Fear of water vapor when installing hardwood floor

Q: Our house was built in 1976. I am unsure of how thick the slab on grade is, but my wife is concerned about the emission of water vapor now after cruising the internet as I just started to lay down the hard wood floor. THANK YOU INTERNET, THANK YOU. Before I go any further, I need some re-assurance to ease her worries or a slap on my wrist with re-education to what I have been taught.

My preparation:

1) Carpet in living room and hallway removed to expose the concrete slab. No cracks were visually present and no visual defects with the exception of about 40 years of spill stains that washed right up.

2) Vinyl tiles in kitchen and dining room removed to expose the concrete slab. The tiles were not terribly difficult to remove, but it was quite a job with pry bars and scrappers.

3) 3/4″ tongue and groove OSB was laid down and ram set into the concrete with about 16 to 20 nails per sheet. 2 weeks exposed to allow the moisture levels to equalize to the relative house levels.

4) #15 roofing felt rolled over top of the sub floor.

5) 700 sq ft of reclaimed 3/4″x 2-1/4″ hardwood flooring moved into a neat stack in the living room and allowed to sit for 1 week before installation began. About 80sq ft of floor laid down so far.

Insert Internet fears here and I will now list my findings of readings from different methods of moisture readings.

1) Plastic sheet method – 18″x18″ plastic sheet was laid down on the concrete and taped down around the edges using t-rex tape. To further seal, I sprayed the edges of the tape with hair spray.
*Result – Removed the plastic 24 hours later to reveal visually dry concrete and plastic with no signs of water droplets on the plastic and no color variance between the covered and exposed concrete.

2) Moisture Meter – A moisture meter was then purchased and readings have been taken from every room after re-exposing the concrete in spots.
*Results over a 2 day period:
DAY 1
Doorwall in kitchen – 10.2%
Dining room – 9.8%
Living room – 9.2%
Hallway – 8.9%
Bathroom – 7.6%
DAY 2
Doorwall in kitchen – 10.9%
Dining room – 10%
Living room – 9.6%
Hallway – 9.1%
Bathroom – 8%
Now that I have a new toy, I have been testing the moisture percentage in everything I can. The upper cabinets have a moisture percentage of 10.7%. The OSB sub floor fluctuates between 3.6% and 4.8%. Hardwood floor is 5.9%. Now having the meter, I will do another plastic sheet test and then take a reading directly after pealing the plastic up.

3) My next test is to purchase a hygrometer and then seal it under plastic for a few days and take the RH readings while it is sealed under the clear plastic.

I do not know what the exact RH of the house is because I do not have the hygrometer yet. We do have a humidifier that is turned off during the summer and has recently been turned on for the winter and set to the lower end of the comfort level setting. I have been through a wide variety of the building trades throughout my employment history, but with all my experience and knowledge, my points of the argument does not ease her mind.

Husbands point of the argument:

1) If there were a high abundance of moisture vapor, the kitchen tiles would not have been so hard to pull up.

2) What is the point of laying down 6ml plastic over the concrete when I am going to put thousands of holes in it from the flooring spikes?

3) If there is a problem with cracks in the slab with an abundance of water coming through, your floor covering doesn’t make a difference. your problems are bigger than she realizes and a 6ml sheet of plastic is not a magic layer to protect.

ANY advice on my current situation is more than welcome!

A: I agree with husband. You’ve not seen any evidence of moisture anywhere. Not on the carpet or tile. Not on the OSB. Not with all your tests. I think it is safe to say, your concrete does not have a river running under it.

Super seal water proof membrane

Q: There are new products out there, designed as sub floor material (ex: Super Seal) to be used instead of the typical plywood sub floor. These are cheaper and easier to install than plywood, but are they as good as plywood?

A: Super seal is a water proof membrane, not a sub floor. I would think this would be used in conjunction with plywood on concrete/below grade installations.

Should I give couple of weeks for wood (installed over concrete) to expand before finishing?

