Tag Archives: fiberglass skylights

Fiberglass Panels, Accurate Info, and Truss Bracing!

DEAR POLE BARN GURU: I have four skylights with old fiberglass panels that are in need of being replaced. I doubt the design of the panel can be matched easily but am wondering if I send you a piece of it if it can be. I understand the way to go is with a polycarbonate, not fiberglass, panel. Thanks DAVE in BAY

DEAR DAVE: As you are finding out, skylights are problematic. Here is some extended reading on why: https://www.hansenpolebuildings.com/2012/01/skylights/.

If indeed you determine the only solution is to replace fiberglass panels with polycarbonate (me, I would replace them with steel panels and be done with the future headache) I would recommend a visit to the ProDesk at your local The Home Depot® as they can order in most anything and it usually comes in freight free, which can prove to be a significant savings.

DEAR POLE BARN GURU: I am buying a building immediately but your website is too intrusive to shop, so I will not be using you. I, like many others, do not like the setup for quotes because in most cases you turn into used car salesmen. BRAD in KNOXVILLE

DEAR BRAD: Thank you very much for your input. In order to be able to provide accurate pricing and design advice to our clients, we do need to gather some basic information. Things like where is your new post frame building to be constructed (so we get the correct climactic loading conditions), as well as how do we best reach you to discuss your proposed project. We get several hundred new inquiries each day, seven days a week, and frankly you are the first to voice an opinion as to our website being intrusive. If you have constructive solutions as to how we can best glean the information needed to be able to best provide our services, without coming across as being ‘intrusive’ we would welcome your input, as we always strive to improve.

Our Building Designers are highly trained professionals whose mission is to assist our clients in the quest for the ideal dream building which melds imagination, budget and available space. Post frame buildings are highly involved, engineered structures, which ideally require a fair amount of interaction between us and the client to arrive at the best design solution. We do not “sell” anything to anyone – we provide the assistance to our clients, as well as the education which enables our clients to invest in The Ultimate Post Frame Building Experience™, should they decide we are the best fit. Most of our clients have spent hours perusing the thousand plus pages of free information on our website and have decided they are going to own a new Hansen Pole Building long before they ever request a quote.


DEAR POLE BARN GURU: Question about my plans. On the drawings, my purlin spacing is noted as 31” OC. On the truss drawing, I see that it says the bracing for the top chord is 24” OC. Am I reading this correctly? 

It states: 

(Switched from sheeted: Spacing > 2-0-0).

and then below it talks about the Bottom Chord: Rigid ceiling directly applied or 6-9-13 oc bracing. What does that mean?


DEAR DAN: Truss drawings are designed without any knowledge of how a particular building is constructed, or what the final bracing system for the entire structure is – the permanent bracing design is left to the engineer of record (see General Safety Notes #2).

You will note the top chord bracing says 2-0-0 purlins then says the maximum spacing is 4-7-0 (least of the three drawings). The 31″ spacing on the plans is far less than the 55″ maximum.

Bottom chord bracing is a function of a maximum L/d (length divided by depth) ratio of L/80 for members in tension (truss bottom chords are in tension as they are preventing the walls of the building from going out). The width of a single 2x member is 1.5″ X 80 = 120″ maximum for a single width 2x member. You will note on the endwalls of the building there is a 2×4 nailed to the face of the bottom chord of the truss. This now makes the member three inches in width so technically it could be braced once every 240″ (or 20 feet). The same goes for the interior double trusses, the three inch width member is good up to 20 feet without being braced laterally.



Old Skylights

Back in the day I spent a year working for the now defunct Mac Truss Company in McMinnville, Oregon. Not long after I began working with them, they decided to relocate their manufacturing facilities across town to an old machine shop. All was fine and good with the move, until the fall rains began.

Fiberglass Eave LightsThe machine shop happened to have fiberglass (FRP) skylights, which had yellowed so badly they let in less light than the adjacent steel panels. One thing they DID let in – was the weather. Not only had the FRP panels turned color, they had also become brittle and cracked. It was bad enough working in a fairly dark building, even worse when the just above freezing rains came in!

For the most part, pole building suppliers and builders have recognized the inherent challenges of trying to use light panels in roofs – very rarely does one see them installed in new buildings. Which is good, as neither FRP, polycarbonate or acrylic panels are designed to withstand shear loading (weight of anything on the roof – like ice and snow) so their use not only weakens the roof diaphragm, it also creates a future failure. A failure – in my humble opinion – being when they fracture around the fasteners due to loads they were not intended to carry and begin to leak!

Another long, hot summer has ended and people with older buildings with failed skylights are beginning to look for solutions to their building’s problems. Hardly a day goes by, which does not include an email from someone trying to find replacement panels for their old fiberglass skylights. Almost always these requests are for some panel configuration which has not been used as common practice for years.

