Basement Insulation Questions

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jon g
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Basement Insulation Questions

Post by jon g » Tue Nov 07, 2017 2:30 pm

First off thanks for taking the time to make the informative videos on youtube.

I live in ST John's Newfoundland Canada so its a WET & COLD climate, my house is 10 years old, i have had it for 6 years. We have our first baby on the way and need the room, so its time for me to finish the basement after a few failed attempts. (long Ugly Stories) I have a full 8' concrete wall in the back of my basement and the other 3 are 4' concrete knee walls with a fiberglass insulation in a 2x6 wall on top. I started with the Removal of my previous attempt right to concrete. The floor is done with insulated Barricade subfloor tiles.

Working on the back 8' wall I reinstalled the Rigid SM 1.5' from sub floor to floor joist, joins are NOT taped. I acoustical sealed the bottom 2x4 to the sub tile and screwed my top plate to the bottom of my floor joists. I decided while i was at it to take the vapor barrier out of the rim joists and add more fiberglass insulation. I added a scrap of SM next to the sill plate so the fiberglass would not fall down onto the concrete. I cut and installed Rigid for the end of the rim joist this was sprayed foamed in. I finished up with installing all the studs at 2' centers.

So my QUESTION ..... i read that the Rigid acts as a Vapor barrier. My plan was to leave it un taped and not air tight. Install fiberglass in the wall between the studs and add a sheet of Vapor Barrier just like a normal wall.

How do i approach the knee wall ?


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Shannon
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Re: Basement Insulation Questions

Post by Shannon » Tue Nov 07, 2017 7:59 pm

SO in some areas they will allow 2" rigid foam to be used as a air/vapour barrier when it is well sealed. In your case you have 1-1/2" rigid foam so I would leave it un taped and then use a poly air/vapour barrier under the drywall.
For the knee wall area you will be doing basically the same process just that you are only half as high. and people usually finish the top with wood/drywall or MDF and create a ledge because if the difference in wall thickness. The air/vapour barrier will come down the upper wall out across the ledge area and down to the floor .
Hope this helps
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jon g
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Re: Basement Insulation Questions

Post by jon g » Wed Nov 08, 2017 12:41 pm

Thanks for the reply !!!
keep up the good work on youtube !

jon g
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Re: Basement Insulation Questions

Post by jon g » Mon Feb 12, 2018 9:17 am

Hi Shannon what are your thoughts on CertainTeed membrain ?

https://www.certainteed.com/building-in ... /membrain/

http://view.ceros.com/orange-tap/certai ... gement/p/6

this might be the answer to many peoples problems



Thanks

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Shannon
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Re: Basement Insulation Questions

Post by Shannon » Mon Feb 12, 2018 7:19 pm

I actually have not used it yet but if it works the way they say then I think it is a perfect product in climates like ours where we get drastically varying weather through out the year.
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jon g
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Re: Basement Insulation Questions

Post by jon g » Tue Feb 13, 2018 11:34 am

Just a update on my MESS

I have the 1.5'' rigid up against the concrete taped and sealed all the joins (re reading your advice now and you suggested to not do this FML)

2x4 wall is studded with pink fiberglass insulation

i was having mixed feelings on what to do next

1. put gypsum up without vapor barrier
2. Put up vapor barrier then gypsum ( this would make a situation with two vaper barriers) what would happen ?
3. use the CertainTeed membrain but they say not to use with a vapor retarder in place (rigid)
4. move

My house is only 10 years old it has a air exchange and the heat is on

I am just overthinking this but for my own sanity i need to come to a definitive answer.

