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Re: [HOn3] Basement Construction 101

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  • boone
    ... Good comments Joe. On the beam issue - steel I beams are always an option,though material and placement (crane) cost can be high. However,they do permit
    Message 1 of 13 , Jan 3, 2005
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      >Brian-
      >
      >To add to what Boone presented, "composite" beams are now more
      >widely available, and allow for greater spans than conventional
      >timber framing methods. Also, the use of steel support beams is
      >nothing new in basements. If you're not a builder, Boone's advice
      >to seek "professional help" (in this hobby, we might all consider
      >that!) is a very good idea.
      >
      >Joe Fuss
      >

      Good comments Joe. On the beam issue - steel I beams are always an
      option,though material and placement (crane) cost can be high.
      However,they do permit long spans. Another option is a "flitch
      beam", involving a thin (10 gauge) metal plate secured between two
      wood members. Using 2 x 14 wood and similar width steel plate, you
      can clear span at least 22 feet..and with two plates and three wood
      members you can get as far as 24 or 26 feet with no appreciable
      deflection.

      The deflection (sag at the center) is the issue with wood...you
      cannot allow it to go more than 1/120 of the span length, and at that
      the floor above will resemble a trampoline! At 1/240 most folks will
      be satisfied, but 1/360 is far better on all counts.

      Yes, within some limits you can relocate columns, but at no time can
      you exceed the maximum span of the beams you use for the imposed
      loads....BAD idea!

      No plug for my profession, but getting input from pros who know how
      to calc out these matters will serve you very well in the long run.

      Aloha, Boone

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    • Mike Conder
      Boone, Is that deflection based on unloaded conditions, with dead load or with live & dead load? And as a professional mechanical engineer, I d never build a
      Message 2 of 13 , Jan 3, 2005
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        Boone,

        Is that deflection based on unloaded conditions, with dead load or with live & dead load?

        And as a professional mechanical engineer, I'd never build a house without using someone who knows how to design things safely and correctly. Also, IIRC, it's always best to design a house that meets the local building codes and UBC (or whatever it's called these days) so it can be financed without problems.

        Mike Conder

        boone <boone@...> wrote:

        > The deflection (sag at the center) is the issue with wood...you
        cannot allow it to go more than 1/120 of the span length, and at that the floor above will resemble a trampoline! At 1/240 most folks will be satisfied, but 1/360 is far better on all counts.



        [Non-text portions of this message have been removed]
      • MJ
        You can use parallel chord floor trusses and eliminate beams and posts entirely. Floor trusses also have the advantage of including all the electrical,
        Message 3 of 13 , Jan 3, 2005
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          You can use parallel chord floor trusses and eliminate beams and posts
          entirely. Floor trusses also have the advantage of including all the
          electrical, plumbing and mechanical system ducts within the floor trusses
          instead of hanging below the floor joists as in a conventional joist-beam-pole
          floor system, Preserved wood foundation walls and floor trusses are commonly
          used in this part of the world and work very well.
          MJ
          >
          > One other comment. I designed and built the house I'm in based upon my desire
          > to build a large RGS layout. I thought I had the basement pretty well
          > designed to fit the railroad until I actually got to the point of detailed
          > track planning. A lot of the posts were in the way! But nothing is set in
          > stone. I was able to add a post here and there (in future mountains), and
          > remove the offenders, all safely, because of the type of supporting main beam
          > that I'd used.
          >
          > You might mention the possibility of being able to relocate posts as an option
          > to your "professional".
          >
          > Joe Fuss
          >
        • gary fredrickson
          Brian (& Joe & Boone), I just logged on and found your interesting topic and exchanges. I m a licensed structural engineer in Washington State and I ll offer
          Message 4 of 13 , Jan 3, 2005
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            Brian (& Joe & Boone),

            I just logged on and found your interesting topic and exchanges. I'm a
            licensed structural engineer in Washington State and I'll offer up yet
            another option from the home of Weyerhaeuser. Weyerhaeuser makes an
            engineered wood joist product they call "TrusJoist". (Note: I am not
            connected to/with Weyerhaeuser in any way except through having used this
            product). One of their standard offerings will allow you to span the 30
            foot width of your proposed basement WITHOUT ANY interior supports.

            Their TJI/PRO 550 joist (16" deep) at 16 inches on center will carry a 40
            psf live load and a 20 psf dead load and yield a center of span deflection
            of approx 1/450th of the span. As Boone said, stiffer is better. Our code
            requires live load deflection to be NO GREATER than 1/360 of the span for
            occupied spaces.

