Tag Archives: polycarbonate

Polycarbonate Frame, Concrete Thickness, and Insulation

This week the Pole Barn Guru answers reader questions about the use of a hard-sided (polycarbonate) frame, how thick a concrete pads has to be to house an RV, and insulation options for a vacation home.

DEAR POLE BARN GURU: Can a pole structure be built as a hard-sided (polycarbonate) frame 20 feet wide, without using trusses or central support poles, and instead using steel rod ties wall to wall/post to post, to keep the structure from spreading? Maximum snow load approximately 2 feet of wet snow. I need a greenhouse (summer) that has no central poles but also no trusses, to avoid shading. ANDREW in THREE HILLS

DEAR ANDREW: Rather than trying to reinvent a wheel, it would probably behoove you to look into an actual polycarbonate greenhouse such as these https://www.growspan.com/ad-growspan-greenhouse-structures-1/?gclid=CjwKCAjwrNmWBhA4EiwAHbjEQADPM4ifhujox0twKMYlU_xupk-R3NwGmFk0eBVXQMIn75wolNx08RoCCpkQAvD_BwE. This would have to be far more efficient and effective than even engineering costs of attempting to design using post frame. Best of success to you with your project.


DEAR POLE BARN GURU: How thick of a concrete pad do I need to park a 16,000 pound RV on under my pole barn that is 16 feet wide by 26 feet long? JOSEPH in BLUE RIDGE

DEAR JOSEPH: More important than concrete thickness will be what you have done to prepare your site. Properly prepared and well compacted, it is possible a four inch thick slab could do everything you need it to be. It might behoove you to thicken slab to five or more inches in zones of wheel travel and add 1/2″ rebar in these areas (less than five inches thick does not provide adequate concrete coverage for rebar to be effective).


DEAR POLE BARN GURU: Using structure as a vacation home. Concrete floors. Which kind of options for insulation? Walls and ceiling – open to spray on ceiling and keeping open – but would do a ceiling if batt was the option r value thought? MARK in MENTONE

DEAR MARK: DeKalb county is in Climate Zone 3A. Here are my recommendations (all based upon 2021 IECC):

Slab – perimeter 2′ down with R-10 rigid insulation

Walls – Weather Resistant Barrier between framing and siding; bookshelf wall girts; R-20 or greater rock wool batts (unfaced); no interior vapor barrier

Roof – 18″ raised heel trusses; roof steel with an Integral Condensation Control factory applied; vent eaves and ridge; blow in R-49 fiberglass on top of a ceiling.

Dear Guru: Where Can I Get FRP?

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:I am wanting to replace the frp skylights on an older metal building but don’t know the brand or where to find some that will fit. the ribs are 10″ o.c. 1/2″ tall 1 1/2″ wide flat tops. any ideas? thanks. HAULING IN HEYWORTH

DEAR HAULING: FRP (Fiberglass Reinforced Plastic) panels used in steel covered buildings can be problematic (as you have found out).

More information on FRP can be found at: https://www.hansenpolebuildings.com/blog/2012/01/skylights/

Depending upon the age of your building and the manufacturer of the steel panels, a replacement polycarbonate panel may be available. Over the years, many steel roll formers, who had unique panel profiles, have either closed their doors, or have been bought out. As such, you may have a profile which is impossible to match.

With some photos and perhaps more dimensions, chances are good if it is a currently produced profile, we can find a solution for you.


Do you have any “garage plus living area” pre-made plans? I own some vacant land and I want to put a pole building/garage on my property that would be approximately 32×32 for the garage part. In addition I want some living space on the garage that I can put some living quarters. I do not want an entire house, rather simply space for a living room and a bedroom.

Do you have any plans that are close to what I am looking for? THOUGHTFUL TREVOR

DEAR THOUGHTFUL: Thank you for your interest. As everything we do is custom designed to best meet the needs of our clients, we do not have any ready made plans – however any of our Building Designers would be happy to work with you to create your ideal dream building.

DEAR POLE BARN GURU: I emailed and got a quote from you back in March on a 36’ x  56’ pole building, I liked your numbers but I have enclosed my material list & drawing of the way I will do it. I have been a carpenter for 30 years so I will be doing it myself. We will be starting building on August 4th so we will be starting construction pretty soon. Can you break down the metal price separate from the lumber price? We are building in Powell WY. PONDERING IN POWELL

DEAR PONDERING: We can certainly appreciate the skills of a qualified carpenter, they are many. The Building Codes have become so complex, over the past decade, we typically shy away from providing structural materials from a pre-prepared list. In order to assure your (or any) post frame building kit package we prepare is indeed Code conforming and capable of withstanding the climactic conditions, our normal procedure is to work from your needs and to design a building which we are assured we last for not only your lifetime, but those of future generations. If you have particular preferences for column or truss spacings, as well as girt or purlin spacing preferences, we can most usually work with those – again as long as they meet structural requirements. We will never under-design a building, but if you want it “beefed up” so you “sleep better” – it’s ok by us.

Eave Lights

For decades, the least expensive solution to bringing natural light into post frame buildings has been what is known as “eave lights”.

Eave LightsEave lights are typically short portions of translucent material installed usually in the upper portion of one or both eave sidewalls.

Back in “the day”, opaque fiberglass (actually fiberglass reinforced plastic or FRP) was the eave light material of choice. The FRP panels were manufactured with roughly the same rib configuration as the wall steel.

A downside of fiberglass panels is they have a very low tolerance for the sun’s UV rays. Due to this, they degrade rather quickly, turning yellow and becoming brittle. This causes them to crack and break. They also become easy prey for youthful vandals who tend to be attracted to them as targets for rocks and other throw projectiles. The gradual fade to yellow is both aesthetically unpleasing and it causes a reduction in the amount of light transmission.

When I was first in the pole building industry, the standard installation procedure was to order the wall steel panels shorter than normal by 18 inches, then place 24 inch long fiberglass panels above them, overlapping the steel below by six inches. While cheap and easy, there were downsides to this installation other than just the inherent issues of FRP.

The six inch overlap, while creating a weather seal, allowed the underlying steel to be seen through the light panel. The manufacturing processes of eave light panels and steel siding are quite different. Light panels are extruded which tends to create more rounded profiles than the roll formed steel panels. The two materials also thermally expand and contract at differing rates. The end resultant being an overlap which never seems to lay smoothly.

In the mid-1980’s a better alternative to FRP panels was developed – polycarbonate. With trademark names such as Lexan and Sunsky, polycarbonates are very durable and have high impact resistance (in the case of SunSky up to 20 times more). Virtually unbreakable, polycarbonate eave light panels have better light transmission characteristics than many types of glass.

In the case of SunSky polycarbonate panels, they are self-extinguishing in the event of fire, will not yellow, retain optical clarity far better than any other glazing material, are hail and wind resistant, afford 100% UV protection and are UL 580 Class 90 recognized.

Installation techniques have also improved from the old fashioned overlap method. Now standard 36 inch length panels are used, and a Z style steel trim is placed at the top of the steel wall panels. This flashing extends up behind the eave light panels, and slightly down the face of the steel sheets. It affords a weather tight seal, and eliminates the poor overlapping issues which were caused by differences in manufacturing process and expansion/contraction.

Polycarbonate panels can also be affordably installed across the triangles of the trusses at the ends of buildings; however keep in mind, the roof truss webbing will be noticeable through the panels.