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Old 09-12-2007, 03:37 PM   #8
Registered User
Join Date: Sep 2007
Location: New Hampshire
Posts: 6
Thinking and Planning...

Here is some more information about my space, and maybe this will help all of you experts to see it better. I can't send any pictures right now, but will keep working on it.

I basically have three areas..
1. The mudroom, 8.5'X11', built above the floor in an old barn/garage.
2. A long 5'X16 then 4'X10 hallway, which is the edge of an addition between the house and barn
3. The 4'X18' hallway in the main house, 120 years old or so.

The long connecting hallway, the newest part of the house, at about 40-50 years (5'wide by 16'long then 4'wide by 10'long), has the best floor, with 9" joists running perpendicular to the hall, every 16 inches. these are covered with 3/4 plywood, to which I fastened 1/4 inch backerboard (screws set every 6-8 inches). Two thirds has no thinset below it, and is already tiled with slate. I am removing the other third of backerboard to add thinset, and then will rescrew it. I did the calculations for this and they seemd to come out alright.

The main house hallway (4' X 18') has 6-1/2" X 2" joists every 16", running the long way along the hall, above 6"X6" beams, every six feet apart. This has 3/4" plywood, but 1/2 of the hall has old liimoleum above that, and 3/8 plywood above that, and newer-old linoleum above that. Someone in the past sloped the floor between these two levels over a three foot section, and the whole thing was previously covered in disgusting carpet.

The mudroom floor (8.5'X11') has, from top to bottom, 3/4 inch plywood (exactly), above 5-1/4" floor joists (of unknown thickness and spacing), above 1" think old wide-pine boards (the finished floor in the room next door, and unfinished floor in the rest of the barn), above a network of 6"X6" and 6"X8" beams (every 3 feet), above series of triple 2X7's every 10 feet, in an overall 30X30 foot barn space, above stacks of cinderblocks and lolly-columns. I have put down backerboard and tiled over 1/3 of this space, and will remove about 1/3 of the backerboard to put thinset under it, then replace it.

Confusing? It is to me!

I am planning to use versabod to attach the backerboard, and flexibond to attach the slate tiles. Once the slate is down I will seal it, then grout with spectralock mini units, then reseal.

Being a complete novice at this, I only just learned (through reading in the forum) about leaving an expansion gap around the edges. There are some small gaps, but some places in the 5 foot hallway where the tiles go right up the the wall. I will now leave a space along the two sides for the remainder of the work.

My original thinset question is answered, but now that I have learned so much more, I wonder about the long-term life of my work. I really don't want to stop, but can't tell from the multiple levels of support if my floor is strong enough. I know that the professionals here are very conservative, for good reason, and I really admire the level of expertise that you all have. So I am wondering...

1. How will my two unusual floor spaces hold up in the long run?
2. In my center hallway, which is along the edge and part of an overall 19'wide X26' long room, does it matter that it is a hallway with walls on both sides? Can I use the 5' wide space for my calculations, or do I have to use the overall dimensions of the floor, even thought I am only putting slate tile on a 5' and 4' X 26' long part of the room?
3. Will the 14' long X 5' wide section I already tiled, without an expansion gap, be alright?
4. Will my 3/8" gradual sloping rise in the hallway pose a significant problem, or will thinset, backerboard, screws, and then troweled thinset under the tiles be alright for that part of the installation?

If more clarification is needed let me know, or if you really need pictures or a diagram to visualize this maze let me know that as well.

Thanks for your help,

Steve the Science Guy
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