In the event you are one of these building owners, my best recommendation is to take the photographs of your panels (clearly showing the panel profile) to the contractor desk at your nearest The Home Depot® or Lowes®. If the profile is available, either should be able to find a suitable replacement.

For more reading on skylight panels: https://www.hansenpolebuildings.com/blog/2012/01/skylights/ and https://www.hansenpolebuildings.com/blog/2014/02/acrylic/

Dear Pole Barn Guru: Where Can I get Hand Lift Jacks?

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: I am building a 32×56 x10 tall pole barn. I would like to install a garage door (18foot) in the eave side corner. How can this be accomplished? I am worried about the weight that would need to be supported from the 2 trusses that will be in this 18 span. MAROONED IN MATTOON

DEAR MAROONED: You should absolutely be worried about the load from the trusses across an 18 foot wide door opening.

We see people buy “off the rack” standard pole barn kits, or putting together their own buildings from the guess and go theory – neither one of which is going to adequately address the issues of how to span openings for doors such as yours.

 Many lumber yards or prefabricated roof truss manufacturers will try to size a glulaminated or LVL beam, based upon trusses which are evenly spaced across the header, rather than having considered the concentrated loads which occur with post frame construction.

 Not only must the dead weight of the trusses and their associated bracing be considered, but also the weight of all ceiling and roofing materials, as well as any snow loads. And this is just for the proper sizing of the beam. Connections to the columns at each end are crucial – both to resist gravity as well as uplift loads. Keep in mind, more buildings fail from improper or inadequate connections, than from any other cause. The columns at each side of the door opening also need to be checked for adequacy against a larger wind load than some, or all, of the other wall columns carry. It is not unusual to have larger dimension columns specified at each side of a wide opening, such as you propose.

 If you have not yet ordered a building kit – make sure to look for a provider who can provide complete plans, specific to your building, with the engineering to back up their design.

 If you are already out building, I would recommend contacting a registered design professional (RDP – engineer), who can adequately provide for you a proper design, given the plans you are working from and the design criteria.


DEAR POLE BARN GURU: I have a late 1970’s pole barn with fiberglass skylights.  They are 94X32 with the center to center ridge peak 10 inches.  The peak is flat and about one inch wide.  These skylights need replaced.  Do you have any product that would work for me. VEXED IN VANDALIA

 DEAR VEXED: I’m never a fan of any skylight in any post frame building roof. Why? They are going to leak or fail, it is just a matter of when. Without seeing actual photos of your situation, my first recommendations are going to be to replace the skylight area in the plane of the roof with steel roofing. If you must have natural lighting through the roof, I’d recommend using a polycarbonate ridge cap.


DEAR POLE BARN GURU: Where do I find a set of the hand lift jacks that are like a boat trailer winch with a top pole cap that allows you to install your purlins on the ground and lift the 2 trusses at once, so I don’t have to rent a zoom boom or boom truck.  I bought one of your kits and have poles set and didn’t think I would have the difficulty of finding these jacks.  THANKS FROM TONASKET

DEAR TONASKET: Thought you could Google anything and get an answer, didn’t you? Me too, but what you are looking for appears to be a well kept secret.

 Every set (either two to lift a pair of trusses, or four to lift two pairs along with all of the purlins between) of winch boxes I have ever seen were fabricated up by the person using them.

 The most common version is a welded up steel box with 5-5/8” inside dimensions and no bottom. The open bottom will later allow the “box” to be slid over the top of a 6×6 column. Attached to the top of the box (usually welded), is a reduced drive hand crank winch designed for a boat trailer.

 Most of the crank units seem to come from Harbor Freight – and the caution is to use the ones with steel gears, as opposed to nylon gears. I’m told the nylon gears just do not have the durability.

 In most cases, steel cable is used for lifting, although straps could be an alternative. Regardless, the winches and cables or straps need to be adequately rated for the weight being picked up.

 Have a column size other than 6×6? If 4×6, add a block of 2×6 to the side of the column. Larger than 6×6, chainsaw a notch into the top of the column to fit the box.

 Another variant of hand lift jacks (requires the use of cables only and twice as long), places a pulley wheel on the top of the columns, and the winch is attached to a flat steel plate which is affixed to the outside of the column. This method does afford the ability to do the lifting from the ground, instead of having to crank off from ladders.

 I’ve successfully lifted two sets of 80 foot span roof trusses, along with all of the roof purlins and truss bracing, using winch boxes.

 Those who have built and used them, rave about the time spent building the hand lift jacks was well worth it.  And these days, so easy to resell on eBay.

 I’ve suggested to several people for them to manufacture lots of these, and rent them out. Even though there is a market – no one has taken me up on it as of yet