Hardwood flooring over particle board?
I am repairing a floor that has a 1/2″ plywood subfloor with 5/8″ particle board underlayment over it. I have to replace some of the particle board
and wondering if I should just take it all up and use something better.
The hardwood flooring installer thinks the particle board should be ok,
but the HO and I are thinking this might be a good time to get rid of it.
The floor feels spongy to me and I am thinking the flooring nails might not hold as well in PB, because it tends to be crumbly.
I think we are going to end up replacing it and was wondering what would be a good replacement. !/2″ or 5/8″ plywood, or would 5/8″ OSB be flatter or sturdier? Is the PB acceptable under hardwood flooring? This floor had carpeting originally, BTW. Thanks for any recommendations.
I think I've seen that partical board that you are talking about, its surface is black, right? Not really a good building product. OSB is cheaper and holds nails better so I think that it would be superior to plywood as an underlayment. Seeing as how you are using it as an underlayment over an existing subfloor, the smallest thickness you can find would be fine (7/16 in my area).
arcflash, the underlayment is just the regular sawdust looking stuff.I have never seen the black type you are talking about.I thought the 1/2" plywood subfloor seemed a little light, I usually use 3/4" T & G ply or osb. We will probably go with the OSB because it is cheaper.I just wasnt sure if we should replace all the PB while we are into it.
On jobs where I have run into particle board I've taken it out b/4 putting down any finish flooring. It holds flooring nails zip. Expands and decomposes in any introduction of moisture. Cheap insurance for good pc of mind.A Great Place for Information, Comraderie, and a Sucker Punch.
Remodeling Contractor just outside the Glass City.
calvin, The PB was water damaged by the patio door as it usually is. I think we wil replace all of it. Do you think OSB will be ok, or would you use plywood?
plywood delaminates when wet, osb likes to swell. Depending on what type of paper you use under the floor (rosin or felt), I still like osb. Is it a leaky threshold, or foot traffic that brought in the moisture?
I'd use plywood. OSB does not hold nails as well, and the back side will sometimes blow out when nailed.
False, OSB holds fasteners much gooder.
Mark, we thought the plywood might hold the nails better too, but maybe the osb would be sturdier and cheaper. Do you think the OSB would blow out if it is laying on top of the plywood? Its a fairly big floor and hallway, probably about 20 sheets, so cost is a factor and wouldnt the OSB be a little easier to work with, since it lays flatter?
I don't think it would blow out if it was over plywood. I don't think it would be much easier to work with though, and it isn't much flatter. If you use it, make sure to leave a gap between the sheets (1/8" or so) since it does swell more than plywood (so I hear). It's commonly used under hardwood.http://www.hoskinghardwood.com/Hardwood_Floors_7/2/All_About_Sub_floors.aspx
Mark, thanks for the link and we will definatley space the OSB. Dont they recommend spacing plywood too? The floor does have a few squeaks, so we will have to screw it down too.
I would first make sure the water problem was corrected.
Then perhaps thinking of how the hardwood assoc. previously avoided osb, might pick plywood. Since I work alone I might also choose ply because it is lighter and I'm soon to be 59.
Still, because now the assoc. seems ok with osb-might use it if it was way cheaper-god knows it's flatter than sheeting.
A Great Place for Information, Comraderie, and a Sucker Punch.
Remodeling Contractor just outside the Glass City.
The water problem (patio door) entry shouldnt be a problem, because we are taking out the worn out patio door and replacing it with a window/wall combination. My thinking is the OSB would be ok if it is spaced 1/8" to allow for expansion, and yes its heavier, but I need the exercise.
Might as well. It would be a change order for you, right? It should. I think that what I'm talking about is particle board with some kind of surface coating(?) I know that they used to use it as sheathing in the seventies. Bad stuff, I mean terrible. I lived in an apartment that used it behind the drywall I'd assume as a sound deadiner. I've never seen a building material rot from just regular air before. Every bit of it was crumbeling and had serious mildew. I proceeded to tear it out. My upstairs neighbor called the landlord on me, but I had already befriended the maintenace man, so he didn't report me. I finally got out of there when I saw the termite damage. I get shivers up my spine when I think about that musty smell.
