Problem with SIP basement / backfill
Last Post 27 Sep 2018 08:11 AM by scottishjohn. 39 Replies.
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dave111User is Offline
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12 Apr 2014 10:10 AM
I've always preferred a jack to the BFH, takes longer, but tears up the materials less and has better control. I would also think that if you have the headroom you could drop the ceiling to support the studs, or perhaps do something with a soffit, but do get a PE involved.
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12 Apr 2014 02:02 PM
Without reviewing the plans and work nobody really knows what happened. Be wary of the person who "knows" sight unseen.
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29 Apr 2014 12:40 AM
Thanks again for everybody's interest and ideas about this subject.  I thought I would stop in again with another update on my situation and bounce some stuff off all of you.
   a few months ago my contractor told me he was in the process of getting in touch with a structural engineer to address this problem.  Well a few weeks ago both made a site visit to inspect the problems so that the engineer could finalize some plans.  So basicly what the SE told me is that he thinks we would not have to dig out the walls.  He claims that you would not gain back all the movement that has happened, kinda like it has a bit of a memory over time and things would not just slide back into place.  What he is proposing is something like adding a framed wall on the inside to shore up the walls and then brace this into the floor joists.  He said that he needed to run a few more calculations, but he was confident that he would be able to stop any more movement.  His engineering firm handles many commercial projects so I feel confident that he knows a thing or two.  So that is where I sit at the moment.  I'm waiting to hear back from the contractor who should by now have the SE plans.  I've been thinking of calling him sometime soon to check up on this.  I'm not exactly thrilled about framing up another wall inside as this will eat up some SQ, but I want the best possible solution so that is what will happen.  As far as the cause, my contractor figures the connection between the top plates and the panel studs was not done right.  Its impossible to tell now that everything is covered up, so this a best guess.  My contractor has been great, he has never tried to pass the blame, or the buck to anybody else.  Although I do make it a point to express my "disgust and disappointment" that this even has happened every time we meet.  Kinda just twisting the knife kinda thing, ha.  He does appear genuinely sorry and embarrassed  this happened.  So at this point I don't see a need to involve an attorney. 
  Now I was kinda relieved that we wouldn't have to dig it back out, but I am starting to think maybe we should.  I dont' know, do you guys think that the walls could be pushed back some?  To me, it would most definitely involve jacks.  I'm envisioning several jacks and rigging across from wall to wall and slowly push/jack the walls out.  Not sure how easy they would move, I'm thinking constant slow pressure over the course of a few weeks could get them to move slowly back. 
   I also wanted to run this by you guys.  We have had a few days of rain now and I have a problem with water pushing up into a conduit pipe where the electrical comes into the house.  I had this issue last summer and the Electrician tried to seal the conduit from the inside.  Worked the remainder of the year but now today is leaking again.  Best way to fix this is dig down and plug the end. sooooo since this should be dug out, maybe digging out the whole wall might not be a bad idea to inspect and assess things.  This also got me thinking about the backfill.  I know somebody suggested gravel in place of the more clay like material that is on site.  But how about backfilling with 6-7 feet of pea rock?  Is this over kill? probally, but it would remove any water pressure against the foundation walls right?  I also realize that anything extra like this may have to come out of my pocket and I'm prepared to do that if need be.  If we dig it out, I want overkill to insure that I have NO problems in the future.  Oh and in case it wasn't stated before, there is drain tile around the house and is working.  Last fall we had alot of rain and I had water coming in the sump till December.
   Anyway I guess I'm just rambling ideas that have been bouncing around my head.  I just gotta keep a positive outlook and know that some people have alot worse basement problems than this.  And a dug up yard is only temporary in the scope of things.  Well thanks for keeping an interest in this.  I'll stop in as I have updates about the fix this spring/summer.
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30 Apr 2014 11:52 AM
It sounds to me as if the builder has found a "friendly" Engineer. You really need to get a "second opinion" from an engineer with experience in design of PWF basements. There is a good bit of design guidance on PWF available on the internet, I encourage you to seek and read as much as possible. From my reading of available data, gravel back fill is very important. Personally I doubt that your house can be "stabilized" without re-excavation and replacement of the native soils by gravel. Without re excavation it is unlikely that the walls can be restored to plumb and level. the cheap way is to build in the damage already done while the right way is to repair the damage by moving the walls back.
Even with gravel back fill the connection between the basement wall tops and the floor deck needs to be substantially strengthened. It may not require an added interior wall if metal "shear" connections between the wall's top and the floor framing are used.
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30 Apr 2014 07:16 PM
dig it out, and work on the drainage
JC1959User is Offline
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10 Mar 2015 05:36 PM
In my opinion using SIPs for subgrade foundation walls is a problem waiting to happen at best and insanity at worst.

