wood flooring. underlayment or no?

  • After Iowa State won the Big 12, a Cyclone made a wonderful offer to We Will that now increases our match. Now all gifts up to $400,000 between now and the Final 4 will be matched. Please consider giving at We Will Collective.
    This notice can be dismissed using the upper right corner X button.

EvilBetty

Well-Known Member
Sep 7, 2012
1,378
1,501
113
remodeling my 1930's home
tore up flooring to relevel the floors. Doubled up the joists as well.
the room is upstairs and i put soundproofing insulation (johns manville rockwool) in the 2x6 floor joists to help reduce sound transfering to main floor.

is there any reason to add underlayment before reinstalling the original heart pine? or just lay the flooring directly onto the brand new 3/4" subfloor? I don't see any reason for a vapor barrier as it is on second floor and the soundproofing insulation should do way more than an underlayment.

am i missing anything here?
 

kirk89gt

Well-Known Member
Feb 15, 2014
798
573
93
For the money, Lumber Liquidators has some nice underlayment that does wonders for squeaks and sound deadening. You can also find similar products at your local big box stores as well.
 

CYEATHAWK

Well-Known Member
Aug 26, 2007
7,142
5,546
113
remodeling my 1930's home
tore up flooring to relevel the floors. Doubled up the joists as well.
the room is upstairs and i put soundproofing insulation (johns manville rockwool) in the 2x6 floor joists to help reduce sound transfering to main floor.

is there any reason to add underlayment before reinstalling the original heart pine? or just lay the flooring directly onto the brand new 3/4" subfloor? I don't see any reason for a vapor barrier as it is on second floor and the soundproofing insulation should do way more than an underlayment.

am i missing anything here?

You don't need u/l under your pine. If your new subfloor is OSB, the only way to keep it from squeaking in the future is using trim head screws. GRK makes screws that are self tapping, so in pine unlike maple/oak you shouldn't have to pre-drill. I know.....a slow go. I have done many, it works great. If your new sub is plywood....then you can use the floor gun just like you would if your sub was the original 1x board. Any choice...put down tar paper or because it's on the second floor rosin paper would do just fine. Wasn't that what was under it originally? Whatever you do......don't adhesive unless it's in a corner/edge where you cannot get your nailing gun, hammer or drill to fasten. Good luck.
 

AuH2O

Well-Known Member
Sep 7, 2013
10,994
16,734
113
You should lay down roofing felt. It can help with squeaks and also some moisture barrier.
OP says this is for the second floor so no need for moisture barrier.

I've got a small sample size with doing wood floors in a different floors and rooms in 3 old houses I've owned, but I've never noticed a big difference in squeaking w/ or without felt. Seems like with a good job on the subfloor most of that is taken care of.

I also am not all that sensitive to it. The creaking and squeaking of old floors is just not a big deal to me and doesn't bother me at all.
 

EvilBetty

Well-Known Member
Sep 7, 2012
1,378
1,501
113
You don't need u/l under your pine. If your new subfloor is OSB, the only way to keep it from squeaking in the future is using trim head screws. GRK makes screws that are self tapping, so in pine unlike maple/oak you shouldn't have to pre-drill. I know.....a slow go. I have done many, it works great. If your new sub is plywood....then you can use the floor gun just like you would if your sub was the original 1x board. Any choice...put down tar paper or because it's on the second floor rosin paper would do just fine. Wasn't that what was under it originally? Whatever you do......don't adhesive unless it's in a corner/edge where you cannot get your nailing gun, hammer or drill to fasten. Good luck.

there was no underlayment. original heart pine was nailed directly to floor joists. no subfloor. no underlayment. i removed everything and put in rockwool sound insulation and 3/4" OSB subfloor.

I guess i still don't understand the point of underlayment in my situation. as i don't need a moisture barrier (second floor flooring), and if i use screws to prevent squeeking, what does the underlayment even do?
 
  • Like
Reactions: cyson

CYEATHAWK

Well-Known Member
Aug 26, 2007
7,142
5,546
113
there was no underlayment. original heart pine was nailed directly to floor joists. no subfloor. no underlayment. i removed everything and put in rockwool sound insulation and 3/4" OSB subfloor.

I guess i still don't understand the point of underlayment in my situation. as i don't need a moisture barrier (second floor flooring), and if i use screws to prevent squeeking, what does the underlayment even do?

You didn't have two layers of floor i.e. 1x8 shiplap at an angle under the t@g pine? And you don't need underlayment for wood floor. I just mentioned the tar or rosin paper because every old home I do has that in between the subfloor and the finish floor. And I figured chances are the guys who did that knew more than myself. As for the screws, I only mentioned that because OSB doesn't have the holding power over time that either plywood or wood does with floor cleats. Eventually you will have a bunch of squeaking. That is why quite a few jobs are now using adhesive along with the cleats. I just prefer to take a little more time and screw it down.
 

