Permissable differential settlement on masonary residential structure

[theonguy]

I am trying to determine whether an enhanced structural study is required for the following strucutral situation.

A 100-year old brick home with foundation base of 25 x 40' received an addition of 25 x 35' some 14 years ago. The addition was constructed on a clay soil, after excavating to a depth of 10 feet, immediately adjacent to the existing structure. New foundations were poured such that the floor elevation of the basements in both the existing and new structures were exactly at the same level. The new construction was brick veneer over conventional frame to match the style and visual look of the historic structure. The new brick veneer wall is inset to abut the existing brick structure and join it approxiamtely 6" 'in' from the corner of the existing structure. (i.e., rather than a single plane between the old and new brick veneer, there is an offset of approximately 6&quot.

After 14 years, there is a visible gap of approximate 1/4" between the intersection of the existing brinck wall and the intersection of the newer brick veneer wall. This gap is easily fillable with an elastomeric caulk.

The question is whether such a gap should cause any concerns over structural integrity, or whether, instead, normal differntial settlement is the likely cause and of no concern.

I'm stumped and looking for a "second opinion".
Any response to theonguy@yahoo.com is greatly appreciated and welcome!!

 

[ishvaaag]

If you don't see signs of structural and nonstructural distress other than the separation, and the joint staying opening, I wouldn't worry much for now on potential expensive foundation reforms, at least till further patent damage signals its necessity.

Other thing is that you want to ascertain the past and prospective futur of the addition, then investing the necessary resources to it.

 

[Focht3]

[blue]ishvaaag[/blue] is right - unless you see other signs of distress, I wouldn't panic.

I presume that you have already evaluated site drainage, weather and vegetation. Be sure to consider plumbing leaks - if the 100 year old portion originally had indoor plumbing, then It's probably a clay tile in the yard, although it could be lead pipe. If it was added later, then it could also be cast iron, ABS or PVC. While the plumbing should be outside the building footprint, it could cause mischief if it leaks...



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora.

 

[catanzarope]

If the joint width is uniform from top to bottom, you are likley seeing thermal movement and not settlement The construction you describe is essentially two seperate structures built adjacent to the other so they will respond differently to temperature changes and the movement will occur on the joint.

If you do detect evidence of vertical movement from one side of the crack to the other, what is its magnitude? Is there evidence of cosmetic damage inside? If not and if the movement is a fraction of an inch, simply fill the gap with a flexible, silicone based sealant. Use an expensive one to keep from having to refill it every so many years.

If further cracking should develop here, you may then have concern for water, gas and electric conduit from one side of the structure to the other.

 

[pmkPE]

Try using crack monitors. A company named Avongard sells crack monitors for a reasonable fee:

http://www.avongard.com

This kind of evaluation takes time, say three to six months to determine if separation is progressing or cyclic.