# Basement subfloor questions



## FirefighterGW (Jan 3, 2010)

I am getting ready for the next step in finishing our basement and have a few questions. All of the walls are framed at this point

1. Does the subfloor go down before or after the drywall is installed?

2. Can I put a high density foam directly on the concrete floor and then cover with t&g plywood? or do I have to strap the floor first?

Any advice is greatly appreciated


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## JazMan (Feb 17, 2007)

Hi Firefighter,

If you're a firefighter you know that water always wins in the end. 

Installing wood framing and a subfloor over a concrete slab either on or below grade then covering with floor covering is almost always a bad idea. You should never install a subfloor direct or over sleepers on a slab. Even when the slab appears to be dry, you can be assured it is not. The small amount of moisture will cause problems years later in the best of circumstances and perhaps in a short time in some cases.

Where will the moisture go if trapped under the plywood and floor coverings?

Jaz


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## 57_Hemi (Jul 28, 2010)

JazMan said:


> Installing wood framing and a subfloor over a concrete slab either on or below grade then covering with floor covering is almost always a bad idea. You should never install a subfloor direct or over sleepers on a slab. Even when the slab appears to be dry, you can be assured it is not. The small amount of moisture will cause problems years later in the best of circumstances and perhaps in a short time in some cases.
> 
> Where will the moisture go if trapped under the plywood and floor coverings?
> 
> Jaz


Just out of curiosity.... how would you recommend he install a sub floor floor in his basement ?...... (other than tile)

I dont see an issue with rigid foam board on the floor (completely sealed, taped along all joints and corners) then 5/8" - 3/4" T&G ply on top via tapcons etc etc.


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## 57_Hemi (Jul 28, 2010)

FirefighterGW said:


> I am getting ready for the next step in finishing our basement and have a few questions. All of the walls are framed at this point
> 
> 1. Does the subfloor go down before or after the drywall is installed?
> 
> ...


1. Subfloor on BEFORE you drywall..... (actually I would've had it down before the framing of the walls.....but thats me)

2. As for the straps, Are u trying to level off the floor? or is that the method ur thinking of going with to build the actual subfloor?...... 

I've seen it tons of times and my honest opinion.... I prefer a 1"- 2" rigid foam glued down (PL Premium etc) tuck tape all joints in between foam boards, corners etc etc than lay the 5/8" - 3/4" T & G board over with Tapcons straight thru into concrete slab. It is best to make sure the floor is as true as can be. 

uneven subfloor = uneven finished floor.....I've seen some basement floors dip up and down like waves....JUST HORRIBLE!

***just remember, any strapping, wood etc etc touching concrete should have some type of moisture barrier in between to assist in preventing any water from seeping into wood from concrete. hope you did that to the bottoms of your framed basement walls.***


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## epson (Jul 28, 2010)

Most basement flooring materials should have a subfloor that provides moisture protection. Ceramic and vinyl tile have other requirements, such as surface flatness and strength that are more properly addressed with specialized underlayments like cement backer board.

The subfloor structure takes the form of a grid of 2 by 3’s (called sleepers) attached to the concrete slab and covered with sheets of 5/8’’ plywood. Sleepers are usually separated from the bare concrete by some type of vapor barrier; either thick felt paper or 6-mil plastic sheeting. Here’s how it’s done:

Sketch out the floor area on a sheet of paper. Figure out how many 2’’ × 3’’ lumber boards you need for the perimeter sleepers and the length each needs to be. Then, establish how many 2’’ × 3’’ lumber boards you need for the lengthwise sleepers; these should be spaced 16’’ center on center. Last, determine the number of 4’ × 8’ sheets of plywood you need for the subfloor.

Now check your local building code for requirements on vapor barrier materials. Lay 15 lb. felt paper or 6-mil polyethylene sheeting on the concrete slab. The goal is to prevent any ground moisture infiltrating up to the underneath of the plywood, which can cause mold, fungus, rotting and bad smells, among other things. Allow approximately 4’’ of vapor barrier laying up against each basement wall as well. 

When this is done you can begin with the perimeter, laying down 2 in. ×3 in. pieces flat along the walls, immediately on the vapor barrier. Then place the 2 in. × 3 in. sleepers inside this frame. Position the first sleeper 16’’ from the wall and the rest 16’’ apart center to center. These sleepers should be installed parallel to the shortest length of the room.

