I have two questions regarding insulation. My 80 year-old house needs insulation and leaks plugged. The house is a two story four square in S.W. Virginia with brick exterior on the first floor and cedar shakes on the second. Some years ago a previous owner had cellulose sprayed in. The house has actual 2×4 studs with 1″ diagonal planks for the sheathing and a 1-2″ gap between the sheathing and the brick exterior. The interior walls are plaster and lath. when I remodeled the bathroom, I realized how hit and miss the blown in insulation actually was. some areas were great while others had gaps and some places had huge voids. I do not want to tear out the interior walls since the millwork is beautifully and would be expensive to reproduce. There is a lot of air movement in the cavities which are noticeable at the floor and electrical boxes. I am removing/replacing or refurbishing all of the downstairs window in the next few months. In defence of the insulation contractor, the cavities have lots of blocking and all of the deactivated knob and tube wiring is still in place. I want to increase the R-value and reduce the movement of air. I read the great book from Taunton Press but it did not cover these questions. I was thinking of filling the cavity between the brick with either vermiculite or foam. I was leaning towards vermiculite since I could do this while the windows were out, one by one, and do it myself. I was also thinking about some kind of pour in place foam that I read about in an earlier post. The brick is tied to the walls with steel strapping that appears to be in great shape.
The second question is for the 30 year old addition. It has a poured footing with concrete block foundation. The joists are 2×10 that sit 1-2″ off the slab. There are a few 3×5″ vents on two sides. I can’t tell what the slab, or even how thick it is. Would be removing a few blocks to gain access and spray insulation to the underside of the subfloor. The subfloor is 3/4″ plywood and has hardwood floor on top. the floor was recently refinished and is in great shape.
Please give me your thoughts and ideas as I certainly need the help. Thanks for your help.
Mark
Replies
On retrofitting insulation into the gaps in the house wall, yes if you want to do the vermiculite as you go, great. Of even fistfuls of FG batting, overstuffed into any voids that you find. You won't get all of them, but you might as well plug the holes you encounter.
If you can get access to the crawlspace of the addition, yes, it would help a bit to add insulation in between the joists. Not that insulation (summer and winter) does the most good in the ceiling, then the walls then lastly the floors. But if the others are already done or are inaccessible, then go ahead with the floors.
I would NOT fill the void between the brick and the sheathing. Brick is pourus and during a heavy rain storm water will seep through the brick and run down the back side of the brick and come back out through weep holes along the bottom courses. If insul is in there it could get saturated and never fully dry out. And wet insul looses R value.
Don't fill the gap behind the brick. There has to be an air space there. Water will get through the brick and has to run down the back of it out the weep holes. If you fill the air space you'll create a sponge bridging the brick to the framing and your walls will rot.
Sorry for the delay, as I changed computers and I forgot my password. Thanks for the advice. I completely forgot about moisture. Thanks again.
Mark