Basement finishing

Old 04-23-21, 08:39 PM
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Basement finishing

Im looking to finish my basement at some point so Ive been doing a lot of research. I was hoping I could bounce a bunch of questions off you dont mind.

The house is a raised ranch in CT and the basement walls are 9 high. I had them add that extra foot when I built the house to avoid having a low ceiling after boxing in ductwork. The house has curtain drains around outside foundation I have not had any water problems (knock wood) since the house was built in 1990. I have also attached a few pics.

Here are some questions and thanks in advance:

Regarding wall framing and insulation:

- It seems like there are so many different viewpoints when it comes to basement wall framing against (or adjacent to) foundation walls. There are also different ideas when it comes to insulation methods. Ive seen some people use thick insulation boards up against the concrete then use 1x3s flat against them, or build a 2x4 walls against the insulation boards. Ive seen other people not use the insulation boards and just frame a 2x4 wall against the concrete or adjacent to it (leaving a small air gap) then fill the 2x4s with normal batt insulation. I even saw one person put Tyvek up against the interior cement wall before building a framed/batt insulated wall up against it. It seems like there is not a universally agreed upon method or maybe its just that more is understood now (and/or better technology) regarding moisture permeation? With that said, what is the best way to approach the wall framing and insulation?

- Will one of these methods cause a double vapor barrier and introduce a problem on its own? If so, I would want to avoid that method.

- When installing basement walls, I plan to use pressure-treated for the bottom plate and attach it right to the concrete slab. If I do decide to put in a sub-floor (see section below), I assume it would go in after the walls are up, correct? I would think that is the normal process. However, I saw some people say the walls can go right on top of the DRICORE type product (or any other subfloor). What are your thoughts on this topic? What do the majority of people do?

Regarding Dry-Lock:

- Even though there is no obvious water problem, would it still be a good idea to use Dry-Lock on all the interior cement walls before framing and insulation?

Regarding basement floor:

- Should I put down a subfloor over the slab like a dimple-based product (ie: DMX-1 or similar) and screw 5/8 plywood on top? or

- Use the DRICORE type product that comes in square panels and has the plastic drainage material already attached to the bottom? or

- Is it feasible to not use any subfloor and just lay down some type of finished floor right over the concrete? This option would obviously save money, plus it would not cause that much of the rise being lost on the first step of the existing steps to upstairs. If it is possible to go without a sub-floor, what are the best choices of finished flooring to go directly on top of a concrete slab?

Regarding the ceiling:

- I plan to frame/box around the ductwork and i-beam then use sheetrock. For the areas that will be normal height (right up to the floor joists), I was planning to screw the sheetrock right to the floor joists. However, I have seen some people install 1x3 strips attached (and perpendicular) to the joists first before sheet-rocking. What is the purpose of doing this and is it advisable?

- When the house was built, I added kraft faced batt insulation between the floor joist with the kraft paper facing the warm area of the house which was the main floor above. The basement is un-heated, but is normally a stable temperature throughout the year. I think it stays between 50-65 degrees, although I never actually took a reading. The house is built into the side of a hill so the backside of the basement is below grade. My question: Since the basement may eventually have heating added, should I pull the insulation down, pull the vapor retarder off and put it back up again?

Regarding ceiling lighting:

- Are canister lights the best option for the basement? Are they safe? If they are IC rated, does it really mean it can be right up against insulation or should a gap be left to play it safe? Any suggestions on good lights to use?

Regarding a bathroom:

- I plan to install a bath in the basement. I have a septic system and the sewage pipe to outside is halfway up the rear wall so I plan to use a pump-up toilet. Im thinking of using the SANIFLO product. Any thoughts or suggestions?

Regarding heating:

- I have a forced hot air heating system which currently supports the upstairs of the house. If I do add heating in the basement, it will probably be by tapping into existing ductwork. If that is what I do, I was wondering if it is worthwhile to run supply and return ductwork to the floor area so the heat will circulate better. Would that be advisable, or should I just use a vent in the ceiling?

Regarding radon testing:

- Should I do a home radon test before starting the project? If I do so and there is a need for mitigation, I understand I will need to seal all cracks and drill a hole in the slab for a vent pipe to go straight through the roof? Can this vent tie into existing plumbing vent pipes? Is it feasible to do the radon mitigation steps on my own or are there other steps (or considerations) that need to be handled by a pro? I know this is only a what-if, but I wanted to ask anyway.

Again, thanks in advance for taking the time to review my questions and reply.



Old 04-24-21, 04:10 AM
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Regarding the insulation, do some searching on this site, a lot of opinions, a lot of discussion, even some disagreements but bottom line there are simple inexpensive options, and then there are some complex expensive options. Personally I am tired of some of the attacks on this subject so I will refrain from further comments!

Dry lock, your choice!

Floor, again your choice, I have always just finished my basements with tile/carpet/laminates, never really felt the need for any type of sub floor.

Ceiling, either options works. Lots of options, take a look at Armstrong country planks, I put that in my basement, sure looks nice!

Insulation is inside a conditioned space (the basement) so it's for sound, somewhat.

Cans are used every day in insulated ceilings, also lots of new LED pucks that are available.

Heat, either is fine!

Radon, sure do it now, they typ are just blowers attached to the sump with their own plumbing, pretty simple install!
Old 04-26-21, 12:12 PM
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Sorry, I'm going to offer some advice here but I want you to know I stopped reading your post after the first couple paragraphs and I know I won't be alone in that - shorter posts are more likely to be read completely.

If you're talking about below grade walls, the standard is foam against the walls to provide a thermal break, which will eliminate condensation. Then, you can build a stud wall inside that and fiberglass or mineral wool will be fine. Generally speaking, no vapor barrier on below ground walls so they can dry to the inside but code may dictate otherwise. Drylok would be a waste of time and money - if there's a water problem, it needs to be addressed outside or some kind of mitigation system installed inside.

As to the floor, if you've done the plastic test and passed, I would simply install whatever flooring type you've chosen and call it good. If there is moisture under the plastic, then it becomes more complicated.

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