Another basement insulation question
Our house was built back in the late 80s. It is a ranch style with a full-width front porch. The long sides of the house face East and West and the majority of the basement is below grade (perhaps three courses above ground everywhere except the North side, which has the garage). (Middle Tennessee, so it’s occasionally teens or below 0, but more common around freezing in winter.)
The basement is 40% garage and 60% finished/heated living space. The section under the front porch is the same depth as the basement and done with an entry from the garage area and a gravel floor. The porch part of the basement has its own French drain system.
I’m in the process of upgrading the insulation in the garage ceiling (and replacing the garage doors with insulated ones). Once that’s done, I plan to add an interior insulated stud wall in the garage (with foam separating the studs and the concrete block) to the North side. What, if anything, can I do to the basement wall that is shared with the porch area?
Even though the ground provides a lot of mass, it’s cold mass so my goal is to extend the internal stud wall around the entire perimeter but I don’t know if that’s worth it or going to be that big a help. Any ideas or opinions? Thanks!
Replies
Hi,
If the basement walls are not insulated on the outside with rigid foam, it will certainly be worthwhile adding the insulation inside.
The largest heat loss in basements is walls --heat loss drops as you get lower, but, it seems to me, it would be worth considering some type of insulating floor -- even if only carpet and pad.
Gary
I'm not quite understanding the layout, but running EPS foam around the wals all the way is the general idea for basement insulation. You can glue it to the walls with a spray foam gun easily.
Sounds like the garage is in the basement but you have no fire rock barrier between it and the living area, which is less than a safe situation.
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you have no fire rock barrier between it and the living area
The original owner built a stud wall to separate the garage and living space. It's faced with sheetrock on the living side and wood paneling (1/4") on the garage side. What is considered a fire rock barrier?
5/8" type X taped.But I meant on the ceiling of the garage
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Did you mention the curb to him?
You lost me
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Is he talking about the need to have a step down into the garage so CO doesn't seep into the living space?
I see, leading to the Q - is there an egress in the living space planned other than thru the burning garage?
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I am sure the former owner thought the wood paneling in the garage was a nice touch.
Maybe the OP has a big enough lot to build a detached garage.
Curb is required around here to keep any liquids in the garage, not in the living space.
That whole Q got me to wondering about the issue - I don't see it much, but aren't the garages on ranches supposed to be something like 18" lower than the house less this or that, because exhaust gasses are heavier than air and will settle to the lower level of the garage instead of migrating to the house? Or is that with gas fuirnace in the garage space? I forget
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I honestly don't know or remember.
IIRC the garage floor must be six inches lower than the basement floor and sloped so that any liquids leaking from the vehicle goes outside. Obviously, the ajoining wall and ceiling must be 5/8 drywall and the door from garage to basement must be fire-rated.
OK, this is rapidly moving to the point that it's got me concerned because we do have the gas furnace in the garage. It's a full basement with a solid concrete full-length floor. They just walled off the garage section from the finished section. The garage isn't lower at all. I don't know what the requirements were back in the 80s when it was built.
So, there ought to be 5/8 fire-grade sheetrock on the garage side as well? Special. There's a huge amount of shelving and a workbench all along that wall all made from 2x lumber so it's nice and solid.
Good. I didn't have enough to do around here.
ought to be 5/8 fire-grade sheetrock on the garage side as well?
In my jusrisdiction, it's 5/8" "X" board on both sides, with all penetrations (j-boxes for outlers, switches and plumbing) sealed with fire caulk and/or 1-hour rated taping.
Otherwise, all you wind up with is a 15-20 minute assembly. So, to get a BI pass in retrofit, you usually need to fill the studbays with rock wool, then apply 5/8" "X" board. But, I've also seen retrofits that required two-layers of "X" board on the garage side to pass (and surface-mounting electrical & plumbing to the resulting outside face.
Strict is as strict does, to mangle a phrase.
If you have living space over the garage, then the garage will need fire-rated board continued on the ceiling plane, too.Occupational hazard of my occupation not being around (sorry Bubba)
"If you have living space over the garage, then the garage will need fire-rated board continued on the ceiling plane, too."
Even if there is no living space above the garage, if the garage roof attaches to the house, then it has to be fire-rated 5/8 drywall in my area. You would only need to tape and one coat the seams and screw heads and foam any openings.
Even if there is no living space above the garage, if the garage roof attaches to the house,
Well, locally, you can save on the drywall, by just continuing the 1-hour-rated wall assembly right up to the roof deck. Then, the garage ceiling can be whatever you want. In fact, often this is given a semi-finished (or paint grade) set of stairs and the storage space is referred to as a "Texas Basement."Occupational hazard of my occupation not being around (sorry Bubba)
That whole 18" thing has it's origins in an electrical code rule for COMMERCIAL garages. It was believed that, since GASOLINE fumes are heavier than air, receptacles should be kept well above the floor.
Later, the plumbing code applied this to any "open" flame cource ... so, when they started placing water heaters in garages (sort of a west coast thing), they were set on little pedestals. These pedestals evolved into a raised platform for all the 'mechanicals' in the garage. Of course, with California having earthquakes, etc. .... it also means your bracing better be good, because they now have farther to fall!
Another reason for this difference in elevation ... in many places the difference between the house and the garage is only a couple inches ... is that fumes, mud, snow melt, etc., are less likely to enter the house (by passing under the door), and it makes 'hosing off' the floor much easier.
Last, let's not forget that many homes are built on pier and block foundations, withe the space under them being used to route the mechanicals. Garages have neither to worry about, it's easier to drive into a garage at grade, and people typically think their cars are heavy.
Any issues running foam on the inside of the basement if you already have 2" on the exterior?
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nope. ICFs are made with 2-1/2" on both sides.
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I'm in the process of converting a block building to an office ... and one wall shows some moisture issues. The floor is level, but does have a few cracks. Some of the ideas I'm toying with might work for you as well.
First, the floor. FWW did an article on making a shop floor. The basic idea was a floor made of wood and rigid foam, with a small space at the wall junction. The foam then supported a wood floor, and carpet or tile was laid atop that.
While you can do the same for the walls, I plan to use 'hat channel' to space it all an inch off the existing block walls. This will prevent problems with any water that might get in. The current thought is: hat channels vertical, wood framing horizontal, outer layer also horizontal. Just what material to be used for that outer layer is still in the air; I'm leaning towards a mix of slatwall and melamine "dry erase" sections. For a residence, a drywall layer is also necessary, as a fire barrier to protect the foam.
Since there WILL be moisture with any sort of masonry wall or concrete floor, one must take pains to not trap the water, or encourage wicking. Hence the 1/2" gap around the perimeter of the floor .... wall sheathing also ought not directly touch the floor. 3/4" base molding will conceal this space.
As for the electrical, I've had the best results attaching the boxes to the masonry, then using extensions to bring the faces to the level of my finished walls. There's a lot to be said for solid support. Since there isn't a hollow wall to fish wires through, I reccomend the use of pipe, at least until the pipe exits into an accessible space.
Which, naturally, brings us to the ceiling. There's electrical, plumbing, ventilation, and Lord knows what else that will need to be run through the space. PROPERLY executed, a drop ceiling can be a real blessing in these situations.
Personally, since I don't have open joists to work with, I'm considering making a 'mooney wall' type of grid of 2x4's on the ceiling .... then attaching 24x48 panels, with exposed screw heads. These panels will then conceal it all, yet be removable for access. If my panels have a 'ship lap' edge, they will help support each other. Did you know there are acoustical ceiling tiles made of gypsum?