Is Two Drainage Systems for Your Home Necessary?

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  • Gutter Downspout Extension
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    LESLIE: Jill in Washington is on the line with a question about a foundation. What’s going on at your money pit?

    JILL: We’re having a small house built up here in the great, beautiful state of Washington. And the builder is recommending a double set of – how do I say it? For drainage. He wants to really be sure that the drainage all is done right. One system will join  with the downspouts from the roof. And then the other is kind of like a perforated, long, 200-foot piece of hose with a sleeve over it. Do you recommend both of those? Is that overkill or how would you do it? Is two drainage systems necessary?

    TOM: So we’re talking about surface drainage here or are we talking about gutter drainage or both? These sound like, from your description, that these are all running away from the house. Is that right?

    JILL: Yes. He wants it around the – they’ve simply just finished the foundation and are about to do the backfill. Before they do the backfill, they want two drainage systems put in place. One is a hard – I’m not sure of the correct terminology. It’s a 4-inch pipe …

    TOM: Yeah, one’s for the downspouts and one’s for the foundation. Is that correct?

    JILL: Correct. Exactly.

    TOM: Alright. No, I mean I think he’s doing it right with two drainage systems. And those steps will help. The one really important thing is that when he’s done with this is not only do those downspouts have to be extended away from the house, but you want to make sure that that finished grade also has a pitch that drops at least about 6 inches over the first 4 feet. Because with new construction, you’ll get a lot of settlement and you’ve got to have good pitch. But if you have downspouts that are extended out away from the house and you have good pitch, you’ll never have to worry about a water-infiltration problem.

    And I also don’t suspect that those additional foundation drains will really come into use much, if at all. But since it’s all fully open right now, there’s no real – there’s no harm in doing that.

    JILL: OK. So, it’s just bite the bullet and just put both systems in.

    TOM: Yeah. Now, have they put the gutters in yet?

    JILL: Oh, no, no. The house isn’t even built yet. No, just the …

    TOM: OK. So, here’s a good tip. Most builders are going to put in what’s called a “4-inch case-style gutter.” That’s a standard gutter. Opt for the next size up – it’s a 6-inch gutter – for two reasons. Number one, it holds more runoff from your roof; it doesn’t get overwhelmed. And number two, it doesn’t clog as easily because the downspouts are much bigger.

    JILL: I see. What a great tip.

    TOM: OK. And they’re not that much more expensive, either.

    JILL: Great. Well, you know what? When we get to that point, I’m going to call the show back and – because it always rains up here. And I will let you know that we took your grand advice and how it all came out.

    LESLIE: Alright.

    TOM: Alright. Can’t wait. Thanks so much for calling us at 888-MONEY-PIT. Good luck with that brand-new home.

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