Tag Archives: truss repair

Will My Post Frame Building Support a Ceiling?

Will My Post Frame Building Support a Ceiling?

One of my frequently received questions – wanting to add a ceiling into a post frame building and wondering if the building will support the added weight. Other frequent questions include condensation issues and ventilation, so this reader has hit upon a trifecta.


Reader BRYAN in SWANTON writes:

“I am having some condensation issues. And I was curious about insulating the building. Also wanted to ask if my building is able to have a ceiling installed. Thanks for the fast reply.”

 

 


By any chance have you recently poured a concrete slab-on-grade inside of your building? If so, until concrete fully cures, it will expel a great deal of moisture inside of your building. Solution – open your doors to allow moisture to escape and keep them open until condensation issues no longer exist. Read more here: https://www.hansenpolebuildings.com/2018/01/condensation-roof-steel/.

 

If you poured a slab without a well-sealed vapor barrier underneath, it will contribute to excessive moisture challenges. If no vapor barrier, top of slab should be sealed: https://www.hansenpolebuildings.com/2018/11/siloxa-tek-8505-concrete-sealant/

 

Your new post frame building and its trusses were not ordered to be able to support the added weight of a ceiling. It may be possible to upgrade your trusses with an engineered repair to be able to carry a bottom chord dead load of five psf (pounds per square foot) or more. Plan upon an investment of $295 (plus sales tax if applicable), even if a truss repair cannot be designed. Contact Justine at justine@hansenpolebuildings.com if you are interested in going this route.

If you are able to get a repair to install a ceiling, this newly enclosed attic area will need to be adequately ventilated. This may be a possible solution: https://www.hansenpolebuildings.com/2018/07/my-pole-barn-needs-ventilation/

In order to insulate, best solution (although costly) may be to use closed cell spray foam insulation. If you purchase an insulation kit for your overhead door, you will need to change out door springs in order to handle the added weight.

 

 

A Retro-Fit, Truss Support? and Sliding Door Installation

The pole barn Guru looks at a Retro-Fit, truss supports, and installing a sliding door.

DEAR POLE BARN GURU: I have a question about Retro-Fit insulating my pole barn. I live in Southwest Michigan and bought my house with an existing 40’x60′ building, just used for storing farm equipment before I acquired it. Steel roofing straight to the roof purlins and steel siding straight to the wall purlins. Can I put a metal ceiling in with blown fiberglass insulation above and metal walls with Batts between the inside wall and outside wall, or do I need to have some sort of vapor barrier? MITCH in MICHIGAN

DEAR MITCH: First things first, in order to retro-fit the trusses, confirm the trusses are capable of supporting the weight of the steel liner panels and insulation. Most post frame building trusses are not designed to support a ceiling. There should be a stamp on every truss which identifies the truss manufacturer as well as the design loads. You need a minimum three psf (pounds per square foot) bottom chord load to support the ceiling. If it is less, and you can contact the truss manufacturer who should be able to provide an engineered repair to upgrade the trusses, for a nominal fee.

You will need to have some form of thermal break below the roof steel – my choice would be closed cell spray foam. On the walls, you should really have a building wrap between the steel and the framing, however an inch or so of closed cell spray foam would work, filling the balance of the cavity with unfaced fiberglass, then a well sealed vapor barrier on the inside.

 

Engineer sealed pole barnDEAR POLE BARN GURU: Pole Barn Guru, do you have to have girt under end trusses. End trusses setting on 2×12 from header and nailed to 6×6 pole with 2×6 blocking below trusses 24″o.c. sheated header 3 2×12 notch blocked and clipped. STEVE in CHEYENNE

DEAR STEVE: In order for me to answer your question, I would need to see the engineered plans for your building. If you are unsure of how to determine from your plans, you could contact the engineer of record who designed your building and ask him or her.

DEAR POLE BARN GURU: On a sliding 4×8 walk in door, on the barn exterior are all 4 sides flat or is the top out the thickness of say 1.5 inches? If it is out will it not seal? If all is flush with it not roll easy? Joe

Figure 27-5

DEAR JOE: The sliding door track needs to be mounted to a ‘track board’ which is typically a 2×6 placed on the face of the sliding door header. This puts the top out 1-1/2″ which allows the door to be able to slide past the adjacent siding without banging against it. Sliding doors do not and will not seal air tight, so this should not be an issue unless you had some sort of unrealistic expectations.

