Hello, gentlemen, I haven't been around for a while so I hope all is well. I am installing a travertine marble floor in my foyer and it will meet up with my freshly installed hardwood floor. I usually use a metal edge in this situation, but I have to admit I like the look of the marble directly next to the wood. Is this advisable? I have seen sanded caulikng; would it be used in this situation? I really don't want to do this more than once and I appreciate any advice.
Respectfully, One Eye

Hi One eye Joe,

A 1/4" gap filled with caulk will work if you hate the "L" channel molding made for this purpose.

I'm kinda concerned about the subfloor and framing where the travertine will go. I doesn't sound like it's what you need for natural stone.

Please tell us; The type and size of the joists, species and grade would be extra helpful, spacing of the joists and the unsupported span of the joists to the inch. Also what's above the joists.

Jaz

Detroit & Windsor, where Canada is south of the USA.

The area where the travertine is being laid is a small one-6x12-and it is being laid over 1/4" Hardi Board that has been thinsetted and screwed down. It is on top of 1 1/8" plywood- that has been glued and screwed down. The plywood is in two layers:5/8" with 1/2 " on top. The floor joists are 2x8 with 16" centres. The travertine is 3/8" thick, but if I need to reinforce the floor joists with bracing it will be done. Would I use that sanded caulking for the joint between the marble and the hardwood? Is it a good product? And finally, would you recommend this or should I stick with the L channel. Thanks.

your floor system is strong enough, as long as the unsupported span of your joists does not exceed 10 feet. I normally but the stone tight to the hardwood and leave that joint "dry". The wood could shrink a little over time, but it is not likely to swell up (unless it gets flooded)

I agree your subfloor should be OK, if in good condition. We normally recommend 2x 5/8" or 3/4 + 1/2" however.

You didn't answer all the questions concerning the framing though. We got 2x8 & 16" o.c. how about the span, species and grade. The span info is obvious, but the species and grade are just as important.

Jaz

I'm not going to sweat 1/8" especially when the top 1/4" is Hardee backer. The condition of the sub floor is brand new; it was all replaced as I've pretty well gutted the entire house. The question of span is one I don't fully understand. If you could explain, I could certainly give an accurate reply. Quite honestly, I have no idea what the grade and the species are. The house was built in the early 70s and whatever the Canadian Building Code and regulations required, I'm assuming, was used. Spruce seems to be the standard now, however, I can check with a neighbour; he built his house shortly after mine was built and he may be able to shed some light on this. Thanks.

Your joists can be supported by exterior or interior walls or a beam.If you can see the floor joists from the basement, measure the distance between the bearing supports,IE: walls or beams that the joists are sitting on.

Your house would have been be built to the minimum Ontario Building Code which is to say that your floor system will only be built for a 1/360 deflection rating.
This is not enough for a stone floor, hence the questions from the other experts to determine what you have.

You certainly have plenty of plywood layers but the joists themselves may not be capable of supporting that floor system for stone.

As pistolpete said, if your floor support is not more than 10' you can carry on.

The direction that the floor joists run would mean that there is a span of 12', which is obviously more than 10'. To reinforce this, would bridging - screwing 2x8 pieces in between the joists every 2 feet- be sufficient?

Aren't you able to actually measure the span? If by bridging you mean simply connecting a board to two joists, I doubt that will do much. X bracing helps a little, but that should already be there.

You need to sister another piece of lumber to every joists to make a difference.

Jaz

I am going to take 3 pieces of 2x8 and screw them together, then at the midway point of the 12' span use two jackposts to hold the beam up. It is in a crawlspace so it is acessible, but low. There is already a support beam there, but of course it is at the 12' mark, so I'll just replicate that in the area under the foyer. I'll have a solid 2x8 beam that will be 4.5" wide, at 6'.

You asked for clarification on the matter of span. The "L" rating of the floor is basically how bouncy it is. The higher the #, the stiffer the floor. A floor system flexes both between the joists and along the entire span. If the span is too long the flexing of the floor can lead to cracks in the stone. stone is rigid, where porcelain is slightly flexible, hence the difference in deflection requirements between the two. If your joists are fir (especially old fir) then it should be good enough for stone. aged fir has a reddish brown appearance with distinct darker grain, where spruce or pine will be dark yellow with indistinct grain and nearly black knots.

From your description I feel confident in saying that it is spruce. That being said, should I put up a beam with jackposts at the midway point of the 12' length?

Edited for spelling

that would be the best possible solution. If it was my house, I'd probably just go for it and hope for the best. If it were for a customer (with warranty) I'd put in the beam or twin the joists with fir 2x6 glued and screwed.

Unfortunately, I've never seen fir in our home improvement stores, so I would be left to using spruce. I'm assuming by stating that you'd "twin" the joists, you mean sistering it? Is the beam a viable solution? Honestly, it would be easier than sistering each beam; that would mean spending less time folded like a jacknife in my crawlspace. Lord knows I been there enough. Believe me, I have thought about it just putting the tile down, but my gut tells me to re-inforce the floor. I will by no means call myself accomplished in tiling, but have done a number of jobs that experienced workers have commended, and I really just want to do this once. Again, thanks for the advice.

After re-examining the crawlspace area, I think you're idea of sitering the joists is far more sensible than the beam. Now, when I sister the new to the old, I will glue them and screw them, however should I use ordinary wood screws, lag bolts, carriage bolts? Thanks.

I use 3" deck screws. It's good to have the screws that have no threads for about an inch below the head so it'll draw the two pieces together.

I've also found it best to start the screw into the existing joist then into the sister which also helps draw them up together tight.

Another thing to keep in mind is that you only have to sister 2/3 of the span, specifically in the middle. So if you have a 12' span, the sister can be 8', centered on the 12' span.

I don't know what formula would be used to calculate the deflection on your joists once they are sistered with 2x6's, but are you certain that's going to be enough? I ask because there's not a lot of difference in price between a 2x6 and a 2x8, and although there's a little more effort involved to use the 2x8, it would also provide quite a bit more strength than the 2x6. In this area I think there's less than $2 difference between the two.

I will be using 2x8"s and since I have access at one one end to the footing, and at the other end to a main support beam in the crawlspace, I would think it would make the sistering that much more secure. It may be some overkill, but I'll never have to worry about it. Thanks for all the advice, gentlemen, and if anyone is free Monday night I have beer and pizza!!

The only downside to using full-span sisters is that they can be difficult to wedge into the space in an upright position. When your original joists were set, there wasn't a subfloor or walls in place. Now you have to work the joists in that tight space on both ends with only 14 1/2" of space between the existing joists.

Another potential problem is that occasionally your new joists might be slightly taller than the existing ones, making them impossible to fit properly. If that is the case, you'll end up trimming the ends anyway.

The weak point of the joist is in the middle, which is the reason for centering the sisters. You have little or no deflection in the first few inches or so nearest the supports, so running the sisters onto the supports is of little or no value.

It may work for you, but I wouldn't count on it. Good luck.