Hello
I’m planning to finish my basement, starting in a couple of weeks. I’ve been spending the last 6 months, at least, trying to figuring out what’s the best way to do it. I read everything possible but the more I read the more confused I get. And that’s why I decided to ask here.
my House was built in the 1940s. Basement walls are dry. Actually the basement in general looks very dry. Temperature without heating is always constant (64/66 degrees in winter time and 68/70 in summer). In summer time I need to run the dehumidifier other ways humidity will be around 75%. The previous owner painted some walls with an oil paint, I started scraping parts that became loose. Beyond the paint there was no moisture.
in some spots (the one not painted) there’s some efflorescence that I’m vacuuming once every 5/6 month.
I want to start with the best insulation for the wall and then I’m gonna concentrate on the rest.
I’m planning to use rigid foam for the walls and then metal studs and gypsum board at the end (leaving the cavity empty)
Do I need to paint the walls before using rigid foam? If yes, which paint?
Wich rigid foam insulation is the best way to go (this is where I’m really scared to make a mistake)? EPS or XPS?
I know that EPS will be vapor permeance while XPS will completale seal the wall.
for me would make more sense to let the wall to transpire but maybe I’m wrong.
Please help me make the right choice.
Thank you
angelo
Replies
If I decide to go with EPS what about this product:
https://www.homedepot.com/p/R-Tech-1-in-x-4-ft-x-8-ft-R-3-85-Insulating-Sheathing-320821/202532854
I would use rock wool because nothing tunnels in rock
Thank you Mikeolder, I’ll check into it. Never thought about rock wool for basement
I have a basement similar to yours and after scraping off all old loose paint I washe'd down all the walls with a 50% bleach solution and rinsed thoroughly to kill off any mold spores. I then patched any holes with mortar spot primed the patches with Zinsser mold and mildew waterproofing paint. Then two coats of the same paint on all walls. XPS on all walls adhered with Great Stuff insulating foam and sealed any gaps with same. All joints are sealed with Tyvek tape. Did the joist band in a similar way with the foam. Bottom plate is treated two by and wall studs are regular twp by. Mildew and mold resistant drywall for the walls and switched to cement board in the utility areas. I was pretty happy with it all in the end.
Thank you user-6819651
I was not sure about painting or not but I think it makes more sense.
And I like the idea of mold resistant drywall, didn’t thought about it.
How thick is the XPS board? 1 or 2 inches?
I used two inch to maximize the R-value. You could do even better my adding unfaced fiberglass in the stud spaces or rock wool. I thought about it but I wasn't sure it was necessary in my case. I think painting the walls is a good idea just because it seals them and you'll have the peace of mind knowing that no moisture is migrating into the space behind the insulation. You said your humidity was around 75% which to me seems pretty high. I keep mine around 55%. My basement has always been very dry but just to be safe concerning any mold I run two dehumidifiers one each in different areas. One is set slightly lower than the other. In tandem they bring the humidity down to where I want it and the lower setting on one helps to maintain the level. That one is in the laundry room and the other in the main space.
Thank you!!
No my humidity is at 75 if I don’t use a dehumidifier. With the dehumidifier I keep it under 55 too.
Which paint exactly did you use? I checked and they make two different kind at least.
Is maybe this one:
Your friend has shared a link to a Home Depot product they think you would be interested in seeing.
1 gal. WaterTite Mold and Mildew-Proof White Oil Based Waterproofing Interior/Exterior Paint (2-Pack)
https://www.homedepot.com/p/204068078
That's the one I use. The oil base. I used a high nap roller to apply so I could get thorough coverage. I roughed up the old surface with some 80 grit sandpaper to get good adhesion and then wiped down before painting. Earlier, after I had used the bleach solution, I also rinsed the walls with water to get rid of any residue from the bleach. I don't think I mentioned that step. Some of my walls had been painted with who knows what several times by previous owners but this paint really stuck. I noticed afterwards what said about the humidity. My apologies. Sounds like you're on top of it.
Thank you.
Yes in my case too, the previews owner painted probably several times before the oil paint on top. I hope the oil paint didn’t came loose because of water pushing in. When I scrap it looks very dry in the back.
Why are you painting walls that will be covered with insulation? It's a whole bunch of work and it doesn't provide any sort of waterproofing. I would just remove anything loose and then cover it with the XPS insulation.
When I did my basement I made sure to leave a 1/4 gap under the sill plate to allow for some air movement and to keep the plate from contacting the concrete (moisture will wick up through the slab) I used some pvc/azek but stacked washers would work too.
Moisture proof sheetrock is good but dense armor plus (fiberglass faced gypsum board) can be completely submerged and then dried out without removal and nominal additional costs.
Should you choose to add insulation to the stud bays use rock wool. It can be saturated and then allowed to dry without loss to the R value. Fiberglass insulation needs to be removed if it get wet.
thank you Steve,
I wanted to cover with paint just as an extra peace of mind. My walls are not wet and never saw water coming trough but I can see that In some spots there could be some condensation.
I’m attaching a photo.
I don’t want that some condensation would be trapped between the wall and the rigid foam.