Sheetrocking Trusses Advice

How Advice Columns Get Interesting…

Just last week, I shared a question from TOM (a reader who reads my blog) in regards to finishing the inside of a fairly recently constructed post frame (pole) building. The dialogue has continued.

Tom: Obviously drywall for the ceiling would be a wiser choice. The truss manufacturer said the trusses were rated for steel 29 gauge panels and blown in insulation, at .65 lbs per square foot for 29 gauge versus 1.28lbs. per square foot for ultra light sheetrock.I’m tempted to roll the dice and go with sheet rock as it would only add 780 lbs of total load to the trusses. Of course with customer approval and he is a certified engineer. Truss manufacturer says it would void warranty. I’m sure they build with an overage percentage factored in but they wouldn’t say how much because of the liability involved.

Customer wanted drywall originally, but because the ball got dropped somewhere with the lumber supplier, the trusses shipped were under rated.

In the event that we go with the steel, would you advise a vapor barrier above the panels? Also would cellulose or fiber glass blown in be the wiser choice? Would the barrier be necessary with painted drywall”?

 Trusses are not designed/built with an “overage percentage” factored in. For any wood structural product for construction, we are able to only design for what is known as 40% of Pultimate (very simplified, it is 40% of ultimate failure strength). This is to account for all of the variabilities in lumber, as well as errors in either fabrication, or utilization on the jobsite. The published values used by engineers are already adjusted to this number.

The potential for receipt of “under rated” trusses is huge when purchased from a lumber supplier, rather than a firm which specializes in post frame buildings and has the knowledge to ensure the trusses ordered match the needs of the building and the building owner. In general, buying trusses from a lumber yard is going to be a gamble, which might leave one grossly disappointed in the results.

 Me: “Can you scan and email the truss drawings to me please?

The problem with steel liner panels is the warm moist air inside of the building will condense on the underside of the ceiling liner panels. With a sheetrocked ceiling, a vapor barrier should not be installed between the sheetrock and the trusses. I like fiberglass personally, but either should work. FYI – Lightweight 5/8″ drywall is 1.65 psf (1/2″ will sag on a ceiling spanning 2′).”

Tom: Here you go Mike, I appreciate you looking into this. One of my thoughts on strengthening the trusses was OSB gussets. There will be a huge 6′ ceiling fan in the woodstove area to help with the condensation issue.

I intend on laying 2×6 on 2′ centers flat to hang whatever goes on or do they need to be on edge. I know edge would be best, was going on lumber supplier’s estimator’s opinion.

Thanks again Mike”.

Me: “Thank you very much. The two psf they designed the bottom chords for would be questionable even to support a steel liner ceiling. For a small nominal fee (usually $25-50), they can design an engineered “repair” to increase the bottom chord dead load to five psf, which would support the sheetrock and any needed framing. The truss bottom chords are stressed fairly close to 100%, so do not be surprised if you have to add some additional webs to the truss, or a “scab” alongside of the bottom chord. Whether you use a steel ceiling or sheetrock, the joists between the trusses should be placed on edge, flat they would overly deflect and your client would not be pleased with the resultant.”

Tom: Hi Mike, Thanks so much for giving this your attention and advice. I am not an engineer but have been curious about laminating osb to the bottom chord and up the webs, say a foot. I joists are made with osb, I’m sure not a common grade, and I’m thinking it should help considerably. I’ve thought about trying it on my own house’s sagging floor joists by jacking them straight then laminating at least one side just as an experiment.

 Could you do the repair engineering if necessary?” 

Me: “Your laminations would only work if you were able to do so without a splice, or to overlap panels (two deep) with staggered splices. If you will notice I joists do not have splices in the OSB webs. On the truss, you would basically end up sheeting one entire side of each truss, with two layers of OSB. The truss repair engineering would be best done by the truss manufacturer (who is actually going to have the truss plate manufacturer do the repair and seal the drawing). It will be quickest and least expensive, both in terms of the cost of the engineering, as well as the amount of materials and time involved.”

