I have finally decided it is time to replace the sagging kitchen floor in my 100 YO house. The current floor is comprised of 2 layers of 1″ pine running across rough hewn 8″x8″ beams 3′ on center. The span is 16′, and the center of the floor sags 1 3/4″. The perimeter of the floor is level within 1/4″.
My plan is to remove all of the subfloor and add 16′ 2″x10″ joists between each beam. This will bring the spacing to 18″ o.c. I will then be installing 2 layers of 3/4″ plywood in prep for tiling.
Any comments/suggestions on whether this will be stiff enough?
Replies
http://twperry.com/spancalc/index.html
at that span, layout 2x10s at 12" OC or use 2x12 @ 16" OC
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You can run a deflection check here - http://www.johnbridge.com/vbulletin/deflecto.pl - keep in mind you need a deflection criteria of l/360 minimum for tile.
How will you handle end bearing of the sistered joists? Would it be easier to support the whole floor at midspan (reducing deflection substantially and possibly allowing all 8" deep floor members?
Jeff
I think you should be prepared to sister on the sides of the 8x8 beams. Once you remove the subfloor, you may find that your beams won't spring back level. The beams will probably stay in the "crown down" position, and don't even think about jacking them back into place. After 100 yrs. it would take considerable time to change their shape. As well, what Piffen said, a 2x10 is over spanned at 16', go with the 2x12's.
sbaillie,
It won't work.. remove all your joists and start over..
the 2x12's won't fit so you need to be creative.. depth adds strength but to a degree so does width..
Get a local sawmill to cut some 12x8's and put them about 12 inches on center.. The ideal wood is ash since it's really cheap right now and stiff as heck compared to say pine or other softwoods..
Edited 11/23/2007 4:01 pm ET by frenchy
What makes you think 2x12s will not fit?
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Piffin,
Well I assume that since there were 8x8's used 100 years ago That was all there was room for. Yes you could notch the ends of a 2x12 but then you have a weakened joist.. The shear point starts at the notch..
Besides that 2x12's would be more expensive than 2x12's I checked the most recent price guide and ash is selling for under 20 cents a bd.ft. thus the price for ash would be around $25.00 each. It's been a very long time since I priced lumberyard wood but I really expect that a 2x12 would be a lot more expensive than $25.00 each.
Frankly an ash 12x8 would be a whole lot stiffer than a 2x12 western white wood joist. Especially if it were made with something like spruce..
Edited 11/23/2007 7:05 pm ET by frenchy
As far as space goes all we can doi is speculate based on our own experiences. From what I've seen most 8x8s are fit into 12x12 beams and are over a crawlspace or less. I'd use hangers so no notching.Nothing wrong with your proposal, but most of us can't get the raw lumber as cheap as you can. Remember that you are in the middle of a golden forrest full of unemployed people willing to work cheap. I'm not sure if he is working alone, but I would hate to have to place green ash 12x8s instead of 2x12s.my first choice would be the 2x10s @ 12" oc tho
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Piffin,
100 year old home and you'd like to use modern materials {2x12's and joist hangers} while I'd like to stay with the timberframe theme.. relatively easy to put mortise pockets in between timbers. I understand our different approaches.
However the prices I looked up on the Hardwood Market Report were similar anyplace in the country.. Ash is flooding the currant markets due to the ash borer. Prices were similar for elm during the peak of the dutch elm disease..
AS FOR HANDLING TIMBERS THAT SIZE , GREEN, WELL I'VE DONE IT THRU MOST OF THIS HOUSE.. oops CAPS'S LOCK. Once you understand how to lift heavy timbers it's not terribly difficult. Lift one end at a time and rollers are your friend. Face it, if a fat sedentary old guy can do it just about anybody can.
Now I'll grant you that your approach would work however to me that would be like putting vinyl siding on the Taj Mahal. Your opinion may vary, objects in the mirror are closer than they appear, close cover before striking..
Heck, I use modern materials and methods on TWO hundred year old homes, as long as there is no historical preservation committee or own stipulating authentic. sometimes newer methods and materials is just better and easier and cheaper all in one! I'm sure you'd agree since we both use ICFs.Anyways, the OP now has at least three or four ways to get tto what he wants, all of them better than what he was planning
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The way to deal with the notch is to strap it. You don't need the strength at the ends, you just need the notch to not start a split, and adding either metal straps or glued/screwed plywood gussets will prevent that. You should be able to use any size lumber (provided there's ground clearance) if you notch and strap the ends.The real trick is working the new joists into place if the old ones aren't removed -- may require creativity and will likely require shaving one end down and then shimming after it's in place
If your view never changes you're following the wrong leader
Keep in mind that 8 x 8 floor beams would normally have been dovetailed into the sill beam so removing them may not be all that easy - and usually unnecessary. As mentioned, sistering usually works fine.
