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wildcat123
12-18-2016, 10:03 PM
ok here we go...
its me again, Chloe

starting prep and research on tile floor in bath
and got a few questions.:shrug:

using 12x24 slate tiles in herringbone layout.
Here is my GAMEPLAN- Please grade my work.


1. Existing 3/4" subfloor with roll style vinyl (staying sorry)....
Going to score vinyl, use modified thinset attach 1/4" Hardi...screw down well with Durock screws at 1 5/8"

2. Check for unlevelness of new floor- if needed, use self leveling compound.

3. Clean and seal tile with 511 Seal and Enhance

4. Lay out pattern on floor starting at doorway and mark lines with pencil

5. Using Tec Brand thinset for Large format tile , Lay each tile one at a time. Starting from center of room.

6. Use QEP Lash tile leveling system going to create 1/8" joints (although ive noticed the tiles seem uneven maybe doesnt matter?)

7. Make cuts with rented 10" wet saw at freaking $40/day
-or use cheap 5" wet saw at $14 day?

8. Clean tile and seal again

9. Grout with 1500 Lacrete sanded grout WITH added Miracle Grout Shield

10. drink beer

THANKS THANKS THANKS:tup1:

Sponsored Links


wildcat123
12-18-2016, 10:04 PM
And i should add this is a jack and jill California, whatever you call it bathroom..
Its basically two rooms. separated by a door.

Would i start tiling at this threshold?

Tool Guy - Kg
12-18-2016, 10:09 PM
Hi Chloe,

There are multiple concerns, but let's start at the most important:
If all you've got for plywood is 1/2", you're begging for cracks in your tile in a rather short period of time. Especially with stone tile.

Is there something limiting you from increasing the thickness of the subfloor?

:)

Steve in Denver
12-18-2016, 10:22 PM
Chloe,

I'm not one of the pros, but I'm sure they will have plenty of input over the next few days. My thoughts:

Your plan will probably need a lot of adjustments in order to work.

1. Existing 1/2" subfloor with roll style vinyl (staying sorry)....

Is the 1/2" the only layer of subflooring, or is that just the top layer? If it's the only layer, are you certain it is only 1/2"? If so, it's inadequate, even for cermaic tile, and woefully so for natural stone.

You will first want to plug your joist system specs into the Deflecto tool to verify that they are adequate for natural stone. When you determine that they are not adequate (by far the most likely result), you will then need to decide if you are able to augment your existing joists in some way in order to meet the minimum requirements for stone (L/720 deflection). If you tell us more about your floor (what's under it? A Basement or crawl space? are the joists covered up, or are they accessible?), someone might be able to make suggestions.

If you are able to get your joists up to snuff, the next thing to tackle is the subfloor, which also has specific and more stringent requirements than does ceramic tile. You will need two layers, properly installed, to meet the requirements. I'll let the pros weigh in on the vinyl, but I suspect it will have to go.


2. Check for unlevelness of new floor- if needed, use self leveling compound.

Depending on what you decide to do with your joists and subfloor, you might be able to correct any flatness issues at the joist directly. If you do end up using SLC for this purpose, you will want to read and follow the manufacturers instructions carefully. Most require expanded metal lath (or similar) when used over framed flooring...I'm not sure if or how the CBU might affect that requirement, but you might be better off to forego that altogether and use something like the Ardex Liquid Backerboard product. I again suspect that the vinyl will have to go in that case.


4. Lay out pattern on floor starting at doorway and mark lines with pencil
How regular is this slate you are planning on using? Is it appropriate for a herringbone pattern? Are you planning on cutting each piece to get consistent widths? Are the pieces of consistent thickness? (slate often varies a fair amount)


7. Make cuts with rented 10" wet saw at freaking $40/day
-or use cheap 5" wet saw at $14 day?
Consider buying a wet saw and perhaps selling it when you are done. I bought a 7" Ridgid saw from Home Depot, and while it's not a pro level tool by any stretch, I've done several tile projects so far, and it has worked for me.


10. drink beer


I suspect this item will show up a number of times as you work through your list.

wildcat123
12-18-2016, 10:41 PM
Thanks for the quick reply Steve in Denver!

Is the 1/2" the only layer of subflooring

Sorry, im certain it's 3/4"

I'll let the pros weigh in on the vinyl, but I suspect it will have to go.