Q: I am in the process of installing hardwood floor with 3/4 plywood nailed down to concrete and 3/4 red oak stapled on. I have been running the heater at 80 degrees for past 10 days. How long should I wait before I start the finishing process such as sand, stain and seal?

I was told that, I should give couple of weeks for the wood to expand before finishing it.

A: I hope you checked the concrete for moisture seepage first, and that you had the hardwood on site, in the area to be installed for a week or more to allow it to adjust to the climate of the space. If you did these things there shouldn’t be appreciable expansion.

If the basement is not really dry then you are going to have a problem. No hardwood manufacturer will warranty solid wood installed below grade.

Stains and coatings will also likely be slow drying also regardless of how hot the air in the room is because the concrete slab is cold and that transfers up into the flooring.

Floor you can coat but doesn’t need nailed down

Q: I am installing a dance studio floor. The owners have a laminate in one of their studios but it is hard on the dancers shoes. They would like some type of floor they can put a topcoat on, but we cannot nail the floor down. It will be going over a tile floor. Any suggestions?

A: I’d probably look at an engineered floor with a click joint for installation so it floats. See what Torly’s or Quick Step has to offer.

Soft cushion-y underlayment?

Q: I am looking for an inexpensive real wood flooring that might be a good bet in Salt Lake City, Utah. I DON’T want really hard stuff that won’t get beat up. (I would prefer a “worn”, very informal, cottage-type look!) All the info I can find relates to hardwood, so I guess this is a strange idea. But if I don’t spend a fortune on the wood, I can always re-do it in 10 years if I want better wood by then, right?

Also, is there any kind of under-flooring moisture barrier that we can install that would also help give wood flooring a softer, more cushion-y type feel so it’s not as “hard on feet”?

A: I’m rather partial to quarter sawn white oak. You might want to contact Timberline Hardwood Dimensions in NY state to see how their prices are. If you wanted something softer, you might be able to get pine or similar from a local mill cheap.

Cork or other sound barrier underlayment can be installed to soften up the floor some, but I wouldn’t call these moisture barriers.

Installing so two rooms transition at the same level

Q: I have laminate tiles in my mud room. I want to replace with tile. The room is next to hardwood floors (kitchen) and I would like to have the transition at the same level as the kitchen floor. What do I have to do to the subfloor of mud/laundry room? How thin could it be to withstand the weight of washer and dryer and sink?

A: If the floor in the kitchen is 3/4 thick you would probably have to peel off the mud room down to the sub floor. Then the concrete-mesh or which ever base method is used for the tile is about half an inch and the tile is 1/4 to 3/8 thick – and that should get you very close to the same level.

Clean off the varnish from the top side of the tongue of salvaged boards?

Q: We salvaged some 7/8 quarter sawn, hard pine flooring. We would like to know how to clean off the varnish from the top side of the tongue edge of the boards? We have a scraper, however we are wondering if there is any easier way, as it seems that the varnish has turned to cement.

A: I would think if you have a router and router table with a straight bit, you could set it up so it will cut up to but not remove any of the tongue. Once it is set up, you can just run the boards through fairly quickly.

Hardwood that holds up to the wear and tear cats bring?

Q: I have 4 cats, 1 of which is sick and has some accidents. I am looking to replace my carpet with hardwood floors. Friends tell me hardwood will be easier to maintain and will hold up better than carpet, with pets. Can you tell me what you would recommend in hardwood that would hold up to the wear and tear cats bring?

A: I feel bad for your pets and for you, as, like us, they get old and ill and need special attention. Certainly a solid wood floor finished on site will repel accidents for the most part, if it is finished well. Avoid pre finished floors. If your situation requires a laminate, look at Torlys laminates.

Gaps due to the head of the nail not bedding all the way

Q: I am in the middle of a DIY floor using prefinished 3/4″ gunstock and using a blind hammer. This being my first time, I started in the den, but now almost done I look back and find gaps due to the head of the nail not bedding all the way.

