insulating old rock house

[Mark]

I'd like to make a little 1920s 'rock' house livable with better insulation and central heating/cooling. Three quarters of the walls are solid rock, the rest cinder block. The house only has about 900 square feet of living space, so I want to limit the impact of interior insultation. There is no ceiling, just plywood over rafters. I doubt there is any insulation 'in' the roof. The cinder block room has a slab floor. The rest is pier and beam, though no crawl space entry seems to exist.

Any ideas? My initial idea is to cover the interior walls with insulating foam sheets and wall paper. It might we useful to put in a ceiling and insulate it, but that will make the space much smaller.

Thanks,

Mark

[mark Ransley]

The best way would be to use r7.2 foam board not the r5 product. Stud out the walls and insert the spaces with foam board then drywall. Wallpapering over foamboard will look bad and wont seal out any fumes foamboard my release. Your ceiling is where you loose the most heat . r35 is minimun but you are better going much higher, r50- r70 and cover ceiling and foamboard with drywall or a good looking wood.

[EL]

Mark,

I'm not an expert, but let me throw out a couple of ideas here.

First, the foamboard: great insulation but expensive, I'm assuming you already knew this! But there's another issue: it is VERY flammable! I suspect having it exposed (wallpapered is about the same as exposed) is against code, and for good reason. If I were you, I'd be thinking about attaching 2x3's to the wall the "wrong way", i.e. so they only stick out 1.5 inches, 24" on center. Then fill the space between them with foam, then sheetrock over the whole thing. The sheetrock will provide some fire resistance.

As for the ceiling, is there plywood on the interior side of the rafters, or are you talking about the roof underlayment? If it's on the inside, you could pull it down, put some fiberglass in there, then replace it. Not a perfect solution (adding venting would be better), but as you may know, most heat loss is through the roof, so there's a lot to be gained by insulating it.

Eric Law Jupiter, FL

[Philip Edward Lewis]

i believe you have to cover the foam insulation with sheetrock due to fire code... The highest R per inch is spray on closed cell foam (close to 8/inch) and it also provides air infiltration barrier.

I just wish there was a slow cure, pour in retrofit that would allow me to do my walls with minimal damage to siding/plaster... :/ (I believe i have baloon framed house (Victorian built in Pittsburgh in 1874) so i should only have to drill in the attic and under windows....)

[JP]

If your walls are lath/plaster or gyprock, cutting holes and filling the voids between posts, with cellulose insulation would be your best bet. the trick is to find the right insulator to do the job. I wouldn't advise the for the do it yourselfer or the fly by night contractor because the insulation blowing machines do not supply enough pressure do do these jobs.

The blowers that are in the big trucks (contractors/insulators that do this for a living have these and they supply lots of pressure to make sure the most amount of voids are filled. And pack the insulation to the right amount so no settling will occur.

Cellulose insulation also contain some borax which will deter vermin.

As for the ceiling, I'd really like to see what you got to be able to make an assesment. Make sure you leave a void with circulation to the outside on the cold side of the insulation to avoid moisture buildup.

Don't use EPS or other types of styrofoam on inside walls, they are f ire hazard, and I'm pretty sure building codes include this.

Here are some links:

I'd like to make a little 1920s 'rock' house livable with better

[Mark]

That's the direction I see things heading.

There is plywood under the rafters.

That's a good idea, too.

Thanks,

Mark

[Joseph Meehan]

I suggest you start with just the roof. Do it well. You may find that that is all it takes to do the job.