out enough beyond the stem wall to match some furring strips that I could attach to the stem wall below each stud. "a" would be a lot easier, but then I wouldn't know what to do with the drywall that covers the stem wall without any studs behind it (i.e., what would it fasten to? and how would I attach baseboard?). "b" would be a lot more work but doing it that way would allow there to be stud spanning the entire vertical distance of the wall and I'd have stud to attach the drywall to down below, and baseboards wouldn't be an issue. But I think that doing it the "b" way would mean all of the studs need to be pressure treated since they would be very close to if not in direct contact with the cinder block? Maybe "c" is the best of both worlds? In either method, is there something that I would need to put over the sill to seal it?

I hope this makes sense. Sorry for the long post. Any advice would be much appreciated. Does this sound reasonable, or is there a much simpler way to go about this? Thanks!

 

[Snoonyb]

Welcome.
Well, were it I, I would have left the flashing, or, just cut the lip even with the edge of the curb wall, use redheads to anchor a 2x3 sill, (leaving the flashing precludes the need for WPT lumber), even with the edge of the curb wall, frame with 2x3's.

You'll also need to address the #12 romex, either in the wall, or surface mount.

There are number of ways to address insulating the new wall cavity, however, a 2x3 wall cavity will only support R-8 batt insulation.

As for addressing the drywall/curb wall attachment, there are any number of construction adhesives, for both drywall as well as base.

Drywallers typically hold the drywall 1/2" above the floor, so, if you hang the board vertically you'll preclude the board edge indent along the base, except at the board joints.

 

[lucyonfire]

I hope you are satisfied with Snoonyb's answer!

 

[ChrisAtTech]

If the goal is to turn this into actual conditioned space then b or c, not a. Option a leaves you with no insulation to the interior of the cinder block and while insulating above it in the new wall won't do nothing, it's not going to do a ton to normalize the temperature in this space since I assume you're also not running hvac to this space. If you built the wall to the floor with b or c, you're on our way to building an airtight double stud wall, which is a highly efficient system as far as heat loss goes. I'd also air seal the current drywall to cinder block connection and over the cinder block to the floor prior to doing b or c

 

[TNW]

Welcome.
Well, were it I, I would have left the flashing, or, just cut the lip even with the edge of the curb wall, use redheads to anchor a 2x3 sill, (leaving the flashing precludes the need for WPT lumber), even with the edge of the curb wall, frame with 2x3's.

You'll also need to address the #12 romex, either in the wall, or surface mount.

There are number of ways to address insulating the new wall cavity, however, a 2x3 wall cavity will only support R-8 batt insulation.

As for addressing the drywall/curb wall attachment, there are any number of construction adhesives, for both drywall as well as base.

Drywallers typically hold the drywall 1/2" above the floor, so, if you hang the board vertically you'll preclude the board edge indent along the base, except at the board joints.

Thanks for the reply!

It's not easy to see in the pictures but I did cut the lip just even with the curb wall. It's also not easy to see in the picture, but the lip stuck out a good 2+ inches from the curb wall so it had to go!

Yeah, the romex is going to be a hassle. I'm thinking that I'll use a spade bit to drill guide holes through the studs, run the wire through, then install the insulation and be sure to have the wire on top of the insulation?

Can you please tell me what you mean by "preclude the board edge indent along the base, except at the board joints."?

Thanks for the help! I'm more of a woodworker trying to learn construction stuff by the seat of my pants.

 

[TNW]

If the goal is to turn this into actual conditioned space then b or c, not a. Option a leaves you with no insulation to the interior of the cinder block and while insulating above it in the new wall won't do nothing, it's not going to do a ton to normalize the temperature in this space since I assume you're also not running hvac to this space. If you built the wall to the floor with b or c, you're on our way to building an airtight double stud wall, which is a highly efficient system as far as heat loss goes. I'd also air seal the current drywall to cinder block connection and over the cinder block to the floor prior to doing b or c

Thanks for the reply!

Correct, there's no HVAC register out there. Hopefully it will be able to equalize with the rest of the house though. Right now it is close to freezing in that room.

Would you mind telling me how you would "air seal the current drywall to cinder block connection and over the cinder block to the floor"? Would plain sheet plastic work, say from the bottom of the existing drywall down to the floor and under the new vinyl plank (to be laid after walls are done)?

Thanks so much!

 

[Snoonyb]

Thanks for the reply!

It's not easy to see in the pictures but I did cut the lip just even with the curb wall. It's also not easy to see in the picture, but the lip stuck out a good 2+ inches from the curb wall so it had to go!

Yeah, the romex is going to be a hassle. I'm thinking that I'll use a spade bit to drill guide holes through the studs, run the wire through, then install the insulation and be sure to have the wire on top of the insulation?

Can you please tell me what you mean by "preclude the board edge indent along the base, except at the board joints."?

Thanks for the help! I'm more of a woodworker trying to learn construction stuff by the seat of my pants.

Drywall is inherently narrower on the board long edges, because those are were the tape joint are and are filled level with the board plane, so, if you hang the board vertically, you preclude the chamfered board edge affecting the versicle plane of the base.

If you hand the board covering the curb wall, and attach with adhesive, it will be sealed, as described; "As for addressing the drywall/curb wall attachment, there are any number of construction adhesives, for both drywall as well as base."

