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Mono-Truss Pitch, Moisture Issues, and Steel Replacement Panels

This week the Pole Barn Guru answers questions about roof pitch on a mono-truss, issues with moisture in Florida, and a reader in need of steel replacement panels.

DEAR POLE BARN GURU: Designing 40 foot MONO trusses for a 200 foot long building and want to know what the pitch should be in North East Kansas. ROBERT in LINWOOD

DEAR ROBERT: My answer is going to depend upon what your proposed roofing material is. If you are using colored steel roofing then minimum roof slope to keep paint warranty intact would be 3/12, this also allows trusses to be built with need for a cap. If you are considering a shingled roof, then minimum slope should be 4/12 – and you are going to have a two part truss as trusses will be around 14 feet tall.

Whatever your building happens to be, it will probably prove more affordable to use gabled trusses with a centered peak. Wind load design considers full truss height in structural calculations and this extra height from monoslope trusses could very well have implications upon other members (especially columns).

In any case, run this by your engineer who is providing sealed plans for your building.

DEAR POLE BARN GURU: I have an existing pole barn with moisture issues. Most questions I see deal with heating issues. My situation is different. I live in the very humid central Florida region. The barn has no insulation, the roof had been covered with deep leaves for a long time. The roof clogged with organic material. The outside had had leaves and such built up enough around the perimeter enough to start rusting the lower in many areas.
I have cleaned around the building and want to repair the lower portions of the steel. I am trying to figure out my best plan to moisture proof and insulate the building from the Florida sun. The moisture is the biggest issue the place is like a sauna at times. JAMES in APOPKA

DEAR JAMES: It may behoove you to entirely replace your existing roofing and siding. As you mention you already have rust on sidewalls panels and organic materials on your roof for a long time has probably ruined any paint finish. Once this is done, use a good sealant on any concrete floors. Spray foam interior of all roof and wall panels with no less than two inches of closed cell foam. Your local installers may recommend a greater thickness. Grade around exterior of building to provide at least a 5% slope, from building walls out. Put gutters on eaves with downspouts ending five or more feet away from building. It may be necessary to have a dehumidifier inside your building, once it is all sealed up.

DEAR POLE BARN GURU: I need to repair some damaged panels on an existing barn. Do you sell individual panels? JULIE in LA CANADA

DEAR JULIE: While we can provide just a few panels, for small quantities you are best to go to the Pro Desk at your local The Home Depot, as they do not get charged inbound freight from steel roll formers. You might pay a little more for panels, however freight savings will more than offset it.

This entry was posted in Pole Barn Questions, Roofing Materials, Trusses, Ventilation and tagged roof pitch, moisture issues, mono-truss, replacement steel panels on August 19, 2019 by admin.

Moving a Building, Moisture Issues, and Siding Options

This week, the Pole Barn Guru discusses moving a building, a building with moisture issues, and siding options other than wainscot.

DEAR POLE BARN GURU: We have a 50 year old Morton machine shed 45X90X12. The posts and trusses are in excellent condition. The roof steel needs to be re-screwed and painted . The side wall steel probably needs to be replaced. The big problem with the building is its location. Our grain drying and storage has grown over the years and now we use semis instead of straight trucks and wagons. the machine shed blocks the grain dump so we have to back every semi in to unload and load. If we could move the shed about 60 feet north and 15 feet east we could still get a lot of use out of it. Otherwise we will probably take it down. Is moving it a practical idea to pursue? TED in DEXTER

DEAR TED: Sadly I just cannot see a scenario where moving this building becomes truly practical. If you have lots of free time, you could completely disassemble it and rebuild in a preferable location. However, you are reusing materials and things never seem to fit back together as tight as they did originally. If you are not going to rebuild, you might consider offering it to someone who will take it down and haul it away – it would save you time and effort and someone else can have headaches of teardown and rebuild.

DEAR POLE BARN GURU: I had a 30×40 built 14 feet high. Vapor barrier was used, insulated walls and vapor shield on top of the trusses, Vented over hangs and a ridge vent, insulated ceiling and metal on the walls and the ceilings.

