Construction Consulting Questions #4 – Are cracks in plaster walls bad?
October 9, 2009
Construction Consulting Questions #4 – Are cracks in plaster walls bad?
Many older homes throughout the East Bay and Bay Area in general have plaster walls and plaster ceilings instead of the newer gypsum sheet rock material. There are benefits to both covering systems as well as issues that detract.
First, let’s look at a few comparisons. Plaster take time to install since you have to preinstall the “lathe” backing board strips prior to putting on the two to three coats of plaster whereas sheet rock installs quickly and requires minimal work to finish the seams and apply a smooth or textured final coat. Plaster, along with the lathe backing, can dry out if it gets wet due to water intrusion whereas sheet rock with its paper backing can become a source of mold when moisture conditions occur on the backside of the material. Plaster is more rigid and crack from structural movement. Sheet rock is more resilient and can “flex or give” more readily.
Why do plaster walls and ceilings crack more easily than sheet rock? There are several reasons, but let’s start with the basics. Plaster is relatively brittle and sheet rock is not. Sheet rock is simply attached to the wall or ceiling framing with nails or screw fasteners. Plaster is applied over lathing strips (which look like yardsticks with a small space between them) and becomes rigid after it cures. Note: the reason that there is a space between the lathing is so that the plaster (after it is mixed) will “ooze” inbetween the lathing and “roll out” onto the backside of each adjacent lathe and form an elongated ridge which is wider than the gap, yet integral with the main or base coat of the plaster itself. In this manner, the initial plaster coating is gripping the back sides of the lathing along the edges at the gap. (Make sense?)
So, with this brief knowledge of how plaster is installed, we’ll quickly talk about cracks you might be experiencing in your walls and ceilings. Cracks in walls generally occur from the differential movement of your framing due to building distortion from settlement or framing deflection etc. (and seismic events of course). Ceiling cracks can have the same issues as walls in addition to the fact that it is on the ceiling (let me explain). With the plaster being applied to the underside (downside of the ceiling) along with the fact that the initial coating is being held in place from the “gripping effect” of the plaster on the back side of the lathing, the weight of the ceiling plaster can cause some slight bowing of the ceiling framing.
Over time, ceiling framing (the joists) can droop or bow due to “long term bending” such that the center of a room’s ceiling might be a little closer to the floor than the ceiling which is nearer the walls. (Get the picture?) Now with this in mind, you can begin to see that the length of a ceiling joist which is bowed is actually longer along the bottom side as compared to when it was originally installed. This lengthening does not fare well with the more rigid plaster and as result can cause the cracking (or stretch marks if you will). Simple cracking due to the gripping portion of the plaster is also a potential culprit due to inadequate plaster being installed to form the “grip” etc.
Are these ceiling cracks bad? Not necessarily so, but usually it is a good practice to physically see just how loose the plaster has become so that you don’t get sizeable areas falling on you. The fix for most homeowners is to either patch the cracks (best method for patching is to utilize wide permeous cloth and sheet rock mud), install sheet rock over the existing plaster and lathe, or better yet, remove all the plaster and lathe and replace with sheet rock. Cracking to the walls are usually not as prevalent as ceilings and patching is more often than not the remedy than complete replacement as it is for ceilings.In closing, “Are cracks in plaster bad?” The answer lies in the arena of “Why are the cracks forming in the first place?” Understand why they are occurring and you will get a better understanding of your choices on how to rectify them as well as have a better feeling as to whether there is something “bad” or not with respect to framing issues, settlement or perhaps seismic activity.
Anderberg Construction Consulting, Inc.
4100-10 Redwood Road #368
Oakland, CA 94619-2363
(510) 482-2779
tomanderberg@gmail.com
Construction Consulting Questions #3 – What does it mean when I see a horizontal crack along my foundation?
September 10, 2009
Construction Consulting Questions #3 – What does it mean when I see a horizontal crack along my foundation?
The horizontal crack that most people refer to along a concrete foundation is usually located at the base of the wooden foundation sill plate which is attached (or should be attached) to the concrete foundation. A wooden cripple wall or floor framing system is normally built on top of the wooden sill plate. Throughout most of the 1900’s up until the 1980’s or so, when stucco was applied as the exterior surface to a structure, the stucco was often toweled on down past the sill plate so that it adhered to the exterior face of the concrete foundation.
Adhering the stucco to the outside face of the concrete foundation was a common practice that made the stucco look flat and uniform at the bottom instead of being formed in or shaped back toward the sill plate which would then cause a visual protrusion so to speak.
The horizontal crack that is referred to by most people is more often than not caused by foundation rotation. When the soil that the concrete foundation is placed upon becomes wetter on the exterior side of the foundation than the interior side, the soil gets compromised “softer if you will” and then the outside bottom portion of the concrete starts to settle relative to the inside bottom of the concrete, and the concrete foundation then begins to rotate outward. As this occurs, the bottom of the wooden wall above the sill plate also goes outward causing a horizontal crack which we are referring to. However, the crack, as you are now beginning to see, is not a crack in the foundation at all but rather the displacement between the stucco adhered to the wooden wall (at the base of the wall) and the stucco adhered to the exterior face of the concrete foundation.
Prime suspects for causing foundation rotation, which in turn can create the visual horizontal crack, usually start with poor exterior surface drainage. Land which slopes toward the structure then creates a low area along and adjacent to the concrete foundation itself. Surface water, as well as, “or in addition to” the rain water which drains down the siding of the structure can thus end up soaking the soil and compromising it to the point where the concrete foundation actually starts to rotate. So there you have it, foundation rotation being more often than not, the cause for the appearance of horizontal cracking along the foundation(s) of a structure.