I have been correcting this by cutting off the excess or tapping it in, but how do I fix the spots that are already too far back to pull up? I can see the nail in the gap but was not sure if putty or likewise would work.

I don’t want to call in a Pro since it is almost done (350 of the 400 sq ft). I may have a pro do the rest of the house, but now one half looks perfect and the first half is the problem zone.

A: Installing this with hammer and nail? You should have been setting the nail flush with the top of the tongue using a nail punch. It would have been much easier to have rented a power nailer firing cleats.

You can get colour matched putty for the gaps. Color-Rite comes in hundreds of shades and is easy to work with.

Should I glue wood planks together as I nail the wood floor down?

Q: Should I glue the wood planks together, as I nail the wood floor down? If it is a bad idea, what could happen if I do?

A: I don’t think it is a bad idea. Maybe not necessary. What type of adhesive are you using? How wide are the boards?

The biggest issue with a wood floor is moisture control. Control that and you won’t have any problem with expansion.

Otherwise, if the sub floor you are installing to is not the best and you want adhesive for better hold, go for it. Probably a polyurethane adhesive is best.

Will painted lines on a salvaged gym floor come off easily with sanding?

Q: I bought old, damp (kept in carport) gym floor maple. I want to refinish it. Will the painted lines come off easily with sanding? Is drying it indoors a few weeks enough?

What other problems should I be concerned about? I need to save money by doing it myself or using a hand man.

A: The only way you can really know for sure if the floor has been brought into the house for a couple of weeks and has acceptable moisture content is by getting your hands on a moisture meter. They come in models with or without pins. You should be looking for readings of about 7-9%. You will also need to make sure the sub floor is within 4% of the flooring and that the humidity in the house is at an RH that is considered your typical year round living condition.

The paint should sand off OK (be careful of lead) but whether it will leave a discolouration because the wood beneath has been sheltered from sun light I don’t know. You will just have to roll the dice and go for it, accepting that this is reclaimed wood and any marks it has are part of the woods character.

Possible to install wood flooring over ceramic tiles?

Q: Is it possible to lay wood flooring over ceramic tiles? What are the pros and cons if any?

A: The first question is how will you secure the floor?

Any floor will be as secure as the foundation it sits on. You are far better off, in spite of the work involved, to strip everything off to the original subfloor, screw down plywood if needed and then install your solid hardwood on top of that.

Related Q: I want to install a floating wood floor in my kitchen, but I don’t want to remove the tiles. Can I lay the wood on top of tile? And if so, what do I use to fill in the grout area so that it’s level?

A: I don’t think the grout lines would be a problem. Just install the recommended foam padding first.

Best weather, temperature, and humidity condition to install wood flooring?

Q: What is the best weather/temperature and humidity condition to install hardwood/engineered floors?

A: That is a tricky question and I don’t think there is any one correct answer. It depends on the general climate where you live for one. If you are most comfortable at 75F with 45% RH IN YOUR HOME then acclimate the flooring to that and try to maintain that environment as closely as possible year round.

If the flooring is installed, for example in very high humidity conditions in summer (even if it is acclimated to that) when the heating season arrives, the furnace kicks in and the RH in the home now becomes 30% or less, the floor will shrink and probably significantly.

If you install the floor in winter, during heating of the house and the RH is very low, in summer if humidity is high the floor will expand and if an expansion space has not been allowed at the walls or if no effort is made to lessen the humidity, you will have a problem with cupping.

Vapor barrier on second floor?

Q: I’m installing 5/8 engineered hardwood floor on second floor over 3/4 plywood. These are 7 1/2 planks. Do I need to install a vapor barrier? We are nailing it with 1 1/2 inch L cleats. Is this workable over floating the floor or gluing it? How does a wood floor expand when nail tight to a plywood floor? How can it move without the plywood moving?

