Parging The Foundation Walls

Posted on 29. Jun, 2009 by Mrs. Mecomber in exterior work, water problems

I have been in the process— oh, for about THREE years now!! — of parging the foundation walls of my home. Most new homes since the 60s and 70s have concrete block or poured concrete foundations. But waaaay back in the olden days (as when my house was built), foundations were built from field stones or cut stones. My home has cut stones. Over the 150 year span that my home has been standing, the field stones are still in excellent condition– it’s just the mortar that stinks.

Stone foundations have limestone mortar. It is water-permeable and over time and rodent-chewing (chipmunks are notorious for chewing away the mortar to build nests between the stones), the mortar begins to fail. In severe cases, this can cause foundation failure. In less severe cases (such as mine) this can mean a pocked, ugly appearance and some water leakage. Parging is the application of a thin coat of sticky cement over the wall surface. I’ve got about half of my interior basement done– what a job! My basement is huge and has 6′ high walls– and about 1/3 of the house’s exterior foundation wall (about 2 feet high).

The mix you use for parging must be special– it has to be sticky (that is, it must stick to a vertical surface without plopping down and off) and must remain stuck to the walls after it is dry. I had one dummy at Lowe’s tell me I needed mortar mix for the job, and me- being the dumb homeowner– listened to him and bought $200 worth of the stuff. Only to find that this is the WRONG stuff and crumbles off over time. :-p What you need to use is something call Sand Mix. It’s a combination of sand and portland cement. It should not crumble off if applied properly. There are even some acrylic additives you can add to the mix to make it even stickier- the additive is a lot like Elmer’s glue and comes in tall bottles. You pour it in to your Sand Mix mix. I didn’t use it. I’m too cheap (the additive is very pricey). I mixed up the Sand Mix and so far, it’s been working well. This is what I did about four years ago, and it’s holding up great:

To make the mix, you add water to the Sand Mix. You should only mix up as much Sand Mix as you are going to use in about 30 minutes. Otherwise, it will start to harden and won’t work anymore. Here’s what you will need for parging your walls:

Sand Mix
a bucket
water (hose or watering can)
spray bottle filled with water
cement trowel
cardboard or kneeling pad for your aching knees

It’s important to mix the Sand Mix *just right*– not too soupy or not too crusty. When mixed properly, you’ll be able to make M’s or S’s in the mix and they will stay in shape.

Before spreading on the stuff, make sure your wall is free from crud, like spiders’ webs, frass, and loose mortar. You will also want to dig down in the dirt a little, so that your parging line will not be seen should the soil shift around your foundation. I usually dig down about 3 to 6″, depending on the soil and the wall itself. Some folks go much deeper down.

Now, get your spray bottle and moisten the wall. This helps the parging mix to stick onto the wall. Don’t saturate your wall with loads of water– just get it wet.

Now lay your parging mix with your trowel, in 1/4″ to 1/2″ thickness.

Corners and around windows are the hardest, so take your time. Parging isn’t a difficult job, it’s just tedious. While parging, I found a few areas where moles and/or chipmunks had chipped mortar away. Grrr. I filled these holes in, to keep them out. Parging helps keep out water, too.

Click to enlarge any photo.

I am not too fussy about how smooth my mix goes on. Just laying on the mix is a 100% improvement!

Allow to dry for 36 hours before moving the soil back into your trench. The parging mix will change color as it dries, to a light gray. You can leave it this color, or paint it with some waterlocking paint, or exterior concrete paint. This job is so easy that you can even have the kids do it. You just have to make sure that they are consistent with the thickness and apply it so that everything is covered completely.

Tags: basement, cement, parging, waterproofing

14 Responses to “Parging The Foundation Walls”

Sugar Cribs

30. Jun, 2009

nice tips and very completed
Rebecca

30. Jun, 2009

Great job! I too have the old cut stone foundation and I’ve been putting this off for way too long. I’ll have to go back into a crawl space under my porch and just the thought of it makes me cring.
Cherry@NewburghRestoration

01. Jul, 2009

Wow, that was a good job. I would not have even thought about tackling a project like that myself.
Rosemary

13. Jul, 2009

Thanks for this information. The pix are very helpful.
Question: I want to cover (with cement) a cinder block wall which was covered with cement placed over metal lathe several years ago. In other words, I want to put a coating of cement over the existing wall which is made up of the above. Do I have to worry about lathe again or can I just start covering it up?
David M

16. Jul, 2009

Great post….! Looks Great..!
I own a 1830 home in MA and I have been patching up the foundation and skirt. Next step is to parge the foundation and the chimney in the attic. Your info helps greatly! Good luck with your next project!
Rosemary

17. Jul, 2009

Another question here: I want to put veneer type stones on an already sturdy cinder block wall. Can I use just regular cement to set them in or does this require a special type of cementing material?
Alun Chisnall

30. Sep, 2009

Thanks for useful tips and photos, Just about to copy you. Will report back later. Cheers
Dawn

02. Feb, 2010

You mentioned you did this on the interior as well. Did you use the same process? Do you have photos of doing that as well?
Mrs. Mecomber

02. Feb, 2010

Yes, I did the same process for the interior. No, I didn’t take photos. Thanks for your comment!
Dawn

02. Feb, 2010

@Mrs. Mecomber thanks! I’m going to try that in my basement I think!
Jeff

04. Feb, 2010

I have a basement which needs waterproofing badly. I tried a waterproofing paint but it didn’t work. I would like to try parging. Do I need to clean the paint off before parging?

Thanks
Barb

26. Feb, 2010

Our basement has leaked since we have lived here. Done drainage pipes in the back, tried with the “ugly” paint sealer, etc, etc. Nothing has worked. I saw Scott McGillivary -HGTV Income Property guy talk about parge today. Do you think this will really help my basement?
Bob

03. Mar, 2010

The cut stones were beautiful. Too bad that you didn’t just tuck the joints. Now your job just looks like cheap concrete instead of rich natural material.
Mrs. Mecomber

05. Mar, 2010

Hi Bob. Yeah, I would have preferred to keep things to the way they were originally– a lot of things, not just the cut stones. However, the side you see here does not reflect the remainder of the foundation. In other areas, the foundation is cracked, pitted, has missing stones, and someone had rammed in ugly orange sedimentary stones and mortared them in. Plus, the chipmunks were eating though the mortar. I’ll sacrifice 10′ of “nice” stone to waterproof and seal up the decaying remainder.