Subfloor Suggestions

[mattgancz]

I am looking for suggestions regarding sawing out a subfloor.  This will be for my own home, and does not need to be inspected.

I would like to saw pine for the subfloor, can anyone suggest an ideal width and thickness?  Is it worth the cost to have the subfloor S4S with T&G?  Any thoughts on screws versus nails? 

I am moving at the speed of cash, so I will need to deck my first floor and cover it for next winter.  Can anyone offer suggestions for making it through a Vermont winter without destroying the subfloor.  I am concerned about moisture accumulation under a tarp with a true wood subfloor.  Any thoughts and experience would be greatly appreciated!

[Don P]

Sawing a plump 4/4 I can usually clean up the dry boards at around 7/8 so that is what I use most times unless there is some other requirement, basically as soon as it is uniform. 6" and wider, typically no more than 10". Lay it diagonally for rack resistance. My advice it is too late for, don't begin framing until you can dry it in and then run for the roof.

[firefighter ontheside]

What are you building?  Conventional framed home?  Joists on 16" center?  What will be your finished flooring? 

[barbender]

 It is simpler to frame it up and get a roof on, than try to keep just a subfloor dry in my experience. 99% of the time the subfloor ends up getting wet.

[SawyerTed]

+1 on do the foundation and stop there if it has to sit during winter, then resume building with the floor framing, subfloor through dry-in the next building season.  It would be easier to protect vertical walls under roof with temporary exterior measures like house wrap than protect a subfloor.  

Even if the house wrap comes down over winter, it is  easier and cheaper to redo than a subfloor. 

[mattgancz]

A bit more information...

The house is going to be stick built — joists will be 16" O.C.  Finish floor will also be wood, but I suspect that we will live of the subfloor for a little while.

Don P, I would definitely do diagonal flooring for a second floor deck, but is it really necessary for a first floor deck?

Any thoughts on edge finishes and attachment methods?

[beenthere]

Agree with stickering the flooring boards and let air dry on stickers rather than laying the floor and hoping for some protection from a tarp.
Especially if you plan to live off that subfloor. Air dry, plane to desired thickness, and lay it down when ready to put a roof over.

[Wlmedley]

I used 1" pine sheeting placed on diagonal one way for 1st floor and the other way for 2nd floor for subfloor. Used 8d nails to fasten down. Put roof on as fast as I could and still had to replace a few boards because of water damage. Probably about two month time frame as I mostly worked alone. Wouldn't recommend going through a winter without roof. I tried to keep subfloor covered during construction but wind was always working against me. Floor has been fine for the last 38 years.

[Don P]

Don P, I would definitely do diagonal flooring for a second floor deck, but is it really necessary for a first floor deck?

That is up to you. It sounds like my crew "Do we have to put a nail in every joist hanger hole". Uhh, unless you can flash an engineering degree  . You will be happy you did when you put a hardwood floor over it, it'll help with gap problems.

Cool, it sounds like you haven't started. If the foundation is backfilled brace it and stack straw inside till you want to start.

[Gary Davis]

up until plywood sub floor was usually 2xx6 or 2x8 perpendicular spanning 4 ft on a post and beam or 1 by shiplap spanning 16 -24 in ran diagonally framing in the PNW everything gets wet during construction, some times the 1 by would be used for the foundation first.

[jpassardi]

You could also pour the concrete and install girder & posts and PT sills, rim joists and joists. Having them exposed over winter wouldn't be too bad, especially if you aren't using KD lumber such as spruce. Most snow & rain will get through. This will give you a good head start for spring which BTW isn't far off.
I wouldn't be concerned about laying the first floor decking 90* to joists, the concrete walls will prevent racking. 2nd floor diagonal is advised.
I would wait on decking though as advised above.

[Southside]

I am not a "builder" but I have done my share of 1.5" T+G flooring right onto the joists and been very happy with the performance of it.  As a bonus you could sand it quite a few times if necessary. 

[Joe Hillmann]

I am building a house using roughsawn board subfloor.  All of my boards are swan at the 1 inch mark on my sawmill so are a bit over 7/8 thick.  I am using them as is, any skinny boards get set aside for something else, and any fat boards get sawed again on the sawmill.  My boards are anywhere from 4 to 13 inches wide.  I straight line one side with a skill saw and a track, then rip the other side parallel with a table saw.  Often I can skip the straightlineing because the cut off the mill is straight enough.

I am running my subfloors at a 15 degree angle.  I think the angle is worth doing because it prevents seams in the subfloor and finished floor from lining up for long lengths causing a weak spot.

When it comes to covering the floor for a winter I would suggest calling local commercial roofing companies and ask if you can buy used rubber roofing material from one of their jobs.  I usually can get it anywhere from free up to 15 cents a square foot.  You can then glue the pieces together and make a seamless waterproof cover for your floor.  You can weight it down or you can nail it down.  If the roofing company is willing to sell it to you they will ask how big you want it.  I usually tell them I want strips 10-12 feet wide and as long as a single man can handle.  Sometimes that has gotten me 12x12 squares other times it has gotten me 15x 40 rectangles that required a forklift to load on my trailer.

On my build I built the walls and roof first before I put in the floor joists and subfloor, that way they never get wet.  If possible I would recommend you do the same.


The house I am living in now was built somewhere around 1900.  It's sub floor is roughsawn pine 1x6 with a very narrow shiplap cut into it.  It is laid 90 degrees to the joists.  My guess is it was still somewhat green when laid, most of the boards have shrunk so much that the shiplaps are no longer overlapping the board on either side of it any more.  The floors squeak all over and is very uneven but after 100 years it is still solid.

[mattgancz]

This is great advice, thank you everyone.  I will conceded, and lay the first floor with at least some angle to prevent the seams from lining up.  I can hear the chorus of onlookers now, "Why don't you just use Advantech?"

[Joe Hillmann]

I can hear the chorus of onlookers now, "Why don't you just use Advantech?"

I get asked why I am not using plywood for my sub floors and roof decks all the time.  My general response is I am poor, and I like working in the woods more than I like going to work to earn money to pay for plywood.

[NE Woodburner]

On my build I built the walls and roof first before I put in the floor joists and subfloor

I heard that they frame houses this way in Sweden and makes for a better insulated exterior as the wall insulation goes down to foundation versus trying to insulate between floor joist ends in traditional framing. Might not be as convenient to build since you can't stand walls up on your floor deck, but might be a better system in the long run.

[Joe Hillmann]

On my build I built the walls and roof first before I put in the floor joists and subfloor

I heard that they frame houses this way in Sweden and makes for a better insulated exterior as the wall insulation goes down to foundation versus trying to insulate between floor joist ends in traditional framing. Might not be as convenient to build since you can't stand walls up on your floor deck, but might be a better system in the long run.

I don't know how a person would do that with a stick framed building(several ways come to mind but I haven't looked into it).  Mine is a log cabin so I am hanging my joists with joist hangers to the inside of the log walls.  It is much easier to do with a log cabin.

[mattgancz]

On my build I built the walls and roof first before I put in the floor joists and subfloor

I heard that they frame houses this way in Sweden and makes for a better insulated exterior as the wall insulation goes down to foundation versus trying to insulate between floor joist ends in traditional framing. Might not be as convenient to build since you can't stand walls up on your floor deck, but might be a better system in the long run.

If you are interested in Swedish platform framing, check out Swedish Platform Framing by architect, Gregory La Vardera.  The lack of thermal bridges at the joists is interesting.

Swedish Platform Framing