SIPs are fine for above grade walls and short spans for floors and roofs, but 1. wood and water don't mix and 2. soils at 8 ft deep can produce loads exceeding 800 psf on the wall. Even halfway down it's 400 psf,... compared to roof and floor loads in the 50 to 100 psf range.

On a quick search, a Porter SIP 6 1/2" thick with a 11.5 ft span has an allowable bending load of 43 psf. That's 1/10th to 1/20th the actual load. And that's not considering the stresses compounded by the dead and live loads of the structure above.

The only reason these walls haven't completely collapsed, judging by the picture of the excavation, is probably due to a high clay content in the soils minimizing pressure on the wall. And fortunately likely a lack of compaction during back fill as well. I've seen concrete walls start to fail when compacting up against them without proper lateral support. Over time, and with moisture, the soil will eventually induce the full load on the wall. When, not if, the wood gets wet, all structural integrity will be lost.

I agree with those that say excavate out the soils, and short of pouring a surrounding concrete retaining wall or terracing the site permanently, ensure the exterior of the wall has a good moisture barrier, with drainage and then install some kind of light weight fill - geofoam, EPS, or similar with a foot or two of top soil on top of that at most.. A second option might be pouring a 500 psi flowable fill in layers against the water proofed and temporarily braced walls. But flowable fill costs anywhere from $75 to $125/ cu yd.

Extreme Panel says max backfill for the 8' wall is 7'4" and the fill material must be granular,.. ie gravel, not native soil.....

"10.
Below grade moisture barrier: 6 mil poly
is to be applied over the below grade
portion of the foundation. A single layer is
adequate, but 2 layers
is suggested for
extra protection when backfilling. Poly is
to be draped over the footing, but is not
to extend over the drainage tile. Joints
in the poly are to be lapped a minimum of
6” and sealed with Panel Adhesive/Sealant
or equivalent. The top edge of the poly
is to be bonded to the panel to create a seal
. This is to be achi
eved by using at least
a 12” treated plywood strip or other strips can
be used for archit
ectural treatment.
Before strip is installed, a c
ontinuous seal of adhesive is
to be applied between the
wall and strip. The strip needs to
extend at least 9” below grade.
11.
Backfilling: Backfilling is not permitted unt
il basement floor and first floor have
been constructed or the walls have been
braced. A maximum backfill height of 7’-
4” is permitted. Granular material is to
be used for backfill. Backfill a distance of
2’-0” out from the wall and 2/3 the height
of the total backfill height. Granular
material is then to be covered with e
ither 30 pound asphalt paper or 6 mil poly to
allow for water seepage while avoiding infiltra
tion of fine soils. The remaining of
the backfill can use the same type of
soil as was removed during the excavation.
Finish grade is to slope a 1/2” per fo
ot a minimum of 6’-0” from structure."


But I couldn't access their load capacities on line. Which is suspicious.


Enercept has technical data on line.

http://dev.identifex.com/enercept/wp-content/uploads/Enercept-Technical-Data-Booklet.pdf


They also say back fill with granular fill. And if it's expansive soils the angle of excavation increases. There are a couple of backfill section details in the link.
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11 Mar 2015 05:16 PM
Posted By JC1959 on 10 Mar 2015 05:36 PM
In my opinion using SIPs for subgrade foundation walls is a problem waiting to happen at best and insanity at worst.


