waterproofing a foundation

[matrass]

Hello and good everybody. wanted to get some opinions on the proper way to waterproofing a poured concrete foundation. I know they used to tar them but in recent years a waterproof membrane seems to be done more often on a new home. looking at the membranes there are ones that are self adhering and some need to be fastened. one membrane may be straight faced while the other one has dimples in it like bubble wrap to allow water to drain ( if it happened to get behind it ) also there is a membrane that is applied with a roller. I am looking into building a new home and would like to have the foundation as waterproof as possible. I understand that drainage needs to be set up correctly as well but water can run down the foundation and if there is a weak spot it will find it. I had spoken with a contractor in my area who has build a lot of houses ,he did around 117 in one development alone very close to me. when I asked him about the foundation he said he uses tar. looking at a house he was almost done with recently, everything about it was built well with a higher quality that you would expect on a new home. been checking online about membranes and there are so many that I would like to get some opinions before asking the contractor if he would install a membrane, even though it will cost a little more. hate the thoughts of tar drying out and cracking and having water in the basement on a house that is only a couple of years old. seems like there are advantages to a liquid membrane, being cheaper and no seams but not as durable and you need to be sure it is applied evenly.the sheet would be more expensive and harder to work with and have more seams in it but it *should * be more durable and have less variables in thickness. any particular brands that stand out or to stay away from ?

 

[donnyj08]

2 Part spray foam insulation. its a sealer, air sealer, as well as and excellent insulator. r-7 for every inch sprayed. have it sprayed on 2 inches thick, and you will have a great seal and insulating properties. weatherization companies specialize in this type of thing.

 

[hemitom]

I would be more worried about the weeping tile being down correctly and the land scaping around the house then the type of membrane being used. The key is to have the water draining away from the house as much as possible.

 

[hemitom]

This also greatly reduces the damp feeling you have in your basement.In my climate this is the route i would go. Another issue to watch for when they back fill the foundation you would be amazed at the size of the rocks they throw back down and possibly damage your membrane.

 

[matrass]

Originally Posted By: hemitom
I would be more worried about the weeping tile being down correctly and the land scaping around the house then the type of membrane being used. The key is to have the water draining away from the house as much as possible.


I did ask how the drainage would be set up and it seemed more than adequate to me. I use to landscape a while back so I knew what I wanted for drainage and you are correct it is super important. the lot has a natural slope from front to back and the sides will slope away from the house also. to me when you are spending a lot of money building a new house why not spend a little extra to make sure it is waterproof. ? my big concern is that tar is water resistant and does crack over time . I would want the best protection so there is no water damage down the road. I know what you mean about the size of the rocks and could see them creating a hole in a membrane.

 

[georgemiller]

http://www.houseguard.com/documentlibrary/TruDry PI Sheet.pdf

The cost to add a Tru Dry waterproofing system at a 2600 sq. ft house is about $ 800-1200 over conventional tar.

Every home builder but one by me uses the tar. The other one uses the Tru Dry system. If it was my own house I would go for the extra bucks and use the Tru Dry System.

Builders use tar due to economics. $ 1000 extra per house can add up quick.

 

[matrass]

Originally Posted By: donnyj08
2 Part spray foam insulation. its a sealer, air sealer, as well as and excellent insulator. r-7 for every inch sprayed. have it sprayed on 2 inches thick, and you will have a great seal and insulating properties. weatherization companies specialize in this type of thing.


I am assuming you are talking about the inside of the foundation. the house I checked out has the inside of the foundation well insulated on the inside of the basement. my father in law and Dad saw the house and both were happy with the build. my Dad used to work for the gas company and knows a lot of people in the construction business. he did some digging around on the contractor ( without me knowing ) and said the guys name came up a few times with very high regards.

 

[hemitom]

Nothing wrong with doing it right the first time and if it means speending more money i'm all for it . After all this will be your house. Tar is old school but it does work, and yes it does dry out and crack, My 40 year old foundation is proof. The spray type sealer or membrane is the way to go, which one will stand the tests of time better is yet unproven.

 

[Indydriver]

Once upon a time, I installed professional commercial waterproofing so here's the basics:

1. You need to distinguish between "damproofing" and "waterproofing". Essentially, damproofing is a coating and waterproofing is a membrane. There are many varieties, all of which will work when installed and backfilled properly in conjunction with properly functioning drainage.

