Insulation question

Over the summer I remodeled my bedroom, partly to replace the radiators which blew over a winter. we put in a significant amount of high output baseboard heat. This winter we discovered that the baseboard was sufficient, but that it takes a tremendous amount of oil to heat the room. After some research we figured out that the room is made of cinder block on the outside coated with stucco. On the inside, there are 1 x 2'c to allow the plasterboard to be hung. There is one inch between the outside wall and the plaster. The only insulation is a sheet of moisture barrier. I am trying to figure out if there are any materials that I can insulate with, without tearing the walls down, that will allow me to decrease my heating bull. I'm thinking spray in foam, but would appreciate other ideas. Any thoughts?

I've got a brick house with the same interior wall construction. It's insulated with sprayed-on polyurethane; very effective, very pricey, but about the only option. You do have to remove the walls to spray it on, though, but that gives you the opportunity to tune up your electrical outlet configuration, add ethernet cabling, etc. There may be a spray-in, low-expansion foam product that will do the job, but I'm not an authority by any means.

I would like to avoid removing the walls if at all possible. There is a slow rise foam product that is designed for retrofitting. I have been able to find vendors who will sell it to me. I am still looking for other options if anyone has any ideas.

A 1x2 is only about 3/4" thick (assuming they are flat on the wall). 3/4" of even the best available foam is only about R3-4. Yes, it would make a difference, but not for the cost to install. Now, if you could only get it filled with an aerogel, it would be wonderful, but cost millions.

There are some systems that fill the cavities of the cinder block. While you'd still have the inside to outside highly conductive structure, you'd probably gain more.

Then, adding a full coverage (well, it wouldn't be full because of the strapping) foam, you might notice a difference.

Keep in mind that you'll need to put a bunch of holes in the drywall (in between each run of strapping) and the efficiency of filling up that space will depend very much on the quality of the installer. Typically, you'd need at least two holes in each cavity to allow air to escape and verify it is filled while the foam expands.

You'd get a much better result if you could live with a slightly smaller room and use a thicker layer of foam - if you made it thick enough, you wouldn't have to try to fill the cavities of the cinderblock.

An inexpensive help (relative to tearing the house apart), but not a solution might be from www.insuladd.com. Neat stuff, and more effective if you go to the trouble to use it both inside and outside.

If the cells of the cinder block are not solid grouted then you can fill the cores from the top with expanded vermiculite. whatever insulation you put in here needs to deal with moisture so loose fiberglass or cellulose won't work. expanded vermiculite can be poured in from the top.

bad news,
if you even want to attempt to do this right the walls need to come down.

Good news,
you don't need spray foam, i would use xps extruded polystyrene foam glued to all the walls then furring then sheetrock ETC. you could also use z bend metal furring strips if you wanted to loose minimal room thickness

Lou

I'm going to pop a hole in the wall and try to figure out how wide they actually are. It could be that the random spots I chose. The insuladd sounds like a great product. its expensive, but if it realy at an R value of 6 its probably worth it.

jadnashua, by the installer, are you referring to the person who installs it or the applicator?

As for cost efficiency, it wouldn't take much efficiency (currently the room quickly takes on the temperature of the outside) to become worth it. I used about 300 gallon of oil to heat just this room last winter, and I only heated it to 56. Once the cost of adding the insulation gets high enough, it will be worth installing a vented gas heater or a pellet stove. Problem is that the pellet stoves don't come small enough.

Where are you located? You may want to consider sacrificing a few inches of interior space and fur out the exterior walls even more, to allow a thicker layer of insulation.

Most of the better foams are not reasonable for anyone but a pro to install...the cans are just too expensive, and tough to ensure good coverage. You need someone who knows what they're doing to do that job.

But, with only about 3/4" depth, I think you are wasting your time...tear off the wall, install a good insulation cover, then put up some new ones. Take that opportunity to update the electrical - it probably does not have the required quanity of outlets per today's code, and if you are going to install some electronics, you probably want to run some new circuits anyways along with some CAT-5 and RG-6 coax. Maybe some more phone lines.

300 gallons of oil in future costs is around at least $1k/year. for that cost, you can afford to do it right to minimize the energy costs and have a liveable space. I do NOT think you can achieve it without adding more insulation, even foam, than that space behind your existing walls.

Keep in mind that you are losing a lot of heat through the floor as well. The ground temp may be in the 45-50-degree range all year and if there is moisture, it really conducts.

You may want to do something with the floor as well. This is problematic in many basements, since they typically don't have all that much headroom anyways.

shluffer said:

but if it realy at an R value of 6 its probably worth it.

Click to expand...

Its not. If it was that easy don't you think we all would have told you to go for it ?

Thanks for all of the advice. I will let you know what happens when I pop a hole in the wall and measure the space.

The bedroom sits on top of a garage. Either way, I plan on tearing the ceiling out of the garage and replacging the insulation. While I am up there I am going to seal any spaces / cracks I can find that may be allowing the cold air in.

The paint does sound to good to be true. as anyone tried it?

It's a radiant barrier, and yes, it does work. There is all sorts of independent test lab results. If it isn't applied properly it will not work. Now, if the walls are cold, it won't stop that, but it will reflect heat from the room back. It does add noticeable texture to the walls. Depending on the paint you mix it into, will vary how rough it feels. I really think your best bet is to tear the walls off, add insulation, then install new drywall. I'd consider either foam panels, or studwalls and fiberglass or foam-in-place.

what kind of foam in place can you use with wood stud walls? I already have wood studded wall in place in my basement and have learned here that foam insulation would be better than the fiberglass batts I was going to use.

While I was looking on line all I can find is foam insulation that is used with furring, I dont want to have to tear down all the 2x4 walls.

I'd consider the studwall as a thick firring. I think you'd get a better result with a pro installation. I've not priced the large spray cans, but my understanding is they aren't cheap. Not sure if in the current construction environment if the prices would be better or worse than normal, but I'd call around and get a few quotes.

How about rigid panels can I make them fit to the existing framing or do I have to tear all that down and use the furring strips?

Also how do I attach the electrical boxes?

jadnashua said:

I've not priced the large spray cans, but my understanding is they aren't cheap.

Click to expand...

I priced them a while back and was stunned by the cost, even though I expected it to be high. This is one job you want done professionally. The sprayed-on foam is applied after the studs or furring strips are in place.

Most foam panels are fairly easily cut. It gets really interesting going around electrical boxes, wiring, and potentially plumbing. The spray foam fills it all in much better.