I have a couple of questions for experienced masons out there . . . .
First some background:
I have a split level house with 2 story single flue chimney on the double story end. Chimney is for a woodstove in the finished family room on lower level. Before I bought the home the previous owners had a chimney fire and the chimney relined with a ss flexible ventilux inside the existing clay tile. Don’t know if that contributed to my current trouble or not. House was built in 1987.
Current problem is that the mortar is very soft in several areas. Total of maybe 5-6 linear feet of brick has this “soft” mortar. The mortar is flaky with algae /moss growing in it and I can flake it out with my pocketknife. Rest of the mortar work on the chimney is intact and solid. Some minor cracks (They appear minor anyway) here and there. I want to fix this. I have an angle grinder and assortment of cold chisels with which to remove the old mortar. I also want to seal the cement cap around the flue at the top of the chimney as it has developed a few small cracks through the years.
My questions:
1) Is this a doable project for someone with decent DIY skills? I have built decks, pole buildings, hung and finished drywall, light plumbing and electrical. All to code and passed inspection of friends in the trades and local inspectors.
2) If it is doable, can you offer any advice? I know I need to grind the old mortar out. (Should be easy as soft as it is). I only plan on grinding out the soft mortar, not an entire repoint of the whole chimney. What type or mortar should I use to replace what I remove? I don’t know what is there currently, but I suspect a portland product? It’s very hard in the areas where it is intact.
3) Pointing tips as I want to point the new mortar to match the profile of the existing.
4) Any tips on getting color to match as closely as possible?
5) What product should I use to seal the cap? I have seen some polymer/elastomeric product mentioned here a time or two.
I can get on the roof and get pics if anyone thinks it will help.
TIA for any and all ideas/help/suggestions.
Replies
generally.... a grinder makes a good tool for raking out the joints
don't over excavate or you will have to relay the bricks instead of just repointing
mortar comes ready to mix in two basic flavors: dark & light.. usually chimneys are built ( especially one dating to 1987 ) with one or the other
the basic recipe is printed on the side of the bag.. one part mortar cement to 3 parts mason's sand.. dry mix in a mortar pan with a light hoe.. add water sparingly.... keep the mix stiff
rake & clean your joints, keep the brick dry ( it can be damp, but not wet )
pick up your mortar on the back of a big trowel and push it into the joint with a small pointing trowel.. work about 5 courses up and 3' - 4' wide
choose a pointing tool that will duplicate the existing joint, concave joints weather best.. raked joints are best saved for interior work
go to a mason supply house to find good pointing tools.. my favorite now is the barbell ( 3/8 on one end .. 1/" on the other )
for the cap.. if the cap is sound, open the cracks and caulk with a polyurethane cement caulk.. like PL
to answer question #1 (Is this a doable project for someone with decent DIY skills? ):
Yes, I just did it for the first time last month. It came out fine - the hardest part was being neat - I did it right before re-roofing so the mess I made on the roof didn't matter, but I got quite a lot of mortar on the bricks and didn't try to clean it with muriatic until a couple days later which was a mistake - should have got up there sooner.
I really could have benefited from the info in Mike's reply - I had all the tools but found that my finger was the best tool (all the masons are cringing now). A recent episode of TOH (the Washington DC project) has a nice segment on doing it right (saw that too late).
Mike's advice is very good. I'll add a few things though-
You could just use a premixed mortar, like a type N. Type N is good for outdoors, but it's fairly soft, so it won't chip your bricks like an overly hard mortar will. I think it's the same mix Mike was talking about if you mix it yourself: cement and lime in equal proportions, and then a 1:3 ratio of cement/lime to sand.
I think cake decorator bags are a great tool- you can find them at a good mason's supply store, they're just a cloth cone with an end cut off. Fill with mortar and squeeze it out, then go back and tool it. I mostly do stone masonry, so maybe bricklaying goes quicker with trowels. But I doubt it.
Third, and very important- clean up. Be neat when applying the mortar, let it just start to stiffen before you tool it, and then use a nylon brush and water to clean up as soon as the mortar won't run from the water. If you find more extra mortar later on, clean with a wire brush, and if necessary, a dilute mixture of Muriatic acid added to water (1:10).
Also, clean the bricks after you grind out the mortar, so it's not dusty.
zak
"so it goes"
Started doing mine last year. Forget the cold chisel until you use your angle grinder with a diamond blade. I used a segmented dry cut blade, and it worked great. Cut out the old mortar to about an inch deep (as far as the diamond blade will reach.) Then clean out any stubs with the cold chisel, and blow out with an air compressor.
Figure out which mortar to use. Then dampen the joint with a spray bottle with water, to keep it from sucking out the water from your fresh mortar. Strike it with a jointing tool when it sets up a bit.
Of course, wear safety glasses (or goggles-it gets real dusty!) and a respirator (not the paper masks), a hat, gloves, long sleeve shirt if you can. Chips and dust get everywhere!
I mixed my mortar, then loaded a hawk and pushed the mortar in the joints with one of those really narrow pointing trowels, holding the edge of the hawk level with the joint. Worked ok. Pack it in well. I though about the squeeze bag and a grout float, but didn't go that route.
Like the other posters said, be neat about it as you go. Rubbing it all down with a piece of burlap is one way to get the big boogers off. Then clean some more per the other instructions.
I started the job because I had to replace a piece of cracked clay flue at the top. The job didn't progress well until I got the diamond blade. Then progress went along pretty well, but it is somewhat tedious and time consuming. Of course, I wasn't too clean about it, and I'm sure I'll have a heck of a time cleaning off everything 2 stories up with acid and a pressure washer.
If you want, you can come finish mine for practice, and I'll supervise. Should make your project go a lot smoother once you're experienced!
Pete Duffy, Handyman