U.S. Waterproofing | Waterproofing a Finished Basement without…

Water­proof­ing a Fin­ished Base­ment with­out Tear­ing it Apart

May 28, 2014 • By Matthew Stock.

Finished Basement

Fin­ished base­ments are great. They can add liv­ing space to a home with bed­rooms, fam­i­ly rooms or oth­er con­fig­u­ra­tions. They can be util­i­tar­i­an as well, hous­ing a work­shop, hob­by space or a laun­dry room. Of course, there’s always the man cave.”

What­ev­er the use of a fin­ished base­ment, it usu­al­ly rep­re­sents a sig­nif­i­cant com­mit­ment of time and mon­ey by the home­own­er, whether it was a DIY project or han­dled com­plete­ly by a con­trac­tor. Under the best of cir­cum­stances, the raw base­ment space would have been ful­ly water­proofed before con­struc­tion began but, unfor­tu­nate­ly, this isn’t always the case.

Some­times, the incre­men­tal cost of water­proof­ing puts the price tag of the ren­o­va­tion out of reach and the home­own­er choos­es to roll the dice. In oth­er cas­es, a DIY-er may not be aware of the need for water­proof­ing or a con­trac­tor may not inform the client beforehand.

When seep­age does occur in a fin­ished base­ment, the stakes are high­er because of the poten­tial for dam­age to car­pets, fur­nish­ings, elec­tron­ics, stored goods and more. Spot­ting water in a fin­ished base­ment often caus­es despair on the part of the home­own­er who imme­di­ate­ly pic­tures destruc­tion of the beau­ti­ful liv­ing space to fix the seepage.

The good news for this home­own­er is that, in most cas­es, a fin­ished base­ment can be water­proofed with­out tear­ing it apart.

How to Water­proof a Fin­ished Base­ment with­out Tear­ing it Apart

The most com­mon source of water in poured con­crete base­ment is a non-struc­tur­al crack in the wall. In an unfin­ished space, these cracks are repaired from the inside but they can also be fixed per­ma­nent­ly from the exterior.

Exte­ri­or crack repair begins by exca­vat­ing a small-diam­e­ter hole next to the foun­da­tion at the site of the crack. The hole, which extends down to the foun­da­tion foot­ings, is then filled with gran­u­lar sodi­um ben­tonite clay, which absorbs water from the sur­round­ing soil to form a per­ma­nent water bar­ri­er on the foun­da­tion wall.

Once the remain­ing hole has been back­filled, the repair is invisible.

If the foun­da­tion is made of con­crete block or oth­er mason­ry, cracks will occur in mor­tar joints and admit water into the base­ment. These cracks can also be repaired per­ma­nent­ly on the exte­ri­or of the foun­da­tion by installing an exte­ri­or water­proof­ing mem­brane.

The dam­aged wall is first exca­vat­ed down to the foot­ings and dirt and oth­er mat­ter is cleaned from the wall. Tech­ni­cians then use trow­els to apply a thick coat­ing of asphalt-mod­i­fied polyurethane to the wall, which will cure to form an impen­e­tra­ble water bar­ri­er. This mem­brane should be dis­tin­guished from damp-proof­ing,” which is a thin coat­ing sprayed onto the foun­da­tion dur­ing con­struc­tion to pre­vent condensation.

If ground water sur­round­ing the foun­da­tion is unusu­al­ly high, the mem­brane should be aug­ment­ed with exte­ri­or drain tile, a sys­tem of per­fo­rat­ed pipe buried next to the foot­ings in a bed of washed grav­el. The drain tile will alle­vi­ate pres­sure from over-sat­u­rat­ed soil and car­ry ground water to a sump pump for dis­pos­al. Heavy-duty drainage board will also be installed on the walls to pro­tect the mem­brane and chan­nel water down to the drain tile.

An exte­ri­or water­proof­ing mem­brane can also be used when water enters the fin­ished base­ment through porous con­crete or over the top of a foun­da­tion wall.

When a home­own­er finds that a fin­ished base­ment is threat­ened by water seep­age, he or she will need the advice and assis­tance of an expe­ri­enced base­ment water­proof­ing con­trac­tor. At U.S. Water­proof­ing, we start­ed in busi­ness in 1957 by doing exte­ri­or water­proof­ing and have grown into one of the largest full-ser­vice base­ment water­proof­ing com­pa­nies in the coun­try with more than 300,000 sat­is­fied cus­tomers. Why not ask for our free advice when your fin­ished base­ment gets soggy?

Want to know more about water­proof­ing a fin­ished base­ment? Post your ques­tions in the Com­ments box below.

Tags: waterproofing finished basement, finished basement waterproofing

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