Interior sealing for damp basement — good idea?
我在密歇根州（第5区）有一间未完成的地下室的房屋。地下室的墙是混凝土的，通常略微潮湿，有些地方比其他地方还差。地板上偶尔会有大雨，可能每年几次。墙壁被涂漆，似乎在油漆下面有某种更厚，更粗糙的涂层，要么是旧的Drylok式涂层或薄薄的东西。当我在地下室的一个角落重新粉刷时，我注意到一些旧的墙壁油漆/涂层正在掉下来，在那些地方，经常出现出现，并在下面散发出散布 - 就像在充满灰尘的油漆下面的小水泡一样。有些也许是镍尺，有些是几平方英尺左右。最多，剥落可能是1/2英寸 - 1英寸深的，但是大多数地方都少得多，而且有很多壁油漆保持完整，没有出气或剥落的证据。墙壁上没有破裂，我并不担心目前的结构状况，尽管似乎还有50或100年可能会导致问题。我目前的项目是删除现有的变质涂层，然后将其散开，然后擦去废水和任何松动的材料。这将使我可能完好无损地拥有80％的墙涂层。
My question is how to best move forward from there without making things worse, and ideally improving things. I have no plans to finish the basement (!), but a bit drier and cleaner would be nice.
排水沟完好无损;落水管里发出的least a few feet from the house and the grade slopes away from the house. There’s simply a high water table in my neighborhood and many basements are damp. Digging down to the footing from the exterior isn’t feasible due to concrete driveway/porch on two sides and a crawlspace on a third. My understanding is that an interior perimeter drain isn’t feasible because the house likely has no separate footing (unconfirmed, just based on local practices of the era) and the slab is likely at the bottom of the wall, so digging down for a footing drain would undermine the wall.
This leaves me with interior coatings (or omission thereof). Here is what I’m considering: skim coat of lime mortar as a sacrificial parging, followed by Thoroseal to manage water and then a couple coats of paint to manage water vapor and for aesthetics. I’ll only be able to do the parging and Thoroseal on the little islands of bare concrete. Are the Thoroseal and paint a bad idea? I know some would say to leave the wall uncoated so it can dry to the interior, but to me it seems like slowing that evaporative flow of water from exterior to interior would be a good thing and slow down the efflorescence. Is the sacrificial parging necessary if I also Thoroseal and paint?
If the paint starts to bubble off over the years, that’s not a big concern — I just want to avoid additional harm to the concrete.
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Replies
Molly,
你读过这篇文章了吗？
“固定湿地下室。”
Yes, but I'm not sure where to go from there. The easy exterior fixes have been done; exterior excavation isn't an option. I don't think we can do an interior drain either, unless someone has come up with a solution for old homes with no footings.
With a foundation that wet, have you measured the moisture content of the foundation sill?
Without a capillary break between the sill and damp concrete sealing the interior is likely to increase the moisture content of the sill.
I am following this with a lot of interest.
A few uninformed thoughts:
1) If you try to seal the concrete from the inside, you may prevent the inside wall from getting wet but you are also eliminating the ability for the concrete to dry to the inside so the mass of concrete may be wetter for longer which is obviously not great and may even lead to moisture going higher up the block or spreading further across the block. Along that line of thinking, maybe you need to embrace the fact that your foundation will let some moisture in and concentrate on ensuring that it can dry properly and quickly when that happens.
2）也许您低估了水在地下流动的潜力，以及通过整个批次的水管理措施影响当地地下水位的能力。很多东西有多大？您说排水沟离房子几英尺远。一个简单的起点是让它排水10英尺。您是否在暴风雨中观察到了排水沟。他们都在工作吗？
3) Does anyone ever drill holes through the foundation to drain water into a sump pump inside of the basement? Is that a thing?
#1, concrete can stay wet forever and it doesn’t care. Remember that they build concrete dams to hold back rivers. Concrete likes to be wet. Capillary draw does allow the water to rise higher in a sealed wall though, which is why a capillary break becomes more important when you seal the wall against moisture with waterproofing, insulation, etc.
