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Masonry/Brick Laying/Gap between steel lintel and brick


I am investigating water intrusion over windows in the brick exterior of a residence.

Field investigations show a 3/8" to 1/8" gap between the bottom of the brick over the windows and the supporting steel angle lintel. The brick above the window shows variation in mortar color and some small undulation as if the brick were failing and had been repaired. It appears the brick was blocked up when set and the blocks removed. The excess mortar in the vertical joints is all that is resting on the lintel.

Water testing shows water is curling around the header brick and running directly into the gap. My guess is that during a heavy ran blowing against that side of the building water builds up and runs horizontally to the end of the steel lintel where is finds the gaps to run back under the lintel to the window opening where there are other installation issues.

I'm used to seeing brick resting on the steel lintel with a minimum of mortar. Other windows of residences in the same area do not show these gaps.

My first run solution to solve the water intrusion is to pack the gap with mortar placing 3 weeps (split plastic straws) at sides and center of the window opening. The brick are frogged so it is going to take a lot of mortar to close the front joint.

Am I getting into any trouble packing this gap with mortar?
Would I be best off just packing the sides and leaving the rest alone?

Thank you for your question Thomas.

From my experience, anytime there is a gap and that mortar is missing, it is a sign that something is going on behind the wall. It is maybe due to the movement of the house, or possible water infiltration. If water curls around the header brick, has that moved with time possibly?

Usually over the window, there should be a flashing membrane (a black paper)that should be installed then you see the steel lintel. Maybe the flashing is damaged, or they maybe a water infiltration behind the brick wall.  

My worry is that if you do repair and fill in the gaps, the problem may occur again. And it could get worse with time. What I do suggest, please consult with a specialist brick layer to have a look at the situation. There may be other signs that could indicate directly to the problem. They may have to take down part of the brick to see what is going on too, don't feel the situation may get exaggerated, not all the signs of damage appear on surface at times.

I also invite you to send me a few pictures. I need more information to see if I can assist you any further. I also need to know if you see any other gaps or cracking on masonry joints in other areas of the wall around that window. That too could help me.  

I hope this information helps you. Please don't hesitate to follow up on this with me.

Best Regards,

Joan Miller

Masonry/Brick Laying

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Joan Miller


Bricks and Stones have always been my passion. There are thousands of products to choose from and to learn about. If you need to know the specifics about bricks and stones, I will be more than happy to answer any questions about the masonry world as in how it is made, how to install it, specifications and quality.


I have been employed by brick and stone distributors for the past 25 years, meaning I have access to all sorts of information provided by the manufacturers that enables me to guide homebuilders and architects to make the best choice for their projects.


Masonry Specialist. Commercial and Industrial specialty.

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