Tag Archives: overhangs

Proper Storage of Trusses at the Job Site

Proper storage of trusses at the job site.

Long time readers (or those with time on their hands to have read my previous nearly 1700 articles) will recall in a past life I worked in or owned prefabricated light gauge steel connector plated wood truss manufacturing facilities. In my first long-term position as Sales Manager at Coeur d’Alene Truss (now Coeur d’Alene Builders Supply http://www.cdabuilders.com/) we fabricated huge sets of “saw horses” so we could store trusses vertically in these bunks.

Sadly I see much mishandling of trusses at manufacturing plants, upon delivery and at jobsites. Below are tips to keep your new post frame building’s trusses bright, fresh and structurally sound.

Trusses store best when standing upright.  

Shore and brace standing trusses well to keep from toppling. Trusses stored other than in a vertical position can and will warp, and become difficult to use.  

Store trusses with “tails” (overhangs) elevated so truss weight rests on the bottom chords, not on the truss tails..

Unload trusses in bundles and store on level ground, but never in direct contact with ground (to avoid collecting moisture from the ground). Allow for good drainage at truss storage location in the event rain occurs before installation. Protect trusses from damage resulting from on-site activities, environmental conditions or weather. Exercise care at all times to avoid damage to trusses due to careless handling during delivery, unloading, storage, and installation.

In warm, rainy weather, moisture regain in unprotected trusses can result in fungal staining. Wetting lumber also results in swelling. Subsequent shrinkage may contribute to structural distortions.

To store trusses for a long time period, cover with a water repellent tarp for protection. Plastic is an acceptable alternative, provided there are side openings to allow air flow.

Handle pole building trusses in such a way as to prevent toppling when banding is removed from bundles. Trusses stored on black top (asphalt) or other impervious surfaces and continuously moved around the construction site are subject to damage when they are slid along the surface with equipment. As a result, galvanized coating on connector plates may be removed, allowing plates to rust and possibly reduce plate thickness.

Free Post Frame Foundation Building Calculator

Free Post-Frame Building Foundation Engineering Calculator

No, such a thing as a free post-frame building foundation engineering calculator does not exist. However there always seems to be someone out there who is in search of “engineering for free”.

Reader KELLY writes:

“Guru,

Do you have a link to a pole foundation engineering calculator?

Looking for column depth / diameter for:

40x60x14

10 ft column spacing

35 PFS load

115 wind load.

No floor for constraint.

thanks.”

Mike the Pole Barn Guru responds:

There is no such thing as a “pole foundation engineering calculator” therefore, there is also no link to one. The design of post frame (pole) building foundations is one which is best left in the hands of RDPs (Registered Design Professionals – architects or engineers). When provided with all the pertinent information about your proposed building, they can design not only a structurally sound column embedment, but also your entire structure (which I whole heartedly recommend).

You’ve provided some of the information a RDP would require, but I will expand upon it:

Will the building have adequate sheathing (which could be roll formed steel roofing and siding) to transfer wind loads from roof to ground through endwalls? And will the sheathing be adequately fastened to underlying frame to take advantage of sheathing stiffness? If yes, diaphragm design can be utilized in your building design.

The difference in forces carried by sidewall columns with and without an adequate diaphragm is a factor of 4! If diaphragm design cannot be utilized, expect significantly larger columns, deeper holes and more concrete around columns.

What type of soil is at building site? Strength and stiffness of your soil will impact both depth and diameter of holes.

How are you measuring your 14′? It should be from bottom of pressure preservative treated splash plank, to underside of roofing at sidewalls. It does make a difference.

Does your building have overhangs?

What is the roof slope?

What is wind exposure at your site? The difference in force against columns between Exposure B and Exposure C is roughly 20%.

In the event you are not interested in procuring services of a RDP, the NFBA (National Frame Building Association) has available a Post-Frame Design Manual and you could attempt to do calculations yourself. For more information please see: https://www.hansenpolebuildings.com/2015/03/post-frame-building-3/.

Of course you could always invest in a fully engineered post frame building kit package. Besides engineer sealed blueprints and calculations, you would also get materials delivered to your site and a multi-hundred page Construction Manual to guide you through to a successful completion.