#3, yes, “weep holes” are sometimes used to drain the hollow spaces in block walls. There are interior drainage systems designed to work with these holes to carry the water away. I suppose weep holes could drain water from the exterior of a poured wall to an interior drainage system too, but I’ve never tried that or seen anyone else try it.
账单
干锁使化学清洁剂可溶解流出。进行清洁时，您可能想使用它或类似的东西。
I had a similar issue to yours, although with a block wall. I extended the downspouts much farther out than usually, about 8-10 feet. That made a big difference. I still get too much water on that side of the house, so a French drain is in the works. I know in my case the surface water is going down into the ground and getting in, so drying out the surface will help.
您的地下室有平板地板，还是只是污垢？有用于平板的切口外围排水系统。您在周围切一个缝隙，在顶部安装排水管，混凝土在墙上贴在墙上以捕获任何水。
There are better water sealing coatings out there than drylock, but they’re all band aids if your wall is leaking — none will last forever. If you recoat, you need to completely remove the old water block coating so that the new one can penetrate the surface to bond. Surface prep is really critical.
账单
Another uninformed thought here. You say:
"Digging down to the footing from the exterior isn’t feasible due to concrete driveway/porch on two sides and a crawlspace on a third. "
Practically speaking, there is very little water that should be entering the ground through the driveway or through the area covered by roof/crawlspace. Water can get through the porch but even that can be managed if needed (for example, you could go to a fiberglass porch deck and drain it away from the porch.)
因此，您现在可以画出一个大周边环，几乎没有从上面的水进来。您可以根据需要将其深入挖掘，并安装外围排水管，即使使用污水泵。
感谢您的回答。
Dana, thank you for your point about the moisture content of the sill. The sill is actually spray foamed, so not really accessible to check. Hopefully the foam is providing a barrier from interior moisture, and it's drying to the exterior. Not much I can do about it anyway...
Zephyr7，地板是混凝土板，但我不确定（当地信誉良好的基础承包商也不是）当板的底部很可能大约等于墙壁底部时，如何进行内部外围排水口下面没有立足点。排水管在哪里挖出并破坏墙壁的轴承？
As for extending the downspouts, there's one that lets out just a couple feet from the house, but at an outside corner and onto a concrete driveway that slopes well away from the house. I could try to extend this one and see if it helps at all, but it's across the house from the dampest areas. The others let out at least 10' away from the basement. Gutters work well and we have them cleaned regularly.
加拿大_DECK, the porch is concrete slab as well and extends pretty much the full length of one wall, so there's definitely no water getting into the ground for 8' in front of that wall, and yet that's one of the two dampest walls. The other dampest wall has a concrete driveway along the entire length, which slopes away from the house. These two dampest walls are on the uphill side of the neighborhood -- the topography generally slopes toward our house from that direction for blocks and blocks, even though the grade within 10'-20' of our house slopes away from the house.
混凝土车道确实有一些裂缝（足以使杂草生长），我从来没有打过密封，因为通过这些水渗透的水量似乎必须忽略不计。车道向右延伸到房屋，该关节被填缝（也被屋檐所庇护），因此它不会进入那里。
You can install dimple mat on the floor with a sump pump to remove the water.
不要忽略确保远离房屋的坡度是水壁障碍（如果水流流过的话，这无济于事）。
回复：“这两个最潮湿的墙壁位于附近的上坡一侧 - 即使我们的房屋距离房屋的10'-20'级别，地形通常从该方向朝我们的房屋倾斜到我们的房屋。。”
同样，我不是这个特定主题的专家……但是这看起来像是关键信息。
这听起来像是有一个沼泽地(基本上低pot) 10-20 feet away from your house. If water is collecting there (from your driveway/porch/gutters in the one direction and from the prevailing grade in the other direction) and then absorbing into the ground, it's not a stretch to assume it may be working its way back to your basement underground - especially if the overall topography slopes in that direction.
A simple measure could be to ensure that any surface water at that point gets drained to the downhill side of your yard. To get fancier you could drain a deeper cross section.