Anderberg Construction Consulting, Inc.
4100-10 Redwood Road #368
Oakland, CA 94619-2363
(510) 482-2779
tomanderberg@gmail.com
Construction Consulting Questions #2 – Foundation Cracks – How do I know if they are significant?
August 26, 2009
Construction Consulting Questions #2 - Foundation Cracks – How do I know if they are significant?
For homeowners, to be told that you have cracks in your foundation, can really make you nervous. With most people being aware that their home is built on top of a concrete foundation, the notion that their concrete is cracking brings them to the question – How do I know if they are significant or not? How many answers would you like?
Since most concrete will crack (but not always), the best way to start analyzing the issues is to get a basic understanding of how cracks occur. Essentially there are two main sources of cracks, shrinkage (installation and curing methods) and stress (forces applied to the concrete after it has been installed). Cracks from installation are not necessarily detrimental to your structure but cracks due to stress can be. This is where “the rubber meets the road” so to speak. Are the cracks going to become larger? Are they a sign of ongoing issues which should be immediately addressed or do I have time to deal with them? Different opinions on what to do will be found in the advice you will get. Sound confusing? It can be.
Getting back to the question of how big does a crack have to be to really impact your home; I would say that if you can put your fingers and hand inside the crack, that would definitely be considered problematic and more than likely should be addressed as to its significance.
Smaller cracks from 1/16” to ½” can be readily found in the concrete foundations of many homes throughout the Oakland Hills and the Bay Area. Whether you live in the hills of the East Bay and San Francisco or the flatter areas in Contra Costa County, soil and ground conditions are typically the root cause for settlement issues which in turn can cause stress on the concrete. Sloping floors, cracks in walls, sticking doors etc. can be signs of possible concrete settlement which can also result in concrete cracking.
To determine the best approach to your concerns with regard to concrete foundation cracking, get experienced input from professionals. Most professionals fall into the categories of contractors, engineers and consultants. A moderate amount of time spent educating yourself by speaking with various people in the trades will hopefully help you with your decision process on what to do and how to proceed to the next step.
Anderberg Construction Consulting, Inc.
4100-10 Redwood Road #368
Oakland, CA 94619-2363
(510) 482-2779
tomanderberg@gmail.com
Construction Consulting Questions #1 – What’s the right drainage solution for me?
August 21, 2009
Construction Consulting Questions #1 - What’s the right drainage solution for me?
Customers often ask, “What’s the right drainage solution for me?” That’s a very good question. Depending on who you ask, you’ll probably get different opinions about what needs to be done. Your best answer will more than likely result from you becoming a critical part of the decision making process. A common approach for those new to drainage is to start by asking friends or contacting drainage contractors to give you some input. Whether you live in Oakland in the East Bay, San Francisco, or the Bay Area in general, there are many contractors to choose from so the question then becomes, “How do I know which contractor to choose and which approach to take?”
Many clients become confused about how to interpret the range of options offered by contractors. This confusion makes it difficult to decide on the best course of action to follow. That’s where educating yourself becomes important. Since there are many common construction consulting questions pertaining to drainage, you may also want to invest in drainage consulting from a professional drainage expert or construction drainage consultant to gain additional insight. Drainage problems can often lead to other related issues that need to be addressed as part of the solution. Consulting a professional drainage consultant can help with identifying a more complete approach to your specific needs.
Digging a ditch and calling it a drainage solution may seem to make things better but is it the right job for you? In the world of drainage, the plan is usually more important than the expertise to implement it. You want both of course, but the plan is paramount for effectiveness. Be patient with the advice you are getting and make sure the costs reflect the desired results. Your final decision for your “right drainage solution” should rest with you.
Anderberg Construction Consulting, Inc.
4100-10 Redwood Road #368
Oakland, CA 94619-2363
(510) 482-2779
tomanderberg@gmail.com
Lic. No. 907859 A,B,HAZ
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10 Common Questions From A Construction Consultant In Oakland, CA
July 3, 2009
10 Common Questions From A Construction Consultant In Oakland, CA
Over the course of the next few months we’ll be answering 10 of the most common questions that we get. We hope this helps to answer some of the questions that you may have. When we have finished this 10 part series we are going to add additional common questions as we receive them and eventually have a Frequently Asked Questions page with all the possible questions you may have. If you have a question that hasn’t yet been answered or have a question that is not listed, please contact us and we’ll answer your question as well as add it to our list. Thanks for your help!
1) Drainage – What’s the right solution for me?
2) Foundation Cracks – Are they significant? (1/4 inch or more)
3) Horizontal crack along the top of the foundation – What does it mean when I see a horizontal crack a few inches above the soil along the perimeter of the foundation?
4) Cracks in plaster walls – What do cracks near the upper portions of doors or windows indicate?
5) Doors do not close properly – What does it mean when my doors won’t close properly during certain times of the year?
6) Settlement – How do I determine the right procedure to correct settlement issues?
7) White powder on concrete – If a white chalky substance appears on my concrete, should I be concerned?
Downspouts – Should they be connected?
9) Water intrusion – How do you go about detecting where water is coming in from?
10) Seismic Retrofitting – Do I need it?
Announcing Tom Anderberg, Professional Construction Consultant On CityScoop!
July 3, 2009
Welcome to my CityScoop website. I’ll be publishing free tips and information pertaining to structural construction consulting. Over the course of the next few months I’ll be answering common questions that I frequently get that you might want to know about. Check back soon for more information or contact us today and we’ll answer your questions right away.
Thanks!
Tom Anderberg
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