vapor barrier and insulation

[Teresa]

We are in the planning stages of a 1920's Craftsman renovation. We
are
not planning to completely gut the house, going to keep original
windows
and plaster walls. We are considering changing over from steam heat
and
no A/C to geothermal- but figure we need insulation to make it worth
our
while. So my questions are;
- do you know any good insulating contractors?
- If the first story is brick, will that be a problem (vapor barrier)?
- what kind of insulation (closed cell foam or the fluffy blown in
stuff)
would you recommend?

Thank you for any suggestions.

[Steven Wilke-Shapiro]

There isn't really a good way to insulate a masonry wall - unless you decide to fur it out (see http://renovatedsm.com/node/68 for a detail of how that typically happens).  Unless you do this, you will not be able to install a vapor barrier.  It sounds like you are not intending to go to this level of work on your project, however, and shouldn't prevent you from installing a more efficient HVAC system.

In fact, masonry walls are one component of a VERY energy efficient temperature control system - natural ventilation.

During the warm months:  Open up the windows at night and circulate air to cool down the masonry walls (thermal mass).  If you have operable double hung windows, pull down the top sash and raise the bottom sash to create a circulation path for the air.  During the day, close the windows and shades and let the cooler masonry walls help regulate the interior temperature.  It also drastically helps to have trees and plantings shade the walls from the exterior - this way the masonry walls don't bake in the sun all day.

I have run across insulating paint (http://www.insuladd.com/interior.html) in my online research regarding insulation options.  I have never used it, though.  I may try it out when I insulate my finished attic space.  It may be a good option to look at for adding thermal efficiency to an existing masonry wall, but might also defeat the natural ventilation system because it would reduce the wall's thermal transfer capacity.

In general, your biggest heat transfer will happen through gaps around windows and doors.  Since you are keeping the windows, make sure they are well fit and weatherstripped as required.  Adding a good quality storm window will also help.  If they need repair, check out the documentation from our recent "How to Reglaze a Historic Wood Window" class at http://renovatedsm.com/node/235.

Spray foam insulation can be retrofit into existing homes.  Closed cell will serve as a vapor barrier, but is typically heavier and more expensive.  You will also need to make sure that there isn't already insulation in your walls (check for plugs on the exterior siding and/or break a small exploratory hole in an inconspicuous location.  If there is already blown-in insulation that has compressed you can probably "top it off" with additional blown-in cellulose. 

For the attic, blown-in fiberglass typically weighs less than cellulose.  Pile it as high as you can - the attic is another big heat transfer spot.

Steve Wilke-Shapiro

[Steve Forest]

  My recommendation would be to insulate the ceiling the best you can with blow in. Caulk all places on the exterior. Replace all windows and doors with the best energy ratings. Use natural methods of tree breaks, summer shading, and winter sun gains.

 

 I would not use geothermal but forced air or water heat and use any zone heat, as in under floor radiant and save some money.

 

 I feel a house built in this era is best left to more traditional methods and it is best not to over improve on a already nicely designed house.  Just build a new craftsman style if you want modern technology and you would probably get more bang for your buck and a better house.

On Wed, Jul 23, 2008 at 10:13 AM, Teresa <tl...@mchsi.com> wrote: