engineered wood laminate flooring

[ajk1]

I am investigationg a recently installed engineered wood laminate flooring in a 30 foot x 90 foot room, on top of the slab-on-grade. The woood laminate has buckled in a few locations. The slab on grade itself has been in place for 45 years. The wood lamiante flooring was installed in about February and the buckling was noticed about 2 weeks ago. Location is toronto Canada. The laminate wood is not adhered to the slab. I suppose if the wood absorbs moisture from any source, it will expand, and if installed tight with no expansion space, it will buckle when force > Euler buckling load. Could the air conditioning be the cause, in that it increases the relative humidity (although it decreases the absolute humidity) when the air is cooled?

Anyone had any experience with this type of wood, its engineering properties and behavious, and what most probably is the cause of the buckling?

 

[MikeHalloran]

Were the laminate manufacturer's suggested practices followed?

E.g. is there a foam underlayment or other barrier between the laminate backing and the concrete?



Mike Halloran
Pembroke Pines, FL, USA

 

[hokie66]

Floating flooring has to have an underlayment as Mike said, and it also has to have gaps at the edges. It is standard practice to conceal this gap with a molding.

 

[Ron]

ajk1....as others have noted, probably restraint of expansion. If the material has a wood veneer facing, you would likely see "cupping" if the moisture content were high. If truly a laminate surface, you won't likely see that.

Yes, the AC can be a culprit. If the flooring created a "barrier" on top of the concrete or even a change in the thermal gradient of the floor, then the ambient moisture within the concrete could condense at the bottom of the flooring, causing it to expand.

 

[ajk1]

Thank you all very much for these very useful comments. I will follow up and see if I can find the answers to these points. I did not specify the flooring or have anything to do with its installation, but I have been asked to investigate and recommend what to do now. I may have some follow up questions.

I was going to carry our an ASTM D4263 test to check for moisture permeation from below the concrete slab. This may tell me if the source of the mositure is from below the slab or from the ambient air in the room. The 6" slab on grade is very old (45 years) but there was a flood in the building last November when a buried water main broke, and perhaps it takes a long time for the soil below the slab to dry out, although the insurer's contractor brought in large fan heaters and ran them for several weeks to dry out the building right after the flood.


Ther original drawings for the building in 1966 specified a polyethylene sheet under the concrete slab, so this may act as a vapour barrier yo some extent if it was not ripped during the original construction.

On top of the concrete slab was placed a "Granwood" flooring in 1966 in the original constrcution. That is in excellent condition. The new lamianted wood floor was placed on top of the Granwood in February 2012. There is a relatively small part of the floor where there was no Granwood; here a plywood layer was installed just before they placed the new laminated wood floor. This is reportedly one of the worst areas for the buckling, but I have not yet seen it...am going there to see late this morning.

 

[Ron]

ajk1....if there was flooding, there is likely a lot of interstitial water remaining in the concrete. Generally, unless saturated and no vapor barrier, the soil is not the issue with respect to upward vapor migration/condensation.

 

[ajk1]

I am told that the wood laminate flooring has an underlayment and that an expasnion space was provided at the walls. I am headed there this morning to see it.

Any suggestions on:

a) what investgation I should carry out and
b) what remedial measures might be appropriate (this may depend in reuslts of any investiagtion)
c) do you think that it will have to be a matter of replacing any buckled boards when they occur?

 

[TehMightyEngineer]

Because it was installed in February (low temp and humidity) and then buckled in June leads me to believe that they didn't allow for proper expansion.

But, like others have said, it's either a moisture issues or an expansion issues. Check for both and see what you can see. You can then move on to remedial measures.

As for replacing boards, that depends on the board and the client. I assume that these boards are tongue and groove. Is it easy to pull out large sections of boards and put in new ones or are they going to have to cut some out? If you have to cut them then a lot of flooring people will just tell you to rip it out and start again.

Maine EIT, Civil/Structural. Going to take the 1st part of the 16-hour SE test in October, wish me luck!

 

[dicksewerrat]

Did the installer let the new flooring sit in the building for a couple weeks before they installed it?

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[ajk1]

In my inspection this morning, I found that they in fact did not leave a gap between the end of the flooring boards and the wall, or at best it was only 1 or 2 mm gap. This is much less than the manufacturer's literature which says the gap should be 15 mm. They have now removed all the baseboards and are correcting this by cutting a piece off each of the floor boards!

The laminated flooring is comprised of :
- an aluminum oxide surface printed on high density finreboard (HDF)
- HDF
- stabilizing layer on the bottom
- locking assembly system between boards

Looking at the end when I break a board in half, it looks really flaky. Anyone had any exerience with this stuff?

