how level to make floors

[brian89gp]

Have a 120 year old house I am remodeling that the back section of it has settled as well as the typical floor sag. How much slope is needed for it to be noticable/annoying?

Along the exterior walls there is a 2" difference between the highest and lowest point. The middle sag (which is being corrected by a beam) is a 4" difference from the same highest point to the lowest point.

I am lifting the house up to pour a slab of concrete on top of the stone foundation and install a new sill plate so I can theoretically jack it all the way up to be even with highest point. It is a complete gut and remodel so this is entirely possible, but raising it 2" can cause other interesting problems. I can get everything to within 1-2" pretty easily but getting it to 0-1" is a lot harder.

 

[gzecc]

One inch from one side of a room to another is exceptable for an old house.

 

[greg13]

Just remember to go SLOW! Listen and watch for problems.

Greg

 

[brian89gp]

Cool, I will shoot for 1". I guess I could always correct anything that remains and is too noticable with sleepers. There is going to be a 10x30 room that runs the length of the house and am really trying to avoid a wave in the floor.

I do it in 6' sections and always make sure to reattach the wall and install crossbracing before moving on to the next 6'. I really hate jacking up houses (not the first time I've done it) but its hard to put $40k into one and not fix the major structural issues that caused the unlevel floors in the first place.

 

[rwthomas1]

If its a complete gut then why not get as close to perfect as you can? You won't be worrying about cracking walls, etc. The framing will move no problem. Worst I've fixed was 1/2" drop per foot over 14ft. Two story colonial with a cracked foundation. Since it was a gut, no windows, doors, it wasn't bad. RT

 

[brian89gp]

If its a complete gut then why not get as close to perfect as you can? You won't be worrying about cracking walls, etc. The framing will move no problem. Worst I've fixed was 1/2" drop per foot over 14ft. Two story colonial with a cracked foundation. Since it was a gut, no windows, doors, it wasn't bad. RT

7" drop, yikes.

I find it unnerving jacking up a 2 story structure from the basement is pretty much the reason.

 

[ewdudley]

I had a contractor botch an addition floor such that the whole floor is 1.5" higher on one side across a 12' span. It's subtle enough that I didn't catch it until after the floor was put down. Without furniture only my brother and I can see it before it's been pointed out. With furniture in place I can't tell.

In the old part of the house the dining room is way out of whack. I jacked it up all around just enough to get even pressure all around and left the original charm as is. Guests are advised to take advantage of the advanced architectural feature that gravy will automatically stay on the southeast side of the plate.

 

[rwthomas1]

7" drop, yikes.

I find it unnerving jacking up a 2 story structure from the basement is pretty much the reason.

View attachment 126186

I'm waiting on the engineering for jacking up a 4000sq/ft, 3 story that is 140 years old. I don't need to go far, I'm just replacing a 16ft 12x12 beam that has been compromised by insects. I'll have three choices: Sandwich the damaged beam with lvl's and steel, rnr the beam for a new composite lvl beam and/or cut the basement floor to add another lally column in combination with one of the above. I let the professionals tell me the best way, then its my job to execute the grunt work. Should be fun!

 

[brian89gp]

That is one big beam. Out of curiosity how do you go about finding level? I have been attaching a laser level to the basement wall and measuring down from the bottom of the floor joists.

I had a contractor botch an addition floor such that the whole floor is 1.5" higher on one side across a 12' span. It's subtle enough that I didn't catch it until after the floor was put down. Without furniture only my brother and I can see it before it's been pointed out. With furniture in place I can't tell.

In the old part of the house the dining room is way out of whack. I jacked it up all around just enough to get even pressure all around and left the original charm as is. Guests are advised to take advantage of the advanced architectural feature that gravy will automatically stay on the southeast side of the plate.

My parents have a kitchen table just like that. I actually found it pretty effective because you could put the watery food on the downhill side and avoid getting everything on the plate sopping wet.

 

[FanMan]

When I moved into my cabin, the living room floor was 8" out of level. I did some jacking, but that was a pretty scary thing laying on my stomach in the crawl space pumping a jack while listening to the ominous creaking of the building above. I'd pump a few strokes, then get out and wait for it to settle, then go back in and pump a few more strokes... when all the windows were able to close properly again, I declared it Good Enough. Now it's maybe 3" out of level, with the only drawback being that I had to cut every piece of wall with a slightly different angle on the bottom.