Adding Steel Ceiling Liner Panels

I Want to Add a Steel Ceiling

This must be my week for receipt of good questions which require lengthy answers in order to do justice to the subject. Here is another one:

liner-steelDEAR POLE BARN GURU: I have a 42 x 60 with insulation in walls and roof, 26 gauge metal, wood trusses, 10 feet o.c. with 2 x 6 purlins. I do furniture and cabinet work and love the insulation but would like to add the white metal ceiling, to help with the heating, cooling, and lighting. Can I add trusses in between existing ones, and build them underneath the purlins? If so can the white metal span 5 feet for a metal ceiling? CHARLES IN BUTLER

DEAR CHARLES: I would begin by examining the truss engineering – if the bottom chord of the trusses is designed for an adequate dead load (oftentimes this will appear as BCDL on the drawings) of five psf (pounds per square foot) or more, then the trusses are probably capable of handling the added weight of the ceiling plus applicable framing.

If the truss drawings are not available, look for the manufacturer’s stamp on the trusses, it should be on the bottom chord and will give the manufacturer’s name as well as the load the trusses were designed to support.

Not having to add more trusses will be the far most economical and practical design solution.

In the event the trusses are not designed to support the weight of the ceiling, I’d recommend asking the truss manufacturer for a “repair” to upgrade the trusses to be able to support the added weight. If you are unable to contact the manufacturer, a registered professional engineer who is competent in truss design and repair should be consulted to design an engineered repair for you.

Once the load carrying capacity has been determined to be adequate, ceiling joists can be placed at five foot on center between the trusses (using joist hangers), so the liner panels can be screwed directly to them.

Could you add another truss between each of the existing ones? Sure, but it is not probably going to prove to be an easy task as they will need to be maneuvered into place. The ends of each new truss are also going to have to be supported by a structural header placed between the sidewall columns and adequately attached to support the weight.  The design of these headers and their connections should also be done by an engineer.

If the purlins are joist hung between the existing trusses, the new trusses will have to be manufactured so as to afford you the ability to have the bottom chords of the trusses all at the same height. This may not be possible.

Steel ceiling liner panels should be able to span five feet, without significant deflection issues making them appear unsightly.

In addition, Here are some thoughts about the use of steel liner panels for ceilings: https://www.hansenpolebuildings.com/2013/08/steel-liner-panels/

Good luck! And let me know how everything turned out for you!

Dear Guru: How Do I Cut into a Truss?

Welcome to Ask the Pole Barn Guru – where you can ask questions about building topics, with answers posted on Mondays.  With many questions to answer, please be patient to watch for yours to come up on a future Monday or Saturday segment.  If you want a quick answer, please be sure to answer with a “reply-able” email address.

Email all questions to: PoleBarnGuru@HansenPoleBuildings.com

 DEAR POLE BARN GURU:The bottom chord of a truss must be cut to allow a set of steps to rise to the loft. How best to make up for the loss of the bottom chord? LIVE FROM LA

CRESCENT DEAR LIVE: Repeat this mantra: “I will never cut into a truss without engineering”. My first recommendation would be to relocate the stairs so as to not have to cut a truss. The bottom chord of a truss is in tension (unless there is a situation from wind which would cause a stress reversal). Think of it as holding the walls together, so the top chord can do its job. Cut the bottom chord and place a load on the roof and expect it to deflect significantly, as well as probably collapse. Neither is a good answer.

It MIGHT be possible to remove a portion of the bottom chord, without a failure.  Start with a visit to the truss manufacturer. Take along as many digital photos of the trusses as possible, or the original engineer sealed truss drawings. Their engineers can tell you if what you have in mind can be done, and at a nominal cost. If it is impossible to determine who built the trusses, or they are no longer in business (over 50% of all truss manufacturers closed their doors during the Great Recession) then the only option is to hire a registered professional engineer.

DEAR POLE BARN GURU: I am in the process of building a 24’x 48′ pavilion. I installed ten 6×6’s 12’ oc, 36 inches in the ground on 4 inch cookies. The holes are 18 inches in diameter. The holes and slab where poured at once, with a 4 inch slab. I used 2x10x12’s inside and out of the posts. 10 foot ceiling. 4/12 trusses 24′ with 2’OH spaced 24″ on center. 7/16 osb with shingles. Installed 5 foot 6×6 Y braces attached to the posts and header using 1/2 inch threadall washers and nuts. Installed wind bracing on trusses (W shape the whole length (48′) both sides.