2. "Tar" technically means pitch bitumen and isn't used anymore. Your contractor is probably referring to an asphaltic mastic. Mastic by itself is damproofing. It can become a component of a waterproofing membrane by "three coursing" it, I.e., one layer of mastic on the substrate, a reinforcing fabric (typically a fiberglass mesh) troweled in, following by a topping course of more mastic. This is probably the most cost effective membrane you can install on concrete or block walls.

3. Backfilling and protection of a waterproofing membrane is as critical to it's success as is proper installation. The membrane or damproofing must always be covered by a protection board. 1/8" asphaltic "Meadows" board is typically used over asphaltic membranes. Peel & Stick membranes should be covered with expanded polystyrene ("beadboard"). Backfill is ideally sand. This provides quick drainage down to the drain tile and creates uniform pressure against the membrane (this is important). A fine dirt fill can be acceptable but may eventually obstruct drainage or clog tile. Do not, under any circumstances, let your contractor backfill with excavation material. You will get large chunks of dirt and debris damaging your brand new membrane and protection board.

4. A lot of contractors skimp on installation of drain tile. If water is backing up over your footer, you're going to have problems. Tile should be 12-18" below the footer, covered with crushed gravel to footer height and sloped to drain or pump.

5. Finally--and this is critical for nearly every material--the wall and footer must be completely dry, clean and free of sharp fins of concrete or mortar. If the wall is wet, the waterproofing won't bond to it. It isn't easy to get footers clean and dry but if the co-joint at the footer/wall intersection is wet, you're dead. If you get a rain after the tile is installed but before the walls are waterproofed--that's good, you'll see how well your drain tile system works.

Ask your contractor what material he plans on using. Get the manufacturer's application instructions and hold your contractor's feet to the fire to prepare the surfaces properly then install, protect and backfill with the best materials available. As you've already figured out, this is a critical aspect of the long term performance of your building and unfortunately, since the work gets covered up, it's a favorite area for contractors to cut corners.

 

[matrass]

Originally Posted By: georgemiller
http://www.houseguard.com/documentlibrary/TruDry PI Sheet.pdf

The cost to add a Tru Dry waterproofing system at a 2600 sq. ft house is about $ 800-1200 over conventional tar.

Every home builder but one by me uses the tar. The other one uses the Tru Dry system. If it was my own house I would go for the extra bucks and use the Tru Dry System.

Builders use tar due to economics. $ 1000 extra per house can add up quick.



Thanks for the link and the approx cost for the upgrade.paying the extra money out of pocket up front will assure that any extra costs do not figured into the mortgage. this is going to be our last house so we want it to be done right.

 

[Pop_Rivit]

When we built our home in 1995 we planned to finish the walkout basement, so it was critical that it be free from moisture and dampness. We used a membrane that has a drainage space between the foundation and the membrane surface (SuperSeal brand perhaps?). This allows for any moisture trapped next to the wall to drain down to the drainstone and drain, where it gets moved away from the home and also keeps the headwater pressure completely off the foundation. We also were careful about the grade and made certain everything on top was graded away from the home. We had extremely wet winter/spring and summer weather in 2008 and 2010, and in all of the 18 years since there's never been a drop of water in the sump hole. With the insulation work and correct ventilation the basement is always warm, dry and very comfortable.

At that time we probably spent an extra $2000 or so to make sure we'd never have an issue, and so far it's been money well spent.

 

[WishIhadatruck]

Without a doubt, a good membrane is important, but I don't have much advice or experience here. I'd say without a doubt proper drainage is much more important. Drain tile inside and outside the foundation, properly installed. How far you need to go depends on the site, soil type, ground water levels, etc. I'd go a little overkill as it won't hurt and is much cheaper to do now than later.

I really like Indydriver's post.

 

[matrass]

thank your for all of your thoughts so far. Indydriver you post was worth it's weight in gold, just on the back filling portion. I really like the idea of the sand as a buffer and for better drainage up next to the membrane, that makes perfect sense to me. I know for a fact that the contractor uses material that was left over from digging the foundation so rocks would be a major concern. Pop_Rivit appreciate your post as I was looking for somebody who had had the membrane in place and how it has performed.

 

[Kool1]

I used the black liquid roof patch sold at Home Depot. I painted the stuff on and it seems to go into the tiny pores of the foundation. It's been about 20 years since I painted the stuff on. Our foundation is still black and we have no leaks. I don't know if we would have never had a leak without the liquid roof sealer but I'm sure it didn't hurt anything. Do not use the thick roof patch which is gooey and will probably dry out and crack.

