Architectural / Structural Concerns - HEAVY TRANSMITTER

[ka4koe]

I am seriously considering acquiring a T-368. However, my shack is located in an upstairs bonus
room over our garage. The floor joists are 2 x 12s spaced per code. I an jest a humble 'lecktickle injuneer, so
I'z noze nuttin' 'bout boards 'n joists.

Question:

If one installs a 700 pound T-368 on 4 casters, any idea if this monster will crunch thru
the floor and plummet smack dab on top of Sheri's (K4SMN) Porsche Carrera?

If that happens, then the least of my worries will be the damage. Sheri is a
country girl brought up in South Central Georgia who knows how to handle a
firearm with deadly accuracy.

Get my drift?

tnx

Philip

[ka4koe]

Not gonna work. Thats an area for the transmitter of 6.9 square feet. At 650 pounds, that works out to 95 pounds/SF. An Architect here tells me not to load up an upper bonus room floor to over 40 lbs/SF.

Moot point.

[W3RSW]

Is 'he' an engineering architect?  Is the 40lb./ft² a local code or insurance  requirement?

Load per unit area can be distributed.
What's the diff. between your T3 and a couch with four 200 pounders sittin' on it and rootin' for a Super Bowl team, waving their arms, kicking their feet and high fivin'?

-Whereby impulse and momentum is twice weight and all the other physical manouverings not defined in static load.

So I assume your 2x12's, second floor are on 16in. centers, as is your roof with potential for 3 ft. of water laden snow.  Is the rumpus room on same joists as upstairs of regular house?  A lot of those only have 2x10's.

Think that's enough. Run the calcs. if you're really worried. It's in the literature.

Load depends on strength and centers of underlying posts, spacing, how tied to overlying joists, etc.

By your implication of financial shape, I'd assume your house is up to reasonable construction standards, not necessarily same as beauracratic edict.

 I'd pad the T-3 area just to prevent gouges and distribute local forces to a quarter sq. ft. or better under each of the casters and not worry about the overall load. Place it between underlying posts, or along a wall, etc.
I'ts going to sit there quietly but swing the monkey.

[ka4koe]

Yes, he's an engineering architect, certificated type.

[KA2DZT]

40Lbs/ft??  I'd worry about the rest of the house.

Your floor with 12" beams spaced 16" will handle way over 40Lbs/ft.  Two people standing next to each other could easily be upwards of 500Lbs.  Depends also on what type of sub-floor and floor you have.

[KK4YY]

You're misapplying the 40 psf figure. It's not that simple.

A T-368 weighs about as much, and covers about as much area, as 3 average ham operators standing shoulder to shoulder in your shack. "Quick hunny, take the picture of me and my ham buddies together before we fall through the floor!" No, you wouldn't have given floor loading a thought in that situation.

Let's say you just bought a fish aquarium, model # T-368, and wonder if the floor will hold...
http://www.cichlid-forum.com/articles/aquarium_weight.php

-Don

P.S. Is your architects name George Costanza?

[W1ATR]

t-368 heavy??  

Where's Johnny Novice and the Iron Curtain fan club?

I've had two, not one, TWO...GPT-750's over the last 20 years. Neither of them has ever stood on concrete. They've always been on hardwood in the comfortable parts of various houses. Never a sag, or a crack in plaster walls. At 950lbs, they aren't anything to sneeze at.

Here's the first one. (a bad poloroid scan anyway) It's stood in that spot from 1988 to 2000 while it enjoyed it's reign as supreme master of the chicken band east coast division. a pair of ten element yagis on a 70 footer outside had that position wrapped up. The second one is in my sig linky. It sits in storage where it's mostly sad. 

 

 

[W3RSW]

I removed my post of more calculation thought.
 Don's fish tank reference just about covers it "concluding" that a 55 gal. Tank (458 lbs. of water plus add'l wgt. of tank) is just about safe anywhere.  Excellent and applicable reference for handling weights of another half a magnitude on common flooring.

[K5UJ]

if you aren't fortunate enough to have an outbuilding for your shack, preferably something like a garage on a slab, then the shack belongs in the basement.  All righteous shacks are in one or the other.   

[WQ9E]

It is a chance to find out just how well your house is constructed    A few years ago when I had a master suite added the general contractor related a story of his early days as part of the crew working for a large contractor who specialized in big subdivisions.  They found none of them could keep up with the speed of a newly hired old gent who was installing stud walls.  When the flooring crew came in install carpets the answer was revealed.  When the carpet stretcher was used his stud walls shifted out of position-you can build faster with fewer fasteners...

