Author Topic: yet another pier spacing question  (Read 6672 times)

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Offline tesa

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yet another pier spacing question
« on: April 07, 2009, 03:32:42 PM »
so happy to have my plans! man, that was quick!

if i remember right, the spacing is 7'6" on the 1 1/2 story

i found a post where someone wanted to space them 8' apart to increase their cabins length

we wish to increase to 40' by adding an extra 10' onto the length

but with the spacing of the piers at 7'6", should we add in 7'6" increments
or can we space them so that we can add the 10'?

i hope my first official question isn't causing too much forehead slapping :-[

tesa

"building a house requires thousands of decisions based on a million bits of information"-charlie wing

Offline MountainDon

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Re: yet another pier spacing question
« Reply #1 on: April 07, 2009, 04:40:16 PM »
The safe assumption with something like this is that it is always alright to close the spacing, but not to expand the spacing. There is likely some leeway built into the calculations that produced the 7'6" spacing, but that doesn't mean one should try stretching the spacing out to 10 feet.

If this was me I'd add 2 extra piers per side and reduce the spacing to make them more or less equally spaced; 6'6". Probably adding one pier to make 8 foot spacing would work.   I don't recall for certain, what is the size of the beam that is called for; 6x12?

That's my answer; we'll see what John says.
« Last Edit: April 07, 2009, 05:51:55 PM by MountainDon »
Just because something has been done and has not failed, doesn’t mean it is good design.


Offline tesa

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Re: yet another pier spacing question
« Reply #2 on: April 08, 2009, 04:14:23 AM »
well, i'm new at this plan reading thing, but it looks like the materials list
says "2x12x16 DF#2

the plans themselves say "built up beam from 3-2x12's"

my hearts not set on adding 10', i want whats easiest, a few feet one way or the other isn't going
to matter in the overall scheme of things, and i'm also trying to be flexible

tesa
"building a house requires thousands of decisions based on a million bits of information"-charlie wing


Offline tesa

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Re: yet another pier spacing question
« Reply #3 on: April 08, 2009, 04:25:20 AM »
i just ran the numbers, at 6'6" using 6 piers, that gives me 39.6 feet

beautiful! close enough to 40' for me!

i'll wait for confirmation from john, but it looks like i've just made my first
modification

thanks

tesa
"building a house requires thousands of decisions based on a million bits of information"-charlie wing

Offline MountainDon

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Re: yet another pier spacing question
« Reply #4 on: April 08, 2009, 05:31:32 AM »
tesa, what you describe for the beam is a built up, or home made laminated beam. There would be three layers of the 2x12's, each with a 1/2" layer of plywood between. the cross section would be...

2x12-1/2"-2x12-1/2"-2x12

There's a sheet that illustrates the process, I believe. The plywood spacers are used to even out the width of the built up beam to fit standard metal post and beam caps and so on.

On the spacing, don't forget that this is given as center to center distances, like 6'6" OC. The two end piers will then have one half their width to be added to that. That is, a  S4S 6x6 (5.5") would add 2.75" at each end. You could also stretch the distance between 2 posts someplace to make the overall length come out to 40 feet if you desired.

IF you used 6x6 rough piers, actual 6" you could build the beam omitting the plywood, but adding one layer of 2x12. That comes out to 6" even.

Ideally the end to end joints of the 2x12 would fall over the center of a pier. If this is not possible John's plans outline what can be done.


Where X is a post and ---- is the space between them, the beam and pier would be something like this...

X------X------X------X------X------X------X

7 posts, 6 spaces times 6'6" = 39 feet plus slight extra as outlined above.



FWIW, I built my beams and cut the 2x's to length to make each end to end 2x joint fall over the pier. This produced a little waste but it was okay with me as each joint was fully supported. Some of those cut offs were used elsewhere for blovking, some made fine kindling.
« Last Edit: April 08, 2009, 05:51:57 AM by MountainDon »
Just because something has been done and has not failed, doesn’t mean it is good design.


Offline tesa

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Re: yet another pier spacing question
« Reply #5 on: April 08, 2009, 06:02:32 AM »
got it

i try to read things many times, to get a grasp and now i see the need for 7 piers. silly me

i do understand about "o.c." and the beams falling in the center of the pier

when i first got the plans, i just looked at them.  on sunday, i looked a bit harder, reading some things, and
glancing at some things

yesterday, i sat down, and actually read every word (well, of the foundation anyway, one thing at a time)

i'm a bit nervous, i was prepared to see thins i didn't understand, but not on my first day  lol

so does one always use "built up beams", or is it either or?  i didn't see any special sheet detailing that, but it might
be a seperate download, i do plan to join the sister site, to access that info too, but i haven't done that yet.

tesa

"building a house requires thousands of decisions based on a million bits of information"-charlie wing

Offline John Raabe

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Re: yet another pier spacing question
« Reply #6 on: April 08, 2009, 06:07:59 AM »
Yes, you can make the foundation outline exactly 40' if you want. The beam spans can be UP TO the plan spec of 7'-6" o/c. Do not exceed this spacing distance.

As Don suggests 6 spans and 7 piers work out to 6.67' o/c for the posts. I spec out a glulam beam (for tight code areas) or the built up beam. Don's alternative with 6" posts with 4 2x12's is even stiffer than the one I show. Follow his advice of having the joints fall on the posts.

Here is the download from out sister site PlanHelp.com (in the Download, Plans Details section).

None of us are as smart as all of us.


Offline tesa

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Re: yet another pier spacing question
« Reply #7 on: April 08, 2009, 06:09:10 AM »
roger that

thanks

tesa
"building a house requires thousands of decisions based on a million bits of information"-charlie wing

 

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