A: Well, the product is engineered which means it is suppose to be, because of it’s construction very stable. You should not need a vapour barrier on the second floor. In fact, if it is nailed down and you are punching a thousand holes through such a barrier, how can it be a barrier? As to specific installation instructions, there is so much variation from one product to another, it is best to follow the recommendations of the manufacturer.

Solid wood floors are more of an issue in significant humidity swings than engineered. And some species are more affected than others. I prefer cleats over staples because cleats allow some stretch or expansion of the floor board. Staples are more resistant and under sever conditions can cause splitting of the tongue. The wood floor moves separate from the wooden sub floor. This is why you can walk into any given building and see gaps between boards. Expansion and contraction.

Installing in small space under the slant fin hot water system

Q: I have problem installing 3/4 x3 hardwood floor. The problem I have is due to the radiant heat slant fin. I cannot nail the starter board under slant fin. If I glue how do I press until glue dries. Need advice. I only have 2 1/4 inches of space under the slant fin hot water system.

A: You will have to have several rows installed out from the rad. Perhaps you can use wedges against the wall to apply pressure to the one row of boards. Or you can gently tap a board between the rad fins and floor board to apply a bit of pressure. Make sure you use a flat, not bowed board. And I would recommend a polyurethane adhesive applied to the floor if able and certainly the underside of the board you are installing.

Bad product or bad installer?

Q: Is there any reason I should expect (or accept) a floor that’s been installed (HW oak prefinished) with dings so that it needs to be filled in and stained by myself? Also it has a micro-bevelled edges and I see pieces that do not line up (or fit correctly). One of the pieces I’ve found so far has a three-inch slice missing along the fitting and you can see the subfloor.

A: That depends if these marks and defects are part of the product you purchased at reduced cost or are the result of rough handling during installation. I’ve seen some very poorly manufactured floors along the way where there was significant variation in the width of the boards. It’s an installers nightmare. So, it really depends whether the problem is the product itself or the result of what the installer did or didn’t do.

Raised/heaved concrete at joint of two concrete slabs inside

Q: How do we fix this problem: old house, original owners extended a patio and made an enclosed sunroom and tiled it. Where they poured the addition, meeting the original concrete, it has raised and split the tiles.. at the joint of the two concrete slabs inside our house. How do we fix this?

We think we should take out the tile, clean and fix the joints, put down a plastic barrier against bugs, then install a floating wood floor. What are your suggestions?

A: I think you will have to pull the tile and find out why that area has heaved.

To install a laminate or engineered floor the substrate must be very near dead flat and you will need to make sure you don’t have moisture coming up through the concrete.

Good quality products such as those from Torly’s and Quick Step have their own pad that must be used. I would check their site for installation recommendations of their products.

Contractor used white oak instead of red oak for repairs

Q: We recently had some remodeling done in a house that we just bought. The entire house has beautiful wood floors with walnut inlays dating from the late 30’s. In building the master suite, some new wood was needed to cover areas that had been carpeted in a previously-built addition. The color does not match very well, and the contractor simply claims to be surprised that it did not work out as well as he planned.

I asked a flooring specialist to take a look, and he claims that the contractor used white oak instead of red. Can I assume that any flooring pro could tell the difference upon inspection, and that it’s fair to say that I can confront the contractor with those facts?

A: An age difference of 70 or more years is bound to show a difference in colour, with the older boards generally darkening.

White oak and red oak are simply not the same colour and a flooring professional would or should know that. A lot of older homes also had white oak, quarter sawn, which may or may not be your old floor. This ‘cut’ shows ‘tiger stripes’ as the grain pattern rather than the heavy, sweeping grain so typical in plain sawn red oak.

If the contractor used the wrong species for the repairs or even the incorrect grade, (#1 common is a lot darker generally than select and better or clear grade) then I think it is fair to say he should be made aware of it and make the correction. Especially if the floor is a natural, not stained floor.

Don’t expect a perfect colour match.