Fastener q

[Poindexter]

Rather than upgrade to a BK king or spend a week in Paris, SWMBO has decreed all carpeting in the house goes to the dump, forthwith, to be replaced with engineered hardwood flooring.

A man does have to choose his battles judiciously.

I am down to bare subfloor in a bedroom a PO used as a dog kennel. Much of that 3/4" actual plywood subfloor is coming out too. Ill be down to bare joists above a 4 foot crawl space.

Joists are 9.75" actual tall site built girders, a pair of nominal 2x3s with a dado on one face, plywood vertical web, black glue circa 1980, on 24 inch centers.

Original subflooring is not tongue and groove, nailed down with 6d and glued to the joists with a circa 1980 brown glue that has become powdery.

I have had both an engineer and a contractor through who say i can put 24" lengths of 2x4 between joists under the unsupported plywood seams. Neither would spec a fastener, and neither suggested a complimentary joist stiffener below each seam supporter.

I got 1800 sf of squeaks to deal with. Once the subfloor seams are supported the plan is 1/2" carb-2 underlayment, then the engineered hardwood on top.

Leaning towards an air compressor, a nailer and some pretty fat finish nails, like 8d diameter or so. I can toe screw just fine, but for several thousand toe nails i am thinking compressed air.

The 2x4 cross pieces under the unsupported seams will be 48" spread max. Open to opinions on spacing the lower stiffeners.

Thanks.

 

[vinny11950]

I kinda of see what you are dealing with but not entirely. Do you have pics of the joist structure or a drawn diagram? and you want to do this for the entire house or just a few rooms?

Also, are the squeaks caused by the old glue and old nails in the subfloor or the flex of the floor joists because of the 24" spacing?

 

[johneh]

For sub floors and decking this is what I use to fasten
http://toolguyd.com/hitachi-superdrive-sub-floor-deck-screwgun/

 

[vinny11950]

For sub floors and decking this is what I use to fasten
http://toolguyd.com/hitachi-superdrive-sub-floor-deck-screwgun/

That is a great tool. I like Hitachi tools, very reliable at affordable prices.

 

[johneh]

Bought one about 4 years ago when redoing 1500 sq. ft. of decking talk about
saving your back . Had to buy a second one for the wife she wouldn't let me use mine
Used then to lay sub flooring for sons new home on engineered joists not a squeak any where
Works like a charm

 

[vinny11950]

Used then to lay sub flooring for sons new home on engineered joists not a squeak any where
Works like a charm

So you are saying nails get loose over time and allow movement in the subfloor which creates the squeak? whereas screws don't?

 

[Highbeam]

Screws for sure on the 2x4s supporting the plywood joint. Screws everywhere else too. I use the square drive screws for underlayment too. Nails are great for lots of things but not the floor.

 

[Doc C]

Glued and screwed for all underlayment to avoid squeaks. The big tubes of liquid nail. Some will say it's over kill but its standard building practice in our area.

In a pinch I have used glue and ringshank nails for some projects but not my first choice.

 

[johneh]

So you are saying nails get loose over time and allow movement in the subfloor which creates the squeak? whereas screws don't?

You got it even using ring nails floor will squeak. counter sunk Robertson head screws work the best
and lots of them . Like 6 to 8 in. apart

 

[Doc C]

I've had screws squeak too. I really think throwing some glue down is the ticket to keep squeaks away. I don't think I have ever had a glued and screwed subfloor squeak.

 

[Poindexter]

Figure I should update.

As planned, I ran a circular saw around the perimeter of the room to cut out the sub floor as far back as i could.

On the walls perpendicular to the joists i was able to get within about 4" of the drywall. On the walls parallel to joists i finished on the centerline of the joist nearest the wall.

So a rim of original subflooring sticking out from under the walls all the way around the room.

The correct name for my engineered joists is "I joist". The current ones are using OSB instead of plywood for the vertical webbing.

I put about 60 web stiffeners in the I joists under this room, before i cut out the subfloor, because I dodnt want them to move any more.

A web stiffener is a 4" wide piece of plywood, thick enough to come flush with the stringers at the top and bottom of the I joist.

So to stiffen up an I joist, one 4" web stiffener every 12" beam to beam on the span of concern.

If your really worried you can then add a cheek piece, a long piece of plywood, mine were 96x9.5 inches, along the span, glued to top and bottom stringer, and all the stiffeners the length of the span.

Besides the 60 some web stiffeners, i did put in two cheek pieces, and then 2x10 blocking between the cheek pieces in that worst area.

In three other areas i laid out my web stiffeners thoughtfully so i was able to install 2x10 blocking without using cheek pieces.

Suggested glues were rl400, rl200 or liquid nails. The wife and I read the MSDSs on all of those and selected West System epoxy, 105 resin with 205 hardener. More expensive, and lots of mixing time, but we know neither of us react to them when cured. I did use dander dust as a thickener for vertical flue joints.

I used the epoxy for all the joints. 2x10 blocking was reinforced with 3" framing screws while the glue was wet. New plywood sublooring was laid into wet epoxy on the joist tops, and then fastened with 2.5" ring shank nails @ 4" oc on every joist.

Unsupported seams between plywood pieces perpendicular to joists have 2x4s underneath in the joist space, epoxy everywhere and finish screws through the subflooring into the 2x4 while the epoxy was still wet.

Overall for being single layer 3/4 pkywood, not tongue and groove, with engineered 2x10 joists on 24 inch centers i have a remarkably still sub floor.

It is not as stiff as i learned to build "back in the day" with actual 2x8s on 16 inch centers with double layer 3/4 TG as the subfloor, but its pretty stiff.