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What's the best insulation to use in a existing home.


mikecsti's Avatar
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06-20-13, 10:40 AM   #1  
What's the best insulation to use in a existing home.

This is what I have. My house was built in 1961, 2x6 walls 1/2" ply with 1" white foam with alum. siding.

I'm gutting my master bathroom soon so I was going to pull out the old batts.
What would be the best for me to put back in to make it air sealed and have the best r-valve? I'm trying to make the house the most energy-efficient i can. one room at a time.

I had some ideas,

caulk where the 2x6 meets the ply and then buy Super TUFF-R R-3.3 1/2 in. x 4 ft. x 8 ft. Foam Insulation. Then use great stuff, then spray foam in the corner to do the edges then put in a batt of r-19. so thats good for a r-22.3.

or the same but use that Roxul R-23 15-1/4 in. x 4 ft. Steel/Basalt Insulation for the batts and that's a 26.3.

or I can put all tuff-r together 5 to make a r-32.5

or I can use Reflectix Reflective Insulation thats 3/8" thick with a r-3.7 and not the tuff-r.

what would be the best for the money too. and I'm going to use blue board 1/2" rock for the walls and ceiling.

and for interior walls I was going to use the Roxul batts for 2x4.

 
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06-20-13, 11:58 AM   #2  
Hi Mike, to be honest, the only time the r-numbers are important is when you need them for meeting code. They do guide you, but air sealing and dense insulation like Roxul will provide better results than counting just r's.

You are cold country so they want you to install the vapor diffusion retarder on the inside and allow some drying to the outside. That is unless you plan to use a lot of air conditioning. Note the term "vapor diffusion retarder" as opposed to vapor barrier. Different materials offer different levels of vapor diffusion control.
BSD-106: Understanding Vapor Barriers — Building Science Information

IMO, just caulk the holes, install 6" Roxul, and cover with a layer of plastic if no air conditioning. It should still allow some drying to the outside through the white foam and sheathing and the Roxul and caulking will shut down any air circulation within the walls.

If you want to take it up another notch, then add a inch of extruded foam and tape on the inside and omit the plastic. Then your drywall.

There are other factors that come into consideration, such as your heat source and other improvement options. If you just want a DER (deep energy retrofit) I completely understand .

Bud

 
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06-21-13, 07:08 AM   #3  
Thanks for the info, yep I do need the plastic, I forgot the Roxul dose not come with a vapor barrier.

I was thinking of the Reflectix Reflective Insulation because not of the r-valve but of the reflectiving valve. Do I not need that? The 1" styofoam on the out side dose not have reflective paper on it. I would say it's from the late 70s to 80s.

Yep I know, been doing it all.

 
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06-21-13, 07:29 AM   #4  
Adding a radiant barrier in a cold climate has not proved to be excessively beneficial, especially on a vertical surface. It gets technical, but a RB in conjunction with an air gap blocks 2 of the 3 modes of heat transfer. However, it increases the third. If you have drywall, air gap, and then a RB, the heat is reflected back to the drywall. That increases the convection within the gap and the RB gets warm and the heat loss continues.

When the benefits of a vertical layer of RB are measured, an equal layer of insulation works better.

Now, when applied horizontally in locations where it is warm above and cool below, convection is suppressed or stopped and a RB can be very effective. In your case, as long as the RB goes on the inside (it may also be a VB) it will not hurt.

No foil on the outside white foam is good. You do not want a VB out there.

BTW, my DER is in the process of adding 3.5" of rigid on the exterior, from foundation to top plate. 1/2 done and results have been impressive. If my old bones hold together I will finish this summer.

Bud

 
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08-08-13, 11:54 AM   #5  
I'm bring this back because I have some other question on what should I do.

Now in another room/rooms.

I had my attic spray foamed last year, so that's helping big time with saving but what else can I so, I thought.

I do not like the idea of that injection foam, do to it may shrink a little and then the walls have 0 insulation plus its prices as hell. So I could get somebody to come in and blow in dp cellulose into the already insulated walls but there no vb if I do this. plus I'm thinking this stuff is not good in my family room that has 0 insulation with block walls on the outside. I'm thinking a mold problem may happen.

I was thinking of putting the Roxul in now insulated walls. But I have to take out the old drywall and old insulation. Plus I would caulk all the joints and so on. Is it worth my time and money to replace the old batts with the Roxul? And then put in a vb and new drywall? Will I see a big difference?

And for the interior walls. there still is some air flow I feel moving in the interior walls so I was thinking of using Roxul in there too. Do I use Roxul with just the sound proffing one or the r valve one? and again I have to take out the drywall to do this. I like the fire rating on this stuff so incase something happens like a fire, it can be contained to one room, thats my thought is away.

thanks

 
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08-08-13, 12:19 PM   #6  
If I'm reading your last post correctly, you're considering blow in dp cellulose into already insulated walls as an option?
I have walls insulated with the stuff (house built 1930's, probably no insulation before this stuff).
It may be better now, but the stuff settles, doesn't get into all the areas (around and below windows) and doesn't have much insulative value without being placed with volume (think 12" thick in the attic). I wouldn't recommend this route personally and don't think it would work with existing insulation. It is better then no insulation, but not nearly as good or cost effective as installing new batt.

Did you ever find out what value or quantity of insulation existed in your other room? The first room may have been a good indicator if the ROI was there to continue with the insulation in other rooms.

Mike

 
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08-12-13, 05:26 AM   #7  
Yes I was thinking about using dp cellulose, but there will be no vb if i did so and that's what I was worried about. my wife thinks taking down the walls is a wast of money and cellulose is the answer. I told her no it's not.

Well I did not start that yet, My plan is to do it all at the same time. But I did open up a section to see it and that's what got me thinking to take the other walls down. Old yellow batts with paper. Looks to be r-19 plus it's all nasty looking, all dirty from so much air movement through the wall. and the papers not really over lapping like it should on the studs. They stapled it to the sides of the studs, not the face so they made the r valve smaller doing that.

 
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08-12-13, 05:48 AM   #8  
R-19 is a lot better then some of us have (currently). I think current code is R-23 in my zone (north of your location).

I would avoid going with the cellulose in the walls, specially if you have reasonable decent insulation currently. It's cost of installing will not be recovered in heating savings.

 
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08-14-13, 08:57 AM   #9  
ok I see what you're saying, I was thinking of getting somebody in my house with one of those ir cameras to see where I can make areas better.

So on to my other question about the interior walls. What should i use? MY attic is air sealed now but I still get drafts down the interior walls. THey sprayed the roof raffers not the floor.

 
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08-15-13, 03:22 PM   #10  
Use the camera. Bud gave a good link in Post #2, Figure 4 if it fits. Add foam board first then any fibrous cavity fill, IMO- R-19 my last choice- inherent with convective loops- read low density, allowing heat circulated degrading R-value immensely. Pp. 45-47; http://www.buildingscienceconsulting...Measure_Up.pdf

http://www.builditsolar.com/Projects...n/Colorado.pdf

Air seal the basement/crawl first, attic next, caulk against the bottom plate/decking joint and ADA the drywall; Info-401: Air Barriers

Gary

 
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