You have all assumed that he would be able to set full-length joists inside of the sill beam and on top of a foundation wall - not typically all that easy. Much easier to set a center line of bearing and work in half-length (+ overlap) new joists.
Jeff
sometimes that center beam is easier and sometimes harder. Only he will know when he opens things up to get a look. Maybe he'll let us see too, via photos..One big advantage of a center beam is that it could really reduce deflection and vibrations with succh a long span - for tile this is imperative
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Have you seen the metal joist "strengtheners?" I've seen them advertised in JLC--a steel triangle for each end and a sort of upside-down ramp looking thing for the middle. Seems like they would work, but might be expensive.
Just found the ad--they are called "CornerCam" and "JoistJack" and the web site is at http://www.ridgwaystructuralsystems.com.
EDITED to correct spelling of "ridgway."
Edited 11/25/2007 6:13 pm ET by Danno
Haven't no. I am imagine a sort of trussing re-inforcement?That links doesn't work for me.
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I don't know how to do links that you just click on. Anyway, yeah, they're like corner braces for the ends and trusses for the middle. But, they probably wouldn't work in this case--I thought the OP was talking about 2x8's, but I see that he was talking about 8x8's. The devices I saw look like they will only work for 2x's.
As others have said, I don't think he can jack up 8x8's that have taken a hundred year set without cracking them or some other bad thing happening. Maybe remove the flooring, put a center beam across under the 8x8's and lift them gradually by jacking the center beam up--but, as you say later, then you are still left with the 8x8 joists being too far apart and the floor decking will probably sag between them.(Although he was talking about two layers of 3/4" plywood--that would be pretty stiff if glued and screwed to the joists.) But once the floor is open, why mess around with the old stuff that is questionable? Just start fresh. It's be a bummer to have the new floor tiles or grout start cracking!
http://www.ridgwaystructuralsystems.com/I googled it and got this link.To make an active link all I do is open the page in a browser tab or window, highlight the URL and rightclick/copy/paste.The system looks interesting and even adaptable for timbers, but I was surprised how much depth it uses below the member
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I'm guessing the depth taken up is variable, depending on the amount of lift you want. Probably in this scenario you could get away with about half of what's pictured.But, as we've discussed, jacking the existing joists isn't really the solution, both due to a century of set and the wide span.
If your view never changes you're following the wrong leader
He could even find that they are full of insects and need to be removed
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Or that the foundation beams are rotted and the whole thing is in need of a match.
If your view never changes you're following the wrong leader
And note that you can accomplish the same thing with turnbuckles and aircraft cable.
If your view never changes you're following the wrong leader
Yeah, I wouldn't try to lift the existing joists, just install the beam below to support the new joists. Try to jack the existing joists and you'll end up lifting one of the walls.
If your view never changes you're following the wrong leader
Yeah, that link is dead.
If your view never changes you're following the wrong leader
I spelled it wrong--who'd have guessed "ridgway" doesn't have an "e?" My bad--I looked right at it while typing it.
Wow, lots of great discussion!
I will not be adding a central beam as there is definitely no chance of jaking 8x8s up 1 3/4" in any reasonable amount of time, besides the fact that I will still have to add joists between them.
As far as using 2x12 or anything larger, I am inclined to stick with my original plan of 2x10s, and increase the number if req'd because I have a large number of high quality spruce 2x10s (full dimension) that I cut a few years ago.
I have considered removing the 8x8s, but they are in great shape, as are the 12x12 sill beams (thanks to cold climate of the Ottawa Valley)
Upon more detailed layout, the span between the sill beams is only 14' (the room above is 16' wide because the sill beams, and foundation are so thick), and they are dovetailed into the sill beam with ends about 6x6.
I am undecided on how to level the 8x8 beams. I have considered bolting new 2x10s to one, or both sides of the beam, and letting the ends the beam carry the load through the sill beam onto the foundation. If I use this method, and add a new joist between each using joist hangers on the sill beam, I will have 2x10s o.c. following a pattern 10", 13", 13", 10".
The other option I have been considering is levelling the top of the beams with cement by tacking level boards to either side, and using them as a strikeoff guide. Using this method (time consuming for sure) and adding a new joist between each beam I will have beams 18" o.c., however every other beam will have a bearing surface 8" wide versus 2" standard. I believe this would effectively reduce the joist spacing to 15"o.c.
Again thanks in advance for any comments and suggestions, the more thought that goes into this process before I get started, the better the end result will be.
Simon
and they are dovetailed into the sill beam with ends about 6x6.