EvilBetty

Well-Known Member
Sep 7, 2012
1,378
1,501
113
You didn't have two layers of floor i.e. 1x8 shiplap at an angle under the t@g pine? And you don't need underlayment for wood floor. I just mentioned the tar or rosin paper because every old home I do has that in between the subfloor and the finish floor. And I figured chances are the guys who did that knew more than myself. As for the screws, I only mentioned that because OSB doesn't have the holding power over time that either plywood or wood does with floor cleats. Eventually you will have a bunch of squeaking. That is why quite a few jobs are now using adhesive along with the cleats. I just prefer to take a little more time and screw it down.

no, no underlayment or subfloor at all. i found it strange too. is what it is. would you mind posting a link to the screws you use for hardwoods. I was planning on lining up the fasteners so they'd hit every joist. I assume that would be sufficient spacing for fasteners if they are hitting (16" center) joists?
 

CYEATHAWK

Well-Known Member
Aug 26, 2007
7,142
5,546
113
no, no underlayment or subfloor at all. i found it strange too. is what it is. would you mind posting a link to the screws you use for hardwoods. I was planning on lining up the fasteners so they'd hit every joist. I assume that would be sufficient spacing for fasteners if they are hitting (16" center) joists?
Can't get it to work. They are "GRK" trim screws. You can get them at any box store. A couple of things if you are serious about doing this. Don't know how thick your pine is. I only use this method on 3/4 t@g. Anything thinner, the trim head is too big. If your pine, being it is so old(old wood is the best)is very hard....you may have to pre-drill each hole. I do that with oak, maple etc.. If you don't you can crack the tongue. Even though the screws themselves are self drilling.....do it anyway. If after all I have stated doesn't scare you off.....make sure you drill at the same angle the ring shank nails were. Better yet...if the old nail holes still exist...perfect place for the screws. And because you put in 3/4 OSB, it's not necessary to screw at the joints. I usually go with 2"-2 1/2" screws. At the proper angle that isn't going to get into the joist much at all. Now they make 3 1/2" screws. You want to go all out with the anti squeak thing, that would be the trick I would think. Never tried. Other than that.....screw every foot or 16 inches. Good luck.
 

BWRhasnoAC

Well-Known Member
SuperFanatic
SuperFanatic T2
Apr 10, 2013
24,822
21,779
113
Dez Moy Nez
no, no underlayment or subfloor at all. i found it strange too. is what it is. would you mind posting a link to the screws you use for hardwoods. I was planning on lining up the fasteners so they'd hit every joist. I assume that would be sufficient spacing for fasteners if they are hitting (16" center) joists?
I would recommend putting down sub floor particle board usually 1 inch. You will be much happier with the results.
 
  • Winner
Reactions: mynameisjonas

ForbinsAscynt

Well-Known Member
SuperFanatic
SuperFanatic T2
Dec 8, 2014
4,705
5,809
113
When I did floor we put down felt paper always. It’s cheap and makes install go faster anyway. At least for new floors.
 

stevefrench

Well-Known Member
Aug 7, 2011
1,923
898
113
Alternative to the screw idea, which I have not done but see no reason that wouldn’t be a quality install. use no underlayment or felt, full spread direct glue or glue assist are good methods of installation given the climate we live in and the humidity changes we experience throughout the year. It is not done as often because it takes more time and glue is more expensive than just staples/cleats/tar paper. There are specific glues and trowel sizes for this method, but full spread glue or glue assist are becoming more common recommendations from wood manufacturers.

Will eliminate most any squeeks and though it will take a bit longer will not take as long as predrilling and sinking trim head screws
 

EvilBetty

Well-Known Member
Sep 7, 2012
1,378
1,501
113
Yes, always use some kind of barrier under hard wood.

again though, what does felt paper (or alternate) actually do if i don't need the vapor/moisture barrier (which i don't as it is the second floor flooring)?

I did put down 3/4" subfloor. the highest quality home depot had to offer. glued and screwed.
 

EvilBetty

Well-Known Member
Sep 7, 2012
1,378
1,501
113
Alternative to the screw idea, which I have not done but see no reason that wouldn’t be a quality install. use no underlayment or felt, full spread direct glue or glue assist are good methods of installation given the climate we live in and the humidity changes we experience throughout the year. It is not done as often because it takes more time and glue is more expensive than just staples/cleats/tar paper. There are specific glues and trowel sizes for this method, but full spread glue or glue assist are becoming more common recommendations from wood manufacturers.

Will eliminate most any squeeks and though it will take a bit longer will not take as long as predrilling and sinking trim head screws

i don't like the idea of glue on tongue and groove not intended for it. if i ever want to remodel, or if i sell and they want to take out floors, it is impossible to remove without destroying everything. especially being original heart pine. breaks my heart when old things like that are destroyed forever.
 

BWRhasnoAC

Well-Known Member
SuperFanatic
SuperFanatic T2
Apr 10, 2013
24,822
21,779
113
Dez Moy Nez
again though, what does felt paper (or alternate) actually do if i don't need the vapor/moisture barrier (which i don't as it is the second floor flooring)?

I did put down 3/4" subfloor. the highest quality home depot had to offer. glued and screwed.
Are you planning on never spilling on the floor? Are you planning on never having a water issue of any kind? Water can come from above, not just below. It's also to minimize sound. It's like $10 for a roll of tar paper and takes very little extra time to lay it down. Helps in removal of flooring in future as well.