Framing a basement with perimeter drainage system

So, we bought our house in August of this year...and as it's getting colder outside, I've noticed our electrical bill is going up higher than I think it should be. Soon as I sat and thought about it, I quickly realized a big part of the issue is our basement. Our basement is unfinished; and additionally, our HVAC system is in our attic, with all vents in the ceiling...so the basement isn't actively heated or cooled.

We do have a wood burning stove downstairs, and it's serviced and ready to go; as such, short-term the plan is simply to burn wood @ night to warm the basement up, and eliminate the temp differential between the upstairs and downstairs. Longer-term, I believe the best way to handle things, especially considering that we eventually plan on finishing our basement, would be to frame and insulate basement walls, something I can do myself/with friends and family. Even if the basement isn't actively heated/cooled by HVAC, I assume it'd seriously slow down any heating/cooling loss through the basement walls.

The 'issue', so to speak, is that our basement has one of those perimeter drainage systems. You can easily tell because, aside from the obvious two big sealed sump pump pits, the perimeter of the basement has about a 6" wide band of different colored cement/mortar, much like the picture below:



This being the case...what would be involved (other than the obvious LOL) in framing out the basement? I assume that I'd basically just have to move the framed walls in to avoid penetrating the 'band' of concrete with framing nails. Anything else to be aware of?

 

Actually, I think I figured it out, to a degree.

From what I understand, I can do either of the following (or both):

1. Use construction adhesive on the bottom plate.
2. Every so often, construct a sort of 'L' bracket. Secure the vertical part of the 'L' to the foundation wall, and then nail the horizontal part of the 'L' to the bottom plate, which will hold it in place.

 

Sounds like you might have moisture troubles. Without taking some measures finishing out the basement might cause a problem.
In the meantime,,
You can spray foam or insulate the floor, and also put more insulation in attic. Another thing that makes a big difference is a solar powered attic fan, these make a big difference and do not cost anything to run. Best of luck on the home maintenance.

 

I finished my basement a few years ago. We don't have a perimeter sump system but I still took some precautions after spraying 18yr Dry-Lok and laying foam board on the foundation. I inset the framed walls with an air gap of ~2in and also used foam board underneath the sole (floor) plate. On heavy rains we'll get some ingress at the foundation/slab and this has completely prevented any issues.

 

Not really. The water table is pretty high around here, and without the sump system, water would just hydrostatically force its way through the walls. Same thing happened in our old house. Soon as we installed the sump system it was the driest place in the house.

We've had a few BIG rains since I've been here (anywhere from 2 to 5 inches in a day or two) and while you can obviously hear the sumps kicking in, the basement itself has been, and is, dry as a bone.

With this said...yes, I absolutely plan on consulting different professionals before I begin.

 

Yeah, I was planning on insetting the walls 2 or 3 inches or so, for the same reason you did, just in case.

 

Don't miss the more important part of foam board underneath sole plate. Found a pic for reference. I even lifted my base cabinets in the basement with 1/4" HDPE strips.

 

Ah, good catch!

Question - I see you're putting foam board behind the framed walls. I assume you're also going to spray foam or put something else between the vertical 2x4's?

 

I live in the south, so nah, that foam board was enough insulation for here.

 

Ah, OK. I mean, 'technically' I do (King George, VA), but all I know is that it's about mid to high 20's outside at night, so I'm thinking I might want more than the foam board.

Short-term, however, if i do nothing other than frame it in, and put foam board up, that alone will STILL make a big difference as far as heat/cooling loss go.

Dumb question - is the foam board also providing some sort of vapor barrier, or is that a separate product?

 

We've got a walk-out basement, so those walls are actually in the dirt. To be fair, if they were exposed, I would've laid batt.

Also, I didn't staple up additional plastic sheeting for a vapor barrier. I figured the Dry-Lok + foam board + air gap was enough barrier, especially considering it was a new build and the foundation has significant water-shedding on the exterior. In your case I'd staple up plastic in addition because it'll only cost $100 and take an extra 2hrs. Not to mention you have a known strip which will always have high moisture content.

Foam board is a high-density closed-cell structure, so it's a great vapor barrier and mat'l to use to safely raise the framing. And, of course, Dry-Lok is another form of waterproof barrier (first line of defense for any moisture migrating through the concrete).

