How do I de-damp the walk-out basement of a lake house?
July 7, 2013 6:15 PM Subscribe
My in-laws have a lake house in Maine that's about 35 years old. It is a great place, except it gets very damp inside, especially in the basement/lower level, which is above ground on the east side and below ground on the west side. (The yard slopes down to the lake on the west side, starting at the top of the house.) What tactics and strategies can we undertake to de-damp the place? Or is this just the way life is with a lake house?
There is an old dehumidifier that seems to suck up tons of water, but it doesn't seem to make a dent on the general dampness or fuzzy mold that grows on many of the tiled surfaces. I wonder if maybe we need a newer, better one. One item conspicuously missing is an exhaust fan for the bathroom in the basement (as well as all other bathrooms in the house).
The first and second floors, both fully above ground, don't really have an issue with dampness at all. This being a lake house, there is no central heat or air conditioning -- just electric heat and wood burning stoves. The dampness is pervasive year-round.
There is an old dehumidifier that seems to suck up tons of water, but it doesn't seem to make a dent on the general dampness or fuzzy mold that grows on many of the tiled surfaces. I wonder if maybe we need a newer, better one. One item conspicuously missing is an exhaust fan for the bathroom in the basement (as well as all other bathrooms in the house).
The first and second floors, both fully above ground, don't really have an issue with dampness at all. This being a lake house, there is no central heat or air conditioning -- just electric heat and wood burning stoves. The dampness is pervasive year-round.
Best answer: Exhaust fans for damp spaces are a must so get that remedied. I suspect the dampness in the walk out basement are due to the underground basement walls not being waterproofed sufficiently. The only real, guaranteed fix is to dig a trench around the foundation, put in drains and waterproof the walls. This is a MAJOR job and very expensive.
There are some things you can do that might solve it, will help it and don't cost so much. Here is what I would do and in about this order:
Does the house have rain gutters? if not, install them and route them so they only discharge on the downhill side of the house. If so, make sure they discharge only on the downhill side of the house. Runoff from the roof may be introducing water around the foundation that is running down the outside of the basement wall and slowly entering the basement so rerouting this water should help. Oh and make sure you get the kind of gutters with covers so leaves and debri don't clog up your gutters, and if you have gutters get these covers installed. Clogged gutters act like no gutters and could be the problem.
Is there are a large uphill area that drains toward the house? if so dig a surface trench (fancy word for ditch) pointing uphill that will divert this water away from the house like this:
.... /\
... /. \
,, / .. \
. / .[]. \ with the brackets being the house
if you are really ambitous dig down about 5-6 feet and install french drains that also discharge below the house. NOte: this is also part of the digging up the foundation fix i mentioned above but this will be much cheaper to do away from the house where you can get equipment to do the digging but it is not as likely to be effective the farther you get from the house. however in an uphill drainage design like this it is likely to be pretty effective.
and lastly improve ventilation on the house. Install those exhaust fans on timers in the bathrooms (should run for 20 minutes or so after a shower). Does the kitchen have a range hood that vents outside? cooking introduces a LOT of water vapor into the house. Is the roof vented on the house? and if it is does it have soffit vents? these are all going to be marginal improvements but can add up to ease the problem somewhat.
posted by bartonlong at 6:39 PM on July 7, 2013 [7 favorites]
There are some things you can do that might solve it, will help it and don't cost so much. Here is what I would do and in about this order:
Does the house have rain gutters? if not, install them and route them so they only discharge on the downhill side of the house. If so, make sure they discharge only on the downhill side of the house. Runoff from the roof may be introducing water around the foundation that is running down the outside of the basement wall and slowly entering the basement so rerouting this water should help. Oh and make sure you get the kind of gutters with covers so leaves and debri don't clog up your gutters, and if you have gutters get these covers installed. Clogged gutters act like no gutters and could be the problem.
Is there are a large uphill area that drains toward the house? if so dig a surface trench (fancy word for ditch) pointing uphill that will divert this water away from the house like this:
.... /\
... /. \
,, / .. \
. / .[]. \ with the brackets being the house
if you are really ambitous dig down about 5-6 feet and install french drains that also discharge below the house. NOte: this is also part of the digging up the foundation fix i mentioned above but this will be much cheaper to do away from the house where you can get equipment to do the digging but it is not as likely to be effective the farther you get from the house. however in an uphill drainage design like this it is likely to be pretty effective.
and lastly improve ventilation on the house. Install those exhaust fans on timers in the bathrooms (should run for 20 minutes or so after a shower). Does the kitchen have a range hood that vents outside? cooking introduces a LOT of water vapor into the house. Is the roof vented on the house? and if it is does it have soffit vents? these are all going to be marginal improvements but can add up to ease the problem somewhat.
posted by bartonlong at 6:39 PM on July 7, 2013 [7 favorites]
Yeah, it's been a really damp year here. We are living right on a lake and it's miserable. I had a garter snake in my bedroom last week. So much rain all the time and now the septic is backed up and failed and we gotta move. It's just that bad of a year, dear.
Are there vents underneath the house? The basement should be vented out during the warm months. I am talking things on either side where there might be windows in a regular house basement. There are louvres that should be uncovered during the warmer months.
Last year I had mold on everything -- in the mudroom closet, coats, etc. Mold growing on my kitchen cabinets. It was disgusting. Our antique dry sink, the side toward the windows, covered in mold. So yes, it really can be like that at the lake.
I would advise getting a professional in to scope it out, any sort of general contractor that the locals might recommend.
posted by Marie Mon Dieu at 7:03 PM on July 7, 2013
Are there vents underneath the house? The basement should be vented out during the warm months. I am talking things on either side where there might be windows in a regular house basement. There are louvres that should be uncovered during the warmer months.
Last year I had mold on everything -- in the mudroom closet, coats, etc. Mold growing on my kitchen cabinets. It was disgusting. Our antique dry sink, the side toward the windows, covered in mold. So yes, it really can be like that at the lake.
I would advise getting a professional in to scope it out, any sort of general contractor that the locals might recommend.
posted by Marie Mon Dieu at 7:03 PM on July 7, 2013
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That will be the issue. Dehumidifying the interior air isn't going to make much of a dent in the underground river trying to seep in through your wall.
What tactics and strategies can we undertake to de-damp the place?
First thing is figure out how the ground water outside the basement wall mostly gets there. If it really is an underground waterway there's probably not much you can do that doesn't involve deep excavation and tens of thousands of dollars. But if it's surface runoff that the house is trying to dam up, you might be able to mitigate it with surface shaping designed to deflect water away from the house.
posted by flabdablet at 6:33 PM on July 7, 2013