Tell the HO its in his best interest to get rid of it. Then work out a change order to do so. He will breathe easier, and you will get a little extra money for some extra work.
arcflash, I know what your talking about now. Its almost like a builtrite material,soft and spongy. They used it under gypcrete as a sound deadning material.That stuff is terrible, and I would never use it on a floor.
There are some very good versions of OSB out there, try Advantech for one ( they do not consider it OSB ). There are a couple of close equivalents out there also, can not remember all the names. Particle board really sucks but if never exposed to moisture will last. I shoveled it out of sister-in-laws kitchen, then fell through the plywood subbloor. Still does not hold a nail in my opinion. Hers had dishwasher leak and poor crawlspace ventilation.
Thanks, I will check into the Advantec, I heard its pretty good. It does look alot like OSB, but if its not too much more it would probably be worth it.
Edgegold is another osb type except it is denser and much more water resistant. Osb has a tendency to swell at the edge and stay swollen after it dries.
There really is a world of difference. It is a little more expensive, at one time pretty much even with decent plywood. I and others I have spoken with like it much better. I think the edgegold is one my local yard carries and it was at least $6 cheaper IIRC.
I would stay away from particle board underlayment at all costs. In my own opinion, use min 5/8" exterior grade plywood with staggered joints and 1/8" gaps for expansion. Also, be sure to place roofing felt on top of the subfloor and mark your floor joists prior to installing the plywood so that you can pop your nailing lines. I used the rosin (resin?) paper on top of the plywood. The wood slides easily.
I think the flooring installer will be using the rosin paper under the flooring.Whats the purpose of the roofing felt over the subfloor, squeaking?
Edited 7/19/2008 9:22 pm ET by wood4rd
You know, I don't have an answer for that. I thought that maybe it had better water resistance. I'm thinking of installing hardwood in my bedrooms and I'd personally go with the felt just because it seems like it would last longer. Anyone here got an answer?
The roofing felt serves as a moisture barrier, that is my guess. My house had it underneath the particle board when I removed it. Perhaps it is used more here in the south, especially with crawl spaces that have no vapor barriers and sealed vents. I also kept the wood in the room for a week before installing. No cupping so far.
There has been many spirited discussion of the advantages of both felt and rosin paper. From my reading of the posts from the carpenters and flooring guys posts, either is a good choice, just pick.
Roofing felt is not really a barrier, more of a retarder I believe. It will help prevent any squeaks between sub-floor and underlayment. Most squeaks end up being between sub-floor and joist IIRC.
The earlier discussions about the "black sided stuff" were probably Homosote and maybe even the Celotex "black board" commonly used for non-structural sheathing. Neither are designed for underlayment. I have put down a layer over concrete to insulate a wee bit, then tapconned 3/4" ply to install vinyl.
If it's real t nd g wood, you can install directly over the 1/2". Remove the particle board as it will not hold the nails. I live in an area where thousands of houses were built with these floors. Hardwood were installed over the 1/2" when they were new and had no problems. If its laminate, you need a new layer of plywood
the best thing to use is an Underlayment rated plywood.
If height is an issue you could get away with a good 3/8" underlay.
but 5/8" would be best.
beware that there is a LOT of $h!tty plywood out there.
advantech would be good but is heavy and it is heavy and it is heavy...
also is T&G so it will require some extra elbow grease to install.
Did I mention how heavy it is??
the red rosin paper is used to facilitate the boards going together
nothing you put down is going to be much of a vapor retarder after it has 5000 flooring fasteners driven thru it..
if moisture is getting to the bottom of the flooring then you got a different problem to fix.
"After the laws of Physics, everything else is opinion"
-Neil deGrasse Tyson
If Pasta and Antipasta meet is it the end of the Universe???