Now take your level and level the 2’’ x 3’’ sleepers, placing shims underneath as needed to ensure the plywood sheets will sit flush. After all sleepers are leveled, fasten them to your concrete slab with ramset fasteners. Use these to drive 2 ½’’ concrete nails at a spacing of 24’’ apart. Trim off the excess vapor barrier along the walls with a utility knife and pencil mark the centers of each sleeper on the basement wall as guidelines for securing the plywood to the sleepers.

When this is done apply a thick bead of construction adhesive on top of the sleeper’s then lay and fit 5/8’’ thick Tongue and Groove plywood sheets over the sleepers, parallel to the shorter wall. Using as a guide the pencil marks made on the wall, screw the plywood sheets into the sleepers with 1 ½’’ ring shank or screw shank nail or flooring screws every 12 inches from one row to the next, stagger the joints of the plywood sheets. 

Creating a wood basement subfloor on a concrete slab is a DIY project that can be done by most homeowners comfortable with a mid-level difficulty project. If you are going to be installing ceramic tiles on the subfloor, be aware that you will additionally need to install ½’’ thick plywood sheets running in the opposite direction over your subfloor, or cement backer board underlayment.


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## JazMan (Feb 17, 2007)

Hemi,

You didn't get my point. A wooden subfloor is NOT recommended and is often a sure failure over a slab. Especially on a slab below grade. 

Thru the years people have come up with ways that they believe might work, rigid foam boards being just one. I'm saying it will not work if there is too much moisture under the slab and it is impossible to know at what % is the threshold of too much. BTW, you can NOT completely seal it, plus even if you could, you would NOT want to since any moisture will accumulate below and cause mold. Moisture needs to be allowed to come thru the flooring and evaporate naturally. 

You can not tell how much moisture a slab emits just by looking at it and the fact that it may have never flooded is immaterial. In addition things are always changing in a basement. 

There is no approved method that uses the method you describe.

Jaz


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## JazMan (Feb 17, 2007)

Epson,

Please refer us to the method & specs you just described as being approved by any reputable association of organization that specializes is flooring or even general construction anywhere on earth. Handymen maybe, but not flooring professionals. 

You won't be able to do that. It may work for some time in some situations, but it's more likely to fail long term. BTW, sometimes things fail to a degree, but the homeowner may not realize it or complain about it.

HUH? CBU on a slab? And you suggest running the second sheet of ply underlayment parallel to the joists? :no:

Jaz


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## epson (Jul 28, 2010)

JazMan said:


> Epson,
> 
> Please refer us to the method & specs you just described as being approved by any reputable association of organization that specializes is flooring or even general construction anywhere on earth. Handymen maybe, but not flooring professionals.
> 
> ...


I have used this method many times and had it inspected by the city with no issues. I just finished this type of set up two weeks ago with the same results.

As per running the second underlayment I said run it in the opposite direction to stager the joints.


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## retired guy 60 (Jun 23, 2009)

I too have seen many home improvement shows on television that show a plywood floor put over sleepers which in turn are placed over a vapor barrier. I think that the sleepers were pressure treated, if I recall correctly. 
Now, I do not wish to add fuel to the fire but I have two questions. Many concrete floors expel a certain amount of moisture and there seems to be no dispute over this. Therefore, that leaves us with the question as to what happens to the moisture trapped between the vapor barrier and the concrete floor. The second issue is whether the holes made in the vapor barrier by nails through the sleepers that attach the sleepers to the concrete floor will have any effect on the ability of the vapor barrier to block moisture.
Many years ago I put up furing stips on cinder block walls in order to finish the basement with wall paneling. I used masonary nails made for the job. Little did I know that masonary nails are prone to rusting so that 19 years later the totally rusted nails (not all but plenty) left perfect holes for water to slip through after a heavy rain. I bring this up because if the nails used to atttach the sleeper rust though, the sleepers will not be securely attched and also because with any home project you should always consider whether the project holds up not just tomorrow but over the long haul.


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## Aaroncarpet (Aug 26, 2010)

The concrete in your basement is the subfloor......You may need to skim coat it for various products....but you need to know the annual humidity variations to know what type of products are suitable... fastening a studded wooden subfloor below grade is not a smart idea....better to work directly over the slab......if you pass certain moisture tests you can glue an engineered floor directly to the slab....if you have flood moisture issues it will be easier to repair than a rotten studded subfloor and damaged flooring material...If you really insist on instaaling like a plywood subfloor...


use pressure treated 2 x 2 and fasten it with masonary screws.


BTW I read Epsons and it sounds good...dummy heat vents and gapping of sleepers will help protect you from moisture building up underneath the plywood and causing delamination
use a good 5/8" plywood... and put in some "Dummy" 4x10 floor vents so that air can travel below the plywood. stagger gaps in your studding so that air travels freely underneath the wood....And buy a good quality dehumidifier to control the moisture percentage in your basement


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## 57_Hemi (Jul 28, 2010)

retired guy 60 said:


> I used masonary nails made for the job. Little did I know that masonary nails are prone to rusting so that 19 years later the totally rusted nails (not all but plenty) left perfect holes for water to slip through after a heavy rain. I bring this up because if the nails used to atttach the sleeper rust though, the sleepers will not be securely attched and also because with any home project you should always consider whether the project holds up not just tomorrow but over the long haul.



Totally true.....thats why I asked............ 

_*"How would you recommend he install a sub floor floor in his basement ?"

*_Wait until these big names & TV shows find out they are teaching people all the wrong methods.....haha

Or better yet maybe they know already and have researched that the methods they use are probably the "best solutions" for these projects..............because everyone knows nothing lasts forever, but by using thier methods Im sure it may last a damn loooong time. :wink:


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## Aaroncarpet (Aug 26, 2010)

retired guy 60 said:


> I bring this up because if the nails used to atttach the sleeper rust though, the sleepers will not be securely attched and also because with any home project you should always consider whether the project holds up not just tomorrow but over the long haul.


 They make dual threaded masonary screws witch you drill a 5/32 carbide tip masonary bit with a hammer drill..In block one should use a lead anchorsystem and not masonary nails....lead anchors work on slab too...but you better have a 300$ drill to cut the holes....


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## Gary in WA (Mar 11, 2009)

Figures #2 and 3: http://www.buildingscience.com/documents/insights/bsi-003-concrete-floor-problems?full_view=1

P.t. wood is not waterproofed, unless you buy it specifically added: http://www.greenbuildingadvisor.com...ressure-treated-sill-plates-and-building-code

Gary


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## rusty baker (Feb 13, 2009)

Many stores have signs on P.T. wood that says "not to be used indoors" in fact it violates code here.


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## Aaroncarpet (Aug 26, 2010)

I personally think studding and sub flooring below grade slab is a big mistake when there are plenty of materials that can go directly over the slab....plus we have codes about gnomes out here ....I am not disagreeing with you rusty...if you have to use another wood make sure you prime all the lumber with oil/petroleum base primer...It will protect the wood incase you have more moisture than expected......besides, everything is outdoors, we just have a few walls and doors and a roof to give us the facade of protection. In my opinion, everything is outdooors....


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## retired guy 60 (Jun 23, 2009)

"I personally think studding and sub flooring below grade slab is a big mistake when there are plenty of materials that can go directly over the slab......"

I could not agree more. I just put down ceramic tiles in my basement using thinset right over the cement with no worries about sleepers, plywood, cement backer board, mold, or moisture. Last year I did one small room in the basement the same way and the tiles look good and are perfectly secure. Why look for extra work and risk moisture problems using wood or laminate when ceramic works fine (unless you hate ceramic for some reason)? Prior to this I had glued down carpet and it was nothing but a dust magnet. Plus when it got wet it held water like a sponge.


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## Aaroncarpet (Aug 26, 2010)

well its one thing to get carpet wet, and another thing to have a moose pisss in your basement....strange things happen in moose territory.....I was once paddling in a river and spotted what I thought was a log.... 10 seconds later a moose shriveled out of the river bed and the "log" was antlers


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## Aaroncarpet (Aug 26, 2010)

Jazman....don't worry, you won't have to repair it......I come from Michigan... I know about the basement.....better off to tell em its gonna be fine.....more money for the trades...If you are going to pay me to do a bunch of stuff that doesn't work, I'll take the money , I'll be in California by the time its all screwed up....