When I was a kid in a different nearby cabin, we loved that we were able to race Hot Wheels cars on the living room floor...

 

[Ashful]

I've leveled more floors than the average guy, having lived in a succession of very old houses (120 years is almost new!). Many will choose to shim on top of the old flooring with laminates, self-leveling pours, or sleepers, but I hate raising the floor level, and doing anything so un-original to the house. If you have the option to jack the house back to square, I'd definitely do all that can be done in that arena. However, you failed to indicate the distance over which these drops are occurring. Also, according to your posted elevations, your room is not just out of level, but your joists are sagging, like a bowl.

It's likely you require a beam at mid-span under those joists, as evidenced by the sagging. This is very common in local Victorian era houses (same age as yours) as they'd run incredibly long spans with 2x6 or 2x8 joists. My last Victorian had a 14" oak beam (it was what presented itself cheaply at the time) installed at mid-span across each large room.

Once the beam is installed and the floor stabilized, my usual procedure is to pull up the flooring, and install the sleepers directly atop the original joists. I do this by setting a laser level between two of the joists, with the laser spinning 3/4" above the highest spot I intend to meet. Then I work thru each joist, clamping a 2x4 to the side of it, using a scrap of 1x lumber (3/4" thick) on top of the 2x4, to level it to the laser. I scribe a heavy pencil line on the side of the 2x4 at the top of the old joist, remove the clamps and take the 2x4 to the shop to cut to the line on the bandsaw. Bring it back in and glue/nail it directly atop the old joist.

Work your way thru the whole room, and voila... flat joist plane. Then you have two options: You could lay subfloor and put whatever you want on top. Or you could go high-class and buy some old-growth or reclaimed southern yellow pine 1x6 T&G (what's used in all Victorian houses around here), and some nice cut nails from Tremont Nail. I've done both, but always feel better about the second option.

For bonus points, you can skip the 2x4's and rip 2x3's on the bandsaw to a full 2" rough width, and use them instead. 100 years from now, no one will know whether that work is original, or something done much later. You can skip clamping them to the sides of the joists, and just lay them on top and mark to the laser line, if you do this. Only down side is that if any of your drops remain more than 1.5" after jacking, you'll need two to make up the height.

 

[brian89gp]

The section with the numbers in it is 20x30. There is a 20x10 addition on the back. I have installed a mid-span beam that I am slowly jacking up to take care of the bowl effect, most of those center numbers are up to around 1.5" from level.

Once the beam is installed and the floor stabilized, my usual procedure is to pull up the flooring, and install the sleepers directly atop the original joists. I do this by setting a laser level between two of the joists, with the laser spinning 3/4" above the highest spot I intend to meet. Then I work thru each joist, clamping a 2x4 to the side of it, using a scrap of 1x lumber (3/4" thick) on top of the 2x4, to level it to the laser. I scribe a heavy pencil line on the side of the 2x4 at the top of the old joist, remove the clamps and take the 2x4 to the shop to cut to the line on the bandsaw. Bring it back in and glue/nail it directly atop the old joist.

Someone has already previously done that on some of it and some sleepers in other sections. Due to my jacking I am going to have to go through and remove a lot of them actually. The floor joists are 2x8 dimensional (1.5x7.5) on a 20' span with a load bearing wall about 7' from one side, I installed the beam beneith that load bearing wall.

I do like your idea. I'll have to see how level I can get it and correct the rest of the floor issues using that method.

This house was hacked apart years ago with absolutely nothing original left other then the stairs, it is a comple gut and remodel with changed floorplan, open concept, modern/traditional mix. Nothing other then the stairs to fix so I'm remodeling in the style that will rent/sell easily.

 

[Ashful]

The floor joists are 2x8 dimensional (1.5x7.5) on a 20' span... This house was hacked apart years ago with absolutely nothing original left other then the stairs...

