h clips

Weather or not there is the 1/8 inch spacing around any sheathing is not going to make a roof buckle…any buckling is most likely the result of a roof that is not properly vented. I see this often with gable vents on low pitch roofs…matter of fact I just finished a roof where we had to replace 12 sheets of plywood and add ridge venting prior to installing the new shingles.

I’ve been framing for over 30 years and have yet to see any framer insure that there is a 1/8 inch space between all sheathing…be it floor, walls or roof.

The APA, like most vendors, are using technicalities as a means to relieve the manufacturer of any liability. They go on to advise that space should be as much as 1/4 around all edges if their is a chance of inclimate weather.

Anyone that has done any framing knows that you would have to either adjust your joist / rafter spacing or cut a 1/4 inch off every sheet…that is just being anal.

Simply dealing with moisture and venting issues will rectify buckling problems.


I’m talking about new construction, Jeff. Roofs that have been sheathed but aren’t yet covered by underlayment and sat through a couple of storms. I’ve seen roofs with no spacing buckle badly after a series of storms.
I was a framer for 25 years and a framing and finish contractor for 5. I’m sure it varies quite a bit by contractor and area but everywhere I worked- CA and CO- from about the early '90s on… eveyone was pretty good about leaving that space. Tack in 2- 8d sinkers per sheet into the tops of the rafters, then yank them out when you’re done. It got to be habit. When I ran work I insisted on it.

When we did stud/ joist/ rafter layout we usually used a 4’ layout stick instead of a tape. We allowed for that 1/8" very easily that way. No cutting 1/8" off sheets. Layout is much faster using a stick too, works like a charm!
I made one for some framing here (see photos). It’s gotten a little warped.

Bad idea to say "Anyone who’s ever framed knows that… " because things are done differently in different parts of N America.

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Another reason to stay away from plywood products.

It was always my framers responsibility to get the house in the “dry”…matter of fact before any other trades comes in, especially electrical, the house had to be in the dry.

While your layout stick is novel (you better patten that…lol)…I don’t see it being practical except for a home whose length is short but you take a ranch that is 60 - 80 feet in length, your going to have problems…especially with drywall. Being that most products are in multiples of 2’ or 4’ you would have to add some additional nailers along the way. At one time I had some documentation where engineers were discussing the nominal thickness of 2x’s…from going to 2 inches, to 1 7/8 to the present 1 1/2 we have today. Considering the APA says to allow 1/4 where there is the liklihood of inclimate weather that means the sheathing is not resting on 1/2 inch of lumber…I’m not engineer but I know we have a problem Houston.

Anyway, I do find it interesting to work with various tradesmen, especially carpenter, from around the country. My favorite employer was from Boston, Mass…he was a true craftsman. We practially did everything (no mechanicals)…from surveying, digging footers, pouring basements, framing, roofing, insulation, drywall, painting, trim, exterior veneers, flooring, landspacing, pouring driveways etc. It was from him that I modeled my contracting business after…which probably accounts for me having a hard time letting go of the working side of the business…of course age and having a sore back is rectifying that right now. I especially loved roof framing…the more complicated the funner it was.

Anyway, have you used Advantech OSB…I swear by the product. I have been using it since it came out however from time to time I like to test new products on my spec homes. I did an upper end home on a golf course where I used Edge Gold on the the first floor and Advantech on the second. It was a large home so the Advantech was pounded with rain and snow…yet it outperformed Edge Gold by leaps and bounds. I have literally had 1 1/2 inches of standing water (didn’t cut out the door plates) on advantech for about 5 days…not one edge was ever swelled.

I know around here plywood is cheaper however its just not worth it…too many problems with delaminating and swelled edges.

As you know, with any home it is important to let the home dry out and specially roofing components. I can attribute many shingle defects to moisture…be it the decking and or felt was wet during installation or the shingles themselves were wet which as you know one of the main reasons that shingles blister (moisture trying to escape).

H-clips have been around at leating going back to the 70’s…I have not seen them on any home built from the 60’s and earlier. I personally like stick framing…its often cheaper and better…not to mention installing h-clips on a steep roof is always a pain in the butt.

I would be interested in knowing how you accounted for the extra spacing on other materials such as drywall and even insulation. Im sure you drywallers often cursed you behind your back. lol


;)Well, as with all that have opinions, I do have my own. :mrgreen:

I do say, that I have to side with Jeffery. H-clips are a pain in the arse and in my 45 years of Construction here in Maine, I have only seen a few projects that have required them.
My Father before me that built houses all his life since the great depression, never had such a thing to worry about. Spacing 1/8" is BS.
Just another way for a manufacturer to deny warranty when things go array.

35 years ago, 5/8" plywood CDX would lay flat on a bundle or on the roof.
Now the same curls up in all corners, what is wrong with the picture.?

It is not the same manufatured product.

Where does that leave us as Builders and Inspectors?

Nowadays, (install per Manufacturers Instructions or else.)

If it reccomends h-clips, I guess we have to install them.