how much R does a brick wall (3 W) have?
![](https://www.finehomebuilding.com/app/themes/finehomebuilding/_assets/img/avatar/avatar_50x50.jpg)
Doing a remodel, stripped the interior wall of lath and plaster. Built a 2X4″ stud wall so that i could insulate/hang cabints easily. There are 3 pipes running up the wall 1 drain and H & C water. I plan on sticking R12 FG etc.. My question pertains to the water lines. They run up against the wall about 1/2″ off. If I put bats of FG they will be between the warm house and the pipes, in the old configuration, the lath and plaster would have let enough heat through to stop pipes from freezing. Is there any way that the R12 FG will allow the pipes to freeze? There will be a cavity of sorts around the pipes and some heat should trickle up as the basement is heated so I’m wondering what kind of R I get from a brick wall 3 wythe thick.
Any input appreciated and thanks in advance.
Oh yeah, I’m in montreal canada, we get 1-2 weeks of -32 F each winter, usually it,s around 0 F ( -15 C ?) for 4 mnths of the year.
Replies
figure 1 for the outer whythe, 1 for the air space, 1 for the next whythe, 1 for the air space, and 1 for the inner wythe = R5, maybe R7..
you bet , those pipes will freeze unless you keep them on the warm side of the insulation
but hey, whadda i no ?
They'll freeze for sure in weather like this week. Put the thickest rigid polyurethane foam behind the pipes that will fit. Even 1/2" will help if that's really all you can fit. You can insulate between the pipes and the studs (beside the pipes), but don't put any insulation between the pipes and the inside walls.
Could you possibly reroute the pipes to another wall, or closer to the inside of the finished wall?
I agree with Mike and Waynel 5, PATRICKOFM*. Details like this make or (anoint?) the job.
What I really want to know is the R of brick. I've taken care of the pipes, the thing is they've been there for 75 + years, and during the last 30 (present owners) they have never frozen, so brick must have a R greater than 1. Anyone know it?
P.S. I set up a pipe warming system, but I haven't plugged it in yet, the walls are already closed, the pipes didn't freeze this week and it was coooold. So now I'm sure brick must have some kind of decent R rating, remember that in three W of brick there is an air space between the courses definatly more than 12" of brick wall.
no.. you could look it up .. but if brick has a better R than 1/12.. i'll be surprised...
ie: if you give it any value other than 1 for each wythe.. you're kidding yourself..
a 3" piece of solid WOOD can have a value of 3... why would brick be anywhere's near that ?Mike Smith Rhode Island : Design / Build / Repair / Restore
You are right, the r-value of bricks is not 1.
It is less.
http://coloradoenergy.org/procorner/stuff/r-values.htm
If I understand that in the past these pipes where either in the open or only covered by plaster. That is why they have not frozen in the past.