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Question DetailsAsked on 4/30/2017

how much does it cost on average to waterpoof basement

basement leaks on several walls . half basement and crawl space

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Arrrghh - the Angies List computer is removing paragraph breaks again - try copying and pasting the test into a word processing or text program and put a couple of Returns everywhere I have "nnnn" - that is where the paragraph breaks belong. Sorry.



Varies widely depending on specifics of the job - foundation size, depth of excavation, water table height, whether you need french drain (recommended while the foundation is opened up anyway - add little extra cost, relatively speaking), distance thae french drain outlet(s) have to run to get to free surface to drain, type of waterproofing (bitumastic, spray-on asphaltic, membrane, built-up, combination, whether being insulated too, etc). Also on whether the entire perimeter only needs it, or only the uphilll sides - sometimes only 2 or 3 sides need it on hillside or daylight basement houses. Also of course, add in any repair costs if foundation is damaged.



For normal size house (say 30-40' by 40-60 foot range) commonly runs in the $4000-5000 range, and with options like complete french drain, multi-component system (my recommendation - bitumastic coating on foundation plus waterproof plastic membrane),and/or maybe insuylation board in the process more commonly runs in the $5,000-10,000 range. Larger homes, ones with a lot of groundwater around the foundation, ones with damaged foundations, etc can rarely run into the $10,000-30,000 range - but thst is rare. nnnnnnnn Choose contractors based on recommendation, THEN get several bids (at least 3-5) because this sort of job typically has a wide variance in bid amounts. nnnnnnnn ===== Depending on what the source of the water is, it might be that the normal fix - keeping the water away from the foundation in the first place - will sole the issue, unless naturally high groundwater is the cause. In the vast majority of cases, using gutters and downspouts to catch the roof runoff and direct it well away from the house, grading and compacting the soil near the house (for 3-6 feet from the foundation) so the water runs off rather than soaking in, and sometimes construction of swales or berms to keep surface water from rain or snowmelt or natural springs away from the house solves the problem with zero work at the foundation itself. nnnnnnnn You can find a lot of previous questions about wet basements, with answers - some of which include fairly complete checklists of ways to determine the source and control it before it gets to the foundation, in the Home > Basement Waterproofing link in Browse Projects, at lower left. nnnnnnnn One hint - most basement waterproofing contractors were not taught the right way to do it, or just get lazy, and put the waterproofing only down to the top of the footer, and lay the drain tile on top of the footer. The problem is, the top of the footer is usually the bottom of the slab level, so that puts the drainage level just 2-3 inches below the indoor slab level, which even though it MAY keep free water from coming up around the slab, still means a mightly wet foundation slab. nnnnnnnn The proper place to put the french drain is outside the footer - with the bottom of the drain pipe at least as low as the BOTTOM of the footer (so 6-10 inches deeper than on top of it) and in areas with high water table, should be a foot or two BELOW the bottom of the footer and typically 6-12 inches outside it. If going below the bottom of the footer, it is of course inmportant to not remove the support from the footer - so the drain pipe is trenched in at least as far away from the footer (to nearest edge of trench) as it is deep below it, and should be dug, drain installed, and backfilled quickly without leaving the drain trench open for any time. In fine-grained or soft soils it needs to be further away (typically twice the trench depth below footer base) and may need dewatering during the work if in wet ground. nnnnnnnn Also - the waterproofing should go all the way to the bottom of the footer, with special care taken at the normal construction joint between foundation wall and footer. nnnnnnnn Also - don't let anyone talk you into putting drain holes through the wall or footer with the claim that allows drainage from both sides of the wall - that is an invitation to basement flooding during high rainfall events or seasonally high water levels or if you get plugged french drain or gutters. I have seen far too many flooded basements (a number to 5-7 feet deep during outdoor flooding events) from this, and also makes an incredible mess if you evfer have a leaking sewer line or septic tank/leach field outdoors which backflows through the drain holes to the basement. If you need drainage inside the basement too due to high, free flowing groundwater which cannot be drawn down by exterior french drains, put in separate underdrains under the slab there leading to a sump pump. nnnnnnnn You can see lots of drawings and photos of how these drains are put in (note not all will be correct - some will show it too high) - google this search phrase - foundation french drain image

Answered 3 years ago by LCD

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