Signs of Foun­da­tion Prob­lems – Struc­tur­al vs. Non-struc­tur­al Wall Cracks

Oct 25, 2012 • By Matthew Stock with Barry Schilling.

In the base­ment water­proof­ing busi­ness we talk a lot about cracks. Cracks in poured con­crete base­ment walls and cracks in base­ment floors are both sources of seep­age that cre­ate base­ment water prob­lems that require pro­fes­sion­al repair. These are gen­er­al­ly non-struc­tur­al cracks, that is, they aren’t caused by sig­nif­i­cant foun­da­tion move­ment and don’t jeop­ar­dize the sta­bil­i­ty of the foundation.

Struc­tur­al cracks, on the oth­er hand, are tell­tale signs of foun­da­tion prob­lems and, even though they may nev­er allow water to enter the base­ment, they rep­re­sent a sig­nif­i­cant­ly big­ger prob­lem so they should nev­er be ignored.

How to Tell the Dif­fer­ence between Struc­tur­al and Non-struc­tur­al Wall Cracks

Non-struc­tur­al wall cracks are, at worst, a source of water in the base­ment and can be eas­i­ly and per­ma­nent­ly repaired. Struc­tur­al wall cracks in poured con­crete walls indi­cate a seri­ous drop or shift in the home’s foun­da­tion and require major repairs to pre­serve the home. It’s impor­tant to be able to tell the difference.

Non-Struc­tur­al Cracks – Non-struc­tur­al wall cracks can occur almost any­where in a foun­da­tion wall; they are like­ly to emanate from open­ings in the wall, like win­dows, doors and pipe intru­sions. Caused by lat­er­al pres­sure exert­ed by the soil out­side the foun­da­tion, these cracks are gen­er­al­ly nar­row, less than 1÷8”, and can even be of the hair­line vari­ety. These cracks will seep water when the soil is saturated.

Non-struc­tur­al wall crack repair is done by the injec­tion method. The expand­ing ure­thane inject­ed into the crack fills it all the way to the out­side soil, form­ing a per­ma­nent seal that pre­vents fur­ther seepage.

Struc­tur­al Cracks – Struc­tur­al cracks in poured con­crete walls tend to occur in pat­terns. One com­mon pat­tern is for cracks to run up at an angle from the low­er cor­ners of the wall, accom­pa­nied by a ver­ti­cal crack in the cen­ter. Anoth­er is for angled cracks to begin in each of the four cor­ners of the wall and inter­sect a hor­i­zon­tal crack in the cen­ter. These cracks are gen­er­al­ly wider, in excess of 1÷8” and may or may not seep water.

Struc­tur­al cracks are caused either by severe pres­sure exert­ed by swollen soil or by the foun­da­tion sink­ing due to soil des­ic­ca­tion. Either case requires sig­nif­i­cant struc­tur­al foun­da­tion repair: fur­ther wall move­ment can be arrest­ed by bond­ing car­bon fiber strips to the wall and attach­ing steel angles at the top; a sink­ing foun­da­tion can be repaired with resis­tance and heli­cal piers.

It’s obvi­ous that the dif­fer­ence between struc­tur­al and non-struc­tur­al foun­da­tion wall cracks is a crit­i­cal one and this arti­cle isn’t intend­ed to make any­one an expert on their iden­ti­fi­ca­tion. A pro­fes­sion­al knowl­edge­able in struc­tur­al foun­da­tion dam­age will be able to iden­ti­fy the nature and source of wall cracks and rec­om­mend the most effec­tive repair.

U.S. Water­proof­ing has long been at the fore­front of struc­tur­al foun­da­tion repair, adopt­ing state-of-the-art meth­ods of foun­da­tion under­pin­ning and sta­bi­liza­tion. If you see cracks in your base­ment walls, don’t hes­i­tate to sched­ule a free con­sul­ta­tion with one of our experts.

Tags: foundation cracks, basement crack, cracks in basement walls, structural foundation damage

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