Existing Concrete Patio Slopes Towards House

by Will
(Knoxville)

What to do when your existing concrete patio slopes towards your house?

So, I bought a 105 year old foreclosure and there is an existing concrete patio off the back door (20 ft x 25 ft and in some places 3-4 ft thick). Because of the age and poor installation the slab is worn and grades slightly towards the house itself. I am very concerned about keeping rain and water away from the foundation but do not have the disposable budget to remove the existing patio (and even if I could not to sure what type of issues that could cause with the house foundation). Is there an option to grade the patio away from the house (maybe with said and gravel) then lay a level of water tight protection material and then sand and gravel on top of it before putting pavers on top?

This is the option I have been considering but haven't been able to find any resource material? I think the paving option is far better than any half attempt to pour concrete on top of the existing patio slab. Any suggestions would be greatly appreciated.

ANSWER

Hi Will,
I don't think that's a practical solution. Your main goal is to keep the water away from the house. I would be concerned about that water tight material you are thinking of. Typically anything like that, ie, concrete, asphalt, etc., should have a deep base of stone under it...at least 4 inches. That would have to be pretty thick up against your house, and how much room do you actually have, elevation-wise? You would actually need the 4 inches at the end of the patio and it would have to be higher at the house for it to grade properly away from the house.

If the existing patio is 20 feet deep, it would have to start at almost 5 inches (at the house) to create a 2% slope away.

In addition, you still have that concrete slope towards the house beneath this stone. Who knows how water will seep into the ground in a storm?

So I see a few other solutions.

1. Remove the concrete when you can afford it.Get some prices. It might be less expensive than you think. Your original idea of stone, waterproof membrane, stone and pavers would not be inexpensive for a 20 x 25' patio. You are talking about upwards in the area of $6000 to $7500, installed.

2. Consider cutting the concrete patio lengthwise along the house and installing a perforated pipe to take the water away. I don't know the elevations of the other areas of your property and if this can be done, but it is a possible option.

3. Remove the concrete and put in a smaller patio. You might not need one that large. Perhaps 15 to 18' x 18' to 20' would work for your needs. The reduction in square footage would bring down the total cost.

4. Consider replacing the patio with colored concrete. This is less expensive than concrete pavers. Visit these pages on this site to see how attractive this can be:

Concrete Patio Design 1

Concrete Patio Designs 2

I hope this was helpful.