As I mentioned, the typical dovetail detail is both strong and makes removal more destructive to a timber frame.
I am undecided on how to level the 8x8 beams. I have considered bolting new 2x10s to one, or both sides of the beam, and letting the ends the beam carry the load through the sill beam onto the foundation. If I use this method, and add a new joist between each using joist hangers on the sill beam, I will have 2x10s o.c. following a pattern 10", 13", 13", 10".
You should be fine through-bolting 2 x 10's to each side leaving the sagged 8x8s alone. Don't forget to provide solid bridging at midspan - essential on floor spans over 12'.
Jeff
Like others say, I would not use cement--you won't be able to nail the new floor deck to the existing 8x8's then, the cement will attract dampness, it will crack, it will add weight without adding strength, etc. Sistering your 2x10's and adding two between the existing joists seems to be the best idea. I thought of shimming the existing 8x8's too, but hard to get the shims exactly right. I suppose that along with sistering (others may reply differently, but I think one 2x on one side of each 8x8 is enough, along with probably two more between each 8x8 (approx 12" o.c.)) you could put a block on top of each 8x8 that is level with the sistered 2x just for added nailing area in the center.
I suppose you could even add boards planed to the appropriate thickness between the sistered 2x8 to the adjacent 2x8 across the existing 8x8 to act as bridging, but I don't know that this would really help stiffen things all that much. It may be better to consider adding a 2x4 "strongback" across the bottoms of all the 2x10's (perpendicular across them at the center of their span).
" The other option I have been considering is levelling the top of the beams with cement by tacking level boards to either side, and using them as a strikeoff guide. Using this method (time consuming for sure) and adding a new joist between each beam I will have beams 18" o.c., however every other beam will have a bearing surface 8" wide versus 2" standard. I believe this would effectively reduce the joist spacing to 15"o.c."
Yeah, but you also have an 8" wide chunk of cement under your subfloor. At the least, a pain to fasten through. Since you say you have a source of cheap lumber, I'd stick with sistering or scribing a shim for each beam.
Mike HennessyPittsburgh, PA
sbaillie...
i'd sure start with a center beam on cribbing... whadda ya mean you ain't got time to jack the 8x8's ?
look... you've got a double 1" pine floor... so THAT is not going to need any reinforcement.... it will absolutely span the 28" space between the 8x8's
so you're left with a nice uniform 1 3/4 droop
put in some cribbing and some jacks and slowly bring pressure on the 8x8's
tack a furring strip ( 1x3 ) to the mid-span of each 8x8 and let them bear on the existing floor
as you jack you can observe exactly how much lift you get by the daylight undr each piece of furring
first day jack til you hear it complain
next day try some more...
and the next day .. some more.. if you start to meet wiht success.. then you can make it permanent and change your long term jacking schedule for the short term trial
one of two things will happen... the bend will come out of the 8x8's ... or the 8x8 will lift the entire floor and walls..
the alternative is reframing the entire floor .... AND probably winding up with a center beam anyways... because the 16' span is on the outer limits of most floor systems
getting new footings and a new center beam is not a problem
the hesitation seems to be that no one thinks they can take the bend out of the 8x8's... well.. i'd sure be trying Mike Smith Rhode Island : Design / Build / Repair / Restore
Mike Smith,
Too be fair most of my experiance is with barns.. watching them try to straighten them back up and remove the sag from them. 100 years seems to be about the point where a farmer or somebody decides to either straighten them or pull them down.. MY parents had a friend who did that for a living..
They'd put come-alongs and chains on timbers and big really big hydraulic jacks (50 ton was a small one) An 8x8 beam is surprisingly stiff and most of that sag occured in the first few years.. Now that timbers has a set on it and no whimpy little 2x material is going to remove that sag for long..
You see lumberyard material isn't really dry. KD 19 is 19% moisture plus or minus 2% and you are asking a piece of green wood to hold it's shape when it's sistered along side a 8x8 beam.. Note he hasn't mentioned what wood we're talking about but most likely it's a hardwood.. a lot stronger than most western white woods that are in lumberyards..
Face it no 1 1/2 spruce /pine/ fir is going to unbow a 8x8 hardwood beam with a 100 year old bow..
You need some really serious beams in there..
frenchy.. wether the 2x center beam would crush or not is not the issue
the issue is: can the 8x8 deflect or not ?
the poster can go in the basement and install cribbing and a building mover's jack or a large hydraulic bottle jack....
if the beam will deflect , then he knows he can install a center beam and jack the 8x8's back to true... or back to acceptable
the center beam then might have to have crush plates at the contact points... but the real questions is .... can i make the 8x8 deflect ... or not ?
if i can... then all of this other work is a waste of time , because all he's trying to accomplish is to take the bend out of the floor... and he's alreayd said that installing a beam in the basement is not objectionable...
he is just under the impression that it won't work.. and that has not been established
Mike Smith Rhode Island : Design / Build / Repair / Restore
I have tried jacking these up and really haven't had great sucess. Most of these older homes are balloon framed and when you start lifting something you end up having to lift it all the way to the roof.
