Author Topic: Question of foundation piers  (Read 58665 times)

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alcowboy

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Re: Question of foundation piers
« Reply #25 on: January 28, 2009, 12:01:24 PM »
John C you are no more confused than I. I guess that the bedroom wall between the living space and bedroom must be a load bearing then??????

The plans do not show it as such.

Also, forgive me with the use of terminology as I am not up on it. The foundation shows a wall around the perimeter of the main building (excluding porch) with 3 piers center of the 24x24 and a beam, with another beam where the 8x12 room and kitchen meet.

I thought that you could use 6x6 for your beams and build the flooring platform on top of that. I am sure I have seen other projects with such on here.

John_C

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Re: Question of foundation piers
« Reply #26 on: January 28, 2009, 12:47:30 PM »
So you have a crawlspace, not a slab.   
What is that perimeter wall made of?  Concrete blocks? How many high?
What's on top of the 3 piers...under the floor joists? 
They are essentially on 6' centers ... correct?

There may have been a house that used 6x6 for beams but that would, in general, be an inefficient use of material.  Usually beams are deeper than they are wide ... say 2 - 2x10's on edge, and they are sized for the specific loadings.  6x6's might be used as posts in lieu of the concrete piers shown on your plans

alcowboy

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Re: Question of foundation piers
« Reply #27 on: January 28, 2009, 01:13:17 PM »
I don't know why but all of the sudden this is beginning to make some sense now. CLEAR AS MUD!
There are 3-2x10 with staggered joints on top of those blocks and a pocket for those on the foundation walls. The foundation is stated as 8" poured or CMU. The three piers are show 5'8" O.C. from the inside of the foundation wall.

So, in hopes I finally understand this, piers - 6' O.C., on top of this I would laminate 2x10 and set on end. and boxed in with 2x10 also then put my joists inbetween rim joists and beam. Do I need a mud seal (board laid flat on the perimeter)?

John_C

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Re: Question of foundation piers
« Reply #28 on: January 28, 2009, 01:57:25 PM »
So somebody has done the engineering and come up with 3 -2x10's on edge for a center beam.

That does not mean the outside beams would be 3-2x10's on edge.  Somebody needs to actually calculate the loads. 

Joists could go between the beams but on top is usually better.  Search the forum. It's been discussed before.

Before you go off on this path will the local building department let you do it?  If they are going to make you do a perimeter footing anyway just build the crawlspace as shown on your plans.

alcowboy

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Re: Question of foundation piers
« Reply #29 on: January 28, 2009, 06:28:32 PM »
There are no specific codes in my area. john C, you stated build on top of beams, thatt is why I thought using 6x6 PT would work for the beams and build my subfloor on top of that. Would that not work? I am afraid the expense of the proposed foundation would not work for my budget, that is why I am asking these questions.

  • Block piers as per ScottA
  • 6x6 beams bolted to these piers per spacing requirements stated (6' O.C.) for a total of 3 rows of 5 piers in 24x24 area plus 1 more on front side where bump out room starts and 3 on front of that room (Total - 19 piers) with beams encompassing the foundation area
  • 2x8 or 2x10 rim joists and floor joists on top of the beams
  • build porch just like a deck (according to plans)

Will this work or am I still WAY off?

Offline ScottA

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Re: Question of foundation piers
« Reply #30 on: January 28, 2009, 06:58:59 PM »
I wouldn't use 6x6 lumber. Too much likelyhood of it warping with the crappy wood they sell these days. I'd go with a built up beam made of 2 by lumber in the longest lengths practical stagared spliced over the piers. It will likely cost less than 6x6 as well. My beams are made of 3 boards nailed together with 20 penny nails stagared top and bottom on a 16" spacing nailed from both sides. In other words if the top nail is on one side the matching bottom nail is on the opposite side.

John_C

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Re: Question of foundation piers
« Reply #31 on: January 28, 2009, 07:06:01 PM »
The short answer is that you haven't provided enough information for anyone to determine if 6x6's would be strong enough. You may be way off, maybe not. I don't understand the affinity for 6x6's as beams.

The center beam on your plans is a nominal 6x10 (3-2x10's).  That is stiffer than a 6x6 beam. The outside beams bear different loads.  And the beam that bears the porch loads has a different loading than the one at the other end of the house. John_R has gone through what he calls a load trace.  Somebody needs to do that.

What loads are carried by the center beam.  Certainly 1/2 the floor load.  It would seem there is a bearing wall and 1/2 the ceiling load is also carried by the center beam.  Are any of the roof loads carried by that beam?  What are the roof loads in your area?

In real terms the additional cost of the perimeter foundation is really small compared to the total cost.  Have you looked into having an engineer spec the alternate foundation?  Have you contacted the designer to see if an alternate foundation plan is available?