I dont want to, afraid of asbestos, and i do this work with toddler and a 7 year old. Already spent too much time in a dilapidated Navy Yard.

You will first want to plug your joist system specs into the Deflecto tool

ok, i will research that

If you do end up using SLC for this purpose, you will want to read and follow the manufacturers instructions carefully.

OK, will do

How regular is this slate you are planning on using?

Regular in length, not regular in thickness

This is HD Montouk Black slate-

Is it appropriate for a herringbone pattern

This guy did it, lol

Thank you again, all very helpful input

wildcat123
12-18-2016, 10:56 PM
f you tell us more about your floor (what's under it? A Basement or crawl space? are the joists covered up, or are they accessible?), someone might be able to make suggestions.

Basement has access from outside. Its 6' tall, easy access to joists.

The house was built in 1980, im sure its all very standard track homey.

How do you augment? Add blocking? 2x10" (im pretending i know what they are) going perpendicular?
If you can rattle a few search words for this, that would really help me.

The bathroom also supports worlds heaviest washer and dryer.

So im assuming supports are needed.

Steve in Denver
12-18-2016, 11:22 PM
It would help to know the dimensions of your joists (2x10, for example), spacing, and longest unsupported span of the joists. Often building a mid-span support under the joists is the easiest way to get them up to snuff - it's quite effective, and often reducing the span by as little as 2 or 3 feet will get you the results you need. If it makes sense to put a wide closet on one end or the other of the joists, you can get some useful storage out of the deal, too.

If you go this route, be sure to ask questions about the requirements in order to make it a proper structural / bearing wall. Not hard to do.


If the house was built in 1980 the flooring is most likely not asbestos (assuming you are in the US) I believe the manufacture of most residential building products with asbestos was halted in 1978, though old stock continued to be used (legally) until it ran out. My understanding is that it is possible to have asbestos in new homes built in the early 80s, but it's not all that common. In any case you can, relatively inexpensively, get the floor tested for asbestos by cutting a small (1 square inch) sample and taking it to a local testing lab. If you live in a medium sized city or larger, there is likely a local option.

I would suggest that you add your geographic location to your use profile as it is often helpful in answering questions. And besides, CX is going to come along any time now and make you do it anyway. :)

wildcat123
12-19-2016, 09:21 AM
the joists are 2x9" (is that 2x10?, lol)

14" spacing

the entire home is 24' wide with an intersecting support joist at 13' that doubles as a partition wall. ( see pic) This intersection is exactly at the doorway entering the bathroom.

I could not add another intersection without compromising the entrance to the basement and storage area.

Under the tub and washer/dryer is a beautiful double joist which im assuming helps with the deflection.

the underlayment is stamped with :
----------
APA
Rated Studi-Floor
24 OC 23/32 inch
T&G Net Width 47- 1/2
Exposure 200
-----------

Underlayment appears to be glued and nailed, which I hope helps with movement

Here is my Deflecto reading :

Thank you for using the John Bridge Forums Deflect-O-Lator :-)

For joists that are SYP or Douglas Fir, in good condition, 9.25 inches tall, 1.5 inches wide, 14 inches on center, and 13 feet long between supports, the deflection calculated is 0.298 inches.

This translates to a deflection of L / 523.

Since the maximum deflection for tile is L / 360, and for natural stone is L / 720, your floor is rated for Ceramic tile, Congratulations!

This is if I input the joists to the support at 13' ...hope this is correct?

ALSO, the washer and dryer combo weight is 511lbs. Bootzcast tub is 90lbs. With water...?

The Slate tile is about 8lbs per sq. foot?

Thanks again- so the picture orientation is all crazy- i cant figure out how to change that.

wildcat123
12-19-2016, 09:30 AM
If the house was built in 1980 the flooring is most likely not asbestos (assuming you are in the US) I believe the manufacture of most residential building products with asbestos was halted in 1978, though old stock continued to be used (legally) until it ran out. My understanding is that it is possible to have asbestos in new homes built in the early 80s, but it's not all that common. In any case you can, relatively inexpensively, get the floor tested for asbestos by cutting a small (1 square inch) sample and taking it to a local testing lab. If you live in a medium sized city or larger, there is likely a local option.

I have a Dremel mm30 oscillating tool.