With all this done I still have side movement. I do realize I have a large structure, which has a ceiling 10′ off the ground with no side walls. I would estimate 2-3 inch movement with me walking around on the peak of the roof. I thought about putting knee bracing to stop the side to side movement. I prefer not to put 2x material as knee bracing which would take away the look I have with the beefy material of 6×6’s as Y bracing I have.

Plus the only thing to hold them would be trusses above since I have no other side to side support material. Should I be concerned with this movement? I am waiting to install 4 inch by 12′ tongue and groove planks on the ceiling. I would think this would also help stiffen up the structure. We do get some high winds in this area. Would hate to wake up and the structure is on the ground.   Thanks.. TEETERING IN TIPP CITY 

DEAR TEETERING: You have discovered the inherent challenge of roof only (pavilion) type structures. By not having any walls, it increases the amount of force (and therefore movement) carried by the columns by a factor of four! In simplified terms – think of the 6x6s now acting as diving boards. Without knowing the loading conditions at your site, it is very possible the 6×6 columns you have selected will not be adequate to carry the wind loads in extreme conditions – which could cause your building to fail.  Before you take the step of adding knee braces – this would be a good article to read: https://www.hansenpolebuildings.com/blog/2012/01/post-frame-construction-knee-braces/ My normal recommendation would be to consult with the engineer who designed your building – as he or she will be able to determine if the movement you are experiencing is within acceptable limits. The easiest way to get rid of the majority of the movement, would be to put a wall across one of both ends. This wall would then transfer the wind loads from the roof to the ground – rather than making the columns do all of the work.

Dear Guru: How Can I Upgrade My Trusses

Welcome to Ask the Pole Barn Guru – where you can ask questions about building topics, with answers posted on Mondays.  With many questions to answer, please be patient to watch for yours to come up on a future Monday segment.  If you want a quick answer, please be sure to answer with a “reply-able” email address.

Email all questions to: PoleBarnGuru@HansenPoleBuildings.com

DEAR POLE BARN GURU: How can I upgrade my pole barn probably built with normal 25-5-2 truess to handle a upgrade to drywall or metal ceiling with insulation. Can the truess have an added bottom piece to them to handle load. ceiling now has R19 insul between truess. Thanks. SAGGING IN SALINE

DEAR SAGGING: Your situation is very common, as most pole buildings (and their trusses) are not designed to support a ceiling load.

 You’ll have two issues to address. The first will be the footings beneath the columns. There is a strong possibility they are not adequate in diameter to properly distribute the weight of the building, with a ceiling and a snow load. An engineer can do an analysis to determine the correct diameter, which will result in having to dig down to the base of a column to compare the “as built” to what would be required.

 The second issue will be the trusses themselves. If they are prefabricated pressed metal connector plated trusses, the manufacturer should have placed a stamp on each truss. If you can find the stamp, and the fabricator is still in business, they can be contacted to determine the adequacy of the trusses to support the extra load, or to design a repair, if needed.

 If you are unable to contact the manufacturer, the solution then also falls back to a RDP (Registered Design Professional) – an engineer – who can do an onsite evaluation of the trusses, and make the proper recommendations.

DEAR POLE BARN GURU: We are working with a pre-existing pole barn structure with 9′ post spacing and want to have 12′ post spacing.  What is the best method for making this alteration and removing the old posts?  The new posts at the desired 12′ spacing are already in place.  More details:  24’x27′ pre-existing structure, making 24’x36′.  Premanufactured trusses 2′ apart.  Currently on 9′ long 2×10″ boards which end on the original posts. EXPANDING

DEAR EXPANDING: You are ambitious! You case is why I encourage people to design their pole buildings around columns spaced every 12 feet to begin with, as it gives the flexibility of wider future sidewall openings, without having to do a total remodel.

As I do not know what your roof loads are, I will work from the assumption the existing “truss carriers” were adequately designed to support the roof loads, which should be adequate to carry a total roof load (live plus dead) of about 33 psf (pounds per square foot). The 2×10 will need to be removed and replaced by a 3 ply 2×12 #2 or a 1-3/4” x 11-1/4” 2800f LVL (laminated veneer lumber).

