Insulation for basement walls

Jimbo_5

Have a 1930s house with unfinished basement.  With 2" supply & return piping  uninsulated running throughout the basement, I think it's time to insulate the perimeter walls.  Any idea where I might look to find out what type of insulation and what r-value would be best?

Jack

I think Corning makes

a system for basement walls.

Al Letellier_21

insulating basement walls

Very good idea to do what you are planning, and there are many options available to you, from the DIY store route to the profession insulating contractor. If your walls are uneven, a sprayed on insulation would be your best option. If poured concrete or block, you can use a rigid board to do the job. Just remember that most rigid and foam insulations have very limited fire rating and have to be sealed or covered for safety and insurance reasons.

Corning does make a system but it is designed to give you finished living space, not just insulation. I would suggest consulting a professional insulation contractor to find out what your options are to match your budget.

nicholas bonham-carter

insulation

maybe starting with the pipe insulation would be a good idea.--nbc

Jamie Hall

Start with the pipes...

minimum 1" on all steam supply lines.  Also on any domestic hot water feeds, etc.



As noted, there are any number of ways to insulate the perimeter walls.  However, a few notes.



First, find and stop all the draughts coming between the house sills and the foundation walls.  There are expanding foams in a can which do a really nice job on that; any big box home improvement and most local hardware stores have it.  Also go after any draughts around windows, doors and hatchways.



Second, insulation from a foot below ground up to the basement ceiling is much more important than insulation from there down to the floor, provided of course that it is sealed at the bottom to the basement walls.  Ideally it will be adhered tightly to the basement walls; as Al pointed out, if the walls are at all uneven, a spray on is going to be your best bet.  If you leave an air space behind the insulation, it is going to get damp, with possible rot or mold problems.



Now a very important point.  Do you have any water coming in to the basement?  Either real streams of the stuff, or persistent slight leakage?  (Not just condensation dampness, that doesn't count).  Because, if you do, that should be eliminated from the OUTSIDE.  I have seen a number of situations in which an effort was made to seal up water entry in basements from the inside, and the results were never, in my experience, satisfactory (with problems ranging from the mild -- damage to the finished basement walls or floor -- to catastrophic -- collapse failure of a portion of the foundation wall).  So, if you do have water entry problems, and you want to eliminate them, you have to provide sealing and drainage on the outside.  No option, in my professional (Civil Engineer) opinion.  On the other hand, you can stop the insulation as noted about a foot below ground level and let the water flow; this may or may not be a problem depending on what you want to do in the basement.



Again, as Al notes, most insulation has a very poor to horrible fire and flame spread rating.  Therefore it should not be left exposed, if possible.  In fact, it is possible that local code may require a fire resistant covering of some kind.

D107

Insulation

HO here. On 'This Old House' and 'Holmes on Homes' I've seen them use spray foam or rigid insulation first, then horizontal 1x3s then vertical studs then non-paper sheetrock. the 1x3s provide a space to run electrical or plumbing lines.......

D107

question for jamie

Should we assume that effluorescence is evidence of water entry? I've seen various solutions to that, from both inside and out.......

Jamie Hall

yes and no...

Efflorescence can be evidence of moisture seeping through a basement wall from outside -- but only at a rather small level; most basement construction materials are not really waterproof (concrete, for instance, isn't really waterproof, although the water moves pretty slowly!).  It may indicate that the exterior waterproofing is damaged -- or was never there in the first place -- but it is not the kind of water entry problem to which I was referring in my original post.  There are several ways to reduce the problem to a non-worry.

Jimbo_5

Here is a photo of

The crawlspace under the in-law's house, 1/4 basement, 3/4 enclosed crawlspace, near NJ shore.  House was built late 1800s, and I'd like to make it a little more comfortable for them.  Until 5 years ago, it was heated by an "octopus" gravity-fed scorched air furnace with 8" & 10" ducts running beneath the floorboards.  As an amateur, I suspect the extreme heat generated by this beastly heating system slowly drew the moisture in through the brickwork.  I'd like to make conditions a little better for them.  As you can see from the 2nd photo, I have tried putting pink board (R-10) against the outside wall.   Any ideas?

rlaggren

Everything I've read

in the last 10 years says to seal up draft leaks first and totally. Below the sill plate, through butt joints in the siding, utility penetrations, masonry cracks, between door jambs and masonry... The whole million nine yards of it. Hateful but nothing else will return your money near as good, and those drafts will sabotage any insulation you install over them.



If you have enough little leaks on a rough surface, than it might be worth doing the sealing and insulation at one (expensive) stroke with spray-on foam.  There are a number of considerations, mostly relating to water and water vapor that you need to settle before taking that step. Talking to several insulation guys and doing a bunch of reading on the net or the library would be the right thing. The big bite is sealing all the drafts but you have to know what's going to happen to the moisture, both from inside the house (stuff we all breath out) and outside (humid summer, cold pipes, moisture rising from below, whatever...).



Rufus

Jimbo_5

Thanks, guys

I thought of covering the pipes, so we covered the new fintube piping,  Never thought of covering the exhaust vent, but will try that.  Will check the return temp tomorrow, yet I do believe it is in excess of 140 degs.  I am thinking of cutting fiberboard to fit between the floorboards to eliminate drafts between the wall studs.  I have heard the boards must be covered, so I was considering cutting paneling or something to fit over the fiberboard, "gluing" them together then installing it.  I can actually feel the drafting between the wall studs.  The outside brick walls have been plugged wherever needed.  And I am laying down 6mil plastic to cover the  dirt floor portion.  I guess I most need some ideas on how best to insulate the sill plate and openings beneath the wall studding.  Any suggestions or ideas or web-sites will be warmly welcomed.

Larry Weingarten

web site

Hello:  Here is a site that should be helpful.  http://www.buildingscience.com/  Joe L. is the go to guy in the "building envelope" field.



Yours,  Larry

rlaggren

Sealing for

poets we used to say about the 001 level science courses.



http://www.habitat.org/env/pdf/air_sealing.pdf



But makes sure you hit all the main points.  Then you go on from there.



Oh, and the link in the previous post might work better for you if you copy it first so you can paste it to the address line where you can then get rid of the trailing blank space.



Rufus