If i had bought the 2'' then studded the wall filled with fiberglass insulation i would have been ok with no VB

anyways thanks again for what you do in this site

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Shannon
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Re: Basement Insulation Questions

Post by Shannon » Tue Feb 13, 2018 8:15 pm

The taped seams will not be a huge issue so don't fret about that.
You for sure want to not do you #1 choice ,skipping the air/vapour barrier. Either #2 or #3 is fine. 1-1/2" rigid foam is not considered tight enough to be a vapour barrier so no issue there. I would prefer the Certain Teed smart vapour barrier. They only state to not have it covered with "low perm. interior finishes like vinyl wall paper or a paint that acts as a low perm covering. so the foam on the other side of the wall is fine. Continue forward ! :)
Here is a link to the Certain Teed sheet so you can read that again if you like .https://www.certainteed.com/resources/30-28-080.pdf
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Re: Basement Insulation Questions

Post by jon g » Mon Nov 26, 2018 8:12 am

The never ending basement project HAS to come to an end for my own sanity and wellbeing, I OVERTHINK everything and want this done RIGHT as our house is our home.

I am back at it again we had a baby boy so life got real busy and the basement project came to a halt again! But we now need the room

Shannon thanks again for doing what you do, I recently watched your videos on electrical rough in and dry walling and you gave good clear honest advice. So to recap

Attempt #1
Installed 2x2 insulated flooring tiles tight to the concrete wall (mistake) Bought 1.5 ridged insulation (mistake) to go up against the concrete, Built 2x4 walls Started to get a smell in the basement as the wall was getting condensation and water was running down on the MDF tiles that were tight against the wall and swelling the edges

Attempt #2
Decided to remove the wall that I had built and go back and cut a ½ to 1’’ of the flooring tile so it would not be up against the concrete wall and wicking moisture and going moldy. I used PVC fake wood cut into small block to space the floor tile away from the concrete wall.
A donation of 2’ blue rigid foam was made and I decided to use this to replace the 1.5’’ to put against the wall and let it sit on top of the pcv fake wood in parts it sits on the 2x2 tiles. This is my moisture barrier so it will not be taped. The 2x4 wall will be made and insulated with fiberglass then vaper barrier and gyprock.

Question #1
I am thinking I have made a mistake here as the rigid form does not go all the way to the concrete floor allowing the 2x2 tile to still be exposed to moisture although it is spaced ½ to 1 away with the pvc block.

Info for question #2
I have some moisture on a section of wall on the front of my house, its damp no drops of water but damp and if you rub it your hand smells like basement I need to address this issue as it will come back to bit me.
House is 10 years old has weeping tile (supposed to) had rain gutters installed one from the main roof drains on the Conner of the wall in question. I will be extending the gutter so it is out into the lawn.

The place where this dampness is down low right next to the floor it has a ¼’’ gap in the cove joint between the floor and the wall. I am thinking that cold air is coming up through the cove joint and condensing on the wall. There is a spot 12’’ away where the cove joint is tight and there is no sign of moisture.

Question #2 I spray foamed the cove joint in this area to see if this would help. I am thinking about doing this to the rest of the cove joint. Wondering your thoughts on my theory of cold air in the cove joint causing this and any reason not to spray foam the cove joint ?



I do not have any other water issues, the heat is on but I admit i do not have enough heaters yet, I also need to add more lines to the venmar but that stupid thing has a list of its own questions.

I also contacted my local building department about getting a permit while I was talking to the on duty inspector I asked about insulation they said
“ 1.5 not taped is fine for renovations, studded wall, fiberglass with vapor barrier”
“ new home construction is 2’’ not taped with 2x6 wall, fiberglass and vapor barrier”

I looked into using the CertainTeed membrane and no suppliers in my province carry it so I guess this option is out.


Thanks again :)

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Shannon
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Re: Basement Insulation Questions

Post by Shannon » Mon Nov 26, 2018 6:55 pm

It would be better to have the foam right to the concrete floor IMO but not the end of the world. I actually don't build my walls on the Dricore floor panels but it is ok to do ,so again you are fine.

Insulating and finishing a basement in cold season does tend to get your walls to be damp. Humidity is higher with the new lumber in the house and the walls are colder, so the moisture does not surprise me at all. Is the moisture coming from the cold joint between the concrete floor and concrete wall? I doubt that is the case but I suppose it could? Basement wall corner areas seem to be damper from what I have seen over time I think a lot of that has to do with less air flow in the corners to distribute warm air?? Foaming that gap should not effect anything so fill it in if you wish.

Now get his basement done before you procrastinate any more! LOl.
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