I agree
Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br />
LieblerUser is Offline
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25 Apr 2015 09:45 PM
These "SIPS" are prefabricated, pre-insulated sections of a PWF and can work as well if installed properly. There are over a million successful PWF installations in the US and Canada. PWF basements are much less problematic than poured concrete, which is why you rarely hear of such issues. The original poster had the miss-fortune of finding a builder who violated several clear warnings and did things "on the cheap" causing clearly avoidable problems. FWIW the Enercept SIP probably shouldn't even be called a SIP as it has 2x8 studs 12"OC . 2x8 studs 12" OC sheathed with 5/8 FDN grade treated plywood on one side, with no insulation is a prescriptively approved construction for a site built PWF basement!
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26 Apr 2015 08:05 AM
Liebler,
You are correct in saying they are not "SIPS" ,many manufactures like to jump on the SIP bandwagon, but the reality is, they do not have anything unique or innovative
what they have is a pre-built or prefab, wall assembly , it may be structural and it may be insulated , but it is not a SIP as I understand a SIP to be or as described in Wikipedia:

"A Structural insulated panel (or structural insulating panel), SIP, are a composite building material. They consist of an insulating layer of rigid core sandwiched between two layers of structural board. The board can be sheet metal, plywood, cement, magnesium oxide board (MgO) or oriented strand board (OSB) and the core either expanded polystyrene foam (EPS), extruded polystyrene foam (XPS), polyisocyanurate foam, polyurethane foam or composite honeycomb (HSC).
SIPs share the same structural properties as an I-beam or I-column. The rigid insulation core of the SIP acts as a web, while the sheathing fulfills the function of the flanges. SIPs combine several components of conventional building, such as studs and joists, insulation, vapor barrier and air barrier. They can be used for many different applications, such as exterior wall, roof, floor and foundation systems."
Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br />
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20 Nov 2017 02:00 AM
Is there any update on this? Early in this thread back fill heights of 8' and 7' were stated. It was also stated that TWO top plates were field installed meaning that there was no top plate in the supplied panels. With 8' back fill the panel must be at least 8" taller. I ignore the taller wall for the sake of a quick calculation. 8' of back fill on an 8' wall will result, according to section 5.4.4 of "PERMANENT WOOD FOUNDATION DESIGN SPECIFICATION" , 340 pounds/ lineal foot of wall force from the studs to the plate and floor diaphragm, meaning that those studs needed to be nailed to the plate with at least 4ea. 10d HOT dipped galvanized or stainless nails per stud. With that shear force level being transmitted to the floor diaphragm it needs to be fully blocked and nailed properly! The two plates needed to be nailed together with at least 4 nails per foot. This should have been in the instructions from the SIP maker. It sounds, to me like nailing of the studs was not done properly. Another quick calculation, the design of the studs, 8' of backfill with 2x8s on 12" centers only works if the studs are grade 1, not the usual #2.
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20 Nov 2017 02:31 AM
Posted By Liebler on 17 Mar 2014 12:24 PM
Juloson,
      This is a very sad situation!  I suggest you talk to an attorney!  The builder is responsible, not the SIP maker! 

Yes and no.  The builder (and the architect/engineer) can only go by the structural info and guidelines provided by the manufacturer.

This is something the builder, the SIP maker and an engineer need to attack TOGETHER.  Simply pointing fingers will wind up with this guy's house down around his ears and (possibly) someone injured (or dead).
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20 Nov 2017 02:54 AM
I'm gonna join my voice in with the "excavate" crowd.

I DO have some suspicions about simply putting up interior wooden structural walls to control the racking.

At this point, I'd be looking at either concrete block or ICF retrofit walls for maximum strength with minimum loss of footage.
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20 Nov 2017 01:02 PM
Posted By Dilettante on 20 Nov 2017 02:54 AM
I'm gonna join my voice in with the "excavate" crowd.

I DO have some suspicions about simply putting up interior wooden structural walls to control the racking.

At this point, I'd be looking at either concrete block or ICF retrofit walls for maximum strength with minimum loss of footage.