I have crushed 2 ply LVl headers trying to lift small areas of 2nd floors. These are in homes that are over well 100 years old.
Possible I am sure it is, but I am not setup for that type of heavy lifting. Mike Smith is right, try it. What have you got to lose? If it doesn't work then I'd install a flush beam.
Install 2 temporary walls under the joists, each 2-3 ft from the center of your span. Giving you 4-6 ft of work area in the center of the span under the joists. Then cut the joists enough to install a flush beam and a ledger for the new and old joists.
At 16' span I'd be looking into a 12" OC spacing to help minimize deflection. ANd if tile is going to be the finished flooring then I wouldn't space it any other way. SYP #1, 2x12's make a stiff floor at 12" OC. But get the beam engineered.
Then locate areas where your new post pad footings will be, cut holes in the concrete floor and pour some 5000 psi footings. Another engineered thing to help determine size.
Matt- Woods favorite carpenter.
If I were going to "jack" I'd consider doing it with steel cables, vs jacking from below. That way you're putting all the force on the beam, vs trying to lift the whole building.
If your view never changes you're following the wrong leader
I am curious with the steel cables. Care to go into some details for me?
Matt- Woods favorite carpenter.
Just build a truss. Trick in the anchorage on the ends; in the middle you'd just run the cables over a length of pipe fastened to the bottom of the joist (possibly with a spacer between to give you more leverage). And turnbuckles, of course.
If your view never changes you're following the wrong leader
You got a portable skyhook to run those ables off to?
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Build a truss. You have 8 inches of depth, plus whatever the sag is. Add another 4 inches or so spacer and you have your bottom center. Cable from there to the ends, near the top. Hard part, as I said elsewhere, is figuring out the end anchorages, though I can think of 2-3 different designs that should work.
If your view never changes you're following the wrong leader
MIKE,
We're not speaking about crush, we're speaking about the ability of a 2x material to withstand the sag built in almost 100 years ago. I contend it won't do it..
8x8 timbers Hardwood (?) most likely took a set shortly after they were put in place.. With a 50 ton jack you'll be able to as you say over time remove the sag without damaging the beam, however once the jack is removed counting on 2x material which in itself is green won't be able to resist the memory of those 8x8's
If I had the wood species I could actually look it up and give you the force those 2x's are going to be asked to resist.
As you say putting a center beam in is another option, however I don't remember the span that would have to cover I do remember length wise we're speaking 16 feet I don't remember width.
I would appraoch it differantly. There are bound to be sawmills around him and large sized beams are their bread and butter..
Put in a couple of proper sized ones between the sagging beams and the new ones will be straight. Then you could sister your 2x material to the sagging 8x8's and not have them deflect back. Sag gone!
you're guessing...
and asserting facts not in evidence
what is really being described is a 16' 8x8 with a uniform load that has deflected OVER TIME.. so when did this "set " occur ?
a 16' wooden 8x8 beam is still going to be very elastic... bet i can deflect it Mike Smith Rhode Island : Design / Build / Repair / Restore
Mike,
Most sag occurs during the drying process, not afterwards.. an 8x8 timber typically would be put up pretty green and dry over the next decade or so..
Of course you can deflect a 16 foot long 8x8 beam, the problem is the wood has a memory and will return with a great deal of force to it's previous condition once external force is removed from it..
This is pretty elemental stuff Mike, Are you testing me?
frenchy.. the jacking is to determine if the beam can be deflected
<<<once external force is removed from it.. >>>
if it can , then jack it and install a center beam .... SO... the external force ( the new center beam ) would never be removedMike Smith Rhode Island : Design / Build / Repair / Restore
Mike,
Unless I miss my guess, He's going to use a sawmill beam rather than a gluelam.. A sawmill beam will be less than 1/4 of the price of a glue lam.. In that case the beam will be green for the next decade or so and whatever force caused the sag in the first place will be forcing that new center beam to deflect.In time it too will sag unless it's pretty massive ( I still don't know the width we're working with) If the room is 16 x 8 then yes a properly sized beam won't sag, but if it's a 16x16 then even a 12x12 will sag some..