Whenever I pull in my vehicles wet and leave them in there I get moisture all over everything. Now I am noticing green mold on the plywood work bench and in some various spots on the loft I built. I do not have any heat in there as I was not concerned about it being real warm in there, but I am wondering if am going to have to heat it to get rid of the moisture?
Any help would be appreciated. GREG in ELMA

DEAR GREG: Your steel liner has created a surface trapping any and all moisture inside of your building. In my humble opinion you have just one more example of why steel liner panels are not a good design solution for most buildings.

Just water alone, dripping from your vehicles, will probably not add enough moisture to create your described situation.

Step number one in solving your challenge – unless you know a well-sealed vapor barrier exists underneath your building’s concrete floor, use a good concrete sealer upon it. This might be a product you should consider: https://www.hansenpolebuildings.com/2018/11/siloxa-tek-8505-concrete-sealant/.

Unless you have taken steps to prevent moisture from migrating through your concrete slab, adding heat will merely draw even more water up through this slab into your building.

Secondly, you need to get moisture out of your building by adding a powered exhaust vent, a dehumidifier or both.

DEAR POLE BARN GURU: Another design question from me, I have too much planning time on my hands. With my house I made the mistake of having the vinyl siding too close to grade and it is showing lots of damage from typical yard maintenance, i.e. trimmers. I want to do a wainscot on my pole barn and probably correct the problem with my home siding at the same time. Not a huge fan of the metal siding for wainscot, not enough style contrast for me. Ideally I would do a stone veneer, but that is pricey. I am considering all options at this point. Stucco, fiber cement board, wood, even toying with the idea of veneering the outside with concrete pavers. Do you have any experience gems to share or any out of the box ideas? Thanks. ROB in ANNAPOLIS

DEAR ROB: Even with Code mandated six inch minimum hold up above grade for vinyl siding, it experiences a significant amount of damage just as you describe. Our house has steel wainscot and it has performed admirably other than where our daughter-in-law drove a riding lawn mower into it. All it took to repair was removal and replacement of a few short steel panels.

Given your preferences, I’d recommend you look into products such as

https://www.hansenpolebuildings.com/2018/10/mortarless-masonry-exterior/

or Thin Brick (http://thinbrick.us/).

This entry was posted in Constructing a Pole Building, Pole Building Siding, Ventilation, Alternate Siding, Workshop Buildings and tagged moving building, alternative siding, Siding, moisture issues, moving structures on January 28, 2019 by admin.

Pole Barn Moisture Issues

Moisture from condensation can be a major issue in initially poorly thought out pole barns.

Reader MATT in SHAKOPEE writes:

“Hi. I am having issues with moisture in my pole barn. It is getting to the point that mold is starting to show up on the walls and cement floor. The barn is about 28 x 36 with 12 foot walls. It has a service door and two 10 foot over head doors and 4 windows on the south wall. The ceiling is tinned, insulated and has a vapor barrier. The floor is cemented and I am unsure if the floor has a vapor barrier. The walls are not insulated or tinned.

The barn is used for storage right now cars, mowers, tractor, etc. The barn is unheated and sometimes the doors stay shut for one to two weeks. We have gone through and cleaned what seems to be mold off the walls but are unsure on how to stop the moisture issue. Wonder if some kind of exhaust fan would help? Or if you have any suggestions? Any help would be greatly appreciated.”

Mike the Pole Barn Guru writes:

I’d start with trying to eliminate moisture source. If you leave a wrench lying upon your building’s concrete floor for a few days and return and a dark spot appears below where the wrench was placed, your building has no under slab vapor barrier. If this occurs, use a good concrete sealant across floor. This in itself might resolve problems – watch the steel wall siding insides and see if they stay dry after sealing.

If this does not resolve problems, then you need ventilation. I will surmise your building does not have enclosed vented soffits and a vented ridge. Can’t go back and correct lack of overhang issues now, but you can add gable vents – a minimum of 242 square inches net free ventilation area in each endwall with vents located in top half of each gable.

Location of your building should also be examined. If soil around building exhibits signs of being moist, you need to make sure grade will allow water to drain away from building. It may be necessary to trench around building and add a drainage system to move water away from your building. Gutters should drain water sufficiently distant from building as well.

If nothing else works, here’s how to determine power ventilation requirements: https://www.hansenpolebuildings.com/2018/07/my-pole-barn-needs-ventilation/.