Do I need to go to the subfloor or just the top layer of glue-
(the vinyl rips off pretty easily, the glue does not)

fyi its not soft vinyl or the padded kind.

it PROBABLY doesnt have asbestos, im making excuses for myself.
I had my popcorn tested and it toook 3 weeks to get results, I dont have that time.
Its 5 degrees today- i cant open windows, or use heat gun. Only so much chemical and dust stuff I can subject little ones too.

Thanks

Flyingscot
12-19-2016, 11:05 AM
I have a Dremel mm30 oscillating tool.

Do I need to go to the subfloor or just the top layer of glue-
(the vinyl rips off pretty easily, the glue does not)


Don't pull the vinyl up leaving the glue. Take a box-cutter and score the floor in 12 inch squares. Pry up a corner and use the oscillating tool to remove the vinyl and glue all at one time. It's way easier and cleaner.

wildcat123
12-19-2016, 11:52 AM
Thanks for the tip Lynne!

wildcat123
12-19-2016, 11:59 AM
If I glue another layer (with full contact) of 1/2" OSB and screw, then thinset and 1/4' Hardi, screw...I wont need to remove the vinyl?

this will help with stability but not deflection?

Also, if I add blocking between joists will this increase stability but not deflection?

Will a sister joist help with deflection spanning from exterior wall to support?

Or is a joist jack stabilizer better?

Majority of weight (511lb washer/dryer, 90 lb tub) sits next to the support and also has a double joist directly under.

From what I can tell this helps with deflection?

Thanks again!

cx
12-19-2016, 07:05 PM
the entire home is 24' wide with an intersecting support joist at 13' that doubles as a partition wall. ( see pic) Sorry, I can't see any such in your photos.

What you need to know is the unsupported span of your joists. That's the distance between whatever is supporting the joists from below. You're the only one of us who can provide that information. It's important also to know a good deal about any beam that might be one of the supports.

I'm guessing your joist spacing is 16 inches on center, which usually yields about 14 1/2 inches between the joists. Is that what you measured?

Finding a grade stamp on one of the joists is very helpful in determining the species and grade of the joists.

The vinyl needs to go. It's very likely that there is something between the vinyl and the subflooring you see from below. Often this will be a thin plywood of a type not suitable for a ceramic tile or stone installation. You need to determine that and if you have such, it will need to be removed also. Check that as soon as you can as it will sometimes be easier to remove that underlayment along with the vinyl rather than just the vinyl itself.

The Marble Institute of American (MIA) requires a double layer of plywood subflooring, properly installed, regardless the joist spacing. You'll not even be able to determine the correct orientation of the second layer panels without being able to see the first layer.

Blocking between joists does not improve the deflection of the joist structure. It does prevent twisting of the joists which allows the joists to display their full capability.

Sistering will definitely help with joist deflection.

The existing doubled joist helps with the floor deflection in that small area only.

My opinion; worth price charged.

wildcat123
12-19-2016, 08:08 PM
Sorry, I can't see any such in your photos.


Im sorry, I should have been more clear...the support runs behind the partition wall that sits directly behind the HVAC system.

I took a few more pics to help show that.

My joists have no markings.

There appears to be 13' unsupported span.

The vinyl needs to go. It's very likely that there is something between the vinyl and the subflooring you see from below. Often this will be a thin plywood of a type not suitable for a ceramic tile or stone installation. You need to determine that and if you have such, it will need to be removed also. Check that as soon as you can as it will sometimes be easier to remove that underlayment along with the vinyl rather than just the vinyl itself.

Good to know- I will check.

You'll not even be able to determine the correct orientation of the second layer panels without being able to see the first layer.

Can you clarify this for me?

Sistering will definitely help with joist deflection.

Is this my best option?

better than intersection with a post?

Thank you so much for all your info and help!

wildcat123
12-19-2016, 10:38 PM
ok, looks Im going with Plainriders Flange style joint stiffinging vs, sistering.

Still a bit worried about load bearing movement with the washer and dryer on top of the slate. Plus the 500 lbs it carries. Luckly the joist underneath is already sistered.. I will just block in neighboring joists to help with movement.

Im going to take up the existing vinyl and glue that covers my 3/4" subfloor...then glue/ screw 1/4" OSB...then add a layer of Ultra Flex thinset with 1/4" hardibacker.

Can anyone recommend a better method than this?
Best thinset for this application?

Thanks again for reading!