Oh he may gain some from the new center beam But I doubt a decade from now the floor will be flat and level.
frenchy..... the new beam doesn't have to be free span...he can post down as often as he needs.... matter of fact ... he doesn't even need a center beam... all he has to do is post down in the center span of each of the existing 8x8's...
this is really a simple thing ... don't complicate itMike Smith Rhode Island : Design / Build / Repair / Restore
Needs a center beam to carry the 2 x 10's in between the sistered 8 x 8s since 2 x 10's is pushing it for deflection.
Jeff
jeff...here's the existing condition:
<<<<The current floor is comprised of 2 layers of 1" pine running across rough hewn 8"x8" beams 3' on center. The span is 16', and the center of the floor sags 1 3/4". The perimeter of the floor is level within 1/4". >>>
there are no 2x10's
he can use a center beam to jack the 8x8's or he can psot down from each of the 8x8's... sounds like there are 5 or 6 of themMike Smith Rhode Island : Design / Build / Repair / Restore
OP - "My plan is to remove all of the subfloor and add 16' 2"x10" joists between each beam. This will bring the spacing to 18" o.c. I will then be installing 2 layers of 3/4" plywood in prep for tiling."
My response included the suggestion to add a center beam to cut the span in half, significantly reducing deflection for the anticipated tile.
Jeff
no... that was his "plan" before he posted..
lord knows what the plan is now....... i'd be confusedMike Smith Rhode Island : Design / Build / Repair / Restore
Mike, you stole my thunder. I was all set to come out against the pack of pros and proclaim that if I lived in that house as I think the poster does, I could raise that floor to level with a simple screw jack. Taking half inch increments the house would never know what happened. Tap in a 4x4 as you go.I can understand as contractors they think in terms of days or weeks to accomplish their goal and get to the next job. As the HO it would be easy to squeeze up a half inch every once in a while until the required goal is met and then install an I beam with a post on each end if necessary. Remove the 4x4's. Simple simon job and it's done. Lots of good ideas though in this thread, but I think unecessary. You know, if they don't bend over a decent interval of time it would be worth heating the area to about 130 degrees for a few days and even add some steam to the area for a while. That would make the white cedar think it's becoming a wet noodle. I don't think that would be necessary though.Mesic
Jeez, talk about designing an elephant to pick up a flea...It's not a trip to the moon.As Mike said...Get under there and start jacking on one of the 8x8's. You'll know soon enough if it will deflect. And my bet is right along with his, that it will. -Without- all kinds of complicated shorage, sistered lumber, and worry about lifting the whole house, etc. Put one beam down the center, and shim between the beam and each individual 8x8 to compensate for the differences in the rough 8x8's. Or just put one single post beneath each 8x8. Personally I'd go with the beam, three points of support, and plenty of shims and crush plates.And dude... don't be setting all this on concrete pavers. Pour some real footers for those supports.
Everybody is born a hero.
Register me then as a total contrarian to the 'see what happens' approach - it is neither desirable nor necessary to jack old timbers in old houses. In his case there is simply no reason to do it.
Jeff
so noted... now.... hand me that jackMike Smith Rhode Island : Design / Build / Repair / Restore
So registered and noted.You make it sound like the house is going to fall down around his ears if a jack so much as touches one of those beams, (before the rest of the elephant is constructed to pick up the flea)... That is NOT going to happen.~~~In my opinion, it is the first thing he should have done.What he would have learned just by trying to move the center one, half an inch, then investigating the ends, the walls upstairs, etc... Would have answered the majority of the questions that have been asked here.It costs nothing to investigate.
Everybody is born a hero.
sbaillie.... so .....
what's up , Doc ?Mike Smith Rhode Island : Design / Build / Repair / Restore
"You make it sound like the house is going to fall down around his ears if a jack so much as touches one of those beams"
Huh? You're kidding, right?I just said it was unnnecessary. Jacking has a tendency to lift the entire beam and can damage the dovetailed tenons at the end. It can shear crack the timber since they do tend to take on a 'set' over time and often are very dry. Jacking is especially unnecessary since there will be intermediate 2 x 10s that are deeper than the 8 x 8s anyway.
Since my point obviously wasn't clear I'll restate it - you don't need to do it and it can cause some damage, that's all. There are well-established ways of dealing with floor sags in old houses and 'jacking just to see what will happen' isn't one of them.
Look, his floor sag is 1 3/4". His 8 x 8s probably measure 7 3/4" - Intermediate 2 x 10s measure around 9 1/4". Difference - 9 1/4" - 7 3/4" = 1 1/2" +/- = almost exactly the amount of the sag. So, if he starts 2 x 10s even with the tops of the 8 x 8s the bottoms of the 2 x 10s will be almost exactly at the bottom of the 8 x 8 at midspan. That would allow for a center beam support to pick up everything with only a minimal amount of shimming and no jacking. Put one 2 x 10 either side of the 8 x 8s for leveling - done deal. If he adds (2) 2 x 10s between each 8 x 8 he (barely) makes deflection criteria and therefore doesn't need a center support at all.