MisterT hit the flooring cleat on the head (yeah, lame joke). My first experience was with my father's family room. We used T&G 3/4" plywood for the underlayment. It was our first experience with hardwood floors (3/4" T&G unfinished red oak, better and select grade or something like that). The ply was heavy as all get out and we had trouble getting the tongues in the grooves. I finally improvised a car jack/2x4 thing that finally got them to go in. Never again. And that was the last time my father used unfinished flooring!
We used Advantech in one room. Nice and waxy-like. Used prefinished Harris-Tarkett. The rest of the house was 3/4" exterior grade, closely inspected plywood.
MisterT was also correct in that if there is a moisture problem, that needs to be dealt with. So basically, we used roofing felt because it is was always used. Hopefully the asphalt/tar might seal any punctures (haha). Also the rosin paper is used as a smooth surface. I only rolled out 2 sections at a time and taped them because I usually ended up tearing places in the back unless lines were needed.
I'll save my sanding, patching, and finishing for another date. At my house, my first solo job was my 357 sqft living room. Beautiful after 8, yes 8, coats of poly. Not my choice but by coat 8, i figured it out! I can wet mop the floor (I don't)!
And the most important point: I am an amateur just sharing experiences. Professionals always trump my "I would use..." ;-)
I will check into the underlayment rated plywood, no advantec if its T&G.There are no moisture problems from below, finished basement and dry.The one problem to deal with is there are 2 or 3 joists on one side that dip about 1 1/4" in the middle, so the floor drops off drastically on that end. Since the basement is finished and sheetrocked we are going to open up the floor on the dipped side and slide in new joists along side the bad ones. It looks like a unanimous decision, get rid of the particle board!
You are wasting your money putting another layer of plywood down and you are even more making a mistake using a t and g underlayment. The t and g underlayment can and will telegraph the t and g at the same joint with a hardwood floor. I never ever use t and g anything when a hardwood floor is being installed. If I do/did then I cut the grooves. Nail the hardwood down to the 1/2" and be done with it. After doing this a thousand times, believe me, it works. No other finished product works on top strictly 1/2' except tand g wood.
Edited 7/20/2008 3:35 pm ET by shellbuilder
SB, I agree, no T&G underlayment. I have seen the 3/4" subfloor used for the floors, but 1/2" seems light to me. I am not a flooring expert, but isnt there a minimum thickness for the flooring and nails? Even right now with the PB underlayment the floor seems kind of spongy. I know PB has no strength at all, but you still have over 1" of nailing. Are you saying the laminated flooring or solid wood flooring both will be ok with the 1/2" subfloor? Also do you use the rosin paper or roofing felt? I just havent seen many homes built with 1/2" subfloor, we have always used 3/4" T&G. Thanks for the info.
Edited 7/20/2008 6:53 pm ET by wood4rd
I framed house for 20 years using 1/2" subfloors and pb over them. We don't use it anymore but the oak will not flex over 1/2". I pomise. I have built hundreds of houses and additions like this. I am only prescribing unfinished t&G oak. I've always used felt. 1/2" plywood subfloor without an underlayment above is worthless except with t&g floors. It wont hurt to double the floor but all those layers of wood are screaming for squeaks.
If I can chime in here;
As a general rule, on new const. I prefer 3/4 Advantech for ul, and had a few " spirited" discussions debating whether or not 1/2 " ply is sufficient for t+g oak. It is.
Look at it this way; houses were built with (very) solid floors for 100's of years with boards alone, sometimes t and g some not, some diagonal to joists, some perpendicular,etc,etc. Full 3/4 oak t+g gives an enormous amount of solidity by itself. The 1/2" ply is something to nail it to :). And yes, it's not my first choice, but I have done it in cases where due to floor heights etc. matching up in an addition,leaving the existing 1/2"( subfloor) was a necessity, and I promise you can't tell where the old floor stops and the new starts. All of this obviously depends on the floor joists being sufficient for span, spaced ok, etc. Check out photo paper for the anti-squeak paper, too. Everybody reputable in my neck of the woods has switched to it.
Edited 7/20/2008 9:19 pm ET by Bing187