Steve in Denver
12-19-2016, 11:06 PM
If you want to be safe on the asbestos, you would want to get a sample of the flooring and the glue. I was able to pay a little bit extra and get 24 hour turn-around time on the asbestos testing, BTW.

The picture of your built up beam - are the individual members the same dimensions as your joists, or are they deeper / shallower? How many support poles does it have, and what is the span between poles / end supports?

(I think those are the questions that the others will need answers to in order to determine the suitability of the beam)

Has anyone tried to talk you out of the slate? Would you like me to try? :)

wildcat123
12-20-2016, 09:14 AM
Thanks for the response Steve!

Id love to hear anything you know about Slate.


Thank you!

Chloe

wildcat123
12-20-2016, 09:31 AM
The picture of your built up beam - are the individual members the same dimensions as your joists, or are they deeper / shallower? How many support poles does it have, and what is the span between poles / end supports?

Yes the individual members are the same... 2x 10"...3 sistered together

The length is aprox. 44' with 3 metal poles spaces every 11'...

I was able to find a stamp...

Spruce Pine Fir, is what Im working with.

Thanks again!

wildcat123
12-20-2016, 10:13 AM
Maybe this might help anyone to understand. Its not the best...but it might give some clarification. The blue dotted lines would be the upstairs bathroom where the tiles are going.

cx
12-20-2016, 11:12 AM
Chloe, I can find you a span table that shows your joists will meet building code (L/360) if they are SPF of at least grade 2. I'm curious to know how you determined they were SPF if you can't find a grade stamp? SPF would have been my guess looking at your photos, but it would be just that. A guess. And not of particularly good grade.

That would qualify the joists for a ceramic tile installation, but not for your natural stone. And my calculation would leave your support beam a little shy of the mark if your floor is the same 13 feet on the other side of the beam. Is that distance a correct assumption, or is the other side only 11 feet? The question is actually academic as it won't really change the load on the beam enough to make a difference.

You'd need to cut that joist span down a couple feet to get to the necessary L/720 for your stone installation.

That's my best guess with the information provided.

My opinion; worth price charged.

wildcat123
12-20-2016, 11:35 AM
Thanks CX for commenting, really grateful.

I was able to find a stamp in the back crawl space.

The joists are grade 1.

Ive looked at the AWA span tables.

Im thinking my best bet is Plainriders joint stiffening technique from previous threads.I like the flange technique and it meets my obstacles of time/money/space...

I can't really intersect the joists to cut down the span simply because it would mean I would need to take down the storage partition walls, rebuild it and it would block the HVAC system, in doing so.

Thanks for helping me with this tough situation.

My husband thinks I'm an idiot got seeking out advice on this matter and to just do it as it. Sorry if my info is not totally correct...the 13' is but the rest is maybe a foot off, its hard to crawl around there in the dark.

thanks again
chloe

JET
12-20-2016, 11:46 AM
Re: post 15, 1/4" OSB over 3/4" subfloor an issue in the same way that 1/4" plywood would be?

wildcat123
12-20-2016, 12:07 PM
Hi John,

I can't answer your question- I wonder if OSB is better/worst than ply?

1/4" OSB over 3/4" subfloor an issue in the same way that 1/4" plywood would be?

But, for my application of slate stone tile...Im thinking I will need to apply ½" plywood over my ¾" subfloor and then add the ¼" hardibacker with the thinset before tiling.

wildcat123
12-20-2016, 02:48 PM
Started adding 2 x 4 to joists to help with deflection according to PlainRider's concept.

Beveled the 2 x 4 to fit under the foundation wall...now seconded guessing that.

Does anyone now if this will will have a negative or positive effect to the house structure? Cause damage OR added benefit?

Thanks!
Chloe

zeaflal
12-20-2016, 03:42 PM
Not completely clear what you are asking.

However one critical aspect of that stiffening approach is good attachment of the 2X4 to the existing joist, especially near the ends. If you are trying to gain a little more length by tucking the end of the 2X4 into some rather inaccessible space without secure attachment, you have not helped at all.

I believe the engineering calculations show you can get most of the benefit from only reinforcing the center 2/3 of the length. Personally I would not skimp if it is practical to use a longer 2X4. My argument is that I think the last foot (or maybe more) of the 2X4 cannot be considered to be securely attached, so the real world working length is always less than the 2X4 length.