 

Avoid Metal Building Insulation

One More Reason to Avoid Metal Building Insulation

 

Photo isn’t showing the inside of a Hansen Pole Building. This view happens to be inside of an eave sidewall looking up underneath a post frame building roof. White vinyl facing happens to be underside of a product commonly known as Metal Building Insulation, having actual R values so low it should be more appropriately described as Condensation Control Blanket.

For previous words of wisdom in regards to Metal Building Insulation, read more here: https://www.hansenpolebuildings.com/2015/05/metal-building-insulation-3/.

This particular building can be found in Western Washington. 20 years old, construction was done by current building owners. A horse barn, building has a concrete slab floor, other than in horse stalls. Each side of building has open (no soffits) overhangs.
Now our challenge – certain days, with high humidity and fog, building has a problem with water ‘leaking’ along first purlin inside building.

My take regarding the problem’s root cause:
Properly installed in a roof, each roll of Metal Building Insulation should be stretched two inches past eave strut (eave purlin). Fiberglass adhered to vinyl facing should be removed from these two inches, folded back over top of intact fiberglass, then fastened securely to eave strut top until steel roofing installation. This takes a bit more effort than merely cutting rolls off flush with eave strut outside and calling it a day.

My guess, this building’s owners were not given instructions advising how to properly install Condensation Control Blanket, so it was done a quicker and easier way. This leaves a raw edge of fiberglass above the eave strut. When those chilly high humidity days occur, underside of roof steel in eave overhang has condensation collecting. Some of this moisture then contacts raw fiberglass edge and wicks up into building. Please note, in photo the apparent puffiness of insulation between sidewall and first purlin up roof. This would be an indicator water has sat above white vinyl vapor barrier.

A solution exists – remove screws from roofing above fascia and eave strut. Insert form fitted inside closures above eave strut, making certain no fiberglass remains exposed to overhang. More information about inside closures here: https://www.hansenpolebuildings.com/2015/12/the-lowly-inside-closure/)

Replace screws (using larger diameter than original screws). Roofing should be screwed to both sides of high ribs into fascia board. We recommend use of 1-1/2″ Diaphragm screws as a replacement.

Purlin Questions for the Engineering Department: Building Disaster Part IV

Purlin Questions for the Engineering Department

For those readers just joining us, go back to Tuesday through Friday’s blogs to catch up to the following story…

Our client (after discussing possible corrections with one or more builders) poses this:

“I have two questions I’d like to ask of the engineering dept.

1.) Is there an acceptable way to inset the grade boards to be flush with the posts? Perhaps with hangers? If so, it would mean the wall girts would not have to be furred out.

2.) Would building frames for the end wall overhangs, and attaching them to the end trussses a viable option? Or do they feel like the end trusses would need to be lowered so the purlins can be extended?

I don’t know all of the terminology. Hopefully the above makes sense.

Thank you.”

Any proposed “solution” at this point is only a suggestion for discussion. A revised set of drawings should be produced and sealed by the engineer of record to incorporate the ultimately agreed upon repair fix.

Answers…

(1) Place a UC4B Pressure Treated 4×4 block at least 7-1/4″ long on each side of the column at the level where the 2×8 skirt board would attach. Use 3- 5″ Ledgerlocks to attach block to column. Pre-drill for them and stagger to avoid splitting. Drive 6-10d common nails through skirt board into 4×4 block. Cut ends of 4×4 block and 2×8 skirt board to be painted liberally with Copper Napthenate. Place (2) Simpson Strong-Tie LSTA12 straps across each column to tie from one skirt board to the next. Any 10d nails driven through the LSTA12 into the 2×8 PT and block would count towards the total of six.

(2) Building a “ladder” floating in space is far from an ideal solution. If they opt for this, I would want to see an LSTA24 on top of each purlin split 50/50 between blocking in the ladder and the purlin behind the truss, with 10d nails in each hole. Ladder would need to be built of 2×6 and also nailed through the 2×6 on the building side of the ladder, into the top chord of the end truss with 2-10d @ 12″ o.c.

Ultimately repairs can be simple, difficult, low cost or spendy. In the end the least expensive solution for question number one will be to furr out the girts by nailing a 2×4 flat across the columns at each wall girt. Fairly easy to accomplish and not overly expensive in time or materials.

The right way to do number two is to remove all of the purlins from the end bay, take down the end truss, cut the notches into the columns to support it (as detailed in the plans) at the correct height, and properly place the truss. This will entail the purchase of longer purlins, however it will give a much better end result.

