[Greenbuilding] sealing plywood floor?

Tue Apr 3 15:22:53 CDT 2012

The one thing I would have added to the plan was a good vapor barrier.
If the vapor barrier can't handle the humidity then you have a larger
problem at hand that should be dealt with before installing the floor.
Apart from that it seems like a viable idea. I like the idea of not
using cement, especially since I am able to salvage all the materials
(sand, insulation, plywood).

Gennaro Brooks-Church
Director, Eco Brooklyn Inc.
Cell: 1 347 244 3016 USA
www.EcoBrooklyn.com
22 2nd St; Brooklyn, NY 11231

On Tue, Apr 3, 2012 at 4:13 PM, Douglas E Lamb
<douglaslamb at columbus.rr.com> wrote:
> Mr. Gennaro Brooks-Church,
>
> Too many elements generate problems for wood materials in areas below grade.
> Moisture being the most pervasive.
> Treating wood to combat the effects of moisture may create more problems
> than they solves.
> Off Gassing by the compounds in the materials used to coat the wood and
> prevent moisture from damaging it comes to mind.
> Appropriate ventilation will be required just to handle this condition.
>
> To offset the amount of moisture below grade in an enclosed space may
> require a dehumidifier.
> Then the issue becomes contradictory.
> That is to say that the wood may become so dried out due to the
> dehumidifying effects that it wrought in both directions.
> Moisture leaching into the wood by proximity to the foundation walls and
> moisture extracted from the wood by virtue of the dehumidification causing
> it to warp.
> The sealant issue between the foundation and the wood cannot guarantee the
> prevention of moisture leaching into the wood.
>
> The balancing act to maintain equilibrium between the all methods would be
> quite a feat.
> This is why I believe it is thus a silly idea to put wood in close proximity
> with the basement floor slab.
> Regardless of the added sand and insulation and surface coating protection.
>
> Sleepers may solve the problem as long as air can flow between the concrete
> and the wood.
> Then if you want the spongy feel of insulation and sand between the layers
> of plywood under your feet.
> This may work.
> But keeping the whole floor assembly away form the foundation walls is still
> a main concern form my vantage point.
> If I am mistaken in my appraisal of this issue please advise.
>
> Regards,
> Doug Lamb
> douglaslamb at columbus.rr.com
>
>
> -----Original Message-----
> From: greenbuilding-bounces at lists.bioenergylists.org
> [mailto:greenbuilding-bounces at lists.bioenergylists.org] On Behalf Of Gennaro
> Brooks-Church - Eco Brooklyn
> Sent: Tuesday, April 03, 2012 2:48 PM
> To: Green Building
> Subject: Re: [Greenbuilding] sealing plywood floor?
>
> Why is it a silly project. I makes a lot of sense to me.
>
> Gennaro Brooks-Church
> Director, Eco Brooklyn Inc.
> Cell: 1 347 244 3016 USA
> www.EcoBrooklyn.com
> 22 2nd St; Brooklyn, NY 11231
>
>
>
> On Tue, Apr 3, 2012 at 2:19 PM, Douglas E Lamb <douglaslamb at columbus.rr.com>
> wrote:
>> Mr. Deumling,
>>
>> Be more succinct in your request next time.
>> You ask for reference to surface finishes on wood mentioned from a
>> previous thread for wood you are putting in you basement. (God only
>> knows why) I provided you a site that offers coating for wood as well
>> as other surfaces that was mentioned from a previous thread and as you
>> requested. (I hate being redundant!) You project isn't worthy of
>> succinctness.
>> It is down right silly.
>> Left it @ that.
>>
>> Regards,
>> Doug Lamb
>> douglaslamb at columbus.rr.com
>>
>>
>>
>> ________________________________
>> From: greenbuilding-bounces at lists.bioenergylists.org
>> [mailto:greenbuilding-bounces at lists.bioenergylists.org] On Behalf Of
>> Reuben Deumling
>> Sent: Tuesday, April 03, 2012 1:40 PM
>> To: Green Building
>> Subject: Re: [Greenbuilding] sealing plywood floor?
>>
>> This is one of the succinct summaries of this sandwich:
>>
>> ---------- Forwarded message ----------
>> From: JOHN SALMEN <terrain at shaw.ca>
>> Date: Wed, Apr 20, 2011 at 9:18 PM
>> Subject: Re: [Greenbuilding] building floor on top of rigid foam...
>> (basement/garage retrofit)
