Tag Archives: LVL beams

Beam Needs, Slab Design, and Attic Ventilation Issues

This Wednesday the Pole Barn Guru answers reader questions about LVL beam procurement, a question about slab in a flood prone area, and A1V in a non vented attic.

DEAR POLE BARN GURU: I need a 3 1/4″ x 7 1/4″ x 12′ beam. Is this something you can help me with? JAMES in TUCSON

 

DEAR JAMES: While we could provide it, freight would be astronomical. Try reaching out to the ProDesk at your nearby The Home Depot.

 

DEAR POLE BARN GURU: Hello Mike, our building lot is pretty much flat. I’m using the elevation of our street at the curb as a zero reference point for our build. We are in a coastal area with occasional very minor flooding, so I would like to have the finished floor level of our radiant slab at sixteen inches above that elevation. The frost depth at this site is twenty four inches as per our building department. I’m wondering if a monolithic frost protected slab would be practical for our 56 x 48 monitor style house? I’m open to any suggestions that will allow me to use the radiant in floor heat. We’ll be requesting a design and quote soon as we still have a few more details to figure out on our floor plan. Thanks RUSS in TILGHMAN

DEAR RUSS: I always tend to error on caution’s side. I would build site up so slab was no less than 100 year (if not 1000 year) flood level. Use embedded columns with rigid insulation around perimeter down 24 inches.

 

DEAR POLE BARN GURU: Hi, I’m building a garage I was planning on heating in the winter. I was planning on drywalling and insulating the entire thing. I mounted the metal roofing directly to the purlins not using any osb sheathing, and instead opted for a metal coated bubble radiant barrier with the required droop for an air gap to control condensation. Upon completing the roof I realized that it is a non-vented attic space. Do I need to cut out all the radiant barrier and apply a closed cell spray foam to seal up the attic in order to maintain a heated space below? It has a drop ceiling FYI. Thank you, ROB in MISSOULA

DEAR ROB: Most high quality closed cell spray foam insulation applicators will only spray onto inside face of steel roofing and/or siding. This leaves you some choices: Cut out barrier, or Vent attic space and insulate directly on top of your ceiling. Personally I would likely opt for choice number two. Vented soffit panels (not every soffit panel would need to be vented in order to keep proportions proper) and vented ridge closures could be shipped to you and fiberglass or granulated rockwool insulation could be blown in on top of your ceiling. This is likely to be less expensive than closed cell spray foam and you would only need to heat area below ceiling (as opposed to also heating dead attic space above ceiling).

Avoiding Being Driven Crazy With Barndominium Questions Part II

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.

Thanks