I like the idea to leave a gap at the bottom.
Even just to inspect.
I was think doing the same for the floor using dmx1 step as an underlaiment for an engendered bamboo floor
One thing I did fail to mention was that I placed felt paper under the treated two by for the bottom plate of the walls just to address the issue of water wicking up through the floor. Local codes required it anyway but I already planned on it before I started the project.
I personally felt the painting was necessary because the basement is being used as a finished living space and I wanted to address any issues with water potentially penetrating from outside the foundation. I assumed that the blocks had been tarred on the outside and I knew that I had tiles on the inside and outside of the foundation but the house is seventy plus years old and there may be cracked from settling and pathways for water that I'm not aware of. I'm just covering all the bases so I don't have to worry about soaked insulation that I have to remove or any water behind the walls that needs to be drained. I think it all comes down to how you want to use the space.
I’m gonna use it a finished living space and like you I don’t want to worry.
Have you seen the pictures I attached in the previews posts? Do you think the walls are good?
I don’t know your name, in the meantime thank you for your explanations
Your walls look a lot like mine did before I started and I had all the same concerns as you. What I did worked well for me. I primed any bare block with the Zinsser's before I started applying the first coat. From viewing the photos, everything looks fine to me. No moisture and no cracks or holes left to patch, I think your good to go. Dennis
Thank you Dennis!
Dennis, how did you finish your floor in the basement?
If you are worried about moisture coming through the walls the paint will be absolutely zero help. The whole beauty of this assembly is that the XPS will allow for gradual drying to the interior if needed and there should be no organic material to support mold growth.
Thank you Steve,
what you say makes sense too. I think there are different approaches. And there's not an universal one. Now I have more info to work on.
Steve my I ask how you finished your floor?
I used Luxury Vinyl Plank (LVP) directly over the concrete floor. It's waterproof and wears well. A better method would be using XPS and plywood over a concrete floor for the same reason as the walls- it will insulate and slow down moisture transfer because of low permeability, but it will still allow drying to the interior. Unfortunately I did not have the head room.
I have the same problem, no too much head room. I was thinking about using dimpled membrane and bamboo floor on top.
I'm four years into my basement and have no issues at all. The dimpled mat is a great product but it's expensive if you dont need it. I would only use the mat if there was clear evidence of moisture from the floor slab. If your slab is fairly dry skip it.
I have used InSoFast insulation panels in several basements. They install quickly. No need for studs. Drywall attaches with adhesive and screws to the black plastic strips. Have to frame around window openings with wood. Highly recommend.
Thank you Paul,
Looks really interesting. I’ll look into it.
Sorry if I am being redundant here: https://www.finehomebuilding.com/2005/03/01/the-no-mold-finished-basement?fbclid=IwAR0d_UUPCBRVMgrgYBEeEgDdCtTI6nTwEecY2vFWplcjPxdaQeIubFoy9n8
is the best article in a while...
Yes I read that article, but still a lot of doubts, it’s a great article but doesn’t have all the answers. Every basement is different and I feel much better listening to different experiences.
My only advice would be to not do what the previous @!$&#*% owner did in my house. It was 2x2’s nailed onto cinderblocks with extruded polystyrene and plastic.
Bugs burrowed the crap out of the insulation sheets and there was a ton of rot and damage.
When I do eventually re-do it, I plan on using the rockwool sheets on top of the block with metal studs over that and rockwool batts in the cavities. Expensive but this is one thing that you want to have right the first time.
Wow, He really made a mess. The biggest mistake was using the plastic sheet on top that trapped any Vapor. I'm sorry. I can understand your feelings. I had to fix many mistakes from the previous owner in my house and still I have many to fix.
I'm not sure where you are located, but before you start your basement project I would advise you to test for radon. Huge areas of North America are affected, and it is the second leading cause of lung cancer after smoking.
If you have children that will be using the space I would definitely test for radon, since they are very susceptible to the effects.
It's far easier to plan out and install remediation, if need be, before the basement is finished.
I was shocked to find that I had levels ten times greater than the World Health Organization limit.
Thank you MrPragma,
I tested already for Radon. That was the first thing I did before even thinking about redoing the basement. Fortunately there are no problems with it.
Hi, i'm new to home renovation service. I started a course few months back which has been a DIY course mainly. And now i'm noticing my basement leaking out moisture due to lack of insulation. So, i am thinking of insulating it myself, though i read a couple of tips share by https://pickmythings.com/basement-encapsulation/ as a clue to basement insulation but still skeptical about it DIY. But if i have to hire a professional i would spend more and that's another big consideration for me. My question, should i do it myself or hiring a professional best?
Pls, i need assist on the way forward......
It all depends on how bad is the leaking. Before trying to finish the basement you need to address the excessive moist or leaking. Attach some pictures, in this way it would be easier to understand your situation
Okay, Thanks, for the suggestions
Came to comment what AngeloDs has already mentioned. It is very hard to assess the situation without some visual.
Here's An article from this magazine
The proper order is XPS furring strips then drywall
https://www.finehomebuilding.com/2004/05/01/built-wrong-from-the-start