BTW Jazman ...are you familiar with Fairway Tile and carpet in Clawson MI....down the road from you on 14 mile.....that's where I learned to install


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## CyFree (Jul 22, 2008)

*My two cents...*

Because we've been working mainly with basements for over 20 years and that is the bulk of our business, I believe we have a pretty good idea of what works and what doesn't.

We ripped enough rotten wooden floors, subfloors and moldy carpets to know one thing... none of them work.

JazMan might not have expressed himself as successfully and he expected but he is correct when he says that you should not use wooden subfloors, furry strips over the slab. 

Actually, if you want to finish your basement and never have to do it over, you should avoid everything that is made with organic compounds, because basements, even when they look dry, always have some level of ground moisture infiltrating the below grade walls through capillary action. 

Combine that moisture with wood and organic materials and you have the perfect conditions for mold and rot to develop.

Placing a poly sheet as vapor barrier straight against the slab will not help much, because it will only trap the moisture underneath and there is no saying what will happen under that poly sheet overtime. 

Furthermore, according to recommendations issued by the U.S. Department of Energy in its Building America's Best Practices series, basement walls and slab should be allowed to dry to the inside of the basement, somehow.

In addition, keep in mind that a vapor barrier would only address the moisture from the slab. But basements get water from more sources than that. Think plumbing leaks, sump pump meltdown, leaky water heaters, burst washing machine hoses, an accidentally overflown toilette. 

Any of those things happen and you will have a stinky and very moldy basement because, according to the Environmental Protection Agency, any organic material that doesn't completely dry in 48 hours will develop mold.

And when that happens, also according to that agency, you will need to rip it all off and discard because there is no 100% effective way to remove mold from things like wood, carpet, paper, cardboard, fiberglass and drywall.

So, what is the alternative? There is, of course, tile and stained concrete.

But if you are looking for something warmer, more affordable and less messy to install, I recommend you look into flooring options that are specifically engineered to work with basements.

They are mainly floating floors, (tiles and laminates) with interlocking features. They can be removed and replaced as needed. They are 100% inorganic and 100% waterproof. They have vapor barrier that, along with the finished surface, is raised a few centimeters from the floor by a system of channels or pegs that will allow the air to circulate underneath and dry the slab, as recommended by the Department of Energy, while offering moisture and some level of thermal protection as well. 

Hope it helps.


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## retired guy 60 (Jun 23, 2009)

CyFree, thanks for a nicely stated and logical explanation that makes sense.


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## Aaroncarpet (Aug 26, 2010)

I was trying to pretty much say the same thing...Hope I haven't offended anyone....


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## 57_Hemi (Jul 28, 2010)

CyFree said:


> They are mainly floating floors, (tiles and laminates) with interlocking features. They can be removed and replaced as needed. They are 100% inorganic and 100% waterproof. They have vapor barrier that, along with the finished surface, is raised a few centimeters from the floor by a system of channels or pegs that will allow the air to circulate underneath and dry the slab, as recommended by the Department of Energy, while offering moisture and some level of thermal protection as well.
> 
> Hope it helps.


Cool!

Great explination.....Thank You 

I know that helped with my previous question.......


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## rookie_diy (Sep 25, 2010)

what i gather from this discussion is that ceramic tiles and laminate should go directly on the concrete floor without even a vapor barrier???


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## adamsparkes (Sep 25, 2010)

You guys ever hear of delta membrane?
Appartently you lay in right on the concrete then attach plywood to it or you can lay laminate right on top of the membrane let me know if anyones heard of this method


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## retired guy 60 (Jun 23, 2009)

rookie_diy said:


> what i gather from this discussion is that ceramic tiles and laminate should go directly on the concrete floor without even a vapor barrier???


 Ceramic tiles are applied directly to the basement floor with thinset. Ordinary laminate is not a good choice for the basement due to water and moisture issues but CyFree indicates that there is a version that is acceptable. I am not familiar with the product he is referring to. For durability, I think ceramic is a wise choise...just my opinion.


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## rookie_diy (Sep 25, 2010)

i am doing it half and half. i just purchased 12mm laminate flooring. it is not mentioned on the box that its AC3 but the HD guy assured me that they carry nothing less than that. he also suggested that the cork underlayment was the best option for the underpad. any suggestions whether its needed or i just go with a vapor barrier???


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## retired guy 60 (Jun 23, 2009)

rookie_diy said:


> " he also suggested that the cork underlayment was the best option for the underpad. any suggestions whether its needed or i just go with a vapor barrier???"
> Cork is an organic material and organic materials are subject to mold. I think this needs to be researched. I like Home Depot but sometimes the advice offered may not be correct. Little mistakes often result in major remedial projects.


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## rookie_diy (Sep 25, 2010)

from all the comments and different opinions, seems like it is safer to just put the laminate directly on the concrete. after all, laminate is supposed to be inorganic and "engineered" to resist damage due to moisture. saves money and peace of mind...


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## Starlight (Sep 30, 2010)

Is it a good idea to use a concrete sealer in cases like this, to reduce the amount of moisture coming up through the floor?


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## rusty baker (Feb 13, 2009)

retired guy 60 said:


> rookie_diy said:
> 
> 
> > " he also suggested that the cork underlayment was the best option for the underpad. any suggestions whether its needed or i just go with a vapor barrier???"
> ...


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## 57_Hemi (Jul 28, 2010)

Came across an article from a canadian newspaper regarding FAQ on how to finish a basement with Mike holmes.........(subfloor, walls etc etc)

*EVERYONE KNOWS MIKE HOLMES RIGHT ???*

I am NOT a flooring expert by all means (never claimed to be) and have prepared some floors the exact same way explained in this article and I was told by the "professionals" that it was wrong........ok then, thats fine with me. I still feel it is a much better method than alot of other methods out there.

Anyway........I cant believe Mr. Mikey is making tonnes of $$$$ educating people the wrong way.....  


=================================================

_'How should I properly insulate my unfinished basement?" That's one of the most popular questions I (Mike holmes) get asked by readers. One, from Longlac, Ont., wrote in to ask how far he had to go down his basement wall with interior insulation. He'd been told different things by various contractors he'd had in to quote on the job — but the general advice was that he only had to go two feet below the outside grade._
_No! This is not only wrong, it will lead to problems in the long run. I guess those contractors were thinking that the temperature of soil below the frost line remains fairly constant year round. It's the upper part of your basement that has wider fluctuations in temperature._
_But it's more complicated than that, and you need to educate yourself before you get a contractor in to do the job._
_The most important thing about finishing your basement is to make sure to insulate the space properly, or you are just going to create the perfect environment for mould and mildew to thrive. Exposure to mould and mildew can lead to health problems — not the kind of thing you want your family exposed to._
_Most people think insulation is important because it keeps the basement warm in winter, but it's even more important in the summer, when heat and humidity can cause a lot of moisture to build up._
_Because basements are mostly underground, they have a unique situation with regard to air temperature. At the level of the basement floor — many feet below grade — the temperature remains fairly constant, just like the soil outside your foundation walls._
_But, as you go up toward the ceiling, the temperature will rise. The air temperature near the ceiling of your basement is always higher than at floor level._
_So, what's the big deal with that?_
_The big deal is, once you've finished your basement (if you haven't insulated properly), warm air from inside your nice new drywall will come into contact with the foundation walls behind the insulation. Warm air holds moisture, and this moisture will condensate when the air cools as it comes into contact with the cold exterior wall. This moisture will collect in your insulation, in your wood framing, and even pool at floor level behind your finished walls. Mould spores — which are everywhere — will flourish._
_And, no matter what, if you insulate your basement the same way you do an above-grade wall — using wood studs against the wall, with batt insulation in between and vapour barrier over that — you will have air movement and problems with condensation, and very likely, with mould._
*I recommend you use rigid foam insulation against all the outside walls and the floor — two inches thick on the walls and one inch thick on the floor. This foam comes ship-lapped, so each piece fits snugly against the next with no gaps.*
*Be sure to glue the foam to your walls and floor with an adhesive that is rated for use on foam, otherwise it will ruin your insulation. Each seam should be tuck-taped, and spray foam used to fill any gaps around the edges.*
_*Then, install studs over the top of the foam layered walls and 3/4" tongue & groove plywood over the top of the foam layered floor and finish your basement.* I'd recommend using mould-resistant drywall as well. (All rigid foam insulation is mould and mildew resistant and won't hold moisture, even if you have a flood in your basement.)_
_What this will do is create a thermal break between the air inside your basement and the air outside. It will eliminate any air movement behind the walls that could lead to condensation._
_Think of it like a beer cooler — they are made of rigid foam insulation. It might be a hot sunny day at the beach, but inside, your beer stays cold and the ice doesn't melt. And there's no dripping condensation on the outside of your cooler either. That's what the thermal break does._
_It's the same as for newer toilet tanks — they all come lined with rigid foam to stop the annoying drip of condensation you used to get on old toilet tanks, caused by the cold water inside the tank meeting the warm air of the bathroom._
_It makes sense to finish your basement and take advantage of that extra living space — for a family room, media room or playroom for the kids. But make sure you insulate the space properly, or you are just going to create the perfect environment for mould and mildew to thrive._