Well, I guess you already figured out those floor joists are newer, then. They didn't have 1.5 x 7.5 dimensional 120 years ago. Most was still full-roughed 2" x 8", and those that were planing to dimensional were doing 1-3/4 x 7-3/4. Most lumber yards did not selling dimensional until after 1900, and the sizes were not standardized to 1.5 x 7.5 until after WW1.

 

[brian89gp]

Must have been a lumber yard special, they are nailed together with cut nails that dissapeared in this area around 1900. Could have also been closer to the 1 3/4 x 7 3/4 range, going from memory of measuring them 6 months ago.

 

[Ashful]

Some interesting reading on this:

By 1900, 2 inches was the most common thickness for joists, rafters, studs, andthelike, and 1 inch for boards. At first, little difficulty was experienced with the varying size standards because the sawmills of a region sold their lumber, for the most part, in certain trade areas. However, as rail shipment of lumber increased during the last half of the 19th Century, lumber from distant regions began to move into trade areas that had been served previously by the local region. Differing manufacturing standards then became important, For rough lumber, the size variations were not great, but for surfaced lumber it was a different story.

Rough lumber has the disadvantage of varying in thickness and width. Therefore, before the advent of mill surfacing, boards were planed by hand or in local planing mills when a uniform thickness or a finished surface was needed. Dimension was fitted into place by the carpenter, more often than not with his hatchet. Some enterprising sawmills started the practice of bringing dimension lumber to a uniform width by passing each piece through a small edger or rip saw before shipping. This was known as saw sizing and the width was usually 1/4-inch scant of the nominal width. Sawmills began to use planers sometime after 1870 and these machines provided an additional means of making rough lumber more uniform. This was really not a finishing operation. It was a sizingprocedure. Boards were commonly surfaced one side (S1S), sometimes S2S. Dimensionwas worked S1S1E. Lumber surfaced on four sides (S4S) could be had at additional charge. This custom of preparing lumber for sale persisted in some regions for many years. Even as late as the 1920’s some big mills based their prices on rough or saw-sized dimension, boards S1S, and made an additional charge of $1 per thousand for lumber S2S, S1S1E, or S4S.

After World War I stopped in the fall of 1918, the pent-up demand for construction resulted in
an ever-increasing demand for lumber continuing all through 1919... demands for better standardization among associations were heard... President of the Pennsylvania Lumbermen’s Association, spoke of standard sizes at an Association meeting and got support for fixed standards like weights and measures. At this meeting the recommendations were for 13/16-inch S2S boards with edges not more than 1/4 inch scant of the nominal width.

 

[Uncle]

Been there, done that....lol

My circa 1810 house 2nd floor looked like the villains hideout on a Batman episode. I went to a structural engineer for advice and did the work myself and replaced the warped 3x8 hand sawn oak with four 2x8's.

Note the saw marks on the hand sawn wood. Also the mud and horse hair they used for insulation that I replaced with roxul and 6 mil plastic moister barrier.

 

[brian89gp]

The house is balloon framed but I guess since it is on the side of a hill and the basement is a walkout the back half of the basement is platform framed with the first and 2nd story sitting on top of a base plate on the first floor joists. Sure made the process of jacking easier. I have gotten the stone all repointed and a 12" thick slab of concrete poured on top of it to bring the foundation level back up above ground level, once it is cured enough in a couple days I can proceed to jack up and permenantly support the house on the new concrete and sill plate. Will probably find out then how level I am going to be able to make it.

For those doing the same job, a while back I made a bunch of beams and support posts for house jacking that work out pretty well and seem to help prevent kickout. The top beam is two 2x10x12' with spacers inbetween every couple feet. The posts are three 2x6 with the center offset 9.5" out of one end to key into the space between the 2x10's in the beam. On the bottom of the posts I have a 3/8" thick steel plate with a hole in it which fits the screw from the large jackposts. Then a handful of keyed posts with a flat steel plate on the bottom and some 20 ton bottle jacks. Have never had it kick out using this method.

Will try and take pics.

 

[brian89gp]

Been there, done that....lol

Very clean work there. Was using the four 2x8 instead of two 2x10 to maintain original ceiling height?

 

[Uncle]

Very clean work there. Was using the four 2x8 instead of two 2x10 to maintain original ceiling height?

Yes, the 2x8's were used because of ceiling height.

I did use 2x10's in the crawlspace below.