Replies

1. 
   DANL | Aug 23, 2004 02:52pm | #1

   There is a special designation for bricks and mortar intended to be used where frost happens. I can't remember what it is though, something like 'FF' or 'SW' (severe weather?). Ask the supplier and they'll be able to tell you--or one of the others who frequent this site will probably know. There may also be a performance rating like 'ASTM 275 SW' (just made the stuff up after the real 'ASTM').

1. 
   HAWK3053 | Aug 23, 2004 08:10pm | #3

   Thanks!

1. 
   csnow | Aug 23, 2004 08:14pm | #5

   How old were the bricks you used?  Were they salvaged from the original chimney top?  What type of mortar did you use?

1. 
   HAWK3053 | Aug 23, 2004 08:22pm | #6

   Thanks for your reply.

   They were "new" bricks, but obviously of the wrong kind.

   I used Sakrete "motor" mix.

1. 
   csnow | Aug 23, 2004 08:48pm | #7

   Suggest Type S mortar for modern bricks.  Good mix of compressive strength and tensile strength.  A common mistake is to mix the mortar too wet, which weakens the mix, and makes it more absorbant. 

   After it sets, keep mortar damp with periodic misting for a couple of weeks.  Covering with plastic helps keep it damp. 

   A metal cap is better than a mortar cap, and allows you to create a drip edge.

   Best of luck.

2. 
   DANL | Aug 24, 2004 12:25am | #9

   You're welcome, but I think others, including RVillaume gave better answers. The mortar I was trying to think of is Type S (I believe the 'S' is for severe weather), like he said. I thought brick had a similar designation, but maybe not. I guess waterstruck is it. I do know that you should not use portland cement (like you'd use to mix up concrete) because it is harder than the brick and will create problems.

1. 
   rvillaume | Aug 24, 2004 03:50am | #10

   You're right - there are bricks made to withstand more weather than others.  It's been a while since I've done this and I just don't recall what they're called, but any masonry supply store in his area should be able to help him out.  A little of the humbleness I use when I go to the electrical supply store, thankfully not often, goes a long way.

   Waterstruck brick are just a solid brick, the "waterstruck" part simply refers to the way they're made (a wet board is drawn across the top of the mold to scrape off the excess clay).  There are usually two types that come from different places in the kiln - a softer, redder version and a mixed (red, dark red, close to black) version that's pretty hard.  There's enough character in the bricks that it gives a nice looking job on old houses or contemporaries.  They're not the easiest to work with, nor are they the cheapest, but they really do look nice.

   I rebuilt our woodstove chimney several yrs ago and used these from the second floor up and out the roof.  Now DW wondering when I'm gonna get around to using the 400 I have stacked in the barn to rebuild the other chimney so they match!

1. 
   DANL | Aug 24, 2004 04:24am | #11

   Well, DW will thank you when you do get around to doing it and you had the foresight to make them match! Well, at least you can delude yourself into thinking that! I do it all the time! ;-)

2. 
   rvillaume | Aug 23, 2004 02:56pm | #2

   Presuming from your post that the bricks are scaling or flaking off from the face.  Certain types of used bricks will do this when exposed to freeze/thaw cycles.  They absorb water, it freezes and expands and pushes off the face.  There are also some types of new bricks that will do this as well.

   I never, ever used used brick for exterior applications for this very reason, and there are some new bricks I never used as well.  You need a hard, dense brick in the north country.  The best, IMO, is what's called "waterstruck."  They're more expensive, but they last and look great in almost every application.  You probably won't get them at your local hardware store - you'll need to go to a masonry supply.

   Also, make sure you use Type S mortar mix.  In VT they might not even sell the others, but it will say so right on the bag.

1. 
   HAWK3053 | Aug 23, 2004 08:11pm | #4

   "scaling or flaking off from the face"

   exactly.

   Thanks for the information.

1. 
   rvillaume | Aug 23, 2004 09:21pm | #8

   Saw from one of your other posts you used sakrete.  definitely don't use that again.