Part II of a two part series. If you didn’t see Part I, go back one day.
Mike’s answers are in italics.
In each house at ends of the “L” layout, I plan to have 1/3 open plan at two stories, for our great room, with nice windows for great views.
The other 2/3 areas will have 2 bedrooms and maybe a sitting area on the second floor.
- Do really need 6” * 6” poles in this area for the 2nd floor?
- I was planning on building the upstairs like you do in a stick built house which would be use the 1st floor wall as load supporting, use 12” floor joists and add a beam where needed and then use steel adjustable poles. (Cover poles later)
- Is this OK to do?
- Would the steel poles need to be on thicker concrete?
- Would the 1st floor walls that will load support the 2nd floor need to be on thicker concrete?
- You are free to say, “Greg if you had a decent floor plan, we should add a few poles, as it would be so much stronger, better, and other”.
- Thoughts? Mike: Personally I would clearspan your second floor using prefabrciated wood floor trusses. There would be supported by LVL beams attached to your perimeter columns. This allows for walls to be placed anywhere without having to create bearing walls or have interior columns. All mechanicals can then be run through this floor truss system. If you were to approach your second floor as if it was traditional stick frame – you would then be faced with how to support it at exterior walls, since they are horizontally girted. Any bearing walls would have to have thicker concrete below and adjustable steel pole locations would probably require some sort of concrete pier (or at least slab being thicker and perhaps requiring some extra rebar). If using adjustable steel poles, I would want them to at least be wrapped with two layers of 5/8″ Type X sheetrock so in event of a fire they would not lose their temper, deform and collapse.
Wall Girt System questions:
- If the posts are 6” * 6” what width are the horizontal girt boards? Are they 2” * 6” * X’ or 2” * 8 “ * X’? Mike: For glulams of 2×6 you would have 2×8 girts, for 2×8 columns, 2×10 girts. These will project 1-1/2″ outside of your perimeter building columns.
- If they are the 2 * 8’s, is there a little board you would put on the post, between the post and the outside metal? (This little stuff drives me crazy too!) Mike: Blocking would be placed on column exterior faces, aligned with wall girts to provide a continuous line for attaching steel siding with screws.
- Are the vertical spacer boards nailed to the side of the post as shown on the attachment, so horizontal bookshelf girts can be nailed vertically into the spacer to avoid toe-nailing all of the girt boards? Mike: Bookshelf girts will be supported at each end with solid blocking against columns – no toe-nailing of girts to columns.
Does the lowest board on the posts, (Grade Board?), does it actually contact the dirt floor before pouring the floor? Mike: Bottom of pressure preservative treated grade board/splash plank is set at grade, so it is in contact with ground.
So the board will have 4” – 5” of cement contact? Mike: Top of your concrete slab would be 3-1/2 inches above bottom of splash plank.
How far does the siding cover the lowest board? Mike: Bottom edge of steel base trim drip leg will be at four inches above bottom of splash plank. This allows for any exterior concrete (walkways, approaches, door landings) to be poured against treated splash plank rather than against steel siding or trims.
Do you ever use a composite board for the grade board? Mike: Splash planks are used to transfer wind shear loads from siding to columns and into the ground. Composites are not structural and do not have an ability to transfer these loads.
Sorry for all the dumb questions. Mike: Only a question not asked would be considered as being dumb.
I appreciate all the effort from Hansen Pole Buildings.
Loading Gambrel Loft Space
Loyal reader ANDY in OXFORD writes:
First, thanks for providing so much useful information to all of us. I’ve read about 1,200 of your blog entries so far, and I’ve learned so much.
I have already priced a 30X36X11 Gambrel Roof building from Hansen for a woodworking shop. I’m committed to the Gambrel roof for aesthetics and just because I’ve always wanted one.
Am I dreaming?? I’d like to hang a steel H-beam from the roof trusses in the loft, extending about 4 feet outside the front wall – just like the old-time hay barns. I’d use it to hoist lumber into the loft for storage. I wouldn’t need to lift more than about 200 pounds per load. I can insure against overloading by using a very light-duty electric hoist. I’d inform your designers so they could design the trusses for the added load.
The thing I can’t get my head wrapped around is how to completely weatherproof such a setup so that rain doesn’t get in the opening for the rail and hoist. Do you have experience or ideas to share? Should I drop the whole idea and just plan to manhandle the lumber from the back of my pickup up into the loft? I’m vertically challenged, so it’s not as easy for me as for you.”
I am impressed you have done so much reading, and thank you for your kind words, they keep me writing more content!
I might be bursting your bubble here, however honesty is always the best policy.
In order to store hay, your loft area would need to be designed for a ‘light storage’ load. By Building Code this is 125 psf (pounds per square foot) – more than three times required load for residential applications. If your intent is to utilize clearspan trusses for this, it may very well prove to be prohibitively expensive. Less costly (although perhaps an interruption of main floor materials’ flow) would be to support your upper loft with strategically placed interior columns. Almost universally, loft spaces tend to be where things go to die – as access and going up and down stairs becomes tiresome and inconvenient quite quickly.
I would instead encourage you to go with a larger footprint and store your lumber at ground level. You will find it to be less expensive, as well as more readily accessible. If you love gambrel looks, by all means keep it as your design.
Should you be dead set upon utilizing this second floor space for light storage – design with a widow’s peak to cover rail and hoist outside of the building and always keep outside. Materials can be loaded through a “bale” door unit, placed in the endwall, sealed against wind and rain (granted you will be limited to materials in length two times the distance from building face to most extreme point of rail). In old time barns, being totally weather sealed was not usually high on priority lists – an ability to get materials easily loaded would have been way higher.
Maximizing Post Frame Gambrel Usable Space With Trusses
Hansen Pole Buildings’ Designer Rachel and I recently had some discussions in regards to maximizing post frame gambrel truss useable space. Most often gambrel roofs are supported by one piece clearspan gambrel trusses. Largest downside to this type of truss system is lack of bonus room width. Usually you can expect a room from 1/3 to ½ building width with smaller span trusses (generally 24-30 foot spans). Sort of like this:
My bride and I happen to live in a gambrel style barndominium (for more reading on barndominiums https://www.hansenpolebuildings.com/2016/04/the-rise-of-the-barndominium/). It is actually probably more appropriately a shouse (shop/house). We wanted just a lot more living space than what could be afforded by a bonus room in a gambrel truss.
This is what we did…..
Center width of our home is 48 feet. We clearspanned this using 48 foot long prefabricated wood floor trusses, placed 24 inches on center. These parallel chord trusses are close to four feet in depth. With our 16 foot high finished ceiling downstairs (it is a half-court basketball court), this made our second floor level 20 feet above grade. Ends of these trusses are supported by LVL (https://www.hansenpolebuildings.com/2013/01/lvl/) beams notched into four ply 2×8 glu-laminated columns every 12 feet.
This got us across from column to column to support a floor, now we needed a roof system! We utilized trusses much like these, only much bigger:
Our trusses were so much larger, they had to be fabricated in two halves, split right down the center and field spliced to create a whole unit. We utilized the “Golden Ratio” (https://www.hansenpolebuildings.com/2012/06/gambrel/) to create slopes and pitch break points. Our steep slope is 24/12 and our upper slope is 6/12/ On the inside, our slope is 12/12 and our flat ceiling ends up at 16 feet above floor!
We also ended up with a very, very tall building. Roof peak happens to be 44 feet above grade! Living at 20 feet above ground does afford some spectacular views – we look due south down Lake Traverse and can see the tops of tall structures in Browns Valley, our closest town six miles away.
In my next article, I will clue you in on things I would have done differently, so stay tuned!