>> To: ArchiLogic at chaffyahoo.ca, Green Building
>> <greenbuilding at lists.bioenergylists.org>, satjiwan at alumni.brandeis.edu
>>
>>
>> I missed this thread somehow. I can testify that putting a floor
>> directly on eps foam is a great system. I have done this in a number
>> of renovations, new homes and a school.  The basic spec. is rigid eps
>> board (minimum 4”)  on a level surface w/ t&g ply sheathing laminated
>> directly to the foam with a suitable adhesive. That is it.  The level
>> surface does not have to be concrete – it can be a granular base (sand).
>>
>>
>>
>> The real point of this approach is to avoid the use of concrete or in
>> the case of insulating on existing concrete to isolate from moisture
>> and to minimize the use of unnecessary materials.
>>
>>
>>
>> As for materials the ‘suitable adhesive’ is generally specified as a
>> polyurethane foam adhesive (enerbond or equiv.). If the finished floor
>> is to be ¾” solid wood nailed -  I specify a min. 5/8” t&g ply
>> sheathing. If it is tile I generally specify either a thickset mortar
>> directly on the foam
>> (w/reinf.) or an additional layer of ½” ply laminated and fastened @ 3”
>> o.c.  I’ve found that most contractors get the concept pretty quickly
>> but the trick is that in putting down the ply it needs to be flattened
>> and weighted down while the adhesive sets (concrete block, buckets
>> with sand,
>> etc...)
>>
>>
>>
>> For your application I would eliminate any subfloor wood framing
> (sleepers).
>> Waste of time and material. eps boards can be ordered cut to the
>> thickness needed for the finished product. Using foam on an existing
>> slab it is nice to have additional thickness – 5-6” foam can span any
>> deflections or defects in the concrete. I would spot adhere the foam to
> the concrete.
>>
>>
>>
>> Essentially the finished floor (eps and ply) is a weight bearing
>> floating floor that can carry standard interior partition loads well.
>> It is a pretty nice floor.
>>
>>
>>
>> On Tue, Apr 3, 2012 at 10:32 AM, Benjamin Pratt
>> <benjamin.g.pratt at gmail.com>
>> wrote:
>>>
>>> wouldn't 1/2 plywood warp over time? I don't knwo the procedure.
>>>
>>> On Tue, Apr 3, 2012 at 12:28 PM, Michael O'Brien <obrien at hevanet.com>
>>> wrote:
>>> > Hi, Reuben--
>>> >
>>> > To clarify what is being finished--I'm sure it's obvious, but the
>>> > plywood should be exterior grade. Practically speaking, moisture
>>> > won't be able to pass through the phenolic adhesive between the
>>> > plys. Are the two layers free-floating over the sand? Is that
>>> > OK--they won't move when there's traffic on them?
>>> >
>>> > It seems like a hardwood would work better than a softwood like
>>> > fir, costlier but might hold up to traffic better, especially on
>>> > half-inch sheets. (I wonder if 5/8" might be worth it for extra
>>> > stiffness?)
>>> >
>>> > I'd suggest coating both sides and all edges with a water-resistant
>>> > finish, while the plywood is dry. Have you looked at Miller's
>>> > Evolution satin exterior paint? It's reasonably priced for its
>>> > performance. Miller staff can help decide if a wood filler is
>>> > needed. The satin finish would make it easier to clean.
>>> >
>>> > Might be good to leave a little space between edges for expansion
>>> > and to stagger the joints between the two layers, to slow any
>>> > moisture from the sand layer.
>>> >
>>> > Is that about what you already figured out? :^ )
>>> >
>>> > Best,
>>> >
>>> > Mike O'Brien
>>> >
>>> >
>>> >
>>> > On Apr 3, 2012, at 9:32 AM, Reuben Deumling wrote:
>>> >
>>> > I'm planning on assembling a floating double layer of 1/2" plywood
>>> > over foam over sand that JOHN SALMEN described here in the past,
>>> > and as this is for a basement wood shop I'm wondering if anyone has
>>> > suggestions about what to seal or paint the plywood with to
>>> > maximize its longevity?
>>> >
>>> > Thanks.
>>> >
>>> > Reuben
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>>>
>>>
>>> --
>>>
>>>
>>> b e n j a m i n p r a t t
>>>
>>> professor art+design
>>> the university of wisconsin stout
>>>
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>>
>>
>>
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