Excavate is certainly the best answer, But then what? The real issue of the inadequate force transmission from the wall studs to the floor diaphragm needs an "engineered" solution, not blocks or ICF. It well may be possible to design triangular wood trusses to transfer the load from studs to first floor. Steel angles may well be part of the solution. Once the force transfer "system" is in place the water-shed poly needs to be verified and fixed, if needed. then re back fill with coarse drainage medium. For the new back fill material I would encourage the use of LWA (light weight aggregate, expanded clay-shale). LWA will reduce the pressure on the wall by a quarter or more.
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25 Sep 2018 10:24 AM
being in the process of considering a sips basement build and doing lots of searches it would seem the root cause is simple from what I read here you say panels are only 4" wide all poured concrete basement walls need to be min of 8" any basement sips I have seen in my searches are 250mm or 300mm --thats 12 " to you using MGO skins bonded to the foam cores in uk lack of thickness and strength is your problem what would I do? --dig out pour a concrete retaining wall around what you have . just my 10cents worth
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25 Sep 2018 11:13 PM
Posted By Liebler on 20 Nov 2017 01:02 PM
Posted By Dilettante on 20 Nov 2017 02:54 AM
I'm gonna join my voice in with the "excavate" crowd.

I DO have some suspicions about simply putting up interior wooden structural walls to control the racking.

At this point, I'd be looking at either concrete block or ICF retrofit walls for maximum strength with minimum loss of footage.


Excavate is certainly the best answer, But then what? The real issue of the inadequate force transmission from the wall studs to the floor diaphragm needs an "engineered" solution, not blocks or ICF. It well may be possible to design triangular wood trusses to transfer the load from studs to first floor. Steel angles may well be part of the solution. Once the force transfer "system" is in place the water-shed poly needs to be verified and fixed, if needed. then re back fill with coarse drainage medium. For the new back fill material I would encourage the use of LWA (light weight aggregate, expanded clay-shale). LWA will reduce the pressure on the wall by a quarter or more.

Sorry about the late response.  I never actually saw this come up in my backlog until now...
Freaking goofy forum software...

Excavate. 
Insure waterpoofing is intact.
Lightweight and high drainage fill with clean gravel in two-foot square (height and depth from wall) "lifts". contained by filter fabric, all the way up the wall.
French drain or other engineered water removal system.
Remaining fill can be either lightweight aggregate or local fill, but properly compacted.

And while prepping for this, talk with an engineer to see what can be done to repair and/or shore the wall.

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26 Sep 2018 09:06 AM
Hi could you confirm that your walls are really only 4" thick as per your earlier post --cos if they are your back fill solution will not work long term . maybe I read it wrong but thats the thickness for an internal load bearing stud wall in a timber frame house where all loads are vertical not side loaded. your solution then would be to excavate and make it a slope so it does not touch basement wall ,you could cover up with a decking right round
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26 Sep 2018 12:29 PM
Posted By scottishjohn on 26 Sep 2018 09:06 AM
Hi could you confirm that your walls are really only 4" thick as per your earlier post --cos if they are your back fill solution will not work long term . maybe I read it wrong but thats the thickness for an internal load bearing stud wall in a timber frame house where all loads are vertical not side loaded. your solution then would be to excavate and make it a slope so it does not touch basement wall ,you could cover up with a decking right round



scottishman,
in a timber frame not all loads are vertical, wind is a great horizontal load that must be compensated for
Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br />
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26 Sep 2018 02:41 PM
I know that but do you agree or disagree that 4"stud wall is not suitable for side loads like a basement which is a continuous load which as wall deflects will just keep on pushing and once the wall is bent strength drops quickly--which was my point . --code in UK is 200 mm min with rebar included in concrete and in some soils types more thickness will be specified
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26 Sep 2018 03:29 PM
Posted By scottishjohn on 26 Sep 2018 02:41 PM
I know that but do you agree or disagree that 4"stud wall is not suitable for side loads like a basement which is a continuous load which as wall deflects will just keep on pushing and once the wall is bent strength drops quickly--which was my point . --code in UK is 200 mm min with rebar included in concrete and in some soils types more thickness will be specified



agreed and a 6" may not enough depending on soil conditions
Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br />
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27 Sep 2018 08:11 AM
I would be worried that the waterproofing will or has been be damaged if panels are bowing -if not yet it will fail if distortion problem is not cured . only permanent solution will be another wall outside with drainage included --so original wall is unloaded and protected from moisture . how easy/cheap is it in US to inject concrete/foam into surrounding ground ? quite often used in bad ground and unload foundations in high water table areas once problems are encountered--a ring of very big polystyrene blocks around it down to slab and a drain ?or sell him some steel faced sips to fix to original --no cheap fix
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