09 July, 2009

What Happens When You Don't Use the Right Mortar

It's a real problem in Chicago. Very few contractors who do masonry work on old buildings use the right kind of mortar for the job. Whenever you need to repoint or replace the mortar on your historic brick building, you should have a sample of the original mortar analyzed so that you can create a mortar with the same components. If you don't, all sorts of horrors can happen.

When we tore down the gypsum ceiling boards in our basement last summer, we exposed about 85 years of efflorescence on the interior wall. When moisture travels through the brick, it carries water soluble salts along with it, which end up evaporating on the surface. Ours wasn't too bad, a bit thicker in some spots than others, but overall probably acceptable for such a length of time. I used a shop vac to clean up most of it, and our basement walls looked like this:

Well, after a long winter and an even longer, damp spring, there seems to be a fair amount of efflorescence collecting in a single spot above one of the front windows.

That's a lot to collect in less than a year. Most of our basement after 85 years didn't have this much. So we went around to the front of the house to take a look at what was going on. What you're looking at here is some really cheap patch work done on the exact opposite side of this wall; we found tubes of Quikrete in the basement, and we think this is what the previous owner used when they said The Box House had been recently tuckpointed.

Whatever they used, the result is that the building is not breathing properly in this spot. The bricks are not able to expand and contract as they're supposed to against the rigid mortar, and moisture is somehow being forced through the brick.

There are earlier repairs to the brick as well; we're not sure when these were done--our guess is maybe 40 years ago when the last owner bought the place--but it looks like a better attempt was made to mach the mortar to the original at that time. At any rate, there are no problems to the brick where these earlier repairs were made. However, it is beginning to crack in certain spots--nowhere near as much as the most recent mortar repairs are cracking--but enough that we'll have to address it soon.

But here's the real problem, and thank goodness it's on the garage and not the main house.

On this entire corner, the PO used Quikrete or some kind of rigid cement to patch the mortar. The mortar does not move at all. So as the bricks here are expanding and contracting, they are literally crumbling against the mortar. If we let it go long enough, we'll have this web of mortar and no bricks. We're going to attempt, very soon, to repair and remortar this ourselves as a way to practice for the bigger task of repointing the house.

Most masonry contractors, when they tell you they can match the mortar, mean they'll match the color. Period. By not using the proper materials, or trying to work with a buildings original materials, such contractors are literally destroying the face of the city. Ever since we learned about the importance of the right mortar at a recent masonry workshop, we've noticed building after building across Chicago crumbling away. It's very sad.

Do you know what's also sad? The fact that the dang squirrels cannot wait until September for our neighbors apples to ripen; instead, they've been leaving half-eaten apples all around our yard. They usually take a bite or two, toss it over their shoulders, and grab another one.

Messy little buggers.

6 comments:

Karen Anne said...

I think The Old House Journal in their better days had an exhaustive article on old mortar.

What is it with critters taking one bit out of multiple instances of the same food item, like tomatoes?

Debbie said...

Thatnk you so much for the information! I've just placed a bid on a 101 year old home. The bricks will need to be repointed on the porch. I now know what to look for when I hire someone!

Andy said...

I don't trust anyone, to the point where I'm going to repoint my face brick myself. Someday. I learned how to do it (I have the notes I don't know where...) and stuff at the HCBA workshop that I attended a few years ago...

I don't need crumbling face brick. Or some idiot trying to tell me what is right and OK even though I know better.

Green Fairy said...

Karen Anne--We all know the first bite is the best, but sheesh. When my fruit trees actually start producing a big enough crop, everything is going to get netted to keep the birds, rodents, and passing neighbors out.

Debbie--Good luck on your bid! I hope you'll be blogging your progress.

Andy--It's funny, I've gained a much better understanding of construction and contractors just from reading other people's blogs. I don't trust anyone else, either--they're never going to care for my home's welfare the same way I will. I know repointing our house will be an insane effort, so we'll take a section a year, starting with the garage, the back of the main house, etc., before tackling the visible street side. Years of work. But I also hope we'll have this building for the next 40 years.

Jennifer said...

Our squirrels do the exact thing with our apples. We've never had any left to ripen on the tree. Sigh.

My best advice for brick repointing? Spend the money for a true restoration specialist or do it yourself. I wish WE had done that! Now I'll have to find time sometime to repair the portland cement patches. Sigh.

Debbie said...

I will be blogging my progress! I should find out tomorrow if they accepted my bid!

I'm so excited! Especially since the wiring has been completely redone in the past 5 years, it has A/C and heating and the bathrooms have been remodeled.

http://yeoldebrickhouse.blogspot.com/