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OT: Finishing a basement

S_Janowski

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May 24, 2009
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Marlton, NJ
Looking for advice on finishing a basement, in particular, walls/flooring. I've read several things on the internet, all of which seem to contradict everything that the contractors have told me and included in their proposals.

Received about 6 estimates, ranging from $30k - $115k, which makes it even harder to trust someone when the quotes are all over the place. I'd say the average quote was around 38-40k.

I've been in my house for two years. Have never seen water enter the basement, however, there is efflorescence at the base of the cinderblock walls. Prior homeowner painted 1/3 of walls in the Drylok crap, which makes me wonder a bit. Basically tells me there is water in the block and water vapor coming through walls. I currently have one sump pump which constantly goes off when we get a good rain, and continues to go off periodically for a day or two following the rain. We will be adding a second sump pump before we finish the basement. Our back yard can get pretty wet as you can imagine. Is there a specific area that we should position the second pump? Caddy corner? Directly across in opposite corner?

That being said, I'm concerned with moisture/mold, and want to make sure I take the proper steps to prevent against these things as best as possible. I want the basement done right.

I've read that you should NEVER use fiberglass insulation for basement walls, however, every contractor indicated that is what they use to finish the walls. I've read that XPS rigid foam board is a better option, due to it being mold/moisture resistant. Can anyone confirm this technique? It's cheaper than spray foam, but seems to be a better application that fiberglass. Do these contractors not know what they are talking about? Are they taking the easy way out? Are they not up to date with current building trends? Also, every contractor said they would use fiberglass batts in the rim joists? Is that a good option or is there something better? I will then have a mold/moisture drywall put up on the foundation walls to create a thermal barrier.

I have a concrete slab. Everything I read says that a subfloor should be installed before flooring is laid down. Again, none of the contractors proposed a subfloor. They all said they would install carpet/laminate/vinyl directly over the slab. Water vapor comes up through the slab, so if imagine a moisture resistant subfloor would be necessary. what is the proper technique for a basement subfloor? I've read so many different opinions. And again, why have all of the friggen contractors just looked past this issue???? If we use a canadian product called DRICore, it will add about $2,225 to the total cost. This product seems to get overall good reviews and appears to take into consideration mold/moisture factors. Just not sure if this is necessary, worth the money, or a good product in general...

And finally, do you insulate a basement ceiling? Some contractors said yes, others said no. The ones who said yes recommended R19 fiberglass batts. I believe the US Department of Energy website says not to insulate a basement ceiling, especially if insulating the walls. I've also read varying things on the Internet, however it seems the consensus would be to forego the ceiling insulation.

Any advice would be greatly appreciated. I live in southern NJ if you also want to recommend a legit contractor.

Thanks!
 
Without putting eyes on your basement it's hard to say for sure but it sounds like your contractors don't know what they are talking about. My background is an HVAC engineer where I used to work for museums so building envelope issues were something I dealt with frequently.

1. Definitely use a closed cell rigid or closed cell spray foam if there is any chance getting wet. When batt insulation gets wet it loses all it R-value because it compresses. Closed cell products tend to have better perm rating which helps keep out moisture by acting as a vapor retarder. (Note: you need about 2' of spray foam to cross from vapor retarder to vapor barrier classification -http://www.energyvanguard.com/blog-building-science-HERS-BPI/bid/52970/Vapor-Retarder-Vapor-Barrier-Perms-What-the-Heck) As far as the rim joist batt insulation is probably ok. Are you putting in a suspended ceiling or drywall ceiling? If your dry walling everything I'd pay more attention to the detail of the basement wall to rim joist interconnection as you want to make sure there is not a gap in the thermal barrier. It's important with a suspended ceiling but you can improve it if necessary but if you're dry walling the ceiling you lose access to that space.

2. Again if there is any chance of it getting wet, don't put carpet in your basement. I prefer the floating vinyl flooring, I used this in my kitchen (http://m.lumberliquidators.com/ll/c/Clear-Lake-Chestnut-Click-Resilient-Tranquility-4CC/10029491). It will scratch if you're not careful moving furniture but they hide pretty well. Your floor has to be flat so depending on your basement you may need to add a subfloor or you may be able to just use a floor patching product. In either case with the floating vinyl I would use an underlayment (http://m.lumberliquidators.com/ll/c/LVT-Underlayment-Sq-Ft-Tranquility-SILENT-LVT/10029179) taping the seems will help with reducing moisture transmission. If your basement slab holds a lot moisture I'd also put down a plastic vapor barrier. Turn it up the wall about a foot before putting insulation over top.

