Jacking up the bearers

[John NW]

I plan to jack up some of my bearers and attempt to level my floor.
My house was built in 1973. The sub floor seems to be permanently dry. The bearer levels seem to be out by 1cm to 2 cm's. Is it ok to jack them one by one say 5mm at a time. I plan to use a long plastic tube full of water for my levels. Can any one give an outline of how they would proceed. thanks

[ozwinner]

Hi John.
What sort of stumps are they?
Is there a reason the place has sunk?

I cant see any reason why you cant just lift everything by 20mm.
20mm isnt a lot, Ive raised old weather boards by as much as 50mm.
You will get cracking of plaster, doors that dont fit anymore,:( doors that do fit.:cool:

Al :)

[John NW]

Thanks, the piers are bricks cemented together. As far as I can work out this place was built in a big hurry. A lot of things have been done in a rough way. I was thinking about jacking up at each pier a small amount at a time.

[echnidna]

If you level the outsides first you can then run stringlines under the bearers and jack the inside bearers to suit the stringlines.

The stringlines need to be say 50mm below the bottoms of the bearers on say 2" blocks nailed under the bearers. So that they clear the inside bearers.

Lot easier than using water levels under the house.

[lexcen]

Buy a cheap laser level. Much easier yhan water and string under a house.
Have fun,
Russell

[Stompa]

I plan to jack up some of my bearers and attempt to level my floor.
My house was built in 1973. The sub floor seems to be permanently dry. The bearer levels seem to be out by 1cm to 2 cm's. Is it ok to jack them one by one say 5mm at a time. I plan to use a long plastic tube full of water for my levels. Can any one give an outline of how they would proceed. thanks


John, I have just had my house relevelled and the builder used stirrups as per the photo and is a simple but effective method. I don't know if this will help you.

Marty

18755

[Phil Mac]

The best method I have come up with is to use large folding wedges.
My house had settled 2 to 3 inches in the middle and I was able to negotiate at a good price.

You need to be carefull in jacking houses too much at the one time as it can crack the plaster.

The beauty of the folding wedges is once you have them in place you can jack say 5 mm and hit the wedges hard and you take up all the free play,

if you jack and insert packing you always have to jack higher to insert the packing and then you let the jack down and loose some of the height

with the folding wedges it is far easier,

The qustion you are probably thinking is how or why did the house sink 3 inches (75mm to you younger folk)
well the answer is a combination of 2 or 3 reasons in my oppinion,
1) reactive clay foundation

2) origional builder did not dig deep enough through the top soil to get onto hard dirt

3)the designer of the house spanned too far between piers for the roof loading points and had too much roof load onto too short a wall length in the centre
ie the house is an open plan with a tiled roof and above the lounge kitchen family area 10 meters x 7.2 meters and the load bearing section in the middle was just 3 meters long and I estimate the load on this wall was approx 2000 kg (allowing 90 kg a square meter for tiled roof and ceiling) on 3 piers or 700 kg for a 300 x 300 mm blob footing,
this was fine in dry weather but the sub floor was not drained proprerly and in wet weather the clay became wet and soft anf the blob footings settled into the mud.

4)Reactive clay (which this house is built on) expands and contracts up to 75mm in height from being dry (drought times) to being saturated, so it is important to keep the moisture level as dry a possible across the house and to 1.5 meters away from the house,
other wise you can have a expansion and contraction move under the house in a wave form over the months as the moisture moves to the centre of the house in extremely wet times and then dries out as the moisture leaves the soil

A path 1 meter wide all the way around a house will reduce the movement dramatically

Another thing to keep in mind is if a house has moved over a number of years it will take a few attempts to get it right as the house readjusts, from my experience it takes adjustment 3 to 4 times to get it right that is major adjustment say now and adjust every month or so for a couple of times, As a carpenter i have had to re level 3 houses with in 12 months of major stabilisation remediation due to minor movement as the buildings settled within themselves

on my place i fitted extra piers between the load bearing piers and this helped immensley I also added extra loadbearing walls

As I am on reactive clay I put movement joints in the plaster where ever there was a crack or potential for a crack to develop (above doorways and windows mainly) I also put one in a long lenght of cornice that continued to keep cracking

if someone tells me how to put pictures onto the forum I will show you haw i did it under my house

Phil

[journeyman Mick]

Buy a cheap laser level. Much easier yhan water and string under a house.
Have fun,
Russell

I wouldn't trust a cheap laser level, I hardly trust the expensive ones.

