screws in Timber frame

[danreed76]

Do any of y'all use screws in your rafters?  No decisions made yet, but the PE is leaning toward putting screws (concealed of course) in all the rafters.  If anything, I will install the joinery as-drawn, and install the screws just to satisfy him.  Maybe this is one of the "pick your battles carefully things".  Any input is appreciated.

[Jim_Rogers]

Yes, we use timberlok screws to secure rafters to plates.

[frwinks]

we, too lagged all the rafters with 1/2" lags

[witterbound]

we also used timber lock screws from rafter into plate.

[danreed76]

I guess there's no shame in putting screws into the rafters.  I hadn't ever given it too much consideration, but I wanted to make sure it wasn't one of those "you put WHAT in your frame?" things.

I definitely appreciate the feedback on this.  I'm drafting the "frame rules" to go with the drawing package for the engineer's stamp.  Any other suggestions for additions to the rules would be appreciated (especially the ones that make my life easier). 

Dan

[Dave Shepard]

I have used several hundred, or so it seems, of the FastenMaster Headlok screws on my two Dutch barn restorations. The Headlok is almost identical to the timberlok, but it has a larger head, about .620", which will seat flush to the surface of the timber. The timberloks I find tend to bury themselves and are hard to extract, if needed. The screws were spec'd by the architect, and were used only where they would be hidden inside a joint, or behind the sheathing, etc. In some instances, using the screws was the only way to safely salvage some timbers. GRK makes a similar pan-head type of screw that has a thicker shank, and more aggressive threads. They may also be cheaper, I haven't checked around.

[canopy]

Since screws typically aren't used elsewhere, what is the reasoning for opting for them here? Why are pegs considered insufficient / sub-optimal?

[Dave Shepard]

I know in conventional framing we have to add "hurricane clips" from rafter to plate, in addition to any nails. A square peg, or a very large wrought spike, driven through the rafter into the plate was a common treatment for this connection. I suspect code enforcement officials are more comfortable with the large screw.

[Aikenback]

grk's are the most awesome screws around, you can run them through a 6x6 piece of dry fir till the bit is buried to the drill chuck, and reverse it right out and do it several times over without skipping the bit. You only need a dewalt xrp battery operated drill. They make concrete screws and trimheads too. also screws for sip attatchment.

[Satamax]

If i may say something. Screws are nice. I don't exactly know what you are working on.

But, depending on the  type of purlin, plate, rafter arangement, you should avoid screws.

imho, only slanted purlins and plate should have atachement between plate and rafter. that's the only time where the roof caves in.

Beveled straight up purlins and plate, or straight up purlins and plate, and notched rafters, you should avoid all kind of fastener in the plate, and notching the rafter onto the plate, due to sliding movements.

Or at least it's what is explained in my books.

Nails, can cope with a bit of shearing, due to low quality steel and bending! But screws, nope, i tell you, how many times i've seen a broken screw due to shearing or even pulling.

[chris.bolton]

grk's are the most awesome screws around, you can run them through a 6x6 piece of dry fir till the bit is buried to the drill chuck, and reverse it right out and do it several times over without skipping the bit. You only need a dewalt xrp battery operated drill. They make concrete screws and trimheads too. also screws for sip attatchment.

I'm a huge fan of GRK's as well. They are a pleasure to work with and a twelve inch screw will go through an 8x8 like a hot knife through butter. They're a little pricey, but sometimes they're called by an engineer.
http://www.grkfasteners.com/en/RSS_1_2_information.htm