3. Do not insulate your basement ceiling. There's no reason to have insulation between conditioned spaces. That said if your intent is to not heat your basement unless your are using it, then maybe I would insulate it but still probably not because you want some heat to migrate down to keep pipes from freezing.

Hope that helps.
 
Thanks for the insight! I'm most likely using 2" of rigid foam, so hopefully that makes it a moisture barrier. Also doing a dry wall ceiling.

So you used the underpayment (I'm guessing it was specifically recommended by the floor manufacturer?), then put a vapor barrier over top? What type of vapor barrier? Moisture won't get trapped anywhere with that configuration?

What do you mean by the wall to rim joint interconnection? Fire stopping? Or something more to do with insulation? What do you recommend?

Thanks!
 
Thanks for the insight! I'm most likely using 2" of rigid foam, so hopefully that makes it a moisture barrier. Also doing a dry wall ceiling.

So you used the underpayment (I'm guessing it was specifically recommended by the floor manufacturer?), then put a vapor barrier over top? What type of vapor barrier? Moisture won't get trapped anywhere with that configuration?

What do you mean by the wall to rim joint interconnection? Fire stopping? Or something more to do with insulation? What do you recommend?

Thanks!

I'll try to sketch something up for you to clarify but if you're dry walling the ceiling I'd run the xps up to the underside of the floor above in addition to putting the batt insulation in the rim joist cavity.

Ideally the vapor barrier (plastic) is already under your floor slab which is why I said about how wet your floor slab is. I prefer to avoid it unless you really have a moist slab. Typical install is the subfloor on the concrete then underlayment then vinyl on top. The underlayment helps smooth out minor imperfections in the concrete and provides a little cushion for comfort and noise control.
 
sounds like you're trying to do the man cave... just do a 1 room extension to the first floor(easy to do if you have a properly built deck).. if he sprayed drylok on it already, you know there can be potential problems, then your whole finished basement would have to be gutted and redone if it kyle floods(hehe).. seen it happen, not pretty.. seriously though
 
One way in which you can simplify your thought process is to consider installing a dehumidifier.
 
When I bought my house it had a minor puddle problem after a big rain, so I had a French drain system put in, and did everything I could, landscaping wise, to have water run away from the house..... This was 30 years ago and since that there has not been any water, giving me enough confidence to put in hard wood floors 10 years ago.

We had hurricane Floyd ( seven inches) and a week of rain once dumping about nine inches of rain without any issue
I had the drain put in at a time it was not expensive, I am sure it is costly now.....
 
Sounds like you've got it under control. The only advise I would give would be to think about a sound barrier. Our kids played a ton in our finished basement. Unfortunately the room they played in was right under the family room. It was great that they were out of my hair but I had power rangers reverberating thru the surround sound right below.
 
I would recommend that you paint the walls with Drylock or equivalent prior to building your stud walls. This is just extra insurance against future moisture.
 
My first question is do you have kids? If not do you plan on having kids? If so, that seems like a boat load of money to spend on an area meant to be destroyed.
 
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Continue to do your research - many contractors don't really know the issues surrounding getting a finished basement "right".

Also consider putting a bit of money into getting the landscaping "right" - not saying it isn't, but make sure nothing is sloped such that water comes towards the house.
One way in which you can simplify your thought process is to consider installing a dehumidifier.
I was gonna suggest this - good idea!
 
I have bi-level home on a slab and had a similar problem.....

You need to reduce hydro-static pressure outside the home

Make sure you have clean gutters and install gutter guard and route all drain pipes away from your home.

Install a drain outside your home to route water away from your house.
https://www.handymanhowto.com/making-a-grassy-drainage-swale/
The steps above fixed the water issue and i dont have a french drain in my house...

As far as the flooring... consider installing porcelain ceramic tile on the floor and underneath it put in radiant heat you will thank me later

No fiberglass on the wall install foam board.

Insulation is not necessary in the finished part of the basement but i would have insulation installed in the garage area that is under a living area.
 
My dad finished our basement.

Used it for maybe 4-5 years.

Definitely no one used it after my sister & I went to college.

My advice: Unless you plan on doing a whole lot of entertaining where you anticipate you'll need a nice place for guest spillover, just go with a partially finished basement with a loft theme -
https://www.pinterest.com/explore/industrial-basement/

[Edit]: It should be noted that it flooded at one point due to a pipe burst. So yeah, definitely would recommend minimum $ in the reno. Just dry wall the section where you will be putting in the entertainment center & couches. I wouldn't bother with carpeting the floor (will get musty) or tiling it ($$$). Get yourself a nice big area rug that can easily be replaced/updated every now and then. And DIY the floor with a nice garage surfacer.

Unless you're loaded with cash, then by all means, Taj Majal it.
 
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