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## acerunner (Dec 16, 2009)

i'm surprised nobody mentions some of the products that were designed for this purpose.

dimpled sheets: deltaFL, platon
interlocking tile: dricore, subflor, barricade

i have no arguments to which is better, but the OP wants to find solutions and these are some, in addition to the "traditional" methods that have already been mentioned.


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## retired guy 60 (Jun 23, 2009)

Mike Holmes is bright and entertaining but to me he is to contracting as the late Steve Irwin was to zoology. Both competent but neither the end all authority in their respective areas of expertise. To me ceramic tiles and thinet are a perfect finish to a ordinary basement slab. Of course this assumes the slab is sound and w/o unusual defects like a crack the size of the San Andreas Fault with a stream of water flowing through. Any other flooring choice should allow the concrete to breathe to prevent mold and other nasty problems. Just my perspective.


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## Aaroncarpet (Aug 26, 2010)

Mike holmes doesn't know about installers that have eaten their work for dinner....retired guy and Rusty have laid some floors....look at holmes.....He is a glorified salesman....his knees don't hurt....I'm about due for knee replacements after 15 yrs of installation.....


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## rusty baker (Feb 13, 2009)

Aaron, you know the old saying, "you can lead a horse to water, but you can't make him drink". Some people come on here wantng to be told that they are doing things right, when told they aren't, they don't like it.


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## 57_Hemi (Jul 28, 2010)

Aaroncarpet said:


> Mike holmes doesn't know about installers that have eaten their work for dinner....retired guy and Rusty have laid some floors....look at holmes.....He is a glorified salesman....his knees don't hurt....I'm about due for knee replacements after 15 yrs of installation.....


Im sure if anyone here had Mr.Holmes' bank account for the last 10 years the knees wouldn't be hurting as much considering they would have probably cut down (or even stopped) with the physical labour by now. 




rusty baker said:


> Some people come on here wantng to be told that they are doing things right, when told they aren't, they don't like it.


Care to elaborate ?
Anyone in particular you referring too ?


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## rusty baker (Feb 13, 2009)

Holmes is like most TV contractors. "Jack of all trades, master of none." A modern day Bob Vila. Growing up I worked for my father, a GC, who did everything. In those days, we poured the foundation, framed the house, did the plumbing, electrical, drywall, everything. When I finished my military time, I started doing floors. So yes, I know when someone on here or on TV doesn't have a clue. And I see a lot of it.


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## 57_Hemi (Jul 28, 2010)

I see...........

I've also encountered (and know) tons of "professionals" out there whos work I wouldnt recommend to a single person out there....even if they were last contractor standing. Heck! some of them call themselves professionals just because they've been doing work for years & years & years. 

I simply say just because you've been doing it for a long time dont mean your doing it right.........and unfortunately alot of times that is the case.


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## rusty baker (Feb 13, 2009)

Holmes, Vila, Dean Johnson, Norm, they all do some stuff wrong.


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## Starlight (Sep 30, 2010)

retired guy 60 said:


> ....To me ceramic tiles and thinet are a perfect finish to a ordinary basement slab..... Any other flooring choice should allow the concrete to breathe to prevent mold and other nasty problems. Just my perspective.


I have a slab on grade downstairs room that I had to remove the wood floor from due to mold/fungus decaying the 50 year old wood. There was no sign of water intrusion, but a drop cloth left on the concrete floor for a few days is a little bit damp. I've killed the mold/fungus, patched the small holes left by breaking out the masonry nails [which held 2x4 sleepers]. I plan to put Pergo flooring down. 