And this my friends, is the end to my story about a building “gone wrong”.

F Channel and Enclosed Soffits

My early days of post frame (pole) buildings came in the Pacific Northwest. In the early years, rarely did buildings have any overhangs…at least not beyond a few inches of roof steel extending past the siding.
When building did have overhangs, they were always “open”. Open, in this sense, did not mean birds and other critters could fly into the building through them, but rather they had no soffits.

With an open overhang, when one stands beneath and looks up at the underside of the overhang, the supporting substructure framing is visible, as is the underside of the roof steel, or roof sheathing.

A decade later and a transition from a provider of post frame building kit packages, to being a pole builder and clients began requesting their buildings to have enclosed overhangs. With a minimal investment over open overhangs, plus the advantages of being very attractive and limiting locations for nests of both barn swallows and wasps – it was (in my mind) a no brainer.

In researching how others were installing soffits, I found the majority use a piece of trim called an F and J up against the building sidewall.

f channelPicture an F channel with the downward leg being attached to a horizontal piece of wall framing, usually by nails. The horizontal “legs” of the F receive the soffit material – usually vinyl, steel or aluminum. From the end of the short (and lower) horizontal leg of the F channel, is another downward leg (envision an inverted J). The sidewall steel then slides up into the J from below.

All of this appears to be a quick and easy install. Nail a single 2×4 against the outside of the columns, attach the F and J to it and slide the soffit panels into the F channel.

Now the problem with this (as happens with quick and easy) – the soffit panels are not attached to the F. When the breeze begins to blow, the soffit panels vibrate in the F channel, making noise. As wind speeds increase, the soffit panels can actually be blown out of the F – creating all sorts of challenges.

So how did we solve the challenge?

Instead of a single 2×4 nailed to the face of the columns, we took two 2x4s and nailed them together to form an inverted L. The short leg of the L now gives something solid to attach the soffit panels to. Below the soffit panels an inverted piece of J channel trim is installed, easily attached to the vertical leg of the 2×4 L.

I’ve now experienced several thousand soffit installations using this procedure and have yet to have a report of a single soffit panel being blown out!

Success.

Square Cut or Plumb Cut Trusses

Square Cut or Plumb Cut

Back in the 70’s, when I first entered the prefabricated metal connector plated wood truss industry, I was a sawyer. Sawyers are the folks who operate the component saws which precision (hopefully) cut all of the components prior to assembly.

The people I worked for over the first few years of my truss career did not have what is now known as a component saw – one which uses a conveyor to pull each board through a series of four or more saw blades. Instead, we had Speedcut radial arm saws which were rotated manually by the sawyer to the needed angle. Very labor intensive.

In order to reduce cutting labor, the majority of the top chords (rafters) we cut were left square (as the lumber came from the sawmill) on one end. This meant the framing contractors had to cut all of the “tails” to length in the field.

 

truss tailsMost truss manufacturers now have the equipment which allows them to precession cut and trim most any truss member by using component saws. Strangely, some of them still leave the “tails” of the trusses square on the overhanging end, rather than plumb cutting. Plumb cutting means the cut on the end of the tail will be perpendicular to the ground.

Now why would how the tails are cut by the manufacturer be problematic?

To easily install gutters, it is far simpler to be able to attach them to vertical fascia boards. When fascia boards are installed on the ends of square cut truss tails, specialized gutter hangers must be used, or wedges placed between the fascia and the gutters.

One other consideration, the most common eave (sidewall) overhangs on pole buildings currently are enclosed with vinyl or metal soffit panels. In our case, we precut white vinyl soffit panels for our clients in 12, 18 and 24 inches. Some roof truss manufacturers who square cut the tails of their trusses measure overhang distances with the “run” of the roof, making the level returns of the enclosed soffits lesser in distance than the length of the precut panels.

Buy trusses on your own (I wouldn’t recommend it – which is the topic of a future article)? Specify plumb cut tails and overhangs measured horizontally.

Truss Butt Cuts

Butt Cuts, not Cracks

In a past life, when I was far younger, I was a newbie in the prefabricated metal connector plated wood truss industry. My first job was as a sawyer, I was the guy who trimmed all of the components prior to their assembly into trusses.

Although my employers had what at the time was a fairly good sized operation, technology had not yet reached us.

