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Discussion Starter #1 (Edited)
First post, but have been reading here a long time. My wife and I would like to finish our basement. They are poured concrete slabs that are in great shape with no moisture that we've seen (I know there could be in the future). I've had some contractors come over with different ideas but the more we think about it, doing it ourselves seems like a good option. We completely remodeled our kitchen and bathroom, so we are comfortable with the project (haha until we get into it). My question is basically on the beginnings of the project. Some say to Dry-lok the walls, some say don't. Some say to use rigid (xps) foam, some hate it, some say wood studs, some say metal, and some say vapor barrier, some are completely against it. My idea was to drylok the walls, install XPS foam board directly to the concrete surface, then start the wood 2x4's our an in or two (to provide some air circulation and to make sure we have some room for squaring up the wall. It seems a consensus to never have a double moisture barrier, would my setup be acceptable? Do I need to fiberglass insulate between the studs?

Also, not sure how much it matters, but we live in Northern PA and the finished piece will be about 700 sq ft.
 

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in order to answer your question, we will need to know if it is above grade or below or anything in between as that makes a difference in insulating. Pictures of your exterior walls with floor joists detailing insulation if any there helps too.
 

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Discussion Starter #3
Sorry! It's all below grade. I guess I've only been in two basements that weren't. About two feet of foundation sticks out but the rest is underground. Exterior walls are just concrete with the foundation, one builder did say they are at least 8 inches thick. No insulation anywhere that we know of (doubt any on outside of walls or in the middle.
 

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If the foundation is waterproofed from the outside drylocking the interior face won't be a great idea as you'll be creating that "double barrier". The foam, I feel, is a good idea. If you're adding the foam, then I wouldn't put batts in the stud bays. I don't feel you need to hold the studs off the insulation as long as you treat the top and bottom of the wall properly. In my basement I kept the sheetrock bottom 1-1/2" above the top of the base plate. Then kept the baseboard about 1/2" off the finish floor. This gives air an entrance/exit point. At the top of the wall I attached the studs to the joists and left it open to the joist bays (no continuous plate) to allow the air flow.
 

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In my basement I kept the sheetrock bottom 1-1/2" above the top of the base plate. Then kept the baseboard about 1/2" off the finish floor. This gives air an entrance/exit point. At the top of the wall I attached the studs to the joists and left it open to the joist bays (no continuous plate) to allow the air flow.
Won't this cause an issue with fireblocking?
 

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I built an interior wall with sill foam on the bottom. I kept the wall 1/2 inch from the concrete foundation, wood will absorb moisture and possibly have a mold issue. I insulated the entire wall with Roxul safe and sound insulation. I then installed the poly to the studs ONLY down to grade level outside. I did this so there will always be room for moisture to migrate and move with the seasons. This was also supported by the inspector who inspected it. I insulated the joist above the top plate and used acoustic sealant around all of my openings. I also used vapour boxes on all of my outlets on the exterior wall. I double folded all of my vapour barrier joints, staple and tape them. This made the inspector very happy and me as well, as my heat loss dropped huge and my sound diminished greatly. Hope that helps you.
 

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Poly in basement spaces is shunned upon as a basement has inherent moisture. Poly blocks and traps moisture which is the opposite of what you want it to do. Alot of inspectors, builders, and designers are still in favor of poly despite research that indicates otherwise. The best basement walls are those that are transparent to moisture (no barriers).
 

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Would you elaborate?
A stud partition that is only one story tall (floor to ceiling) does not need fire blocking. If the stud wall is balloon framed where it extend 2 or more stories without a demising plate, then fire blocking is needed to prevent fire migration from floor to floor within the stud cavity.

If the space is to be finished then a fire block will be needed to seperate the wall cavity from the floor system cavity. This could be done within the joists to allow the top of wall to still ventilate.
 

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In your photo it seems that the wall is a temporary wall or am I missing something here? Looks as though the wall behind it may even be an interior wall, as the angle of the photo is not able to show weather it is an interior or exterior wall. When taking a closer look you can see that the wall has gyproc on the other side so it is NOT an exterior wall.
 

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Discussion Starter #16
This is from Owens Corning's website. The majority of contractors said they would put a vapor barrier in the basement...

Question: What is the proper way to install a vapor retarder?

Tim writes from Hainesport, New Jersey: "I'm trying to determine the proper way to install a vapor barrier. I've just recently begun refinishing my basement; even though I've never experienced any water or moisture problems I chose to seal the walls and floor with DryLok just as a precaution. Now I plan to install 2x furring strips along the walls and put up 1 1/2" extruded foam insulation, tape all seams and caulk all joints. Then I will frame the walls with 2 x 4's and insulate with fiberglass batts. My confusion comes with the installation of the vapor barrier. Some things I have read state to install the vapor barrier closest to the warmest side of the room directly under the drywall. Others say to install the plastic along the concrete walls. Which is correct? Wouldn't the installation of the DryLok and rigid foam essentially be a vapor barrier? And, should I use fiberglass insulation that has a paper facing, or not, in conjunction with a plastic vapor barrier? Sorry this question is so long but I want to make sure I do the right thing."
Answer: We do not recommend a plastic vapor retarder anywhere in the basement. In your application there is no need to install an additional vapor retarder over the foam. You can install either unfaced or Kraft-faced insulation in front of the foam. If you choose Kraft-faced insulation, the vapor retarder should face the inside of the wall, which will be the warm side in winter.

:eek:
 

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Note: The vapor barrier is ONLY to be installed where the building is "ABOVE GRADE". Installing a vapor barrier below grade is not good, as concrete is not water proof and will allow moisture to penetrate it, therefore you need to allow it to move. The idea of a vapor barrier is only a small part of what is necessary to keep a basement dry. Drain tiles being set at the proper height, ground slope, soil type, location of house (city) etc etc, they all play a part in determining the needs of the building.
 

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Won't the basement end up being way too humid with no vapor barrier? My neighbor didn't have one installed and his drywall molded. I'm planning to just spray foam the concrete to act as a vapor barrier and insulation.
 

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Spraying your foundation walls with spray foam is a completely different set up all by itself. By the way, will you be using open cell foam or closed cell foam?, as there is a big difference and the end result might not be the outcome you would like.
 

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bmw 38, where is your location? This on fire-blocking, required in most all the U.S: R302.11 Fireblocking. In combustible construction, fireblocking shall be provided to cut off all concealed draft openings (both vertical and horizontal) and to form an effective fire barrier between stories, and between a top story and the roof space.

Fireblocking shall be provided in wood-frame construction in the following locations:
1. In concealed spaces of stud walls and partitions, including furred spaces and parallel rows of studs or staggered studs, as follows:
1.1. Vertically at the ceiling and floor levels.
1.2. Horizontally at intervals not exceeding 10 feet (3048 mm).
2. At all interconnections between concealed vertical and horizontal spaces such as occur at soffits, drop ceilings and cove ceilings.
From: http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_3_sec002_par031.htm







Page #2 should help you: http://www.diychatroom.com/f98/how-fireblock-framing-37190/index2/


Gary
 
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