Tag Archives: insulation board

Minimizing Excavation in Post Frame Buildings Part II

Minimizing Excavation In Combination With Post-Frame Frost Protected Shallow Foundations Part II

In our last thrilling episode Snidely Whiplash had tied our fair damsel in distress, Nell Fenwick, to railroad tracks.

Oops – railroad engineers are not what most of you were expecting!

Continuing with a simplified solution response to reader DAVID’s ideas regarding site preparation and Shallow Frost Protected Foundations (SFPF) for post frame buildings.

Dear David ~

Thank you for your patience. As you may know from reading this column, I tend to research everything to best of my abilities prior to writing an article or responding to questions. Areas of site preparation and concrete flatwork are ones where I have a more limited amount of personal experience, so I have been doing a plethora of reading and contacting (and discussing) with concrete experts. I also am not married to a position, as better information becomes available, I take advantage of it.

Article you reference in (1) has been updated since you last perused it. Even though many RDP (Registered Design Professionals – architects and engineers) specify sand over under slab vapor barriers, I have now become a “no sand above vapor barrier” school convert.

To follow, a summation of my thoughts in regards to this subject, with top of slab being fixed 3-1/2” above grade.

(a) Excavate entire site to remove organic materials. Area to be excavated should be a minimum of three feet outside of actual building foot print. Depth of excavation below zero point (grade) should allow for any concrete thickness greater than a nominal four inches (3-1/2″ actual), two inches of insulation board (if desired), two to six inches of sand or sandy gravel and six to 12 inches of sub base. Assuming a nominal four inch slab, total depth of excavation should be 16 inches if doing a FPSF.

(b) Auger holes for columns, stand columns in augered holes and backfill with concrete per engineered plans.

(c) Install splash plank/skirt board, with board bottom even with grade (zero). There would be no reason to increase dimension to greater than 2×8, as vertical insulation boards prevent any concrete in a slab thickness greater than a nominal four inches to “leak” to outside world.

Side bar – 2×10 or 2×12 pressure preservative treated material will be available, however many times only via special order. If any portion were to be entirely embedded below grade, then appropriate treatment level would more probably be UC-4B – as UC-4A treatment levels are strictly for ground contact.

(d) Place vertical and horizontal insulation boards for FPSF – backfilling with sand or sandy gravel sufficiently to hold vertical insulation boards in place.

(e) Place sub-base, then base material, compacting in lifts.

(f) Place 15mil vapor barrier (make sure to run it up insides of splash planks); Under slab insulation (as desired); pex (https://www.hansenpolebuildings.com/2016/08/pex-tubing/), rebar and/or mesh, and then pour the slab.

This minimizes excavation by eliminating need for a trench.


Climate Control and Sliding Barn Doors

One of my favorites is when new clients want to climate control their building and also choose to use sliding barn doors.

If you are unfamiliar with sliding doors, they are typically made from 1-1/2” thick steel or aluminum members which are screwed together at joints and then sheathed with steel siding. The doors are suspended by means of pairs of trolleys from an overhead track which mounts on the face of the building. Sounds fairly simple, doesn’t it?

The challenge is, in order for the door to be able to slide past the steel siding on the main portion of the building, it has to be able to clear the high ribs of the steel. Allowing for even a minimal clearance, this means a gap of an inch. There will also be gaps at both the top and the bottom of the door. For practical purposes, a sliding door will naturally seal down just about tight enough to allow a bird or your neighbor’s cat to enter the pole building. There goes your climate control…right out the door!

There are some options.  Many sliding door component companies offer a vinyl weatherseal which can be installed on the sides and across the top of the door.

While I have never personally used the product, a company called Sealeze, manufactures a brush weatherseal which is said to close gaps of up to seven inches around all types of doors including barn and aircraft hangar doors. The Brush Weatherseal conforms to irregular surfaces to provide the most effective seal possible. More effective than vinyl or rubber seals, it consists of thousands of filaments which form a solid wall, closing gaps with a complete weather-tight seal without impairing door movement. These seals are made from nylon and polypropylene filament materials.

Now assuming the air infiltration problem has been resolved, what can be done to really climate control the building by insulating the door itself?

One option is to order the sliding door in the 3-1/2” thickness instead of the standard 1-1/2”. While slightly more expensive, it will afford a thicker cavity to insulate. Spray polyurethane foam is most expensive, but will yield the highest R values at 6.4 to 6.8 per inch thickness. In a 3-1/2” cavity an R value of up to 23.8 could be achieved. Rigid foam insulation boards can also be cut to fit between the sliding door horizontal members and glued to the inside of the sliding doors steel siding.

Several types of insulation board are available. These include polystyrenes, polyisos and polyurethanes with R values which vary from 4.8 to 8 per inch.T

Look at all the efforts and costs involved in an attempt to climate control your building. The heat (or air conditioning) costs involved with sealing and insulating a sliding door, it makes sense to consider an insulated sectional steel overhead door as an alternative. And my favorite reason to order one – an overhead door can be easily fitted with a remote electronic opener!