Mick

[echnidna]

laser level is near enough to useless under a house.

[ozwinner]

At least in the dark you could see the pretty light.

Al :p

[John NW]

I used my cheap laser level to estimate that the problem is a middle area which drops down 30mm from the outside heights. The level is only a rough guide and I hope to run a string line underneath tomorrow. I had a quick look underneath to try to see 30mm worth of drop. A bearer has sagged under the load of a middle wall in this area, maybe 5mm, I guess it is load bearing? My worry is not to crack the gyprock, those wedges sound interesting. I had planned to jack up 5mm at a time but if the gyprock cracks I probably would leave it.

[Skew ChiDAMN!!]

A string line's what I use. I drive a 6" nail about 1/2" into the bottom of the bearers at the start/finish points and tie the string line just above their heads before levelling it out. This allows the line to clear any sagging bearers... unless they've dropped several inches.

I use an old steel 6" rule to measure clearances to other bearers from the line, it makes things easier if you measure the clearance at the first bearer (& nail) and mark it on the ruler with a brightly coloured adhesive tape... taking measurements in the dark can otherwise be a PITA.

Oh... and don't forget to relevel the line should you jack one of the bearers with the mounting nail, otherwise it can totally ruin your day. DAMHIKT. :o

BTW, the gyprock itself shouldn't crack; it's the plastered joints that'll probably go first and they're usually a simple enough repair. If cracks do develop, it's a damned good indicator that the house was either built out-of-level in the first place, or the lining has already cracked (as it settled) and a prior owner has patched it without fixing the root problem. Both are equally likely...

[Phil Mac]

A few more thoughts that may be of help

When I have jacked houses, I try to get a balance between getting the floor level and lifting the floor untill all the doors and windows are neatly fitting into there frames etc,

When a house is built it is built basically level, say over a a 250 square metre house (30 meters long x 7.5 meters wide) the piers may vary in hieght by 10-15 mm, you put the bearers on and a 100x 75 bearer could be between 95 to 105 thick, the joists are the same, and unless there is an obvious hill or hollow you live with it, as the frames and roof are are erected and fixed these slight variations become a permanant part of the house. When the doors and windows are fitted they are fitted to be level and plumb.

A 10 -20 mm hill or hollow over 2-3 meters is not noticable in the floor if the doors and windows are fitted plumb and level at the time of construction, so if you have a pier that was errected 10 mm low below a door way and you jack the berarer to level, you will have a door that will either bind or have a huge tapered gap at the top or bottom.

Above is the theory of jacking a house, being able to apply this is the art of leveling a house, it take time and experience

Phil

[John NW]

I have run two string lines underneath the problem area which showed that the piers haven't sunk and in fact are reasonably level. What has been done is to place the central load bearing wall on top of a bearers mid way between piers. Hence the bearers have sagged down about 20mm. I want to remove the buckled chipboard floor and replace it so i can tile. I don't realy want to put in new piers so would putting new shortish bearers across the span do the trick?

[echnidna]

It might work but ....
A concentrated point of loading should be supported by stumps/piers.
Maybe the original house was altered without regard to the piers.
If it was my house I would put a new pier or stump in.
If you're gunna replace the flooring it won't be a real difficult job as you can dig and jack it up when the floor sheets are removed.

[ThePope]

Jack up your bearer so it's straight and slide a new deeper bearer in next to the existing one and bolt the two together. Cut the new bearer over the brick pier so it has support. As you don't want to be doing it twice don't skimp on size, I'd use a 200*75.

ps: as a matter of interest how far apart are your piers spaced ?

[John NW]

The piers are 155cm by 160 cm.
My goal is to update this house so I can sell it.
The sagging floor is about a metre wide and I am now looking at possibly packing this area with a rubberised davco product then putting villa board on top then tile. Putting in a new bearer or new piers would take too long for the timbers to resettle? I'm not absolutely sure about this but now that i can see the problem Davco looks like an easy solution?