Tag Archives: PFDS26B hangers

Twelve Foot Addition, Wall Insulation, and Purlin Settings

This Wednesday The Pole Barn Guru answers reader questions about extending an existing 60′ long pole building by twelve feet, the best way to insulate outside walls to prevent sweating, and the reasoning behind setting purlins flush with the top of the truss top chords.

DEAR POLE BARN GURU: I have an existing 40 x 60 pole building, built in the late 80’s. It has double trusses spaced 12 ft apart. I would like to extend it from 60 to 72 ft. We originally were thinking we would extend using stick frame construction but now I am wondering if this will affect the integrity of the existing building. I would like to leave the end of the pole building in place and add a door into the new space at each end. Your advice on the best way to go about this? The extension is planned for a bathroom and laundry space and would have a concrete floor. Thanks for your help. WENDY in VANCOUVER

DEAR WENDY: Adding as a post frame (pole) building will be your most economical and easiest route to go, especially as your Building Department will require engineer sealed drawings and verifying calculations. In order to determine how best to achieve your end goals, we would need detailed photos of inside and outside of your existing building, measurements at eave sides and dead center from bottom of pressure preservative treated splash plank to underside of roof steel, spacing of existing endwall columns, etc. We make deliveries into Western Washington and Northwest Oregon frequently, so freight costs will be quite reasonable. Please forward your information to Caleb@HansenPoleBuildings.com along with site address and best contact phone number.

 

DEAR POLE BARN GURU: I built a pole barn last year and am having the floor poured this week. Once completed, I will begin building an apartment inside the barn area. What is the best way to insulate the outside walls for great R value and prevent sweating? DAVID in PORTSMOUTH

DEAR DAVID: If you placed a Weather Resistant Barrier (think Tyvek or similar) between your framing and siding, then fill your insulation cavity with Rockwool and have a well sealed vapor barrier before interior finish. If no WRB, then have two or more inches of closed cell spray foam applied to inside face of your siding, then fill balance of cavity with rockwool and no interior vapor barrier. Depending upon what you do with your under slab and roof for vapor barriers and insulation, you may need to mechanically dehumidify in order to prevent condensation (sweating), as your walls alone are merely a small piece of a big puzzle.

 

DEAR POLE BARN GURU: I understand your roof design is with purlins flush with the top of the truss. Why do you use this design? Sorry if this info is on your website, I didn’t see it. Regards, STANLEY in DOSWELL

DEAR STANLEY: Here is an article on this subject: https://www.hansenpolebuildings.com/2019/02/where-oh-where-should-my-purlins-go/

Having roof purlins flush with top of trusses has many advantages:

It does not take up extra height (purlins over top of trusses either reduces interior clear height or increases eave height).

Purlins are then in perfectly straight lines, allowing for pre-drilling of roof panels (this eliminates misses). Others may try to align purlins over top of trusses using butt end splices. This makes for a very poor connection attempting to get adequate fasteners into 3/4″ (1/2 width) of truss top chords. When purlin joints are lapped, it causes a stagger of the purlins, resulting in inability to pre-drill and a significant chances of screw misses.

Purlins can be connected to trusses using engineered and Code conforming parts (in our case, quick to install Simpson Strongtie PFDB26B). Codes (as well as sound engineering practice) require purlins on edge to be solid blocked or otherwise prevented from rotation at ends. A nailed only connection would not meet this requirement).

NEW Hansen Pole Buildings Roof Purlins and Connections

NEW Hansen Pole Buildings Roof Purlins and Connections

Hansen Pole Buildings has always utilized what is known as recessed roof purlins, where purlins are placed between roof truss top chords.

Top of roof purlins and top of trusses are at same height and purlins were connected with typical standard joist hangers. This resulted in clients (or their building erectors) having to carefully place joist hangers to keep purlins from being too high, or too low in relationship to their respective trusses. Adding to this complexity, joist hangers were to be attached to double trusses with 10d common nails (.148” diameter x 3” long).

We wanted to make this into an easy connection, so now are providing a Simpson Strong-Tie PFDS26B (for 2×6 roof purlins) or PFDS28B (for 2×8 roof purlins). This part easily slides into place over a pair of trusses, automatically establishing proper purlin height. It fastens to truss pairs with SD9212 screws – three each side for 2×6, four each side for 2×8. These screws also are used to pair truss top chords, where previously two or three 10d common nails were required, usually roughly every eight or nine inches. SDWS9212 screws are also used to attach hangers to purlins, rather than 10d x 1-1/2” joist hanger nails.

Roof purlins were previously evenly spaced, resulting in some challenging measurements. We now have standardized spacing to fall so measures are evenly divisible into eight (8) feet. Examples are 32”, 24”, 19.2”, 16” all of which are keyed to markings on tape measures.

By again utilizing high strength msr lumber for roof purlins, spans previously needing to be 2×8, or in some cases even 2×10, can be done with 2×6 lumber.

We have even made it easy to quickly identify lumber to be used as roof purlins – one end will arrive spray painted PURPLE for ‘field’ purlins and PINK for purlins in high load areas – such as drifting near ridge in snow country. If you (or your erector) need to trim a board, please trim unpainted end, as this makes it easy for you (if you hired a builder) or an inspector, to quickly identify wood as being properly utilized!

We have improved speed and accuracy of installation, reduced dead weight of roof system and increased system strength and reliability!

BUT WAIT, THERE’S MORE

I mentioned how double truss top chords are usually nailed together with lots of nails. Well, we are now connecting truss webs and bottom chords with Simpson SDWS16300 structural screws – spaced much further apart than nails were. Fewer and stronger fasteners!

Call 1.866.200.9657 TODAY to participate in “The Ultimate Post-Frame Building Experience”.

And, don’t forget to watch for our next article!