Q&A / 

Cracked Brick Bay Window

DEAR TIM: I’ve just placed an offer to purchase a two-bedroom house. It’s an older building, probably close to seventy, or more, years old.

After placing the offer, I then took a closer look around the exterior and noticed some cracks in the brick under the bay window. Is this a serious problem?

Like many, money is a little tight and I can’t afford an expensive repair. What is your opinion and do you think it’s something a woman with gray hair can repair? Sheryl E., Aberfan, Wales

DEAR SHERYL: I looked at the marvelous photos you sent.

Great Photos Help Provide Answers

They give me all the information I need to know to render an opinion I can give and sleep at night. I feel the cracks in the mortar joints are very minor settlement cracks and should not give you any worry.

One way to tell if the crack is causing issues is to see if the crank-out windows on either side of the bay operate with ease. If you can open and close them and they don’t bind, that’s a good sign.

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Now I say that but I need to qualify it. it appears the bay window that’s resting on top of the brickwork is not original. It has modern detailing and looks to be vinyl. It’s possible the older window had issues and the new installer shimmed the new window so it would operate properly.

The brick below this bay window is decades old, many decades. The cracks in the mortar joints at the top are cosmetic. © 2016 Sheryl Edwards

But if you look closely at the window, it appears that it’s been in place for some time. If I had to wager a generous order of Welsh rarebit, bara brith and some Glamorgan sausage, I’d say the brickwork is stable and there are no issues at all with the window operation.

Based on your photos, it seems your house is part of a multi-family building. If any of the other units have similar bay windows made like yours, ask the owners if they’ve had any issues. Sometimes builders skimp a little on the foundations under bay windows. Not all are full foundations and if the connection detailing isn’t right, the bay windows can move ever so slightly.

Repairing the crack in the mortar joint is a DIY job. I know you can do it. I say this primarily because you’re a woman and most women have an infinite amount of patience and possess great attention-to-detail skills.

Both are required to do an expert job of patching the mortar joint so it looks like nothing was done to it. Most masons I know don’t take the time to do mortar repairs correctly and the patch jobs often look worse than the crumbling mortar they’re trying to fix.

The first step in the process is to wash the brickwork below the window. You want to scrub it like you would a floor with a stiff scrub brush and soapy water. If you can locate any oxygen bleach in Wales, it would be best to use it on the mortar as I believe I see mold and mildew on the mortar and some of the brick.

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Oxygen bleach is a powder you mix with hot tap water. You stir until it’s all dissolved and spray it on dry brick and mortar. You want to saturate the brick and mortar and keep it wet with the solution for up to an hour. After the dwell, or wait, period, dip a brush in the oxygen bleach solution and begin to scrub. You can add some liquid dish soap to the cleaning solution to help clean. Rinse the brick with clear water and allow it to dry.

Once the mortar is dry, I want you to look very closely at it. You’ll discover, as I can see some in the photos you sent, that you see hundreds of individual grains of sand that was used to make the mortar. Note the color range, shape of the sand and the size of the sand particles. These different pieces of sand are responsible for creating the overall look and color of the mortar joint when you stand back and look at it.

You need to visit local sand pits where the sand is harvested from the earth. Since your town is located on a river, I suspect the source of the sand used all those years ago is quite close by. Since the geology of your area hasn’t changed in millions of years and the sand in the river, or sand pits, is a result of the erosion of the rock upstream from your town, I believe you’ll have a great chance of finding the same sand. It’s mission critical that you do.

If you can locate any older masons in town, talk to them. Ask them if when they were just starting in the trade if the old master masons used hydrated lime to make the mortar. Hydrated lime is a superior material to use instead of a modern mortar mix that contains mostly Portland cement. Lime has some give to it, it’s sticky and it has a self-healing property where it can grow new micro crystals in case very tiny cracks develop over time.

I’d make up a sample batch of hydrated lime and the sand you find. Blend three parts sand to one part hydrated lime. Mix these ingredients dry before adding water. Add just enough water to make the mix like stiff applesauce. I want you to repair just one small area where the mortar is missing. Don’t do widespread repairs yet.

The hydrated lime will coat all the sand and give the fresh mortar a monolithic color of gray. Right now the mortar is multi-colored because you see the sand.

After one month, I want you to lightly acid wash the small area you repaired. Use muriatic acid diluted one part acid to ten parts water. Read all the safety warnings on the acid container. Apply the acid with a cheap paint brush and try to expose some of the sand by washing off the thin layer of lime that’s coating all the sand. Rinse with plenty of clear water.

Allow to dry for a few days and stand back to look at the repair joint. See if the color is very close to the rest of the mortar. If so, get to work! If the color is not right, then consider blending different brick mortars until you get a grey color that matches the existing brick mortar.

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