 

[Donald]

Originally Posted By: matrass
Hello and good everybody. wanted to get some opinions on the proper way to waterproofing a poured concrete foundation. I know they used to tar them but in recent years a waterproof membrane seems to be done more often on a new home. looking at the membranes there are ones that are self adhering and some need to be fastened. one membrane may be straight faced while the other one has dimples in it like bubble wrap to allow water to drain ( if it happened to get behind it ) also there is a membrane that is applied with a roller. I am looking into building a new home and would like to have the foundation as waterproof as possible. I understand that drainage needs to be set up correctly as well but water can run down the foundation and if there is a weak spot it will find it. I had spoken with a contractor in my area who has build a lot of houses ,he did around 117 in one development alone very close to me. when I asked him about the foundation he said he uses tar. looking at a house he was almost done with recently, everything about it was built well with a higher quality that you would expect on a new home. been checking online about membranes and there are so many that I would like to get some opinions before asking the contractor if he would install a membrane, even though it will cost a little more. hate the thoughts of tar drying out and cracking and having water in the basement on a house that is only a couple of years old. seems like there are advantages to a liquid membrane, being cheaper and no seams but not as durable and you need to be sure it is applied evenly.the sheet would be more expensive and harder to work with and have more seams in it but it *should * be more durable and have less variables in thickness. any particular brands that stand out or to stay away from ?


The factor for a dry basement is about 95% proper drainage and 5% waterproofing. I would suggest all hard plastic pipe, none of the flex pipe that comes in coils. It can crush and then costs a fortune to dig it up and fix it. My house also has some "sumps" built into the basement with covers. I think the building inspector required them in case things got wet. I can take off the cover and look down and its dry. They are empty sumps, no pumps.

 

[Papa Bear]

Originally Posted By: Donald


The factor for a dry basement is about 95% proper drainage and 5% waterproofing.


+1 drainage and grade

 

[mechtech2]

Indy has a great post there!

 

[doitmyself]

Originally Posted By: matrass
Originally Posted By: donnyj08
2 Part spray foam insulation. its a sealer, air sealer, as well as and excellent insulator. r-7 for every inch sprayed. have it sprayed on 2 inches thick, and you will have a great seal and insulating properties. weatherization companies specialize in this type of thing.


I am assuming you are talking about the inside of the foundation. the house I checked out has the inside of the foundation well insulated on the inside of the basement. my father in law and Dad saw the house and both were happy with the build. my Dad used to work for the gas company and knows a lot of people in the construction business. he did some digging around on the contractor ( without me knowing ) and said the guys name came up a few times with very high regards.


Some years ago I read that "in theory", exterior basement insulation is much better than putting insulation on inside for many reasons (think about it). A recent, quick google search (and paying attention to local practices) seems to indicate that this "theory" may never have caught on.

Google "exterior basement insulation to learn the details.

Comments?

 

[matrass]

Originally Posted By: doitmyself
Originally Posted By: matrass
Originally Posted By: donnyj08
2 Part spray foam insulation. its a sealer, air sealer, as well as and excellent insulator. r-7 for every inch sprayed. have it sprayed on 2 inches thick, and you will have a great seal and insulating properties. weatherization companies specialize in this type of thing.


I am assuming you are talking about the inside of the foundation. the house I checked out has the inside of the foundation well insulated on the inside of the basement. my father in law and Dad saw the house and both were happy with the build. my Dad used to work for the gas company and knows a lot of people in the construction business. he did some digging around on the contractor ( without me knowing ) and said the guys name came up a few times with very high regards.


Some years ago I read that "in theory", exterior basement insulation is much better than putting insulation on inside for many reasons (think about it). A recent, quick google search (and paying attention to local practices) seems to indicate that this "theory" may never have caught on.

Google "exterior basement insulation to learn the details.

Comments?

You are correct, it seems like the idea of insulation on the outside has never caught on, at least that I have seen. their picture seems like a good idea. I wonder what happens to the insulation next to the foundation when it gets wet ? maybe if they had some waterproof barrier over the insulation ? maybe the price and labor of installing the insulation is why contractors are not using it. with the weather here recently it seems like I have a few more weeks before they begin digging. will have to sit down with the contractor and discuss the options before they start .