Fiberboard Sheathing Used For Waterproofing?

terri23April 22, 2010

We are building on a hill and there is a concern with having a dry basement since it is a walk-out and will be finished. To address this, the builder has put a thick coating of tar on the exterior cinderblock walls. Now over that they have attached GP Stedi-R Regular Fiberboard Sheathing. In reading about this product on their website, it states it is for above-ground applications as underlayment under wood, vinyl, aluminum, etc.

Is there any benefit to using this below-grade as a waterproofing agent? I had asked the builder about using something like Miradrain, but this is not what I had in mind. Besides that, it has been applied with gaps of 1 - 2 inches between panels. Does anyone know anything about using the product in this manner? I've contacted Georgia Pacific about this, but haven't heard back from them yet and I hate to let them backfill until I know if it should be left like this.

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Not claiming expertise on that product or application but it sounds to me to be a really bad situation. Do get more information from reliable sources. Personally I think the stuff should be removed and the walls again coated to correct damage from installing those sheathing panels.

    Bookmark   April 23, 2010 at 8:15AM
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GP Stedi-R Regular Fiberboard Sheathing is a wood product intended to be used above grade. It should not be used below grade. It would be a termite problem until it eventually decomposed.

The waterproofing material is unlikely to be tar but if it is a trowel-on asphalt product it is probably dampproofing instead of waterproofing.

I don't know what else to tell you without knowing specifically what the material is and how it is applied. I usually use a spray-on modified-asphalt material and cover it with an insulating drainage membrane like Owens Corning rigid fiberglass insulation.

There should also be a drain pipe at the footing level that drains to daylight.

    Bookmark   April 25, 2010 at 9:01PM
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macv--You are correct, I don't recall what the "black" product was, but I do remember the word "dampproof" on the container. It was applied with a roller, similar to a paint roller.

I asked the builder about the fiberboard sheathing and he said that it was put there to protect the waterproofing product from being scratched off by stones and rocks when the backfilling is done.

I was wondering about the possibility of it causing a termite problem. Also, in the meantime we've had heavy rains and the fiberboard has now bowed away from the wall and is wavy and soaked.

I'll ask the builder to have the fiberboard removed, but I wonder if you can spray something over the dampproofing. Also, with further research on applying insulation, it said that it could hold the moisture inside if applied in a humid climate and since it gets pretty humid here in TN, is it okay to use here?

    Bookmark   April 25, 2010 at 9:57PM
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If the builder has represented "dampproofing" as "waterproofing" he has intentionally misrepresented it to you.

Dampproofing is only suitable with very well drained soil or crawl spaces but even then it doesn't last long. It's really just a thin asphalt coating that can't bridge cracks.

This is all common knowledge in the construction industry so I seriously suspect your builder's competence and/or honesty. The link below expains the issue well.

If you want the basement to be dry you need a better membrane than rolled-on asphalt dampproofing. In general waterproofing is made of modified asphalt so perhaps there is a liquid or sheet membrane system that can be spray-applied over the dampproofing. You need to find a competent waterproofing consultant/contractor right away. You could call WR Grace and ask if their Bituthane products will work.

The wood fiber board protection board is a serious mistake and should be removed. No organic materials should ever be buried in the ground anywhere near a house. An inexpensive substitute is 2" rigid fiberglass drainage/insulation board from Owens Corning. Don't forget the footing drain.

Here is a link that might be useful: dampproffing vs waterproofing

    Bookmark   April 26, 2010 at 4:45AM
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macv, thanks for the help! The company who applied the termite application agreed that the fiberboard should be removed. I am meeting with the builder tomorrow morning to discuss what should be done for the waterproofing. I have checked with WR Grace as you suggested, and believe the Bituthane product will work and then will have the rigid fiberglass drainage/insulation board applied. The footing drain is already in place. I feel much better about the foundation waterproofing.

My builder, on the other hand, still insists that what was done was alright and that it is common practice among other builders here. That may be, but it is probably because it is an inexpensive way to dupe homeowners into thinking that their homes have been waterproofed when in fact they have not. Now,unfortunately, I have lost confidence in my builder. I am willing to give him the benefit of the doubt, this time, and since he is older chalk it up to the use of "out-dated" methods, but I will definitely be looking over his shoulder now (and have a lot more educating of myself to get done if I want to stay a step ahead in this building process, rather than fixing things after the fact as I am with this issue.) I expect to be spending quite a bit of time in this website so you may be "hearing" from me again!

    Bookmark   April 26, 2010 at 8:05PM
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You might want to look into engaging a home inspector to do periodic inspections of your new construction. You would have to find a competent, conscientious inspector with solid construction industry experience, which may not be easy.

If your build is anywhere near Knoxville, I can recommend someone.

    Bookmark   April 26, 2010 at 8:28PM
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Good idea, creek_side. I'm near Nashville, so Knoxville may be too far. But thanks anyway.

    Bookmark   April 26, 2010 at 10:10PM
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Some things I leave to others and waterproofing a foundation is one of them. So, from observation only, here is what our foundation guy does.

A black goop is troweled onto the foundation wall. This stuff is way too thick to roll on, never dries out completely and appears to have something like bits of fiberglass in it, it looks a bit "hairy". I've never looked to see what it is, brand name and all, sorry, but it must be the modified stuff others refer to.

Over this his guys lay on a mesh fabric, looks like real fine screen material but is lighter. This is troweled onto the wall, not unlike how you squeegee a tile membrane onto thinset.

Now a second layer of the black stuff covers the mesh.

Lastly they cover all this with a dimpled, plastic drainage board that is nailed right into the wall. The "nails" have a collar or gusset on them and are hammered into a drilled hole.

Now he uses drain rock contained within geotextile to surround the perimeter drain and come up over footing and to the bottom of the drain board.

Once the perimeter drain is rocked the geotextile is flapped over top and back filling proceeds.

Depending on the site and sometimes just a certain wall he often back fills with drain rock (using a thumper to compact) quite a ways up and the entire perimeter is done by hand, not machine, until he is well off of the perimeter drainage system. Even when he uses his machine he is very careful.

We often pick up the "last lot" in an area, the lot that no one else wanted to build on and lots of rain and groundwater are givens around here. We warranty our homes and the last thing you want is to be digging up landscaping and such to hunt down a leak and this guy has never once failed us. No water, no dampness, no call backs.

Worth it to me.

    Bookmark   April 27, 2010 at 3:20AM
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