 

Ours are as well. (Walls being in the dirt.) The front and right-hand side are completely under grade; the back is under grade up to about 5'; and the other side is mostly exposed (walk out).

Well yeah. Even if it's not required...am thinking that I'll set the walls in 2" or so and staple up plastic just in case. It can't hurt.

Great point. Excellent info. Thank you!

 

My basement is insulated and finished. It’s notoriously cold down there.

 

Well you're also in Wyoming. I'm in Virginia.

On a serious note...I don't expect insulation alone to do the job...but when it's not insulated at all *and* it's not actively heated or cooled, obviously any heating or cooling the HVAC does on the main part of the house will get leached by the basement. I don't just plan on finishing the basement, but doing that will at least slow down the big fat heat/cooling sink. LOL

 

The floor joists are insulated, right? If not, do that before framing interior walls.

 

If you have any kind of seepage or weeping after several days of heavy rain, drylok is incredible. Any hardware store will have it, cheap brush to apply.

 

Of the basement ceiling? Yes, they are.

 

I'll likely use it; but with that said, nope, there's no weeping or seepage. I suspect in the past they may have had issues with seeping/weepage, and the couple that owns this house was older. From what I understand they basically said "We want whatever will make damn sure this will never ever be an issue again ever" and they paid like $18K for the perimeter drainage system.

We've had a number of heavy rains since we've moved in here...and no moisture or weeping or seepage or anything. BUT...I like to plan for the worst case scenario, and will likely use the Drylok anyways.

 

I had the same french drain repair done in my basement several years ago. Company that did it suggested using liquid nail on the floor if I were to ever finish it out (nails would void their warranty).

 

Update:

So, this is essentially ending up being somewhat of a non-issue, at least in the short term. LOL!

As stated in my first post, for some odd reason, when the previous owners of our house got tired of not having HVAC, they installed a heat pump in 2002 - in the attic. It's insulated normally up there, meaning it'll get down to 40 or so in the wintertime, and 120+ in the summertime. Obviously, this taxes the HVAC system....the previous owners spent something like $20K (!!) in repairs to it over the last 23 years.

I went back and forth between whether or not to have the attic spray-foamed, or to relocate the HVAC to the basement when it craps out; and realized that to keep it where it is, I'd not only need to spray foam the attic ($8K or so) but would STILL need to insulate the basement ($6K) and have a secondary HVAC system installed there ($8K to $18K depending on the system). For the same amount, I can insulate the attic (with cellulose) and the basement better AND still relocate the HVAC for about the same price.

Turns out that they can apply the spray foam directly to the walls of our basement and add insulation to our attic for like $6K, which won't solve the reliability aspect of the current HVAC but it *WILL* insulate far better, leading to far more heating/cooling loss, which will prevent the current one from working as hard...and in the short term, that's more than sufficient.

So, they're coming out in a few weeks to do that, which should lower our bills and make it more comfortable, and then we can frame out later this summer or next year.

 

Sounds like you've got a plan! Quick item, may not apply to you. In my crawl space, the overhead floor joists had insulation, but it had absorbed moisture over the years. I insulated the walls with foam board, installed French drain, sump, and dehumidifier...pretty close to your plan, but I also pulled all the floor insulation out. Whole house more comfortable, feels healthier, and crawl space MUCH less unpleasant when I need to go under there. And power bill was a better, until everything started getting more expensive...

 

The basement of your house is not a significant contributor to heat loss if you live in VA. You’re wasting your money, especially if the basement ceiling is already well insulated.

 

What would you propose, then? At the very least I would think the basement ceiling needs to be (better) insulated, and the rim joists aren't insulated at all. Additionally, parts of the basement are above ground - one wall is entirely exposed (is not underground), which is why the plan was/is to insulate only those areas above ground.

I suspect the bigger 'issue' is two-fold:

1. The fact that the basement isn't environmentally controlled right now, as the HVAC system (heat pump) is in the attic; and that (parts of) it need to be (better) insulated.
2. The fact that more insulation (quite a bit more) is needed in the attic.

Given the above two, heat or cooling loss is likely greater than it should be. I assume (once the heat pump shoots craps) that, once a new system is installed in the basement, with ductwork going both to heat/cool the main level and the basement....the current temperature delta (which is likely a good 15 degrees or so) will prevent heat or cooling from being 'leached' from the main level.