On a more serious note, hams and vintage gear are like the old Lays potato chip commercial where you cannot stop at just one.  That nice flat T-368 top is the perfect place to stack more gear including a nice heavy tube type receiver.  Next comes a smaller setup next to the T3, a desk, etc. etc. etc. finally followed by a CRASH.  At least keep it as close as possible to a bearing wall where the floor joists are supported.  Remember Archimedes and his discussion of the lever effect.

[w4bfs]

hello Feelip .... spread the load out iffin no other way .... a half sheet of stacked plywood would do it

I passed my EIT in 1979 .... at that time very few EE would take the test as it was heavily stacked for CE and ME .... later on all were required to take the exam ... I remember it as the worst 8 hours I ever spent at somephin

I wasn't able to sit for the PE because I never found 2 PE's at the same time willing to recommend ...all that is ancient history now  73   John

[kb3ouk]

If the load on the floor shouldn't be any more than 40 lbs./sq. ft., then you probably wouldn't even be safe standing on it. Do what I've seen done with some rather heavy (about 600 pounds empty, I believe) gun safes around here, put it as close as possible to the wall, then under the floor put 1 or 2 floor jacks as additional support.

[KB2WIG]

P,

Can you get to the floor joists easily?? Not too much difficulty adding a few 2X12s and some bracing ( them little Xs between the joists. If you can get to them easily.   Place her close to a wall?

And/Or add a few lally columns under where you want to add yer '368? Like this.


klc

[WA3VJB]

Ask Don K4KYV about the time he noticed the ceiling in his dining room was gradually settling toward the table.

Wonder how old your garage structure is?  Construction techniques and materials have changed over the years, with newer places generally inferior to structures built 40-50 years ago. Your place looks like maybe 10 years old?  Nice, BTW, I like how the street doesn't look into your garage in case you leave the door open.

The load at each of the 4 casters might indeed cause the wheels to poke through your subflooring. That's a very high concentration of the weight across a small area. I'd be curious as to the thickness of the subflooring along with any additional flooring on there. (tongue and groove hardwood would help a lot, for example)

There's also a strength parameter as to how the subflooring is joined with the outer perimeter of your garage. When you put stress on that subflooring it can load not only the nearest junction, but also other, interactive elements of the building.  I'm not being alarmist, but placement is more involved than just keeping the transmitter near a wall up there.

And the joist spacing is important, not just that it's "per code."  Older homes routinely used oversized joists and shorter spacing to exceed code.

There is probably another set of specifications in your building code as to whether the "bonus room" is for live loads or dead storage.  A developer could tell the zoning people one thing to get approval, and the sales department might say another thing about potential use of that room. ("Oh sure, that room would hold a PORSCHE !")

When we built the Radio Lodge on the back of the property I went through a lot of discussion about floor loading and how the builder's design could accommodate, say, a 1300 lb transmitter that might be placed anywhere on the floor plan.  He designed accordingly, including the ramp outside to get there.

Turns out I could drive up the ramp, clear the double doors, and store our Datsun roadster in there if I wanted to.

[KU8L]

I dont think the joists are the issue.  It is the point loads of the decking between joists that could be the problem.  I would add a sheet of high quality, solid core 3/4 ply over the carpeting or subfloor just to distribute the loads from the castors.

Or roll it up onto a couple of pcs of 3/16 x 4 steel channel that spans the joists.  Anything to prevent the wheels from punching down thru the decking.  Remember at some point while rolling, much of the load will be shifted to only 1 or two of the castors.

FWIW

Curt
KU8L

[ka4koe]

"I wasn't able to sit for the PE because I never found 2 PE's at the same time willing to recommend ...all that is ancient history now  73   John"

If you ever change your mind, then let me know. Be glad to recommend you.

Philip

[ka4koe]

"Wonder how old your garage structure is?  Construction techniques and materials have changed over the years, with newer places generally inferior to structures built 40-50 years ago. Your place looks like maybe 10 years old?  Nice, BTW, I like how the street doesn't look into your garage in case you leave the door open."

We hate "front loader" houses with the garage door in front. If you look closely at the sat photo, you can just see my KMA log periodic VHF/UHF antenna. Looks like a big TV antenna (works great on HiDef BTW) when I'm not squirting RF into it.