Do you think I should use a concrete sealer to keep moisture down? 

Pergo recommends that I use a vapor barrier and nothing else. I'm inclined to seal the concrete, put down ridgid foam insulation and Pergo on top of that.


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## rusty baker (Feb 13, 2009)

With sealer, moisture can accumulate, gravitate to the edges and wick up the walls.


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## acerunner (Dec 16, 2009)

rusty baker said:


> With sealer, moisture can accumulate, gravitate to the edges and wick up the walls.


how about densifiers or epoxies? Are those any good at controling moisture? Is there such a product that can seal the moisture well enough to the point where you can freely put down any flooring material you want?


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## retired guy 60 (Jun 23, 2009)

I installed Pergo Accolade laminate in my upstairs bedroom and it was inexpensive, easy to install and looks really nice. This product has a foam-like pad on the bottom surface and does not require anything additional . Like all laminates refinishing is not possible so when my HVAC guy dropped a tool, the only way to repair the damage was to replace the board which was fortunately at the end of the run. I would never install this product in a basement where there is any dampness or the possibility of a water leak. The Pergo I used seems to have a masonite base under the laminate surface and this material will swell from dampness and absolutely self destruct from standing water. 
Now a bit of trivia. While the television home repair and renovation personas that are popular today such as Holmes, Johnson, Abrams might make a decent living, Bob Vila was only earning a high school teacher's salary way back when. After he became a spokesman for Sears Craftsman tools to boost his income, the producers of the show felt there was a conflict of interest and when they could not come to a compromise they gave him an ultimatum. That was the end of Bob Vila's role on This Old House.


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## Bud Cline (Mar 12, 2006)

> Is there such a product that can seal the moisture well enough to the point where you can freely put down any flooring material you want?


NO!

Boy, that'll get an argument going I suppose!

Basement concrete floors are always susceptible to rising moisture. Moisture is always present to some degree. A natural phenomenon is for moisture of this type to seek evaporation. To evaporate, it must rise. Trying to seal it [in] isn't at all practical in most cases. For long lasting results without mold and mildew a floor must be allowed to breathe (evaporate). Tile is the most practical application for the promotion of overall uniform evaporation of the substrate.

If a tarp left on the floor has resulted in moisture on the tarp, then there is moisture in floor.


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## retired guy 60 (Jun 23, 2009)

Bud Cline said:


> NO!
> 
> Boy, that'll get an argument going I suppose!
> 
> ...


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## Bud Cline (Mar 12, 2006)

> *Isn't it possible to waterproof a slab at the time it is poured either by putting a vapor barrier below it* or laying out a barrier so it lies midway within the slab?


Moisture barriers below a slab have their issues and questions as to their life-expectancy have arisen over the years. Some of that poly is biodegradable over time. Some guys swear by the process and others wouldn't touch the idea with a ten foot pole. I suppose region of the country also enters into it.



> Isn't it possible to waterproof a slab at the time it is poured either by putting a vapor barrier below it *or laying out a barrier so it lies midway within the slab?*


Never heard of that! That's not to say it may or may not have some merits. Sure would change the definition of "monolithic".

This kind of stuff is really arguable in a place like this. I have my own thoughts on the subject but that doesn't make me an engineer.


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## acerunner (Dec 16, 2009)

Bud Cline said:


> NO!
> 
> Boy, that'll get an argument going I suppose!
> 
> ...


that's what i thought. But if there's a way to control the path at which evaporation occurs. For example, as rustybaker states, moisture will gravitate to the edges, so you can then vent moisture away there where it would be much easier to do that when moisture is coming up through out the floor.

as for tile. I'm not convinced thats a fool proof solution. Over the weekend, I pulled up the tiles in my foyer that was laid directly on concrete (slab on grade). A lot of it was very easy to pull up because the mortar had become separated due to mold.


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## Bud Cline (Mar 12, 2006)

> For example, as rustybaker states, moisture will gravitate to the edges, so you can then vent moisture away


Yow-well, good luck bringing that theory to fruition. Rusty is correct but what happens to the moisture as it is en route to the edges? The substrate turns into farmland - that's what. A perfect place to grow crops of fungus.



> as for tile. I'm not convinced thats a fool proof solution.


It is the only fool proof solution. Evaporation would be naturally occurring throughout the entire area through each and every grout joint. Are ya kiddin' me?



