Subfloor Questions

Ban.

 

IBTL

 

Ohhh dont worry I will start a new thread once that gets underway which is looking like next weekend. Im still removing and fixing electrical in the kitchen then its on to dry wall repair, existing floor removal and some priming.

 

Nyet

No new thread , put pics here

 

I will give you pictures of the subfloor and blocking and tile here but the kitchen remodel well that will get its own thread.

I need to pad the post and thread count

 

Fair enuf

 

i'd recommend taking a look at this document before starting... it has a couple diagrams and shows the proper overlap, gap spacing, placing edges at the "1/4 points" between joists for maximum stiffness/strength...

http://www.johnbridge.com/images/mike2/For%20Liberry%20Stuff/Underlayment-Nielsen-Woeste-0604.pdf..pdf

i'll also note that they recommend you screw (or nail, ..but i prefer screws always ) your plywood sheathing to the subfloor, so that the fasteners fully penetrate the subfloor profile, but do not penetrate the joists... again, i'm just echoing the recommendations by the article... this is the exact procedure i followed to renovate my small guest bathroom..

 

Interesting article . I don't see how screwing the top layer into the joists will make any difference , especially with the Ditra as an isolation membrane on top .

 

yep, i spent a bunch of time on johnbridge before i did my first renovation, a lot of knowledge on that forum, ..and they have a bunch of "recommended practices" and such - i eagerly soaked up as much as possible!

... as for their recommendation on the fastener penetration depths, ...my presumption would be that it may be more trouble than it's worth to try and screw through both layers into the joist,.. unless you really map out where the existing screws are, you're doing it blind, and could be hitting screw heads or nicking joist edges... i think their rationale, is that make sure the subfloor is fastened down real good to the joists, ..then fasten the next layer to the subfloor real good w/ the recommended spacing pattern in the field...

BTW, when i did it i also took the extra step to pre-drill holes in the top layer, so as to reduce the chance of "jacking", and having unwanted voids..

 

I would say it's more likely that they are worried about introducing new squeaks between the orginal layer of plywood and the joists .

Do they even recommend subloor adhesive between plywood layers ? I didn't notice , if not , that's dumb .

Anyways , with the Ditra , it's irrelevant

 

.. i don't think they recommended adhesive between the layers... i will say that, i remember this being a topic of division w/ the johnbridge folks... you had one cabal that swore gluing the two layers together was the right way, and another cabal that said you're better off not because it wasn't worth the risk if "done wrong"... so, go figure...

 

Well , by adding glue and screwing the whole works together you essentially end up with a thicker subfloor , and therefore less deflection . No glue between layers can allow for squeaks .

That article is interesting in that they are basically offsetting the plywood seams in both orientations so to not transfer any potential roll in the floor through to the subsequent layer of plywood . I believe it is a good idea , but is also written from a standpoint that there is no opportunity to access the underside of the floor system , as would be what a tiler would find in a typical tile job in renovation construction.

In this case the OP has the opportunity to lessen floor roll with blocking , and the added layer of subfloor will limit delection .

 

yep, they are trying to address the deflection (and thus curvature) that occurs w/in the subfloor/sheathing "between" the joists... certainly if you have stiff joists spaced closely together this would become more insignificant, ..but nonetheless, i guess a lot of folks have joists 16" OC, 24" OC, ..etc.. they make an analogy to the strategic placement of splice joint on bridge beams, at the "1/4 point", ...since bending stress is highest at the center of the span..

i think that if the OP adds some blocking underneath the subfloor, and ties it in good to the joists, ...he's really stiffening the joist system, by tying the individual joists together...

 

Yep