Confusion on Basement Insulation
Hello All,
This is the first time I have posted anything here so please be patient with me. I am a DIY’er who is in the process of finishing a basement that was once finished. We bought our house as a foreclosure and at some point after the previous tenants moved out and the bank took over the finished basement had flooded. The bank removed about 7′ of drywall and the insulation that was installed previously.
The basement is block with a waterproof coating on the exterior. The builder had put a sheet of 6mil poly against the block, insulated the stud bays with fiberglass and then applied another sheet of 6 mil poly and then the drywall. From everything I have read this sounds like it is not the best option for a basement.
I have finished a couple of spaces in the basement with ridged foam and spray foam. I have removed the poly that is against the block, and the stud walls are still in place and sound. I have cut 2″ ridged insulation to fit between the stud bays and to seal it I have gone around the edges of the bay and sealed the studs to the foam board with spray foam. From there I have drywalled and finished as normal.
My question is, is this a sound method of insulating a basement that already has the stud walls in place? I have seen methods similar to this except the board is run directly to the block and the walls built in front of that. I am looking for any feedback you all may be able to offer.
Thanks in advance for your time!
Replies
There is no perfect way to finish a basement wall.
At first look it seems ok - it depends on some vaiables though. What part of the country are you in, what are the local building codes, etc. Where I am we have to have a 1" gap between framing lumber or non-rigid insulation and the concrete walls. We also need to have solid horizontal fireblocking at the top of the walls, and vertical fireblocking every 10 ft. I prefer having the 1" gap since it makes me feel like moisture isn't running down the back of the insulation necessarily, but the fireblocking limits some air movement.
Definitely good to get rid of the double poly sheet sandwich.
Check out Joe Lstiburek if you have a bunch of time on your hands - he writes extensively on the subject of moisture and walls and such and explains some good theories.
Scroll down. Click on the Green Building Advisor link you'll find. Search "basement insulation."
Your thinking is pretty good. The biggest flaw I see in your approach is the question of whether the framing is in contact with the basement wall. It shouldn't be. But even if it is, what you've done is probably better than what was there.
Thanks Andy
Thank you for the recommended link. I will check that out.
As far as the framing goes, it is about a 1/2" from the block.
Thanks again,
Ben
Try these things called paragraphs.
They break up your block of text and enhance comprehension.
A blank line between the paragraphs will further enchances this 'R' level.
Good luck.
Yeah, but then you gotta figure out the topic sentence and summary sentence and how much to indent and you're right back in high school!
Sorry...
Like I said, it was my first time in a forum environment. Now I know better...
ben
Welcome to BT.
I sat here and read and used the search and didn't bother to post for several weeks. This was around '98.
The last century.........
After a while I got up the courage to post. Glad I did, the information and friendships I've acquired here are priceless. Below are some thoughts to keep in mind.
There are several things you can do to help put forth your message. Paragraphs, sentences with periods........all that grammar stuff. This is not texting, so the need to fill out the post with all the pertinant info is a good thing.
Pictures help too. We can only see through your words and you know the saying about a picture.
Background of both yourself and the project is real good. Your location doesn't hurt one bit either. Area / seasonal / regional differences are important as they guide answers to your specific situation. Something in Alaska might not get an answer of what to do from someone in the Sahara.
Don't get discouraged easily and try to have a bit of a thick skin. And take info given as maybe not gospel. Some that frequent this site are experienced builders, some are skilled diy'ers. There's of course the occasional 14 yr old with too much time on their hands.
Remember to take the replies and to study further. Some replies are valuable, some worth what you paid for them.
Best of luck.
Thanks!
Thank you Sir for the advice, I really appreciate it! I will add some more info as a follow up post above. I just got carried away trying to get it all down and left out some information that would probably help. Thanks again!
Additional Information
Hello All,
After reading some of the replies I have received, I thought it may be a good idea to add a follow up to my original post. Here are a couple of other items I should have included in the previous post:
- I live in Southern Minnesota:
We really experience swings in the weather. Summers are hot and humid, and winters are COLD. As far as moisture it is somewhat hit and miss. Last winter we had 12" of snow total and a very dry summer. This year it has been the complete opposite.
- Existing framing and distance from block wall:
The framing is about 1/2" away from the block and this is consistant throughout the basement. Wall have top and bottom plates and studs are 16"OC.
- Photos:
I have attached a photo of a small section so you can get a better idea of what I am thinking. It isn't pretty, but in my mind it makes sense. 2" rigid insulation cut to fit between stud bays and sealed all the way around with spray foam. Drywall would be applied after that.
Thanks again for any feedback, take care.
Ben
I second what Andy Engel said: what you've done is leaps and bounds better than what you had. Ideally the wood framing would be completely isolated from the foundation wall, but this isn't likely to be a dealbreaker in your situation. Best of luck on keeping things dry!
Flooding!
You write that the basement was flooded!
Before you spend any time and money - you need to consider what will happen the next time it floods and the time after that.
Sealing the walls on the outside, hasn't worked and is still leaving you with a problem.
You need to look outside and find out where the water is coming from - and sort that first, before you throw your time and money away. You may be flooded again tomorrow!
The Flooding
The flooding from my understnading was becuase it had gone into foreclosure and there was no electricity in the home. This was during a very wet winter and the sump pump was not running. Since we have been here we have put in a new sump pump and a Sump Jet system that runs from municipal water pressure.
We are in the middle of an extremely wet spring, the sump pump is running like crazy and aside from a small pinhole in a section of the morter that has let some water in, the basement is dry.
Basement flooding.
You have a serious problem.
All it takes is for your pump to break down and all your work, plus the contents of your basement will be spoilt.
I propose that you fit another standby pump that will be actuated by a float switch with a siren to alert you to the problem.
You really must find out where the water is coming from and deal with this externally.
Are you on a hill? Is the rain running down the hill? Where are you pumping the water to - hopefully down hill and away from your property.
Watch the water running down your yard, does it come towards the home or perhaps you have clay and the water is running underground? A ditch round the home to intercept the water and run it away downhill will work. You can do without the worry that your pump might die the next time you have heavy rain.
Basement flooding.
There are many issues as i understand first of all where are you living? what is the building codes in your area and have you checked your basement wall again because may be there any damage remaing so it is my suggestion to you you have to consult with the good builder. we can give you many ideas but buider or renovtor can give you good suggestion to prevent any further damage and it will save your money and time also.