Offline MountainDon

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Re: Question of foundation piers
« Reply #32 on: January 28, 2009, 07:15:39 PM »
FYI:   Built up beam info ...

http://www.countryplans.com/builtupbeam.html

Just because something has been done and has not failed, doesn’t mean it is good design.

Offline ScottA

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Re: Question of foundation piers
« Reply #33 on: January 28, 2009, 07:29:27 PM »
I hear what you're saying JohnC. If he uses 3 2x6's built up into a beam and spaces the piers 6' on center with the blocks running with the beams he should be fine so long as those beams are under the load path. If that center wall is bearing then it needs a beam under it. I'm assuming the ceiling is vaulted in the living area? 

Just a note of something I've noticed. Alot of these stock cabin plans are designed for snow country so they can be overkill engineered for a southern build.

I need to point out that is is important to determine that the soil will support the piers.

John_C

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Re: Question of foundation piers
« Reply #34 on: January 28, 2009, 07:39:36 PM »
I don't know Scott.  As you go farther south in Alabama you get closer to hurricane country.  There's no real snow load anywhere in Alabama, but the design wind loads get higher, towards 140 mph in the extreme southern part of the state.  He described the plans as having ceiling joists so I'm guessing no vaulted ceiling. 

Without getting any real numbers on loadings were in the dark. 

Offline ScottA

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Re: Question of foundation piers
« Reply #35 on: January 28, 2009, 07:41:33 PM »
I'd agree with the hurricane issue. If he's near the coast an engineer might be in order.

Offline MountainDon

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Re: Question of foundation piers
« Reply #36 on: January 28, 2009, 08:13:15 PM »

I'm not certain what I'd do about hurricanes other than use Simpson H1's for the rafters.

Do you think the joists would be okay toe nailed to the beams as in any place not faced with hurricanes?

Would the posts be PT 6x6 set directly in the ground a couple feet. If drained well that could work and not be too bad for hurricanes? Or would they be CMU's (concrete masonry units, for those who weren't sure. Would they be laid level and high enough so piers could be done away with? If so they could be tied to the CMU's with Simpson straps.

That thought raises the question of how high off the ground is desired? Code says that the bottom of the beams be no closer than 12" to the ground, IIRC.

That's just a bunch of random thoughts; thoughts that need answers in making this change from what the plan shows to what is wanted instead.

FWIW, IF I was not wanting to pay an engineer to come up with something certified for the foundation, I would guess that you would be quite safe with the two outside beams being built up 2x12's in four layers. I would lay the beams and joists out as shown in this very rough hand sketch. I'd sheath the floor with 3/4" T&G Advantech sub flooring, nothing less as this may be exposed to some wether before it gets dried in. Then I would build the rest of the cabin on that platform.

EVERYTHING above and below is guesswork. There are no engineered calculations to prove anything.

Just because something has been done and has not failed, doesn’t mean it is good design.

John_C

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Re: Question of foundation piers
« Reply #37 on: January 28, 2009, 08:36:53 PM »
Quote
Do you think the joists would be okay toe nailed to the beams as in any place not faced with hurricanes?

No, that wouldn't do.  In ye old days we used the metal plumbers strapping, nailed to the beam, nailed to and up & over the joist and nailed to the beam on the other side. you could let it into the top of the joist if you were feel'n fancy.  Today there are lots of connector choices.

After hurricane Donna hit the Key a friend of mine was renovating a house in Islamorada that had basically been underwater during the storm and had survived the winds and storm surge full-on.  It had seaweed lodged in the soffits.

The house had been built after the Keys took a terrible hit in 1935.  The only remains of the CBS house next door was the slab, but the old wood house hadn't budged.  Randy said they pulled off some siding and he stuck his hand inside the wall and ran it along the underside of the top plate.  The plate was a 12 x 12.  The house was built on a slab and the 1" J bolts went down into concrete poured in holes in the coral rock. They extended all the way up the walls and through the 12 x 12  top plate with steel plates and bolts securing them.  No stink'n Simpson brackets back then.  The whole place was built like that...  massive timbers of Dade county pine bolted together. With no indoor plumbing, dry wall, electric or insulation a brief swim wasn't the catastrophe it would be today.  It survived into the 70's when it was torn down to make way for a resort. :(

alcowboy

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Re: Question of foundation piers
« Reply #38 on: January 29, 2009, 04:52:16 AM »
Sorry guys. I guess I am just stupid. Sorry for the confusion I have caused. Don I believe you have actually answered my question as well as ScottA.

There is no reason as to why 6x6, only trying to keep costs low and thought it would work as well as a built-up beam. Thanks for the drawing Don. It is the THING that brought everything together for me. Exactly what I have been thinking. I am in the middle of the State of Alabama so no biggie threat of hurricanes but there is some.

