Buried downspouts can be a necessity or a preference depending on your house. The problem is it’s possible for them to freeze. Particularly if you are WAY up north and the cold is… aggressive.
Do underground downspouts freeze?
Yes, they do freeze. But it all depends on where the frost line – how low below ground level the ground freezes – is for your area, how cold it gets (under 20 degrees Fahrenheit), and for how long it’s below freezing.
If you live in a cold climate, the frost line will be between 3 and 4 feet below ground level. To be sure that your downspouts don’t freeze, they should be buried lower than 4 feet. If you live in a warmer climate you still may have frozen downspouts due to the likelihood of them not being buried deep enough or not being insulated sufficiently – if you have an unseasonably cold spell, they could freeze.
Elbows in downspouts are prime spots for freezing due to the pooling of water in those spots.
Related: Icicles + Ice Dams on Gutters: Causes, Prevention, Removal
How to keep buried downspouts from freezing
Assuming your downspouts are not buried below the frost line, what options do you have?
- Install self-regulated heating cable or heat tapes. The self-regulated heating cables adjust temperature as needed but it is an expensive option. Run a heating tape through the downspout all the way through the underground downspout. You can draw it in and through with a fish tape (Amazon link)
- Make sure the heating cable/tape is MADE to be run inside the pipe. If you’re looking for some serious pipe heating elements, check out Heatline.
- The pitch of the buried downspout has to be at least .25 inches drop in elevation per foot of underground pipe to ensure adequate water flow and should divert water 10 feet away from your house
- Before cold weather hits, clear gutters and downspouts of debris. Keep downspouts free of debris and leaves. This means when it’s the fall you keep leaves out of your gutters and make sure the path from the gutters on your roof all the way down through your buried downspouts is clear. If water is freely flowing and isn’t blocked by any debris there is less of a chance of water getting trapped and becoming ice
- Insulate pipes with underground insulation
- Implement perforated and knife-cut draining pipes. You can find an excellent supplier for a fresh install of a buried downspout that will limit freezing at the French Drain Man
How to fix a frozen underground downspout
Okay, say it’s too late, your buried downspout pipe has frozen and it’s too late to implement any of the measures above. Here are your options:
- Run warm water UP from the bottom. Insert a hose at the bottom of the runoff and run water up to the ice by pushing the hose up as far as it will go. This will melt the ice from the bottom up and will keep the water from backing up into your house. Because if you start pouring hot water DOWN the pipes it will back up as the hot water works to melt the ice.
- Pour hot water down the downspout to gradually melt the ice. This can work if the ice blockage isn’t too thick and if you aren’t able to run hot water up from the bottom as suggested above.
- Disconnect the downspout to the underground downspout portion – to stop the water from continuing to melt, getting stuck, and backing up into your house or foundation due to a blocked underground pipe. You’ll want to divert the water away from your house so you could get some temporary PVC or corrugated piping to divert it far enough away from your foundation.
- Along these lines you should also have a gap or vent between the downspout and the underground pipe in order to allow water to flow out even if the underground pipe is frozen. Either something like this debris strainer (Amazon) or this clean out assembly combo (French Drain Man)
And this creative fellow threw everything at it and it took him all day! Hot water, hose in the underground pipe, and his wife’s hairdryer:
How bad is it to have frozen buried downspouts?
The primary issue is that when ice fills up and backs up gutters leading to flooding or seepage in your house and basement particularly as the snow and ice start to melt on sunny days.
If the ice gets too heavy, it could also damage gutter and downspouts.