            TrusJoists are nice to work with: They are relatively inexpensive ( about
            25% more expensive than equivalent 2X framing lumber), and offer uniform
            properties, ie, straight, flat, lighter weight and higher strength than
            equivalent 2X lumber. There are, however, restrictions on penetration
            location and size that require forethought with regard to placement of
            utilites (electrical wire runs, plumbing, and heating ducts).

            As I said above, Brian, this is just another suggestion. Your "design
            problem" has an almost infinite number of solutions. There is no one
            "correct solution". It comes down to cost comparisons between alternate
            designs, availability of materials, etc. What your house above the floor
            looks like will have a major bearing on what floor design will work/be
            required.

            Again, as both Boone and Joe said, your project is not a do it yourself
            affair. You will have to get a building permit before you can begin
            construction and, depending on your local requirements, you may be required
            to have your design approved by an engineer and/or an architect. I'll close
            by echoing Boone and Joe -- get some professional help.

            P.S. for Boone -- want to bid on this job and split the fee????

            Gary Fredrickson


            ----- Original Message -----
            From: "bassb04011" <fishingmaine@...>
            To: <HOn3@yahoogroups.com>
            Sent: Monday, January 03, 2005 5:45 PM
            Subject: [HOn3] Basement Construction 101


            >
            >
            > I am roughly designing my future house and basement for when I get
            > out of the Navy and start my RGS/DRGW empire. I was wondering if
            > there are any architects or enginneers that can give me a basic Idea
            > of what to expect with load bearing walls and columns for a
            > basement. I am planning on a 30' x 42' basement with a 20' x 15 '
            > extension off one side. I would prefer to use metal poles vs walls.
            > Is there a rule of thumb for how far apart the supports need to be?
            > Does the upstairs architecture affect where the supports need to
            > be? Any help would be a good starting point for my layout design.
            > Thanks, Brian
            >
            >
            >
            >
            >
            > HOn3 list web pages are:
            > http://www.railwayeng.com/hon3/
            > http://groups.yahoo.com/archive/Hon3/
            > http://groups.yahoo.com/files/HOn3/
            >
            > Yahoo! Groups Links
            >
            >
            >
            >
            >
            >
            >
            >
          • Joe Fuss
            Gary- The Weyerhauser product you mentioned is one of those composite products I was thinking of. It s a great product for basements; I just wish it had
            Message 5 of 13 , Jan 4, 2005
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              Gary-

              The Weyerhauser product you mentioned is one of those "composite" products I was thinking of. It's a great product for basements; I just wish it had been available 25 years ago!!!

              Another feature that Brian should consider that hasn't been mentioned is "ceiling height". That is, the final height of the ceiling in your basement AFTER all the ductwork/wiring has been installed, and the final ceiling added. If you're going to use the basement for a railroad, or for that matter, any type of use where people will be walking around (which includes most everything!), I'd suggest not having any location with less than a 7-foot clearance, even under supporting main beams. This will probably mean making arrangements with your contractor (before the digging begins!) of having an extra course or two of block added to the foundation walls. If you use a foundation wall other than block, the height of the walls will need to be extended.

              In my case, I had to compromise. The house sits on top of solid rock, and short of drilling and blasting, I ended up adding an extra course of block and having fill hauled up to make the home appear normal. I still came up a bit "short", tho, on my ceiling height and am having to live with it.

              Joe


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            • Kjb80401@aol.com
              In a message dated 1/3/05 6:48:06 PM Mountain Standard Time, fishingmaine@hotmail.com writes:
              Message 6 of 13 , Jan 4, 2005
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                In a message dated 1/3/05 6:48:06 PM Mountain Standard Time,
                fishingmaine@... writes:

                << Is there a rule of thumb for how far apart the supports need to be? Does
                the upstairs architecture affect where the supports need to be? >>

                Brian,

                See Boone Morrison's reply for a 'rule-of-thumb'. The spacing depends on the
                size of beam utilized. The larger the beam depth, the greater the span
                possible between posts. Do use steel posts (code 40 preferred), they're typically
                3" to 3-1/2" in diameter and can be concealed within walls. Steel beams are
                smaller in overall size compared to wood beams and offer greater span distances
                between posts.

                The upstairs design can affect the quantity of beams and their location,
                however most residences are designed with clear-span roof trusses throwing the
                loading on the exterior walls and minimize the impact on interior walls.

                My house was designed with the stairs to the basement towards the middle of
                the house. This permits an around the wall layout design in the basement (no
                duck-unders needed). I have a couple of rooms along the exterior walls but the
                resultant clear basement was worth it. One strong recommendation here, be
                sure you have sufficient clear area at the bottom of the stairs to bring 4 x 8
                foot sheets of whatever down into the basement. I've seen houses where the
                bottom of the stairs was but 3 feet from the exterior wall, a horrendous
                situation.

