Bowed floors, suggestions for leveling off?

[ewans]

this is a different problem to my last post and i think needs a different solution.

I have two bedrooms, upper floor, both dip to wards the centre of the room from the east /west walls, the dip is not so bad that the floor needs replaced and its pretty typical of flats of similar/age/constriction in the area. The floors are getting carpeted so a perfect finish is not essential.

Using a self leaving compound screed is not a great solution because i don't really want to add all that extra weight to the middle of the room, where the levelling compound would pool. So any suggestions for other creative solutions? i was thinking about a solid setting expanding foam covered with 9/12 mm ply...or is that just a bit crap.

thanks
e

 

[masona]

You need to investigate what's happening by lifting the floorboards up and have a look at the joists etc

 

[gcol]

My parents had the same thing in a room in their old cottage. They were having a lot of work done at the time and the joiner that was there took up the floorboards, saw that the joists were sinking in the middle and fitted wooden fillets to the areas that were dipping so that they were straight again. Quite impressive work actually.

 

[masona]

Very common problem in old properties before herringbone structure was put in

 

[mattysupra]

Very common problem in old properties before herringbone structure was put in

what do you mean by this?

 

[noseall]

Very common problem in old properties before herringbone structure was put in

what do you mean by this?

i think masona is talking about herring bone struts or noggings, usually fixed at third or half spans between joists.

 

[masona]

Yep, depending on the span, normally 1/3 or in the middle although you can make one out of timber or solid noggins

Joist strutting should be used to prevent sideways movement or buckling where spans exceed 50 times the joist width. With 50mm wide joists a single row should be used over 2.5m and up to 4.5m.
HJS400, HJS450 and HJS600 for 400, 450 and 600 nominal joist centres.

 

[joe-90]

Herring bone struts stop joists twisting not sagging. If you can get the boards up then you can bolts straight 4x2's next to the original bent ones and put the floor back flat.

However, I believe you can get some latex levelling compound that might do the trick but I've not used it.

 

[masona]

Herring bone struts stop joists twisting not sagging.

It does up to the point, make it less bounce & more rigid

 

[ewans]

i reakon i just leave it as it, there just spare bedrooms and to be honest i'ts not worth the hassle to replace the boards etc.

I pulled up some boards and had a look, looks like some of the joists are short and have 2 have been bolted together mid span to make one longer length, maybe you couldn't get long enough signle spans when the house was built... who knows, anyways this problem with bowing is very common in old tenaments so not worried about it at all.

I have the smae problem in my kitchen and i am planning on replacing the floor in there so its all nice and level. no dount i'll be back from more advice when the time comes.

thanks
e

 

[rancher1]

The floor joists on our old two story ranch house dining room were badly bowed -- a two inch drop or more on each end. A bathroom off one side was 2 1/2 inches lower. We added a foundation and more beams to support the ends and researched how to level the subfloor.

We looked at planing the tops, cutting a "V" to let them settle and replacing them. To replace them, we would also have to replace beams that were supporting them. That seemed too much of a challenge for a DIY and a two story house.

We had to replace flooring and stud ends on two sides of the room and were able to do some raising and leveling. The whole house sloped to the back and we raised it close to level by jacking up beams and replacing the supports.

Using leveler would have been the best solution, but it was over $1000.00 for materials and would be real heavy at the deep ends.

We finally decided to install a level 1/2 inch plywood floor over part of the subfloor and leveler to the plywood. We marked the points on the subfloor where the 1/2 inch rise and backer board would be level with the high point and installed wood strips level with the high point along the walls. Where it dropped to the bathroom, we did a cutout for the door and a small riser to the dining room. Cutting the support strips for the edge was tedious with a lot of re-cutting and shimming. To support under the plywood, we found we could mark short level spots, measure the gap and cut strips in one thickness for each gap. We glued the strips to the floor and to the plywood.

It seems to be working all right. The plywood is tight. We're getting ready to install backer board for tile and leveler to fill up to the plywood from the high point. We bought Red Guard to waterproof the leveler and help prevent cracking.

I'm a little concerned about shifting between the plywood and the leveler, so if anyone has a suggestion, I would appreciate it.