TN_DIY
12-20-2016, 03:49 PM
It should not make it worse. But you have not turned a 2x10 into a 2x12 for example, not yet. Theoretically it could make it much stiffer like an engineered beam if you could do that but must be attached properly. That is difficult.

I think you need an engineer doing the math. Again I think then the method and amount of attachment to the joist is probably the critical factor for this to really be beneficial. I would guess glue and many more fasteners than I see and a good species of 2x4.

I would add sisters to those joists if you can slip them up in there. While more expensive if you put same size you have doubled it. If you go 2" shorter and attach to the lower portion of what is there probably 50% stiffer.

What are you trying to achieve ?

TN_DIY
12-20-2016, 03:50 PM
I agree with Larry who types faster than me...

wildcat123
12-20-2016, 04:24 PM
191389Yeah, the 2 x4 are not the best quality but they are full contact glued and screwed to the 13' joist.
only 1' is not supported with the flange and this is due to the ductwork.
you can see in the picture.

Im just wondering if the gap between the concrete wall to the joist is there for a reason? Like maybe the wall needs movement. And if Im wedging tight 2x4 in there- somehow if the house has movement- over time the structure can be harmed.

But maybe this isn't something I should be asking here...

thanks for the tips guys!
Chloe

Plainrider
12-20-2016, 05:34 PM
Chloe:

If I understand correctly from your photos, the ends of the joists would be sitting on a horizontal (flat) lumber 'sill-plate' (which rests on top of the concrete wall). This sill plate is not as wide as the wall thickness, thus creating a short gap (say about 1.5" in the vertical direction) between the bottom of the joist and the top of the concrete wall (i.e. where the end of the joist enters the wall).

If my conception is correct (?), then it does no harm (structurally) to extend the re-enforcing board into this gap. However, this also does not add much structurally to the stiffness of the joist. So, I wouldn't bother to extend the re-enforcing board into the gap.

However, it is best (and relatively easy) to attach the re-enforcing board so that its ends are as close as 'reasonable' to the concrete wall, but really not necessary to extend the re-enforcing board right into the gap.

By the way, if you are using the LASH system, you may wish to make a simple clamp to easily compress the clips. See the Youtube video: https://www.youtube.com/watch?v=vYTizned9_4
Regards,
Michael

Steve in Denver
12-22-2016, 12:10 AM
My husband thinks I'm an idiot got seeking out advice on this matter and to just do it as it.

I guess we could have a discussion about whether it's more idiotic to seek out expert advice, or to just wing it, but that just doesn't seem necessary. :)

I have no personal experience with slate. My concern was based on the requirements for using natural stone, and the difficulty meeting those requirements in a remodel situation.

It looks like you are doing what you can to stiffen the joists, but I would echo the concerns that the others have. I have never tried what you are doing, but I do think the theory is sound...it's the translation to practice that always concerned me. It does look like you have a pretty good point to start from (accessible space, clean straight joists, etc) What type of glue are you using? What type of screws, and what is the spacing? Have you done anything to support the joist while the glue dries (maybe a jack post mid span, or at least a 2x4 wedged under it)

If it were me and I really wanted slate but couldn't sister the joists, I'd probably do what you are doing and brace myself for some cracked tiles in the months and years to come. I'd also make sure to not skimp on the subfloor in any way. I think you mentioned 1/4" something, and that's not a good idea. 1/2" exterior glue plywood with face grade C or higher is the common suggestion around these parts. If I had the space, I might spring for 5/8". If the 1/2" seems like too much height, I'd ditch the cement board in favor of Ditra.

But, again, I haven't ever installed any slate, so I'm just saying stuff.

Plainrider
12-22-2016, 08:25 AM
Hi Steve:

You have made some very good points. I'll try to address some of the uncertainties that you mention. However, I would say first that my own project using this joist 're-enforcing' add-on board approach has been very successful. After some 8 years of constant use, my re-enforced long-span (tiled) floor remains as stiff and sound as the day it was completed. No cracked tiles and no evidence whatsoever at all of any deterioration in the effectiveness of the approach over this period.

Adhesives: Now, there are many commercially-available 'construction' adhesives that would work well for the application. Typically, these adhesives have been substantiated by credible tests. Polyurethane construction adhesives and others have decades of actual-use experience. This can be verified by manufacturers' data.