                In many areas of the country manufactured floor joists (I-beam style) are
                being utilized. They allow for greater spans with less deflection than solid
                wood joists. They are dimensionally stable and straight. They also don't warp
                as solid wood ones do. TrusJoist is one brand commonly being used here in the
                Denver area.

                A STRONG RECOMMENDATION: Insist on at least 9 foot tall exterior basement
                walls (10 foot is even better). Ductwork typically is installed beneath the
                floor joists of the first floor and robs you of clear height to a ceiling in the
                basement. A 9 foot wall will yield about 8'-9 1/2" for distance from the floor
                to the bottom of the floor joists, allowing for an 8 foot ceiling in most
                places. A 10 foot wall yields a foot more to hide more of the plumbing,
                ductwork, and beams. Poured concrete walls are common these days and the cost of
                additional height is nominal when compared to the results achieved.

                I wish I were at your stage of construction, I have 8 foot exterior walls and
                working around the ductwork and plumbing interferences has been a bit of a
                struggle.

                Keevan
              • boone
                ... Mike: Total load ... Code that applies is a local jurisdiction matter - here we use UBC. Agree, you MUST meet Code for permit, insurance and finance
                Message 7 of 13 , Jan 4, 2005
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                  >Boone,
                  >
                  >Is that deflection based on unloaded conditions, with dead load or
                  >with live & dead load?


                  Mike: Total load

                  >
                  >And as a professional mechanical engineer, I'd never build a house
                  >without using someone who knows how to design things safely and
                  >correctly. Also, IIRC, it's always best to design a house that
                  >meets the local building codes and UBC (or whatever it's called
                  >these days) so it can be financed without problems.

                  Code that applies is a local jurisdiction matter - here we use UBC.
                  Agree, you MUST meet Code for permit, insurance and finance purposes.

                  Aloha, Boone

                  [Non-text portions of this message have been removed]
                • boone
                  ... Yep, Gary...right you are. We use those here but they are not always in ready supply so we often fall back on common 2x material. That flitch beam trick
                  Message 8 of 13 , Jan 4, 2005
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                    >Brian (& Joe & Boone),
                    >
                    >I just logged on and found your interesting topic and exchanges. I'm a
                    >licensed structural engineer in Washington State and I'll offer up yet
                    >another option from the home of Weyerhaeuser. Weyerhaeuser makes an
                    >engineered wood joist product they call "TrusJoist".


                    Yep, Gary...right you are. We use those here but they are not always
                    in ready supply so we often fall back on common 2x material. That
                    flitch beam trick is also real handy when deflection must be held to
                    a minimum - such as a garage door opening or long run of sliding
                    glass doors - my most common situation here in Hawaii.

                    >As I said above, Brian, this is just another suggestion. Your "design
                    >problem" has an almost infinite number of solutions. There is no one
                    >"correct solution". It comes down to cost comparisons between alternate
                    >designs, availability of materials, etc. What your house above the floor
                    >looks like will have a major bearing on what floor design will work/be
                    >required.

                    Gary is right here - the whole affair is interlinked and must be
                    considered as a whole, not just the basement issues.

                    >
                    >Again, as both Boone and Joe said, your project is not a do it yourself
                    >affair. You will have to get a building permit before you can begin
                    >construction and, depending on your local requirements, you may be required
                    >to have your design approved by an engineer and/or an architect. I'll close
                    >by echoing Boone and Joe -- get some professional help.
                    >
                    >P.S. for Boone -- want to bid on this job and split the fee????
                    >
                    >Gary Fredrickson

                    Gee...this one is yours, Bro Gary! My plate is full and besides I
                    am not licensed in Washington state..

                    Aloha,Boone

                    [Non-text portions of this message have been removed]
                  • brian bass
                    Thanks for all th e info guys. Brian
                    Message 9 of 13 , Jan 4, 2005
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                      Thanks for all th e info guys.
                      Brian
                    • Boone Morrison
                      ... That s what happens when you ask guys like us a question! We love to go on and on.....:-) Aloha, Boone [Non-text portions of this message have been
                      Message 10 of 13 , Jan 4, 2005
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                        >Thanks for all th e info guys.
                        >Brian
                        >


                        That's what happens when you ask guys like us a question!

                        We love to go on and on.....:-)

                        Aloha, Boone

                        [Non-text portions of this message have been removed]
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