Deck nailing pattern

Guys

I have been told by an engineer that the IBC codes do not make any mention of whether the 1x4 roof deck boards need to be removed when decking a roof with plywood or OSB. I’m bidding a job in a city where the decking requirements are to comply with the IBC building codes. I would rather not remove the 1x4 boards due to the extra time involved and extra dump fee associated with it. With that in mind how would you approach the nails spacing if leaving the 1x4 boards in place. I was wanting to go with 6" along the edges and 12" in the field. Do you feel this is sufficient and what size and type nails would you use. The home is in Houston and I do need to consider this a high wind area although it’s not on the coast but 30 or so miles from it.

we nail all trusses over top of old deck.

Use a 3" nail. I think 6" at edges and 12 in the field is fine. That is code around here.

You do not remove the old 1x4 ?

It seems to me that you would want to leave the plank decking.

The plank decking will make the roof assembly much stiffer than sheeting alone.

The biggest issue I see on redecks over plank is that the roofers seem to think that nailing the sheeting into the planks is adequate, well it’s not.

Most of the redecks we do have oddly spaced rafters, we often have to cut every sheet to fall on a rafter.
If you don’t hit rafters when nailing your sheeting the sheeting will eventually lift.
Sometimes it will only be in certain areas, others it will be all over the whole roof.

I don’t know about down south but up north if a home needs redecking it is usually an old home.
Being an old home it has seen plenty of winters with significant snow load.
The extra weight of the sheeting is not an issue up north.
If it has rafter construction like the majority of older homes do, adding collar ties helps quite a bit in stiffening up the roof assembly.

[quote="-Axiom-"]It seems to me that you would want to leave the plank decking.

The plank decking will make the roof assembly much stiffer than sheeting alone.

The biggest issue I see on redecks over plank is that the roofers seem to think that nailing the sheeting into the planks is adequate, well it’s not.

Most of the redecks we do have oddly spaced rafters, we often have to cut every sheet to fall on a rafter.
If you don’t hit rafters when nailing your sheeting the sheeting will eventually lift.
Sometimes it will only be in certain areas, others it will be all over the whole roof.

I don’t know about down south but up north if a home needs redecking it is usually an old home.
Being an old home it has seen plenty of winters with significant snow load.
The extra weight of the sheeting is not an issue up north.
If it has rafter construction like the majority of older homes do, adding collar ties helps quite a bit in stiffening up the roof assembly.[/quote]

All of this. That is why I say use a 3" nail. You must hit rafters.

Going over the 1x4 planks should be ok, and the nail pattern you are talking about sounds fine also as long as you are nailing into the rafters. If your really worried about high winds then use a ring shank nails and add a few in the field along with h-clips

The only redeck I’ve done around here had odd spacing on the rafters and we had to cut every sheet. Also it had gable overhangs, and the 1x decking was just cantilevered, ie no barge or fly rafter. I decided to screw (opposed to nailing) the plywood to the 1x decking in these areas.

[quote=“noserider”]

You do not remove the old 1x4 ?[/quote]

yes we leave it unless theres a mold problem or something to that effect.

You spacing sounds good and just make sure you land on rafters the best you can. if there are areas you cant then id use screws to hold. nails dont hold in the old dry wood well.
Our city code is to have two nails per 1x? per side of the end joint. otherwise your hitting mid air before the rafter and can sink the sheeting down to much. Also be sure to use 1x? to fill in the spaces where your top and bottom edges meet so you wont have any uneven edges. I recently just went back to using wood instead of H-clips because it makes it much more solid and if you by chance nail near an edge with no board, you wont suck down the sheet creating an edge.

I screw the ends of osb on redecks

Thanks guys

We leave the 1x and nail 6" edge 12" field O.C. We always try to land it on the rafter. We are also allowed to nail 2 per 1x when It does not hit the rafter We screw them, Better to be safe then sorry.