It is less than ten years old. We are the first owners. Sheri K4SMN, my father in law, and myself finished both upstairs bonus rooms. My room/Mad Scientist Lab is 12x16 with a peaked ceiling and a flat center. Wired the whole thing myself (two subpanels, 1 for me and 1 for the combo Sheri's craft/inlaws bedroom). Nothing arced and sparked, which is remarkable since I'm an EE and not an electrician. I need to go upstairs and check the stud size/spacings.

I do, btw, have great respect for the old craftsman electricians. My bacon was saved on a couple of big projects more than once by those longtime guys. But, that's how you learn how things are put together.

[ka4koe]

I think I will check with a Structural engineer in town that I've known for 20 years. If this TX kills K4SMN's Porsche below, as stated previously, my life won't be worth a "plug nickel". She has a Springfield Arms XD40 pistol and knows which end of the tube from which the round exits.

The analogy about the 3 football players makes a lot of sense to me. But I've been conditioned by experience, PAIN (butt chewings from my previous bosses), and grey hairs, not to assume anything and take chances.

[ka4koe]

 "then the shack belongs in the basement"

I need scuba gear here for a shack in this location. I'm by the coast, and if you dig down more than a couple of feet, you hit water!

[WQ9E]

"then the shack belongs in the basement"

I need scuba gear here for a shack in this location. I'm by the coast, and if you dig down more than a couple of feet, you hit water!

Basements were a novelty to me when I moved to IL after growing up in Gulfport MS where water was only a few feet down (or out in any direction).  The old timers on the coast talked about one of the first projects at Keesler AFB involved driving some deep support pilings and when they were almost to the desired point they fell into the earth.  Part of the chosen site was over a cavern composed of loose sand and water.

My house is on a hill so my basement is dry but there are plenty of people in the area who needed scuba gear to get in their basements this spring.  After last year's drought we are now 7 inches ahead of normal for what is already the wettest time of the year.  Two weeks ago several basement walls in Peoria collapsed from the water trying to get in. 

My Desk KW and BC-610 are on the first floor but a lot of other heavy stuff is in the basement.  The only stuff upstairs is some much lighter VHF gear and a lot of manuals and magazines.  The basement under the original part of the house (built in 1901) mostly holds storage space for gear although I do have a couple of operating positions there while the 1,000 square foot basement under the master suite added a few years ago is the operating position (or museum as my wife calls it).  I did the wiring and plumbing work when we added this area and except for the lighting all wiring for this basement goes through a shutoff switch to a second panel.  I got very tired of 2-12 wire before this wiring process was completed

[w3jn]

t-368 heavy??  

Where's Johnny Novice and the Iron Curtain fan club?

I've had two, not one, TWO...GPT-750's over the last 20 years. Neither of them has ever stood on concrete. They've always been on hardwood in the comfortable parts of various houses. Never a sag, or a crack in plaster walls. At 950lbs, they aren't anything to sneeze at.

Here's the first one. (a bad poloroid scan anyway) It's stood in that spot from 1988 to 2000 while it enjoyed it's reign as supreme master of the chicken band east coast division. a pair of ten element yagis on a 70 footer outside had that position wrapped up. The second one is in my sig linky. It sits in storage where it's mostly sad. 

 

 

My GPT-750 is in a ground floor room that's on a concrete slab.

I did have enough receivers and other heavy crap on my operating desk that the letgs collapsed though.  What a mess that was.  It's now resting on stacked 2X4s.

[ka4koe]

Had a second registered architect repeat the first's story. I'm gonna pass on the T-3 for now and not risk K4SMN's ire.

Philip

[W1RKW]

There are plenty of factors involved but suffice it to say putting a 700lb transmitter on a suspended floor I would not do and that's considering a static load with nothing else in the space. Add furniture and other stuff then a dynamic load (people) and it gets worse.   Even if it was positioned along a load bearing wall you'd still have to deal with the single point force by the castors. Add in the bending moment that is created on that wall.  You need to worry about whether the floor sheathing would support the castors. Assuming a perfectly distributed load on the wheels of a 175lbs per wheel on a very concentrated point, probably a good decision not to attempt this.

[kb3ouk]

Just curious, would it be possible to put the T-368 at ground level (as in inside the garage below) then run audio lines, etc. to it from the shack above it?

[K5IIA]

i think I remember don k4kyv telling a pretty good story of an a.m. transmitter up stairs in his house before the shack. or maybe another qth.

shoot put some plywood under it. get some kickers off the wall, and hang a few cables from the ceiling you will be ok. where there is a will there is a maul.