 

Yeah, there's currently insulation in the ceiling of the basement, but it's pretty old; I plan on replacing it within the next several months or so. The previous owner did the French drain, sump, etc. (one of those perimeter drainage systems) so all I need to do is

- better insulate it and
- in the future, relocate HVAC to the basement.

 

In the south (which VA is considered in my mind, I lived in fairfax for quite awhile), it's pretty normal to have the blower located in the attic. Insulating the attic doesn't necessarily help the efficiency of the hvac, and in some cases may work against it like in the summer. A solar powered attic vent fan like mentioned above is an option for summer. Really good insulation in the attic floor is much more important than insulating the walls/roof of the attic. Most attics have vents at the top corners or along the apex, too.

Apologies for my lack of reading comprehension - I would consider insulating the basement wall that is exposed, but it still probably won't make a huge difference. Consider for a moment how a room built over an attached garage behaves. With the garage door closed, the room above it is not affected all that much by external temperature swings as long as it has correctly balanced hvac airflow. Garages are rarely heated or cooled, and garage doors are rarely insulated. There's very little reason to insulate the other walls that are below ground, though. The ground itself is an excellent insulator.

If your hvac is underperforming, then that's the place to put some money, and check the condition of the attic floor and basement ceiling insulation. I'd be very wary of a professional opinion/quote. They will do their best to get you to spend a ton of money on stuff you don't necessarily need.

 

I’m going to weigh in here again as a former hvac guy. Every residence/space is different as per zone/size/architecture. Get with a couple local contractors (couple and local for advice) to figure out what’s right for your particular situation.
What I’m used to in so cal/az is wrong here in VA. Codes are very relaxed in my opinion on the east cost compared with out west. I’m blown away with what is ok here vs CA, electric/plumbing wise.
As far as your equipment being in attic vs basement, equipment doesn’t care. Your living space being better insulated is better all around ( energy saving, equipment not running as much) yes. It’ll be better overall with a well insulated home. Homes out here in VA are all different.
My VA house is WAY Les energy efficient compared to my AZ house.
To make a multi level house truly efficient it needs its own system for each floor, or a complicated damper/thermostat system to equalize temps. Hot air rises, cool air drops.

 

I’m not exactly sure of the layout of your basement walls, but I thought I read that one wall isn’t buried? In that case, could you install a mini split on it to cover the hvac said and compliment the insulation?

 

Ok, so I need to clarify something that will likely make a HUGE difference.

When I originally wrote this thread, given that the HVAC system is in the attic, my thought was that putting it inside an 'envelope' (fancy term for insulating the entire attic) would bring temps down and the like. While this is true, I realized two things.

1. The previous owners of our house put $20K over 20 years into *fixing* (not updating or replacing - FIXING) the current HVAC system.
2. Having done some number crunching, I realized that for the same cost as insulating the attic (spray foam), installing an attic vent fan, insulating the basement walls and putting an HVAC system down there....I can just insulate the attic *FLOOR*, the exposed parts of the basement walls, and buy a new HVAC system and have it installed in the basement when this one craps out in the future.

So yeah, for now, the two things I plan on doing are to insulate the attic floor (and maybe an attic vent fan, and only the exposed walls/parts of the walls of the basement. If that prolongs the life of the attic HVAC, so much the better.

 

I don’t disagree that a well insulated house is top priority…but the previous owners put $20K over 20 years into *fixing* (not replacing or upgrading – fixing) the heat pump system. Based on talking to an HVAC tech or two, it's sized correctly....so the only thing I can think of that'd cause that much maintenance/breakdown over 20 years (we're talking like compressor replacements very 2 years or so, capacitors, new inside components (I forget what the big inside box is called LOL) is the more extreme temps in the attic, coupled with the lack of insulation making the system work one hell of a lot harder than it should have.

I may be wrong but I’ve got a tough time believing that an attic HAVC system providing AC to a house in the summer doesn’t care that it’s sitting in a 120+ degree attic vice a 70 degree basement. If I’m wrong on that, though, please correct me - I don’t WANT to spend more $ if I don’t have to.

 

Another factor is efficiency improvements...I replaced two heat pumps at 22-25 years, saved me a HUGE amount in power bills.