brick veneer cracks
brick veneer cracks
(OP)
Back elevation of house is brick veneer (about 30 feet wide). X-shaped crack pattern in mortar joints above back slider, with some vertical cracks in brick itself (see right side of photo 2). Lateral horizontal offset up to ~1/2" at corner. Do you agree that this movement in the brick is due to thermal horizontal expansion and contraction, AND NOT SETTLEMENT? There is no vertical joint in the brick over the ~30 foot length of the elevation. House is about 50 years old. See attached pics. Thanks.






RE: brick veneer cracks
With that being said, those are some large cracks that have opened up, which might indicate some movement of the underlying structure.
What type of foundation is under the house? Is it a slab? If so, perhaps the corners of the slab are curling up/down as the moisture changes around the perimeter. For example, it rains for a day or two and the ground around the perimeter swells, then it shrinks as it dries out.
Also, is there any sort of bond break between the bottom bricks and whatever the bricks are bearing on? In Texas, the bottom course of bricks sit on 6 mil plastic which (in theory) allows a little bit of differential movement between the slab and bricks.
RE: brick veneer cracks
RE: brick veneer cracks
RE: brick veneer cracks
RE: brick veneer cracks
RE: brick veneer cracks
RE: brick veneer cracks
RE: brick veneer cracks
RE: brick veneer cracks
Dik
RE: brick veneer cracks
I agree it is probably not just the lintel, but on a wall like that, and in a 50 year old house, lintel corrosion is often an issue. The products of corrosion are much larger than the steel, so create large forces.
Don't understand what you mean by the lintel being bolted. I take it as a loose lintel.
RE: brick veneer cracks
RE: brick veneer cracks
On current brick facades in Texas, the longer span lintels usually get bolted to the wood frame header. Typically you see this at 2-car garage door openings where you have a 16ft-18ft spans. I believe the common practice is 1/2" lags with a 2ft spacing. I have also seen bolted lintels on spans above sliding doors if they were more than 6ft.
Although I have never seen an engineering analysis on it, I think the bolts allow enough load to shift off the lintel to prevent significant deflection and subsequent cracking. In my pre-engineering days, I worked for a large Texas homebuilder. Unbolted lintels above garages were a common warranty item and a real pain to fix because you had to tear out the brick to fix. Usually you then ran into color matching issues with the homeowner, which was a losing battle.
Anyway, I doubt the lintels were bolted on a 50 year old house, so that could be contributor to the cracking problem on the subject property. Personally my thought on the subject property is that there is some expansion and contraction going on combined with some seasonal slab/support movement.
Here's a photo from a house I built a few years ago. I don't know who the mason is, but he's proud of the bolted lintel! You can also see the poly they put down as a bond break in the photo too. :)
RE: brick veneer cracks
I agree with Hokie. Some of this has already been said or implied above, and I might just be saying it in slightly different words. The crack pattern shows how it is working now, not necessarily how it was designed. If the sliding door is working well, the lintel most likely is not the problem. What you really meant to say is the brick tends to act in an arching fashion over a lintel, with any lintel deflection and the cracking pattern shows that. But for the arching action to really work correctly and not cause the cracking you see, there must be a strong ability to impart arch supporting inward thrusts at the spring line of the arch (the head of the door opening elev.). The brick plane (or panel) on the left of the opening is stronger (stiffer) in this respect, than the shorter plane of the right. So, these thrusts tend to push things to the right. Then, you have the fact that brick is a naturally expansive material with age, and the more so with any water getting into the brick from (around) the window opening above. You could also have some thermal expansion, again pushing to the right due to that area being the weaker reaction plane. Finally, there could be some found. movement on the right corner. It is really good/helpful if you can watch these kinds of problems over a year’s worth of seasons, and if you can see them develop, rather than having them so well developed, that you are to late to see what caused what.
RE: brick veneer cracks
I would continue to measure the cracks in different seasons during the next 1 to 2 years to see if there's seasonal variation. If no seasonal variation then I think the cracks are most likely thermal changes, although I'm not sure expansion of the brick explains the diagonal cracking above the opening; expansion should lead to cracks forming in the return wall on the right as the wall pushes outwards, so confirm if theres vertical cracking in the return.
Being a 50 year old building I would just tell the builder to repoint and live with it. Life isn't perfect and they can't expect an old building to behave brand new.