 When all of this is said and done, I feel chances are good you will ask yourself why didn’t I just construct a brand new building with the dimensions I needed?

 

 

Truss Connectors: What to Use on Damaged Trusses

As noted yesterday, damaged trusses warrant a repair design by a professional…a licensed engineer.  This is not something for “guesswork” or scabbing on a bunch of lumber.  First the forces of where damage occurred need to be analyzed, and then only an engineer with solid experience in repairing damages should be engaged to elicit the repair design using appropriate truss connectors.

Fastener selection can often prove to be a challenging exercise, due to the wide variety of truss connectors available. The metal plates used in the manufacture of wood trusses have excellent grip due to the numerous teeth embedded into the lumber. When calculating the quantities of other mechanical fasteners required to repair a damaged plate, it is often surprising to see how much larger the connection areas become.

Generally, the nail is the most widely used fastener for wood construction. Nails are commonly referred to by penny-weight. Unfortunately, this designation does not have clearly defined dimensions. There may be four or more different nails commonly referred to by a single penny-weight. For example, a 10 penny (10d) nail could refer to a sinker, common, box, cooler or pneumatic (gun) nail, all of which are slightly different. To eliminate confusion, it is important to note nail length and diameter.

Wood screws are another option. Wood screws can have higher values than nails, but often require pilot holes to prevent splitting. Note many general purpose screws, such as deck screws and drywall screws, may share a common gauge number with a heavier wood screw, but are not considered structural due to the lower grade steel used in their manufacture and should be avoided for truss repairs. Recently, specialty screws have become available, resulting in superior performance in relation to standard screws. These screws are manufactured by United Steel Product, Simpson Strong-tie, and Fasten-Master, to name a few.

Machine bolts are generally used where high forces are involved. Truss connectors in wood trusses rarely benefit from high strength bolts, making them unnecessary. Carriage bolts are not recommended; the lack of a washer and solid bearing on the head of the bolt results in poor performance in relation to machine bolts. Lag screws may be used, but are of limited capacity due to the relatively thin (1-1/2-inch) thickness of the truss members. The lack of penetration limits their lateral strength significantly.

The use of adhesives for truss repairs raises considerable debate among engineers. The quality of some adhesives today allow for bonding wood with greater strength than the wood itself, resulting in much smaller connections. However, the conditions under which many truss repairs are performed can compromise the glue bond. For example, freezing temperatures, surface dirt, and unsupervised labor make the capacity of the glued joints difficult, if not impossible, to judge.

Mechanical fasteners can be counted to verify conformance with the repair specification. Unfortunately, once the glue is applied and covered, it cannot be seen without destroying the repair. Therefore, adhesive use is best left for controlled environments, such as factories and jobs where the responsible engineer can observe the application of the adhesives. If an adhesive is to be used, the curing time must be considered. In many instances, a truss must be repaired in place. Once a repair is completed, temporary supports are often removed and construction materials are placed on the truss immediately. This practice does not allow proper time for the adhesive to cure. One solution to this problem is to provide mechanical fasteners, designed to support the construction loads, allowing the adhesive the required time to gain sufficient strength before the full design load is applied to the truss.

One other school of thought is to specify the adhesive, but not to consider it in the calculations. This is most often done when repairing floor trusses. The mechanical fasteners transfer the forces and the adhesive provides insurance against squeaks. If the adhesive is omitted, the repair is still valid. If it is used, it only adds strength and stiffness to the repair.

A common practice used by many engineers to reduce the connection size is to “clinch” the nails used with gussets. In order to properly clinch nails, a gusset is placed on each face of a single ply truss. The gusset must be clamped or held in place securely during the nailing procedure. Nails are driven through the front gusset, through the truss, and through the gusset on the back face. The nails must then be bent over flat against the surface of the back gusset.  Please bear in mind clinching must be performed properly. Unfortunately, many repairs specifying clinched nails are performed incorrectly at the jobsite.

Due to the lack of code provisions governing truss repairs, engineering judgment becomes critical in the determination of what is acceptable. While the design capacities of various materials are available to aid an engineer’s calculations, there are times when repairs tend to bring the art of engineering to a level almost equal to the science.  Need a truss repair?  Call an engineer experienced in designing repairs for damaged trusses.  I always have, and always will.  Like concrete finishing, there are just some things best left to the experts.

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