I am going to weight it, submerge it for 12 hours, then weigh it to see what percentage moisture it picks up.

I can also take a piece that was lying in the room on site and weigh it, then microwave dry it, the weigh it again to see what its moisture content is.

Do you think these might be useful tests?

 

[Ron]

ajk1...yes, I've seen this same type of board. I have experienced it buckling from both lack of spacing and moisture. It is highly susceptible to moisture gain.

Don't use a microwave for the moisture content. Use a drying oven if available or your oven at home on low temperature (preferably below 150F). Hopefully your scale is accurate, with a resolution at least to 0.1g. The equilibrium moisture content of the fiberboard part of this material is fairly low, but not zero.

 

[ajk1]

Ron - thanks for the advice. Any suggestion as to how long I should dry it in the oven? And how long I should leave ot soak to determine its absorption?

 

[ajk1]

My electronic digital scale is calibated in gramd,not 0.1 grams, but I have specimens that weigh 350 grams so that should I think be ok. I have smaller speciemns tsat weigh 8 grams but based on what you say, I think I should not use them in the test.

Can you help me understand the equilibrium moisture (EMC) content? Does it depend on the RH and temperature of the ambient air?

If the EMC is say 5%, and the actual mositure content of the specimen taken from the floor is found to be say 10%, what is the practical meaning of that? Does it mean that the speciemn is absorbing moisture from the surroundings and will continue to do so ubtil the surroundings are changed?

 

[hokie66]

The quality of these floating floors varies a lot. Generally, you pay for what you get. My neighbor had some cheap flooring which was ruined when his dog peed on it.

 

[RFreund]

ajk1 - attached is some basics on moisture content that I received from woodworks at one of their seminars. They don't seem to give an equation for EMC but they do give a definition. I'd be curious to know exactly how the values are found in the table (I should have asked).

EIT
www.HowToEngineer.com

 

[ajk1]

Thanks How To Engineer- The EMC moisture content table is aklso in The Canaf=dain Wood Council Handbook, which I had read prior to your email, but what you sent includes some worked examples which are always useful. Thank you.

 

[Brad805]

I am a little perplexed. Laminate flooring using a HDF core is not a high end product, and if the installer did not install per the manufacturer's recommendations and there is no excess moisture coming from the slab for some reason, then I don't follow why a structural engineer is investigating this. Laminate flooring does not really require any acclimation time before install because the HDF core is a stable product so long as you do not soak it. HDF is used because it is cheap, easily machined and is about the flattest products you can find. There are literally hundreds of these discussions on the fine homebuilding site, woodweb, and examples of poor installations can be found in Charles Peterson's hardwood flooring book. Charles is an engineer and is very knowledgeable when it comes to this. I build Medallions and engineered flooring (hobby) and have done tests before fabricating in my vacuum press. I do not use either MDF or HDF in my work because if moisture is ever a problem it is difficult to salvage.

This seems like a case where you get what you pay for. Cheap product and installers = problems.

 

[ajk1]

Thank you Brad805 for this information. A structural engineer (me) is investigating because this is a place of worship and I am a member there and was asked what should be done now. The actions and principles are similar to the effects that structural engineers deal with daily, whether they are designing wood or concrete and must consider the effects of shrinkage and expansion, so it is not totally illogical to have a structural engineer involved. Of course it would likely be better to have someone who has a lot of experience with laminated flooring but we don't have such. The information that you have provided is interesting. Thank you again.

Are you aware of buckling having been caused by the air conditioing? The buckliong occurred on a weekend when the room was full of people and the air conditioning was on that week. The air conditioing (and the people) increases the RH because cold air can hold less moisture than warm air. This is what mechanocal engineers tell me is the case unless slecial demudifying provisions are built into the system, which is not the case in our building. Others to whom I have spoken attibute the most likely casue to the air conditioing and the lack if any expansion space at the end of the flooring boards where they met the wall.

The manufacturer's printed instructions seem to me almost impossible to meet, in that they require the RH in the room to be betwen 45% and 55% when installing the flooring...can be done, but would require special controls on the environment. And there are other stringent requirements that are required to be met when installing.


If this had been my project, I would have retained an inspection and tsting company to carry out site review during installation to verify, at least on a random sampling basis, that the work was being carried out in general accordance with the manufacturer's specifications. I alos reoutinely speciy that the manufacturer's representative visit the site at least once at the start of the work, to verify that the cntractor understands what is to be done to neet the manufacturer's specification.

 

[ajk1]

Another thought: Does laminated flooring with HDF core meet Code fire resistance and flame spread rating requirements for assembly occupancy?

 

[bylar]

I did not see where you mentioned expansion joints. I have installed many lam floors and all require expansion joints at least every 30'