Note also that the adhesives for this application work in 'shear' (not tension) - and are especially strong (just like the adhesives in conventional plywood, laminated structural beams & columns, etc.). So, considering this along with the substantial adhesive-area of the joint, this is an especially efficient method of joist re-enforcement. That is, this approach could be a viable alternative to joist sistering even where sistering might be easily performed.

I would NOT brace the joists before attaching the re-enforcing boards. This ensures that the adhesives and structural re-enforcing boards cure 'naturally' to then later support floor load changes. After all, this approach is designed to substantially stiffen the floor - not to make it straighter or stronger. (In any event, the floor likely will be much stronger after board re-enforcement and it could be made straighter by bracing during adhesive curing).

Theory and Practice: There is no 'magic' in this joist re-enforcing approach - just as there is no magic in joist sistering. Consider that the stiffest wood joists are manufactured' with ('glued') top & bottom lumber 'flanges' e.g. 2x3 or 2x4 (often with a composite wood web). In the situation at hand, the bottom-flange approach will substantially stiffen a joist just as shown in the charts listed in my earlier thread of several years ago.

Hope this is of some value.

Michael

wildcat123
12-22-2016, 08:34 AM
Thanks Steve!

I'd also make sure to not skimp on the subfloor in any way

I know right?!

Thats why Im trying to get the best possible solution given my circumstances. Like the VERY BEST thinset for this application, Ditra instead of Hardi, 5/8 ply Grade C...THIS IS GREAT AND VERY HELPFUL info, THANK YOU

I understand I could make it perfect and by the book, but I cant sister and I cant intersect.

I wish I could return the slate, but I cant either. I sealed it, like an idiot...so I guess this is what I get- lesson learned. Im over it. Cracked tiles might be in my future- and hey, ok...this house was a urine infested foreclosure before my family moved it. Its not worth more than 150k totally upgraded. We will move in 2 years when the husband is out of vet school- Im not a totally horrible person, i want to do things correctly...but at a certain point i have to draw a line with what will work in our circumstances. If that makes sense.

I wish I could get more precise info from these threads.

It feels like a get more subtle criticisms ... which is fun for discussion between pros but I really just need to know what the F to do, but I understand, I dont want any pro to offer advice that would tarnish their credibility. So Im guessing thats why its so hard to get clear answers.

Anyways, thanks for all your help!

chloe

wildcat123
12-22-2016, 08:45 AM
Morning Michael,

I would NOT brace the joists before attaching the re-enforcing boards.

Is this correct?

Are you saying we should have installed the underlayment (ply /thinset/ ditra) BEFORE stiffening the joists?

Thanks for all your help. We are a family of science, love the concept.

I have spent much time traveling to India- you should see the construction concepts ive seen- wild stuff. And it works for their circumstances. There are many ways to solve old problems.

anyways, thanks again
chloe

Todd Groettum
12-22-2016, 09:03 AM
This is a pretty small bathroom and will not be subjected to 4 or 5 fat uncle joes or aunt marthas standing around yapping their jaws....

We are not doing a kitchen dining room..Its a small bathroom

While it would be Ideal to have the perfect set up this sometimes doesnt happen...As Pro's we HAVE TO do things by the book...as a Homeowner YOU make the ultimate decision..

Were this my home I would Tile it and Not even Blink..Really...You far exceed ceramic requirements and for that small area the risk is so minimal I would get er done!!

My opinion only...Do as you will :tup2:

Plainrider
12-22-2016, 09:55 AM
Hi Chloe:

The stiffening of the floor (by the addition of the joist re-enforcing boards) should be done BEFORE any attachment of Ditra or tiling work is performed. It would probably be best to wait a couple of days for the adhesive to 'cure' before doing any work on the top of the floor (i.e. Ditra attachment, etc). Follow the instructions of the adhesive manufacturer in this respect (as generally printed on the adhesive tube/container).

I appreciate your focus on logic and evidence.. I was a Scientist/Engineer (one of my titles) prior to retirement and I understand the value of doing your research and developing an understanding of the underlying considerations for any projects before doing them. Your asking questions (and then analyzing the answers) is an integral part of this approach. And especially, your being skeptical - e.g. of opinion-based (mis)information masquerading as 'experience' - is an important part of this process! (For example, when you hear that a certain person has, say, 10 years of experience in performing a particular physical activity, it often really means that the person has had 1 month of experience times 120, if you catch my drift).