I don't want to get others, like engineers and government, involved in my project as that would only be someone with a hand out and a big possibility of "I really don't know, $500 please." I knew I could trust you guys to figure this whole thing out. As far as the load bearing wall, I would have to agree the wall between the kitchen/bathroom and living/bedroom would have to be load bearing for that great of span and, yes, there is a beam shown underneath at that point. According to the plans there is no vaulted ceiling.  I am beginning to believe these plans are not true and complete as there is a lot of information missing that you guys keep asking me which I cannot answer. There is even no materials list - which goes back as to why I am working up the plans in BHG.

This conversation has taught me more than I ever thought I knew about doing this - which was nothing in the beginning. I feel like an idiot. Sorry guys.

Offline ScottA

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Re: Question of foundation piers
« Reply #39 on: January 29, 2009, 05:06:37 AM »
Na that's not an idiot. I had this lady call me about not having any hot water once. I went to the house and she goes to the faucet and pushes the lever to the right and says "See no hot water". I pushed the lever to the left and said "There it's fixed. That'll be $75." Now that's an idiot.

Offline glenn kangiser

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Re: Question of foundation piers
« Reply #40 on: January 29, 2009, 05:07:23 AM »
There are no stupid questions.  :)











Well -- OK ....granted there are some, but we are going to pretend that they weren't.  While the rest of the world is watching TV and pretending it isn't stupid at least we can learn something. ........ [waiting]

"Always work from the general to the specific." J. Raabe

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alcowboy

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Re: Question of foundation piers
« Reply #41 on: January 29, 2009, 07:04:23 AM »
By the way MountainDon, can I use curled wood like your drawing shows? J/K!!

Offline MountainDon

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Re: Question of foundation piers
« Reply #42 on: January 29, 2009, 07:09:14 AM »
As long as the 'curls' match and fit tightly there's no problem at all.   ;D ;D ;D
Just because something has been done and has not failed, doesn’t mean it is good design.

alcowboy

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Re: Question of foundation piers
« Reply #43 on: February 01, 2009, 05:54:13 PM »
These plans have little to no room for washer/dryer combo. I have actually squeezed my WD into what is suppose to be a linen closet. If I put a bump out ib the bathroom to give space to put WD would I need any piers below that? Not sure if WD wll be housed there or actually move shower into bump out.

Offline MountainDon

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Re: Question of foundation piers
« Reply #44 on: February 01, 2009, 06:23:49 PM »
If I put a bump out ib the bathroom to give space to put WD would I need any piers below that?

You can build a cantilevered bump to accommodate that. The method used would depend on what way the floor joists are running at the bumpout. Easiest would be if the floor joists are perpendicular to the exterior wall at that point.

I think I'd prefer to bump the laundry rather than the shower, myself.
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline considerations

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Re: Question of foundation piers
« Reply #45 on: February 01, 2009, 06:46:49 PM »
My W/D will be a very small operation, and crammed into the "Batroom".  But then, I live alone, so the usage is less than for many.

Offline glenn kangiser

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Re: Question of foundation piers
« Reply #46 on: February 01, 2009, 07:57:32 PM »
I think someone is calling Batgirl.... [waiting]
"Always work from the general to the specific." J. Raabe

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alcowboy

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Re: Question of foundation piers
« Reply #47 on: February 02, 2009, 06:21:39 PM »
the joists will run perpendicular to the bump. Thanks for the info and confirming the idea of putting the stack washer/dryer in the bump rather than the shower. So, basically, the "batroom" as it has been deemed will stay the same adding the bump to allow for a combo and I will be able to put the tankless water heater there instead as "decoration" on the bathroom wall. I plan on putting a curtain to close it off from the actual bathroom. "Pay no attention to the man behind the curtain!" Maybe I will even put up the green velvet curtains similar to Scarlett's famous dress  ;D. NOT!

Offline Jens

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Re: Question of foundation piers
« Reply #48 on: March 09, 2009, 04:22:15 PM »





I know this was just a quikie Don, and I am not harping on you, but when you joist up your floor, have only the middle section of the joists offset.  That way, both ends will line up as a full sheet of ply on the edge of the joisting, and only the middle joists will need their plywood trimmed.  In other words, your first set are on layout, second set lap the sides of the first so they are 1.5" off layout.  The next lap should go back to layout.  It's a little thing, but can get annoying.  Also, if you can plan it so that there is enough overlap in your joists, you won't have to add nailers to your off-layout joists. 

I may just be speaking Greek here...don't really feel like drawing a picture right now...tired, sorry!
just spent a few days building a website, and didn't know that it could be so physically taxing to sit and do nothing all day!

alcowboy

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Re: Question of foundation piers
« Reply #49 on: March 09, 2009, 04:34:05 PM »
 :-\
Huh?

Now I am really lost...

 

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