The best way to insulate a house

jp_2

blown in walls will give higher R values, unless you use really thick foam board on the outside.

both is best though.

bosshog23

best way to insulate a house?

I have a 3 story circa 1884 steam heated house that needs more insulation. Which is better wrap the house and put new siding on top or cut holes in existing siding and have insulation blown in? Thank you

CC.Rob_4

blow in

It is very much worth it to shoot a bunch of IR pictures before and after the blow-in to make sure you have complete penetration of the fill. Houses that age can often have irregularly spaced studs, blocking in odd places, etc. Some of the less experienced blow-in folks assume modern 2x4 framing at 16" OC, and can miss a lot of territory.

And yes, both blow in and exterior when you can do it.

JJ_4

Blow in from the inside

Just a suggestion. I had two 1920's houses, plaster and lathe, that I had insulation blown in from the inside. One hole at the top and one in the middle of each frame space. The contractor even patched and textured to match. While they were there they blew R-36 in the attic too.

This saves trying to patch holes in wood siding or, in my case, very hard to match stucco. Also, if the original weight-type windows have been replaced with modern double-hung units, they can blow into the weight pockets.

Mark Biro

JJ is right -- inside is great, if possible

Amen. In our neighborhood STUCCO is common, and looks real rough if you put a lot of holes in it. Well, so does most other siding, I guess. ;-)

We were lucky enough to be able to clear access to the walls in our house, shoot 'er up from the inside, and then do the remodel, patch, paint, etc., which we had intended to do anyway.

Weigh your options, right?

kevin coppinger_15

ditto...

did that w/ my 1800 ad home this spring...the wall paper was comming down anyway....it was messy though.kpc

D107

not necesssary to drill through clapboards

to blow in from outside. I had my house done. They cut two lengths of clapboards on each side of the house, drill a row of 2 inch holes into the sheathing between the studs, blow in the cellulose, seal the holes with styrofoam plugs and then re-nail the clapboards. You'll never know they were there. One row of holes was about 3 ft up from the bottom clapboard, and the other was another 6-8ft above that.

In my case I later added 3/4" styrofoam and vinyl over the clapboards. So far so good; but some wallies questioned whether the outside insulation was thick enough to prevent possible problems with condensation problems, position of the dew point. I think one said that they like to see twice the insulation outside as inside to prevent that problem.

So far by my calculation, by all that insulation plus fireplace flue capping, weatherstripping doors, removing rad covers (and not yet even insulating attic) I've saved about 35% fuel consumption. When I do attic and get rid of oversized boiler I might be good for another 35% savings.

David

Mark Biro

Brute force insulation is ugly

Uh, I guess we are not so smart, here in Minnesota. About removing a clapboard before drilling. (Open mouth, say "Ah" before drilling.)

I was picturing my brother-in-law's house. Nice holes in it. I'll bite my tongue next time I see it... but remember your suggestion. :-)

Brad White

Both

This is what I did in my 1873 balloon-framed farmhouse style house in Boston. I did this in 1984 so some products have changed.

Siding was coming off anyway so that was a no-brainer (but you can pull off a clapboard row every six feet or shingle "intelligently" here and there).

Holes were drilled in the sheathing between studs and every 6 feet in height.

I had short-fiber fiberglass blown in to high density, R-4 per inch. Today I would use Nu-Wool or similar dense-pack cellulose.

The blowing pattern was "four feet down and two feet up" which accounted for the six-foot hole spacing. Tapered wood bungs were hammered in and tar paper stapled over them. Next, I used Tyvek over the entire house. The current stuff is better, has a weave. The old stuff was a giant postal envelope.

Today as mentioned I would use Nu-Wool dense-pack cellulose and the newer Tyvek products, but this I would also do: Remove the exterior trim including windows and corner-boards. What I found is that most remaining leaks occur around these and especially the corners where the most I could do is "tuck" the Tyvek in a bit and caulk. So a wrap and even double on the corners, then TAPE the Tyvek with that special clear tape. That old spruce sheathing has pencil-wide gaps so coverage is important as is taping.

Something else I would do now: Being balloon framed, some of the blown-in fill "spilled" into the joist bays which are open to the joist cavities. Today I would make a point of injecting slow-rise formula Tigerfoam to block off those joist ends. I am doing that today as a retro-fit and it is NOT fun. From the outside would have been a breeze. So to speak.

I would be cautious about using exterior board insulation which has a foil wrap or any vapor-retarder properties. With insulated walls to R-15 or so, the first cold thing moisture will see is the inside face of your exterior board. Your sheathing will rot in short order depending on your climate.

D107

rim joist problem

hey brad, don't wish to divert the thread but throw in a question about the rim joist overflow. I had cellulose blown in and of course quite a bit went laterally through the rim joists above the plaster ceiling.

In your retrofit--where you are foaming that area, any concern about the de-compacting of all the blown-in insulation stacked above as you clear away the stuff to get at the rim joist? It sure is messy and unpleasant to deal with.

Thanks,

David

Brad White

I just figure

that the moving foam will carry it along and harden it in place. Messy-shmessy, I want to save heat! I am injecting via holes drilled in the ceiling which will be covered by crown moulding. Will I get full coverage? Not sure but am doing my best. An IR gun will tell before I put the crown up.

GW

home energy

concentrate on the top of the house, then the bottom of the house, then the sides of the house... in that order.

Have a foam dude seal up the attic, then basement. if yoy still have cash in your wallet, hire the blown-in guy.

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Keith C

insulate

Remember that the most important thing to consider when tightening up the shell is not insulating to prevent thermal conduction but to prevent air movement. Spray foam and blocking or other suitable air barrier placement will do more for you than putting cellulose or fiberglass in. Air moves very easily through those two materials. Go get a professional foam gun from Hilti, and spend a few days up in the attic. You'll be surprised at what you can do yourself.

Hope that helps,
Keith

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Randy_7

One of the problems with blowing cellulose or fiberglass insulation into walls of older homes is the lack of a vapor barrier, which often results in condensation in cold climates, as water vapor hits the more solid surface at home exterior (and soaks the wall insulation). As has been mentioned, condensation can be minimized by installing vapor permeable rigid insulation on the exterior(never use anything with foil on the exterior as it is not vapor permeable). If the exterior is not to be addressed then vapor barrier paint can be used on the interior of the home. If there are already several coats of paint on the walls, that may be enough of a vapor barrier, but you won't know until you check for moist wall insulation during the winter or Spring.

Moisture is one of the greatest enemies of homes. One of the reasons old homes survived so long is due to the air circulation through the walls that removed moisture and allowed them to dry out. When we tighten those homes we have to remove moisture from the interior with proper venting (fans, and covering soil in crawl spaces too). "Insulate tight and vent right" - ignoring the venting can definitely lead to problems when retrofitting insulation in older homes.

An excellent reference is "Builder's Guide To Cold Climates" by Joseph Lstiburek, PE.

I recently cut a hole through the lath and plaster of a home that had the walls insulated in the Fall. The back side of exterior sheathing was quite wet as was the cellulose in contact with the sheathing. The weather has been quite cold (minus 10 F at night). I recommended bath and kitchen fans exhausting to the exterior, vapor barrier paint on the interior walls, and then monitoring the walls for moisture. I hope this information will prove helpful to some.

Randy