Why on earth would you need to jack the old configuration level?
Jeff
Edited 11/29/2007 10:02 am ET by Jeff_Clarke
"Why on earth would you need to jack the old configuration level?"Because he wants a floor, not a bowl ????
Everybody is born a hero.
A 2 x 10 each side of a bowed 8 x 8 IS part of a level floor. The sag or set is ignored but the strength and integrity of the 8 x 8s and the sill timber are maintained.
Jeff
jeff... you are the one installing the 2x10's..
but in order to do that you have to remove two layers of 1" pine subfloor
so ... who's preserving the "integrity" of the structure...??
it's a 16' square room... with 8x8 joists 3' oc...
c'mon......Mike Smith Rhode Island : Design / Build / Repair / Restore
??? He'll have a tile floor ... think nearly no deflection - l/360 or better. He is the one adding 2 x 10s in between because he has to. Why jack it when you could break it and it doesn't get him anything? Why leave 2 layers of pine floor spanning 3'???
Think about it from a construction standpoint - by removing the two layers of pine and leveling with 2 x 10s he can then add 3/4" T&G subfloor, 1/2" cement board, setting bed and tile and come close to the original floor level. That saves him all kinds of problems at base, doorways, etc.
Jeff
two layers of 1" pine boards on a 28" span EXCEED the deflection limits for tile
the ONLY thing that has failed in this case is the deflection limits of the 8x8's ... whci can easily be corrected with a center beam
why do you want all of this unneccessary work ?
wouldn't it be nice is sbaillie would come back and let us know what he's found ?
won't you come home , sbaillie,
won't you come home ?
Mike Smith Rhode Island : Design / Build / Repair / Restore
Edited 11/29/2007 1:14 pm ET by MikeSmith
This is getting better than a good pld tavern fight!;)I stepped asside because everyone is arguing their own method based on assumptions they have made from their own experience.i've seen a couple beams that could be jacked back straight and think you might be right there since these sound like cedar, but most I've dealt with are not jackable without damaging something.There are two assumptions you are making. One is that he can get in under that floor without tearing it up. I have worked on several where the only way to access it was to go down through the floor.You other assumption is that his floor two ply pine is as good as the books say. I replaced one at just about 28"OC a couple months ago that had spruce 1x10 subfloor and pine 1x6 T&G long stock finished floor. It was scary bouncy between joists.Jeff is assuming that the beam is dovetailed in. I rarely see that.Frenmchy is assuming...well, you get the point
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Piffin,
Yeh, I'm with you, too many assumptions made and the OP hasn't come back to clarify.
and bill bailey is gonna keep us all in the dark...
oh woe.....Mike Smith Rhode Island : Design / Build / Repair / Restore
so save the last dance for me.;)
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I assumed what?
No, I read the OP's posts - like http://forums.taunton.com/n/mb/display.asp?webtag=tp-breaktime&msg=97437.33&js=y
"Upon more detailed layout, the span between the sill beams is only 14' (the room above is 16' wide because the sill beams, and foundation are so thick), and they are dovetailed into the sill beam with ends about 6x6."
Jeff
Edited 11/29/2007 5:42 pm ET by Jeff_Clarke
A-ha!So you only assumed that they are hardwood that ccannot be jacked straight.Sorry
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Actually, I think a poured floor with wire lath would probably meet the deflection standards.
If your view never changes you're following the wrong leader
For all the posters of jacking beams:
- I agree it would work
- I am not going to try, because I do not want anymore posts in my basement.
I like the idea of a poured floor, but I would still remove the old pine flooring, as it is too spongy. I think pouring it over a new layer of plywood would be better, but the concrete would add approx 4000lbs at an average thickness of 2". Also, I have never done this before, and I have no idea what kind of concrete to use, nor how much it would cost.
I am still leaning towards adding new joists between the beams, and 2 new layers of plywood followed by cementboard. This appears to be the most economical solution to me.
Simon
Yeah, I'd only recommend the concrete if the existing joists were braced mid-span. If you want to have a clear basement then the new joists is the way to go.
If your view never changes you're following the wrong leader
so , what happens to the 8x8's ?
do the new joists run parallel to the 8x8's or do they bear on the 8x8's ?
what's the span ?.... 14' ? 15'? 16' Mike Smith Rhode Island : Design / Build / Repair / Restore
Read post #1???
If your view never changes you're following the wrong leader
well.......
something about the forest and the trees ?Mike Smith Rhode Island : Design / Build / Repair / Restore
Heck, trees is all we've been talking about for the past 94 posts.