In today’s manufacturing process, most cutting is done on specially designed machines with as many as six blades which can precision cut lumber as long as 20 feet, as quickly as it can be fed into the saw! When I began, the saw I was trained on was a radial arm saw with a pivoting table. This allowed for only a single cut to be made at a time.

Bottom chords on triangular pitched trusses most often have a long sloped angle cut at the junction to the truss top chords. At my first job – we sawyers made a single cut, known as a feather cut. Due to slight differences in the crown of the lumber, this taper to an indeterminate point lead to some variability in assembly.

Once I had moved on to the sister plant of my first employers, I convinced the managing partner we would be producing a much improved truss, by using the industry standard “butt” or “Heel” cut at the end of each bottom chord of ¼”. The downside, it would take two cuts on the end of each bottom chord. The plus, more accurate assembly in the shop, and easier installation at the jobsite as framing contractors had an exact and consistent point to work from.

This cut also allowed the framers to position sheathing on the walls so the top edge was even with the top of the wall. The ¼” butt cut allowed the tail of the truss to clear the edge.

When I relocated to Oregon to manage the truss plant at Lucas Plywood and Lumber, I was exposed to an entirely new application of butt cuts. Most wood framed construction there was done with overhangs which were open (no soffits). 2×4 exterior stud walls were framed with a 2×6 double plate, with the extra 2” held to the outside of the wall. The siding would then be installed so it abutted the underside of the 2×6.

truss-tailsOn a 30 foot wide building, the measure from outside of double plate, to outside of double plate was 30 feet and four inches. In order for the truss tails to clear the extra two inches on each wall, the butt cut was increased appropriately for the slope of the truss top chord. With a 4/12 slope, a ¾” butt cut was perfect.

Years later, my brother and I worked as truss designers for a company which built lots of trusses for pole buildings, however did not have any 2×6 lumber graded higher than 1650msr (https://www.hansenpolebuildings.com/blog/2012/12/machine-graded-lumber/).

We found we could manipulate the height of the butt cuts, gradually changing 1/16th inch at a time, to be able to eliminate overstress in truss designs by as much as 10-12%!

Fascia Trim Dimensions

How to Calculate Fascia Trim Dimensions

Justine (aka Hansen Pole Buildings’ wizard of deliveries) and I were discussing this subject today, so it makes for a good time to share!

In most cases, pole buildings with sidewall (eave) overhangs have fascia boards. These are most generally 2×6, 2×8, etc., depending upon snow loads as well as the “look” the building owner wants to achieve.

I say “in most cases” because there is one fairly significantly sized company who believes it is apparently satisfactory to just run the roof steel a foot past the sidewall without supporting it in any way…..sure hope the building owner never needs to get on the roof, and there are never any ice dams in the winter!Fascia TrimIn most instances, fascia boards will be installed vertically, attaching to a plumb cut on the ends of the truss or rafter tails. This application allows for the easy installation of gutters, which are required in many jurisdictions.

When steel or vinyl siding is used, I happen to feel it is a right nice idea to put steel trim on the wood fascia boards. It happens to look nice, and it keeps the fascias from having to be painted (after all, the idea is to be maintenance free) or turning gray, then black, then just rotting.

Along the I-5 corridor in Washington and Oregon, there are plenty of builders and pole building kit suppliers who rely upon “cheap is the king” and leave the fascia boards exposed. I am not quite understanding this in a climate where 60 inches a year of rain is not unusual!

Fascia trims are most easily done as an “L”, which covers the “street” side of the fascia board, as well as the bottom side (which will always be 1-1/2 inches in width). The height is the variable.

Done right, the top edge of the fascia board should be run through a table saw, to cut a bevel on the top of it matching the slope of the roof. This bevel cut allows the roof steel to be applied to the top, without crinkling or otherwise damaging the roofing when attached with screws.

The remaining height of the street side face of the fascia board can be determined by deducting the thickness of the bevel cutoff. Multiply the 1-1/2 inch width of the fascia board by the slope of the roof (e.g. 4/12). 1.5” times 4 divided by 12 = 0.5 or ½ inch. For a 2×6 fascia board at a 4/12 slope, the trim size would be 1-1/2 inch x 5 inches for an overhang without a soffit.

When soffits are added, the thickness of the soffit material needs to be added to the vertical dimension. Most typically steel or vinyl soffit panels will be no greater than ½ inch in thickness.

No rocket science involved, just an opportunity to brush up on the math skills we learned in grade school!