> Over the weekend, I pulled up the tiles in my foyer that was laid directly on concrete (slab on grade). A lot of it was very easy to pull up because *the mortar had become separated due to mold*.


No-no-no-no-no! That's not how it works. The mortar had become separated for other reasons giving mold an opportunity homestead the voids. There are any number of reasons why the mortar may have separated but mold isn't one of them.


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## Bud Cline (Mar 12, 2006)

By the way......
Your front door has a leak. I can see it from here.


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## acerunner (Dec 16, 2009)

Bud Cline said:


> Yow-well, good luck bringing that theory to fruition. Rusty is correct but what happens to the moisture as it is en route to the edges? The substrate turns into farmland - that's what. A perfect place to grow crops of fungus.


 U are right, it is just a theory i was curious about. I will likely have many questions & theories as I try to understand the whole issue of moisture-concrete-flooring.

Relating to moisture enroute to edges, is that not the same idea behind tiles? What happens to moisture under the tiles enroute to grout lines? Shorter distance, true, but still traveling in the same form, whether it be moisture in a vapor phase or liquid phase.



Bud Cline said:


> No-no-no-no-no! That's not how it works. The mortar had become separated for other reasons giving mold an opportunity homestead the voids. There are any number of reasons why the mortar may have separated but mold isn't one of them.


what are some reasons, and how can they be prevented? I plan on retiling that area, so i'd like to know what to watch out for.


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## acerunner (Dec 16, 2009)

Bud Cline said:


> By the way......
> Your front door has a leak. I can see it from here.


quite possible, but not sure that's the reason.

The front door is inset from the front face of the house. The door never sees rain directly.


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## Bud Cline (Mar 12, 2006)

> Relating to moisture enroute to edges, is that not the same idea behind tiles? What happens to moisture under the tiles enroute to grout lines? Shorter distance, true, but still traveling in the same form,


OK, now you are over-analyzing this whole thing and maybe yanking my chain just a little.



> what are some reasons, and how can they be prevented?


Use a better quality tile thinset mortar next time and this time follow the directions on the bag.



> The front door is inset from the front face of the house. The door never sees rain directly.


And I suppose the wind never blows either!


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## acerunner (Dec 16, 2009)

Bud Cline said:


> OK, now you are over-analyzing this whole thing and maybe yanking my chain just a little.


I'm not yanking your chain, at least not intentionally. Yes I admit, I do tend to over analyze things. I like to understand the science of things. articles on buildingscience.com are the type of explanations that get me to go "Ooooh, i get it now". There was one article on this topic that said epoxies or dimpled membranes are "bullet proof" solutions, and tile & grout is a good solution but will not work on slabs with high vapor emissions. Of course science lab results and real-world results do no always match, so I'm curious what you think.




Bud Cline said:


> Use a better quality tile thinset mortar next time and this time follow the directions on the bag.


 Tell that to the previous owners or contractor. 



Bud Cline said:


> And I suppose the wind never blows either!


It's inset maybe about 6ft. Even on the windiest storms, the bottom of the doorway barely gets splashed.


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## 57_Hemi (Jul 28, 2010)

> Just a question regarding this. Isn't it possible to waterproof a slab at the time it is poured either by putting a vapor barrier below it or laying out a barrier so it lies midway within the slab? I'm thinking that the slab might suffer weakness with the barrier imbeded within it, assuming it can be done.


That is a good question..........


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## Bud Cline (Mar 12, 2006)

That may be a good question but Bud Cline didn't make that post as it appears above. That question was asked by someone else and mis-quoted in the above post.


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## 57_Hemi (Jul 28, 2010)

Bud Cline said:


> That may be a good question but Bud Cline didn't make that post as it appears above. That question was asked by someone else and mis-quoted in the above post.


 
DONE!!

Dont worry........ WE KNOW that U KNOW what ur talking about.

(I quoted from a post that had quoted you first. Therfore your name was posted up top......)


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## acerunner (Dec 16, 2009)

Bud Cline said:


> That may be a good question but Bud Cline didn't make that post as it appears above. That question was asked by someone else and mis-quoted in the above post.


so budcline, what is your opinion on that question? I have my theories on it, but since all my theories have been shot down, I'm curious to know what you think before I answer.


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