Recently (for two months) I traveled throughout India and, like you, I was impressed very much by the ingenuity, resourcefulness and ability to improvise shown by local people to accomplish amazing things without the technology we have in the West.

Michael

Steve in Denver
12-22-2016, 10:08 AM
My thought of supporting the joists was to prevent movement while the adhesive cures. If anyone will be walking on the floor above, the joists will deflect, even a little bit, and the glue joint might not be as strong as you would like as a result. If you can keep people off of the floor during the cure period, maybe it's not necessary. Heck, maybe it's not necessary even if there are people walking above, but I'd want to do it for peace of mind.

I agree with the polyurethane construction adhesives. That's what I would use in your situation. PL Premium is what I get at Home Depot, and I believe it to be good stuff.

As far as getting subtle criticism vs precise info (not sure if that was directed at me or not), there is a tendency around here to present a sanctioned method (or three) and if you pick one and stick with it, you will get the precise answers you seek...but if you venture out on your own you won't get a lot of input. It's easy to give advice on traveling the well worn path, a little harder to have confidence in a non-standard method.

I'm not suggesting that your approach won't work (in fact I think it has a good chance), but you are venturing out of bounds a bit. I haven't seen the span tables / analysis of the bottom flange method, but I'm confident it makes a significant difference...I'm not sure if it will get you to the L/720 deflection requirement for stone. But failing to meet that requirement isn't a death knell for your project, anyway. For all I know the quality of the slate is the more important factor in the longevity. Only time will tell, eh?

If you haven't found it, this thread is helpful. Be sure to read the article linked to in post #11 about installing a second layer of subfloor. Be prepared to be amazed at how many screws you need to put into each panel. :)

http://www.johnbridge.com/vbulletin/showthread.php?t=114739

epalmer
12-22-2016, 10:28 AM
To go along with what Todd said. Many, many years ago, before the internet and so many resources that let me know just how much I don't know, I decided I wanted to put down slate in my front entry.

Technically I did it all wrong, wrong, wrong.... no reinforcement to the 100 yr old subfloor and I installed the tiles with pretty much no grout lines.... all wrong and destined for failure.

BUT - it's a very small space- 4'x5' and I've had absolutely no problems with the 12x12 tiles moving, chipping or cracking over the last 20 years. These days I know better and would probably do it all differently, but I still love the way it looks and I don't regret doing it for an instant.

Plainrider
12-22-2016, 10:30 AM
Hi Steve and Chloe:

I agree with Steve's comments in not putting any substantial loads (e.g. walking) on the floor until the adhesive cures.

It is also important to clean any dust, debris off the bottom of the wood joists before applying adhesive. A damp rag should be adequate. (If I am not mistaken ?, some dampness on the wood surfaces is an actual benefit to the curing of polyurethane adhesives).

Note that the screwing of the boards onto the joists is only for positioning and clamping requirements while the adhesive cures. Otherwise, these screws provide no meaningful structural benefit to the floor itself.

With regard to the subfloor requirements, I would be very confident in following Schluter's recommendations regarding Ditra installation. The Schluter website provides ample & clear information in this respect.

wildcat123
12-22-2016, 02:31 PM
Steve,

Never was that comment directed towards you. You have been a huge help.

Thanks again!

Ill post a pic when Im done:)

wildcat123
01-17-2017, 08:05 AM
Hello!
Im remodeling my bathroom floor and the tile isn't exactly 24" long? It's more like 23 ⅝"... I want to do a thirds layout... stepped... im not sure how to divide this tile? 7 15/16"? Does it matter how percise? I'm trying to do a ⅛ grout line and am not sure if I take that into account to make up the difference?
I was going to do Herringbone layout but have decided this might be better as a newbie!
Thanks again as always:)
Chloe

Houston Remodeler
01-17-2017, 08:06 AM
If you use your metric tape measure you will find the tiles are 30 centimeters by 60 centimeters

wildcat123
01-17-2017, 08:24 AM
Thanks for the reply, do you try to have the center of the grout line fall at 20cm?

cx
01-17-2017, 10:08 AM
Chloe, you can have your grout joints fall wherever you like, so long as you're consistent with them. Presuming consistent is what you're looking for, of course.

You'll also want to get a bunch of your tiles and measure them to ensure the sizing is sufficiently consistent to allow the grout joint width you plan to use.

My opinion; worth price charged.