If your view never changes you're following the wrong leader
Well I finally got to work on my floor. I decided to leave the existing beams in, and scribed 2in shims to fit them, and cut level. finicky work, but overall went quite well. Next step was to add 2"x10"s between them 12" o.c. The span between the large sill beams (10"x10") is actually 14.5 ft, and assuming the 8x8s are equivalent stiffness to the 2x10 spruce the floor comes out around L/460. With the 1.5" glued plywood subfloor, it should be very stiff.
Next step, replacing the lath & plaster, fun times await!
Thanks for all your suggestions!
Thanks for the pic - that's pretty much what I was suggesting.
Jeff
he's alreayd said that installing a beam in the basement is not objectionable..."I must've misunderstood him. I thought he said it was something he couldn't or wouldn't be doing.But if the beam is an option, you are mostly right
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I think you are probably right, and I could jack the beams back to level. The beams appear to be white cedar (very plentiful in this area) and I know from canoe building that white cedar, even dry, is quite elastic. The problem is that the beams are not all 1 3/4" sag, some are more, some are less. I think I mentioned that the beams are hand hewn, so there is substantial variation in their dimension, probably close to +/- 1". Also, even if I did jack the beams back to level, I don't believe 1 1/2" plywood spanning 28" between each beam will be stiff enough for a tile floor (especially large 1'x2' tiles).
It appears that 2x10s spaced 12" o.c. is my best option. I have close to 2000 bd.ft. of good quality spruce lumber on hand, so this is my most economical option. This will yield a floor deflection better than L/500 which should be more than acceptable with 2 layers plywood, and 1 layer cement board under 1'x2' tile.
Whether I sister to the old beams or remove them I think I will decide after I have everything opened up. Because the old beams are hand-squared, it may become a chore to sister a beam to them. I am tempted to cut them flush with the sill beam, and install all new joists with joist hangers on the sill beam. If I proceed with this approach, would cutting the beams out before installing any joists place too much lateral force on the foundation wall/ sill beams? It appears to me that all the force on the sill beam should be vertical, but in a 100 YO house anything seems possible.
Simon
8x8 timbers Hardwood (?) most likely took a set shortly after they were put in place..
Listen to Frenchy - he's correct on old beams taking a 'set' - this has absolutely been my experience with older houses. There is no need whatsoever to jack anything at all or to remove the beams. Just sister as described.
Jeff
Edited 11/26/2007 9:05 pm ET by Jeff_Clarke
if you can get the 8x8's to jack
then you can level it with string lines on the top of the first floor
as for wether or not the floor would be stiff enough for tile:
you described two layers of old 1" thick pine boards.... ie: you have a two inch floor spanning 28" ... i think you have a floor that is stiffer than the tile institute would be looking for..
so... if you can get the floor back to level.. strip it down to the top layer of the 1" boards, install 1/4" hardiebacker and tile away
if.... if .... if.........
start with a jack and see if you can move the 8x8
Mike Smith Rhode Island : Design / Build / Repair / Restore
Heck, just staple two layers of expanded wire lath to the subfloor and fill in with thinset. Lots simpler than any other scheme and guaranteed to give you a stiff, flat floor.
If your view never changes you're following the wrong leader
Never thought of that, despite it being what they are doing at the house I worked on in Alabama--mesh and "concrete" (they called it that, but it is like thinset (thickeset?)) over the whole, currently "spongy," floor and tile over that.
Would certainly take care of the dip in the center of the flor and no need for jacking, etc.
i'd still be installing a center beam, since the dip indicates the deflection resistance / load carrying capacity of the 8x8's was exceeded
but yes.... if you can't jack the deflection out, i'd reinforce what's there and do a mesh/mud jobMike Smith Rhode Island : Design / Build / Repair / Restore
Simon,
Spruce is not one of the stronger woods. I think (I'm not checking my referance manual so it's purely a guess) that spruce might deflect more than you'd like..
Second,
look at using 2x material rather than plywood for your sub floor. I found that sawmill wood winds up much cheaper plus it it's easier to put down.. No wrestling with heavy and awkward 3/4 sheets of plywood.
My whole house's subfloor is 2x material from a sawmill. Some is 2x12's and some is 2x6's some are 2x10's or 2x8s I used tamarack, hackberry, eastern white pine, and ash because they were all unbelievably cheap. 32 sq.ft. (same as a 4x8 sheet of plywood) of 2x material wound up costing me only $6.40 while two pieces of plywood covering the same area would have cost me nearly $40.00 I saved nearly $3000 on the subfloor alone!
third..
save yourself some money, mix a dry batch of mortor and put down a couple of guide boards to screed the mortor level. It's much cheaper and also easier than. using cement board. Just lay down some 15 pound felt tack it in place, mix a dry batch of mortor pour it in place and use the guide boards to screed across. You can slide the guide boards down and use a trowle to fill the space with mortor and level it back. Not a lot of skill required and pretty darn fast and easy to do.. Not only will you wind up with a cheaper base for your tile but it will be flatter than most people can do with cement board.
