I’ve got a question regarding the exterior landscaping of a Philadelphia Row-home, circa 1925.
I need to redo the patio (20 X 20– it’s the whole ‘backyard’) and stop the basement moisture at its source, I’m planning on doing the following:
1) Renting a Jackhammer and removing the existing (badly cracked) concrete.
2) Digging 6 inches to 1 foot down, grading away from the property
3) Renting a plate tamper and compacting the soil.
EITHER
Putting plastic sheeting down (in successive strips from lowest to highest) to make the water shed to the alleyway
OR
Installing a French drain to the alleyway
5) Laying down crushed rock
6) Laying down sand
7) putting in pavers
The online sites that I have gone to talk about a french drain’s pros and cons. They say it needs to be dug up and cleaned out every few years.
nobody I have talked to seems to have an idea about putting down sloped successive layers of plastic sheets– I came up with this idea on my own and it may have some terrible fault that I’m not considering.
I don’t want to install a French drain system that will require me to dig up my patio every 2-3 years if I can avoid it. Can I avoid it? What do you think of my idea for the plastic sheets? We live on 100 year old Coal-ash fill and have a fieldstone foundation so we need to limit moisture in every way we can.
Replies
You can do BOTH the french drain and the plastic layered.
The french drain is to lead water away - it has to have someplace to go to daylight with the water it collects tho.
And done right, it should last 20 years or so.
Do not place crushed stone on the plastic first - it will poke holes in the plastic. Use sand first.
Arte you topping this with concrete or field stone or slate?
There are also strong moisture stop materials than plain plastic.
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
I'm putting pavers on top, a herringbone brick, I think.
So the French drain just needs to be at an angle, too? It's going to lead out to the alleyway behind the house.
angle relative to what?It does need to have some pitch to it - say an eighth inch or so per foot
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
They sell 20x20 cross linked poly that is much stronger and
you won't need layers.
Grading the yard away from the house is half the battle. Any way to
slope it so the water WANTS to go down the alley?
no dice on the alleyway. The alley crosses 20 other homes' backyards and the land in south philly is as flat as a tortilla.
You said the hardest part would be grading the yard. what are some problems many people encounter?
The hardest thing is to get friends to help without spending $$on beer and pizza:)
He's in Philly. No pizza. Just cheesesteaks.One other comment, I prefer stone dust over sand, even for setting bed for pavers. It sets, compacts, and locks down better than sand and is less likely to be washed out with heavy rain.
I would use 3-4" stone dust compacted for setting the pavers, but sand under it. The sand will let water wick away better.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
What about ants? Pretty common to have them with a bed of sand.
pretty common to have them without a bed of sand.Don't slop[ sugar drinks there to feed them and add borate to the mix if it is a concern.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I didn't mean it was hard. I meant, by pitching the surface a good deal of the water
problem is solved. But no dice anyhow...
If your current issue is because of the existing grade sloping towards the house, simply fixing the grade to slope away will take care of 95% of the problem. You don't mention what the existing soil is like, but unless your soil is very free draining/sandy it is better if you make sure your subsoil is sloping away from the house also (ie. dont just fix the grade by adding extra stone dust/gravel near the house. If you properly prepare the base and slope, adding the poly will likely make little difference because the water will be shed away before it ever reaches the poly layer. But if it makes you feel safer it probably would not do any harm ( I have fixed many landscape grade issues without ever needing such a barrier).
Whether you use a thin sand layer or not below your pavers is personal preference. Some folks find it easier to set pavers in sand than atop the crushed stone but either is fine.
If you want to really make sure that hardly any water even penetrates the paver layer, sweep the paver joints with polymeric sand... not regular sand. It is a great product that is very effective in helping to shed water. Once it dries and cures it creates a mostly waterproof layer all by itself. But.... proper grading is THE most important part of your job.