 

[slownsteady]

If you don't mind losing the extra inch or three of floor space, I would build a new stud wall from top to bottom - as if it was new construction. That way you could put together the framing while it was flat on the floor and then tip it up into place. No having to notch studs either.

I don't know whether you would have to demo the old wall; depends on any moisture issues you might have with the concrete block. Is the exterior of this wall above ground?

 

[TNW]

If you don't mind losing the extra inch or three of floor space, I would build a new stud wall from top to bottom - as if it was new construction. That way you could put together the framing while it was flat on the floor and then tip it up into place. No having to notch studs either.

I don't know whether you would have to demo the old wall; depends on any moisture issues you might have with the concrete block. Is the exterior of this wall above ground?

Hi. Thanks for the reply. I wasn't planning on doing any demolition at all - it never occurred to me to consider whether or not that would be necessary. I just want to cover up the curb wall and insulate the room in the process. Yes, the 2 exterior walls are above ground, roughly the same height as they are inside if not a little more. Another wall goes to the rest of the house, and the 4th wall is the one that divides the whole room (a 1 car garage) into a smaller garage and a laundry room. I made a picture, hopefully it shows up. The wall that goes to the garage is insulated so I won't do anything with it. The remaining 3 all have the curb wall that needs to be hidden, and then the 2 exterior walls need insulation.

 

[PJB12]

Thanks for the reply!

Correct, there's no HVAC register out there. Hopefully it will be able to equalize with the rest of the house though. Right now it is close to freezing in that room.

If it is easier than duct work, you could install hard wired electric baseboard heaters with a thermostat in that room. By doing that, there is no extra load on your furnace.

 

[PJB12]

Thanks for the reply!



Yeah, the romex is going to be a hassle. I'm thinking that I'll use a spade bit to drill guide holes through the studs, run the wire through, then install the insulation and be sure to have the wire on top of the insulation?

The electrical wire is best if it's in the center of the insulation batt. Two main reasons include:
A) It enters the box near or through the rear of the box, so you won't have to violate the insulation's vapor barrier.
B) The cable will be farther back should anyone tap in a picture hanging nail.

Ideally, the electrical cable will be about half way from back to front of the stud bay. Slice the batting from the non-vapor barrier face 1/2 way deep and lay it over the cable. It'll close itself back up.

Be sure the holes in the studs are at least 1-1/4" from an edge. If not, put nail plates on the face(s) of the studs.

Paul

Side Note- Believe it or not, if electrical wire is against the back (or close to the back) of the plaster or drywall on an outside wall, soon you will see dirt stripes on the wall.

 

[TNW]

If it is easier than duct work, you could install hard wired electric baseboard heaters with a thermostat in that room. By doing that, there is no extra load on your furnace.

Thanks. I wasn't planning on adding any duct work, as ours runs through the crawlspace and there is no crawlspace under the laundry room - it's just a concrete slab, and the crawlspace stops at the wall between the laundry room and the rest of the house. I actually wasn't going to do anything, and just let the air from that room and the rest of the house flow as they will. I had not considered the baseboard heaters, I'll look into that! Thanks!

 

[TNW]

The electrical wire is best if it's in the center of the insulation batt. Two main reasons include:
A) It enters the box near or through the rear of the box, so you won't have to violate the insulation's vapor barrier.
B) The cable will be farther back should anyone tap in a picture hanging nail.

Ideally, the electrical cable will be about half way from back to front of the stud bay. Slice the batting from the non-vapor barrier face 1/2 way deep and lay it over the cable. It'll close itself back up.

Be sure the holes in the studs are at least 1-1/4" from an edge. If not, put nail plates on the face(s) of the studs.

Paul

Side Note- Believe it or not, if electrical wire is against the back (or close to the back) of the plaster or drywall on an outside wall, soon you will see dirt stripes on the wall.

Thanks. I ended up reading about that not too long after I posted my message to you. Thanks for confirming - it's good to her things multiple times!

 

[PJB12]

Thanks. I wasn't planning on adding any duct work, as ours runs through the crawlspace and there is no crawlspace under the laundry room - it's just a concrete slab, and the crawlspace stops at the wall between the laundry room and the rest of the house. I actually wasn't going to do anything, and just let the air from that room and the rest of the house flow as they will. I had not considered the baseboard heaters, I'll look into that! Thanks!

Baseboard heaters are kind of cool (hot?) because they can be on their own thermostat. I installed one in our front porch since we don't use it often (and I'm too lazy to install a separate zone from our hydronic system).

If the room isn't warm enough-
Another option would be to install electric heating mat or cables on the existing concrete floor and using an appropriate floor covering over it. Tile is allowed over all brands & types. I think Warmly Yours still makes one called "Envron" that can go under carpet. Others here would know if wood or laminate flooring can go over electric heat cables or mats.

Plan C, although not ideal, would be to install an in-wall fan between rooms. They are sometimes called "Through The Wall" fans or "Heat Transfer Fans". People use these to when they enclose a porch & wish to send house heat or cooling to the porch. Tjerlund makes a really quiet one called Aireshare. There are round (and less expensive) ones, too. The benefit here is that cooling will also be transferred in air conditioning season.

Quick Plan: A ceiling fan in your new room, blowing upward, might also cause air to be drawn in from the adjacent room when the door is open.

It sounds like you have a very fun and interesting project. I hope you enjoy working on it and using your finished creation for years to come!

Paul