Yeah, a center beam should certainly be considered. Trick is getting footings that are consistent with the existing, so you don't end up with a hump or another ditch 20 years down the road.If a center beam is used, some pre-planning will make it easier to adjust it down the road (adding/removing shims) so that foundation creap is compensated for.
If your view never changes you're following the wrong leader
Jeff Clarke
We're both assuming things. I didn't assume dovetails rather simple mortice joints.
If there is that much sag in the floor now I doubt that you'll successfully sister 2x material successfully. An 8x8 that's had 100 years to sag that much isn't going to repond nicely to a jack. I've had to work like crazy to get a 3x to move even 3/4 of an inch. It took several posts and a 50 ton hydralic jack over a month to achcieve.. Big timbers don't move like an 1 1/2 joist will.
Finally we don't know if the timbers are exposed or not if exposed sistering joists would be too crude for most peoples taste..
I've put a sliding tenon into a mortice pocket when I retrofitted timbers into my existing timberframe so I know it can be done relatively easily.
As for a centerpoint wall to act as a load bearer I doubt that's possible. That would divide an existing 16 foot room into a less than 8 foot room. Fine for bathrooms and closets but not so fine for modern living spaces..
Agreed - we've never jacked old beams - just sistered in place which is relatively easy to do. As the OP states, the less removed the better (if possible).
Definitely skip the cement!
Jeff
Edited 11/25/2007 10:29 pm ET by Jeff_Clarke
My impression of this stuff is that there ain't no "normal". You have to get in there and see what you're working with, then make the plans.
If your view never changes you're following the wrong leader
I came to read this again, to see if I was missing something when frenchie said there would not be room for 2x12s. I don't see that you give any info that indicates that, but it may be,
But what I do notice on re-reading is that you only planned on one 2x10 halfway between the existing. That is far and away from inadequate! I was picturing you sistering to them also at least. They will definitely remain with the sag in them so you need to straighten thaat out.
Using 2x10 @ 12" OC would allow you a consistant layout that works with typical milled KD lumber and the existing beam would fit between every third space.
Ading strapping along the bottom would help too.
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Can you build a beam to carry the center of your existing floor joists?
This is by far the easiest route.
Gord
"This is by far the easiest route."Except for cutting them and jacking them up to level, and stitching them back together and dealing still with the deflection in between them for 28"
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Why jack them?
If the centers are supported, and the 16'span is reduced to two 8' spans, 2X8's would suffice for the fillers.
The floor has already drooped 1 3/4", whats to stop the 8X8's on a 16' span from sagging further?
Gord
Because he doesn't want to just stop them from sagging further. He wants to get that 1-3/4" sag out. In order to do that, he'll have to slice through them at the beam abut 2/3rds of the way and jack up there.
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Its hard to call these from the armchair without seeing the job at hand.
I'd be tempted to rip a shim to lay atop a decent sagging 100 yr old beam supported or not.
Slicing a 16' long 8X8 seems sacrilegious to me but who knows?
They might be split, twisted, half rotted, waterlogged, worm eaten, sapwood pieces of junk.
In this day of simple digital photography, and 5 or 6 posted pics. We could deal with these things and concetrate on the solutions rather than debating each other.
Gord
Well, he says he will not be placing a beam in under, so I would sister a 2x10 to one ise of them and layout from there @ 12" oc
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Excuse me while I remove the shoe from my mouth...
Note to Gord:
Read ALL insightful posts by original poster before posting.
Gord
sbaillie, Where are you? If you are out there please speak up. As I was reading this I got a chuckle at all of the conversation and speculation going on about sbaillie's problem but you were conspicuously absents I hope you are alright. Oh, and by the way, you might consider 13/4"x71/2 LVL's.( f=3000 +/-and E=2,000,000 +/- ) Just a thought. Much stronger & stiffer than standard lumber. Now I'm doing it. It would help these guys if they knew more about the conditions. Good luck, opps
Yup ... they're $tronger and $tiffer alright!
Jeff
In all this joist replacement talk -- Are you able at all to utilize a poured leveling floor, like gyp crete? You could reinforce the floor the easiest of ways and add the lightweight leveling to create the rigidity and level condition. Might not work if you're in the boondocks, but it sure would be easier than repalcing everything, as long as you were sure that the structural capacity would be there for the additional weight of the floor and tile.