[MilkBone2020]

I have an unfinished basement that occasionally leaks water. I’ve trenched my gutters and worked on the grade around the house. Both helped tremendously but I still get water with heavy rains. The basement is a walkout and has a garage door. The front wall is against soil and the side walls the soil slopes away.

Eventually I want to finish the basement. Water only comes in along the walls where soil is above the footing. I’ve also seen it bubble up through a concrete crack.

I’ve had two quotes for installing an interior French drain and sump pump. Both came in around $70 per linear foot. So pretty expensive!

I also know that my house has radon. If I keep my basement windows open then long term average levels stay under 2.5. I’ve seen daily rates as high as 10.

One of the products was a water guard system and the other was corrugated PVC pipe. Both products had a lip against the concrete block wall to allow any hydrostatic water to drain.

A couple of questions:

1) do I need a full perimeter interior French drain? Or just against the walls with soil and leakage?
2) does the lip against the concrete wall allow more radon in? If I later install radon mitigation will I have to seal that lip?
3) Can I discharge the sump pump into one of the trenched gutters or is that too much water? 2000 sqft roof, 4 total gutters. Front gutter trenches to rear gutter, connected together and then trenched 50Ft away.

 

[AllanJ]

What do you mean by a trenched gutter?

Also remove any depression along the foundation that you filled with gravel or mulch. Replace that porous material with hard soil comparable to the rest of the lawn and grade it so rain water runs away.

Additionsl although not perfect radon mitigation is had by putting a sealed lid on the sump pump pit and adding a port in the lid so the radon system will try to suck air from the pit This will make the inside of the perimeter drain systm (a French drain) a negative pressure region and some radon seeping into that along with ground water seeping into that will migrate to the sump pump pit to be removed.

 

[MilkBone2020]

Trenched gutter is where I attached my downspouts to corrugated pvc pipe and buried the pipe in a trench that extends 50 feet away from house.

Will the gap between wall and drain let more radon in? Is it possible that a sealed drain could eliminate the need for radon mitigation? Or would that cause additional problems?

 

[AllanJ]

If water comes in (seeps in) above floor level and runs down the inside surface of the foundation and than has to be collected then the sealed lid for the sump pum ppit has limited value. Makeup air will be drawn from the wall to floor slab gap near the pit so no negative pressure will remain in the French drain to collect radon from the far side of the basem ent. Also the water seeping in will have some dissolved radon in isome of which will enter the atmosphere much like carbon dioxide from a soft drink bubbles into the atmospher.e Bu I would expect that a radon mitigation system built disregarding the presendce or abxence of a French drain will do the job.

 

[MilkBone2020]

To prevent hydrostatic pressure, aren’t holes drilled into the block? Wouldn’t this create more spaces for radon air to enter?

 

[stadry]

you will continue to get water into your very fine home no matter what you're alrealdy done,,, the reason's simple - water runs downhill even underground,,, 1st it hits the top of the wall then looks for the easier path down where it escapes/drains into your bsmnt

Eventually I want to finish the basement. Water only comes in along the walls where soil is above the footing. I’ve also seen it bubble up through a concrete crack. this suggests the water table is artificially high from leaking water

A couple of questions:
1) do I need a full perimeter interior French drain? Or just against the walls with soil and leakage? since water takes the path of least resistance, installing a system which serves the leaking wall's is not a gamble as you're, in effect, managing the leak,,, 'waterguard' is a term used by basement systems' franchisees,,, its an extrusion that sits on top of the foundation & is visible above the replaced conc floor.
2) does the lip against the concrete wall allow more radon in? If I later install radon mitigation will I have to seal that lip? depends,,, if you also install the exhaust fan from inside the sump, monitor the readings - possible you won't need to seal it
3) Can I discharge the sump pump into one of the trenched gutters or is that too much water? 2000 sqft roof, 4 total gutters. Front gutter trenches to rear gutter, connected together and then trenched 50Ft away. what is the estimated amount of water now being pumped ouside or leaking inside ?
you could also install a fresh air exchanger in lieu of a radon system

 

[stadry]

To prevent hydrostatic pressure, aren’t holes drilled into the block? holes are drilled into the block to darin the affected cells
Wouldn’t this create more spaces for radon air to enter?it
may or may not,,, need to monitor radon levels

 

[Nealtw]

If you have a walk out basement there should be no need for a sump if the yard slopes away from the house.

 

[stadry]

that's a retired framer posting,,, we've treated many walkout bsmnts in nj, pa, ct, ny + ga,,, maybe they build differently in canada - nope, evidently not - here's https://www.basementsystems.ca/
remember, builder's warranties only guarantee leaking water for the FIRST YEAR

 

[Nealtw]

that's a retired framer posting,,, we've treated many walkout bsmnts in nj, pa, ct, ny + ga,,, maybe they build differently in canada - nope, evidently not - here's https://www.basementsystems.ca/
remember, builder's warranties only guarantee leaking water for the FIRST YEAR

Well retired framers don't pump water down hill.:biggrin2:

 

[stadry]

typically water won't leak on the backside of a walkout basement - i've never seen a rear wall at grade that was leaking UNLESS the backyard sloped towards the rear wall,,, most leaks occur at the front buried bsmnt wall,,, sometimes 1 can install a gravity drain & no pump's needed,,, usually its less expensive to install sump/pump ($1,300) compared to installing drain channel to gravity discharge at back wall ($2,100)
its all about getting the collected leaking water to a spot where God will then command it to run downhill